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Canon SX60 Review Part 2 Ergonomics and Comment

SX60 Well designed handle. Looks like a DSLR but doesn't work as well.

This ergonomic evaluation follows my usual format. You can readabout it here.

Setup Phase

The Main and Func Menus use the standard Canon Powershot layout which is easy to navigate and use and sufficiently comprehensive for this type of camera without being over complex.

Items which appear in the Func. Menu can be selected from a list and those not required sent back to the main menu.

The graphical user interface is clear and well implemented.

There is a My Menu, which is desirable, but I could not find a way to allocate items from the Setting Menu to it, which is annoying because I use the ‘Format’ command frequently and that takes 20 button presses.

Setup score 10/15

Prepare Phase

The main Mode Dial with 13 positions is easily operated.

Most functions required in Prepare Phase are accessible via the [Func/Set] button or one of the 4 Way keys or the Shortcut button and Red Dot (video) button both of which allow user assigned function.

You don’t have separate set-and-see dials for Drive Mode and Focus Mode as might be the case on a more advanced camera but overall access to Prepare Phase functions is well catered for.

The only problem in Prepare Phase is the flat, recessed 4 way pad which I found irritatingly awkward to use.

Prepare Phase Score 9/15

Capture Phase

Holding

Holding is the best aspect of the user experience with this camera.

The handle is of the desirable inverted L shape. The center of the shutter button is inset 28mm from the right side of the handle which is just about where the index finger wants to find it. The Thumb support is of the desirable diagonal type.

Holding Score 16/20

Viewing

The Monitor is the optimal fully articulating type. It provides a clear, sharp preview/review of images. Camera data is overlaid on the lower part of the preview image which is not optimal as with some subjects the data is difficult to see. There is no option to configure the monitor to ‘viewfinder’ style.

The EVF provides a good viewing experience. It is clear, decently sharp, provides reasonably accurate although a little oversaturated color and good highlight/shadow detail. It is a bit jerky when panning in low light but overall is one of the better EVFs on a camera in this price bracket.

For some reason which eludes me completely I find the EVF is less sharp in portrait orientation than landscape. Strange…….

Camera data is clear but is overlaid on the lower part of the image with no option to set ‘viewfinder’ style with the data beneath the image.

Some reviewers have criticised the absence of an eye sensor for EVF/monitor switching but it is not really necessary. The monitor is active when turned out. The EVF is active when the monitor is turned in. Easy.

The rubberised EVF eyecup is rectangular in shape which seems to be the fashion across brands at present but I cannot imagine why as nobody has a rectangular shape eye socket.

Viewing Score 11/20

Close up of the control panel with recessed buttons and epoxy blobs on the 4 way module.
The flat 4 Way pad and recessed buttons are examples of poor haptic design. The look all right but in practice are very difficult to locate by feel and are awkward to operate even when looking at them. The epoxy blobs improve operation a bit but are no substitute for good haptic design in the first place.
Compare this with the photo of the control panel of the Panasonic TZ70 in a later post.

Operating

The SX60 doesn’t manage this very well. The controls look like those of a DSLR but they are not well designed.

The principal criterion for evaluating operation is that all primary and secondary exposure and focus parameters should be adjustable while looking through the EVF without shifting grip with either hand.

The SX60 does not enable this due to numerous problems with the user interface.

The Func/Set button, 4 Way pad and [+/-] button are recessed making them really difficult to locate and operate by feel.

The [AF Frame Selector] button is in completely the wrong place on the thumb support and is recessed making it even harder to find without looking. To change position of the AF box the user has to find and press the [AF frame Selector] button then find and press the 4 Way pad which is 30mm away and difficult to locate and operate by feel. To complicate matters further you have to press the Menu button (which is 45mm below the [AF Frame selector] button) with the AF box orange to switch from large to small size.

The only control which is reasonably easy to use without looking is the Front Dial, which changes

Aperture and Shutter Speed, depending on the Shooting Mode. I would prefer this to be moved about 5mm forward, closer to the shutter button for easier access. Apart from that the dial has good elevation, sharpish serrations and is easy to turn.

The irony is that the Front Dial gets little use.

Why ? Bear with me, please.

This camera needs to operate with the lens at its widest aperture (smallest available f stop) just about all the time. This is to keep the ISO sensitivity as low as possible because high ISO settings are so noisy and damaging to image quality. In addition the optimum aperture for the lens is around f 3.5-4. In the mid range and long end of the zoom the aperture is already smaller than this so further reduction of the aperture will only lead to more luminance noise (because the ISO setting has to increase) or more blur from camera shake (because of the low shutter speed) or reduced sharpness from diffraction at the aperture diaphragm.

Therefore Aperture Priority AE setting is minimally useful.

But Shutter Priority AE can be problematic also, especially at the long end of the zoom range which is where it is most useful on other cameras. If you set a high shutter speed it will demand a high ISO which impairs image quality.

So I set Program AE Mode most of the time, with the confusingly named Auto ISO ‘Rate of Change’ (which is really an auto ISO range setting) setting at ‘Standard’. The camera keeps the ISO setting low which means using some really slow shutter speeds. But with careful usage practices (which means holding the camera really steady) the results are often decent enough. Fortunately the image stabiliser works very well allowing me to use a shutter speed of 1/125 sec even at a focal length of E800mm and still get decent sharpness.

Operating Score 6/25

Review

The camera enables the user to locate images easily, zoom in, move around the enlarged image and scroll from one image to the next at the same enlargement and position on the frame.

The process of doing so is not elegant as the front dial is not used at all and the 4 Way pad is so darn user unfriendly.

Review Phase Score 4/5

Overall Ergonomic Score 56/100

SX60 at the long end, focal length E1360mm. I used very strong sharpening for this original RAW capture. In ACR Amount 100, Radius 3.0.

User Improvements

I dropped a little blob of 5 minute clear epoxy glue onto each quadrant of the 4 way pad and also the center Func.Set button. This is not exactly elegant but does make the task of locating and operating the buttons easier than is the case with the unmodified product. Readers wanting to try this need to avoid getting epoxy in the gap between the outer ring and the Func.Set button.

Best/worst features

Best: Overall size/mass; handle/holding; picture quality with RAW capture in good light.

Worst: Poorly implemented controls on rear of camera; High ISO picture quality, especially JPG.

Who’s it for ?

My guess is that the most likely buyer and user will be a JPG snapshooter who just wants to zoom-de-zoom then press the button.

But the user who is most likely to make the best pictures with the SX60 is going to be an enthusiast/expert who understands how to operate the camera at the far end of the zoom (it’s not easy), how to get usable results in low light (that’s not so easy either) uses RAW capture and understands how to get good image files from the noisy sensor (and that requires a good Raw converter and the experience to use it to best effect).

SX60 near the wide end of the zoom. Decent amounts of detail. Some highlights are blown out and unable to be recovered even in the original RAW file.

Comparisons

I have a Panasonic TZ70 and will be publishing a comparison with the SX60 in due course.

How could Canon improve the SX60 ?

Ergonomics: A few changes, costing nothing, could make a big difference.

Some things are obvious enough, such as revise the 4 way controller from the present ‘rocking saucer with rim turned down’ to ‘rocking saucer with rim turned up’, plus making the [+/-] and [AF area control] buttons both available for user assigned function.

I would prefer the front dial to be about 5mm closer to the shutter button for easier access.

Picture Quality: This one might be a bit more difficult from either the marketing or technical perspective.

My feeling is that this and several similar cameras are playing to the numbers (of pixels and zoom range) for marketing purposes and might be more effective picture taking devices if they had fewer pixels and a less ambitious zoom range.

I compared the SX60 to a Panasonic LX100, a camera which makes 12 Mpx pictures. The LX100 can resolve more detail in photos, indicating that the SX60 is not utilising all its 16 Mpx. In fact I would be surprised if it is delivering much above 8 Mpx resolution even in the best focal length range and base ISO.

The lens softens quite a bit at the long end. When I look closely I see no more actual information in a photo taken at E1360mm than one taken at E800mm focal length. I just see the same visual information but enlarged. In addition the longest focal lengths are quite difficult to use effectively.

If the lens zoom range was confined to, say, E24-800mm, I suspect it could probably have a wider aperture (smaller f numbers) and better optical capability at all focal lengths and apertures, making for a more photographically competent device.

Do I think the SX60 is a keeper ?

My original personal brief for the SX60 was to use it as backup for my main camera, a Panasonic FZ1000, in the event the FZ1000 should fail in one of the remote icy realms to which my group will be travelling.

I found I can capture about the same amount of image information from the SX60 at E800mm as the FZ1000 at E800mm (that is, a 5Mpx crop from the E400mm full frame of 20mpx).

So the argument for the SX60 is not strong.

Sure, it’s only 55% the price of the FZ1000 but I wonder if a better backup might in fact be another FZ1000. It is in all respects but the super zoom range, a very much better camera than the SX60.

Upgrading from the SX50 ?

Sorry, I can’t help with this question, having no experience with the SX50.

However I read on user forums that many people bought an SX60 and returned it, electing to keep their SX50. Some sold their SX50 to pay for the SX60 then returned the SX60 and bought another SX50. In each case where specified, the complaint about the SX60 related to image quality.

Users vote with their wallets so I take that as a vote for the SX50 and against the SX60.

SX60 as a standalone camera ?

The SX60 is not a particularly good all rounder mainly due to the mediocre performance indoors. But it is also not wonderful as a wildlife/birding camera either with less than very good lens acuity at the long end.

I can’t help feeling that a camera with a larger sensor and less ambitious zoom range might be a better all rounder.

Summary

Overall I found the SX60 rather unconvincing as either a backup camera or as stand alone photo capture device.

The types of photo which it can do well can be done even better by other cameras.

Some photo commentators are predicting the demise of the very small sensor (“1/2.3 inch”, diagonal 7.3mm) but I think that with better implementation there could still be a future for the superzoom camera based on this sensor size as it gives lens makers a lot of opportunity for big zoom ranges at moderate cost and size.

We shall see. Early reports suggest the new Nikon P900 has a better lens. But no RAW !!!

I despair………………..what on earth were they thinking ????? This is a big camera with a huge zoom range which will attract enthusiast/serious amateur/bird/wildlife photographers many of whom will want to use RAW capture. ………………….

Do camera makers pay the slightest attention to their customers ??? I see evidence to the contrary with almost every camera I use. And they wonder why sales are in decline..........................

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Canon Powershot SX60 Review Part 1 Picture Quality and Performance

Mẹo sử dụng đồ gia dụng 17:46

Canon Powershot SX60

I wanted a backup camera to my Panasonic FZ1000 for an upcoming holiday. The SX60 looked suitable based on published specifications. So I bought one and tested it over a two month period.

Focal length Equivalent 81mm I have printed up a frame from this series to 390x640mm actual picture size. The print looks strong, clear and sharp on the wall with no visible grain, although grain is easily seen on screen at full size.

Description and features

On paper and to some extent in the polycarbonate, the SX60 has considerable appeal.

It is a mainstream entrant in the ‘all purpose, do everything’ travel/holiday superzoom genre.

Size and mass are right in the goldilocks zone. It is large enough to have all the key features of a proper camera yet small and light enough to carry anywhere in a small bag.

It has a well designed handle and thumb support, fully articulated monitor, decent EVF over the lens, built in flash, hotshoe, zoom range from very wide to very long, a decent lookingset of buttons and dials, programmable function buttons and [mode dial + front dial] control system just like a DSLR.

It has RAW + JPG capture, single or continuous shooting AF, Macro function, video, Wi-Fi and all the usual features of a modern, all purpose consumer camera including such gems as ‘Smile Detect’ and ‘Wink Self Timer’ (really) for the inveterate gimmick lover.

The ‘Frame Assist-Seek’ feature is welcome. Pressing a button on the side of the lens barrel pulls the lens back to a wide setting so you can find your subject. The lens zooms out again when the button is released.

Macro Focus Mode is very useful. It allows the camera to focus on small objects like insects and little flowers while retaining useful working distance. This permits close ups on the run without having to use a tripod or any elaborate preparation. The fully articulated monitor makes the process even easier.

The spec sheet and my initial ‘hands on’ with the camera were encouraging.

Some reviewers have complained about the lack of a touch screen but for hand held work especially at long zoom, I find a touch screen is of little use.

Other reviewers have complained about the lack of an eye sensor for automatic switching between the EVF and monitor. Fair enough an eye sensor would be nice but it is not required. The EVF is active if the monitor is turned inwards. The monitor is active if it is turned out.

Focal length E500mm from RAW

Picture Quality

Just like similar superzoom models from other manufacturers the SX60 uses a very small sensor, measuring 6.17 x 4.55mm with a diagonal of just 7.66mm. This is less than half the area of my little fingernail. Somehow they get 16 million photosensitive pixels onto this tiny area. I can’t even begin to imagine how the micro engineering for this might work, but somehow it does albeit with some compromise to image quality.

The moored yachts were about 750 meters from the camera. Hand held Focal length E1360mm, from RAW original with strong sharpening

At its best the SX60 can produce images of very high quality, able to print up to A3 size and still look clear and sharp with a commanding presence on the wall.

At its worst the SX60 can turn out smeared images which resemble impressionist watercolours more than photographs.

The camera can make images of very good quality outdoors in good light, especially at the near/wide and mid section of the zoom range.

The more adventurous photographer who wants to work indoors, in low light, with moving subjects such as children at play with high ISO settings or at the long end of the zoom range will soon find him or her self struggling with the luminance noise in RAW files or the smearing, watercolour effect of heavy handed noise reduction in JPGs.

The SX60 does close ups on the run very well. This Grevillea was at about waist height. I opened out the monitor, set Macro focussing and quickly made a series of exposures. Several were sharp even though a breeze was blowing the flower about. Focal length E180mm.

The built in flash might get plenty of use indoors.

* Exposure is excellent in all conditions.

* Dynamic range (highlight and shadow detail) is quite good at low ISO settings with a mild tendency to blow out highlights if subject brightness range is high.

* Colors look natural with RAW capture but unbalanced in the JPGs with oversaturated greens and yellows.

* Luminance noise is evident in RAW files at base ISO sensitivity and is very prominent at high ISO settings, detracting from resolution, sharpness and color.

JPGs utilise heavy noise reduction (NR) even with [HI ISO NR set to LOW] leading to watercolor effect which impairs rendition of human faces and hair. The effect is prominent at high ISO settings.

General subjects without humans or cute furry animals fare better with the JPG rendition.

JPG Contrast, Sharpness, Saturation and Color Balance are adjustable via Func.Set>My Colors>Custom Color.

JPG NR is only user adjustable via the ‘High ISO NR’ tab in the Shooting Menu. I set this to ‘Low’.

Focal length E786mm. Hand held. JPG original, uncropped. I set Continuous Shooting AF and made about 250 shots of surfers that day and discarded almost all of them. This sort of photography is actually very difficult, mainly because it is extremely hard to keep the subject in frame let alone in focus. Many frames had the surfer more out of frame than in.

* The lenshas an amazing 65x zoom range.

Sharpness varies with focal length.

At the wide end, focal length Equivalent 21mm, the center of the frame delivers impressive amounts of detail but the corners are a bit soft and don’t really clean up when the aperture is stopped down.

This might not suit landscapes but for most subjects the corner softness is not a problem.

Very good results across the frame are obtainable from about E28 – E400mm focal length. When I think that these pictures are coming off a sensor only 7.66mm in diameter the results seem quite amazing. I printed a test photo from this zoom range at an actual picture size of 635 x 390 mm and it looks really good with excellent detail and quite good highlight and shadow detail. Luminance noise (grain) at ISO 100 is not visible in the print .

This is what happens when you shoot 500 meters across a local geographic hot spot, in this case a beach, on a warm day. The combination of the softish lens at the long end and atmospheric distortion produce this impressionist painting appearance. By the way, any camera with any lens would be equally affected by the atmospheric distortion. I just put this in for fun.

But as the lens zooms out towards the long end it loses contrast and sharpness, with a tendency to local flare in bright conditions. Which could be a problem because you really need bright light to hand hold at the long end of the zoom.

I can still make good A4 prints and decently presentable A2 prints from shots made at full zoom.

Chromatic aberration and distortion are well corrected presumably in post capture software.

Purple fringing is common at high contrast edges and appears in JPGs. It is mostly correctable in

Adobe Camera Raw (and presumably Lightroom which uses the same process).

* The Image Stabiliser works very well, allowing the careful user to handhold at the long end of the zoom. My tests indicate approximately a 2 EV step shutter speed advantage with the IS on. This might not sound like much with some cameras claiming 5 stops of benefit. But it is still very useful.

In fact this camera would be unusable hand held at full zoom without the IS.

The IS allows me to reliably get sharp pictures at the long end of the zoom from a shutter speed of 1/125 second with careful holding technique.

JPG or RAW

I imagine that many, perhaps the majority of this camera’s users will probably use JPG capture exclusively. If they keep to the wide-to-mid range of the zoom, outdoors, good light and reasonably static subjects I think most will be well enough pleased.

But RAW capture and careful editing in a good RAW converter such as Adobe Camera Raw (which I use) can produce much better results.

And therein lies the paradox of the SX60.

The camera will very likely be used by the group least able to get the best image quality from the camera.

ISO 1250, JPG straight out of camera.

This is from the RAW version of the same photo as above converted in Adobe Camera Raw to the best of my ability. You can have either the watercolor look of the JPG or the sharper but more grainy appearance of the converted Raw file. The converted RAW file could be processed to look like the JPG but I prefer the 'grainy but sharper' look.

* Sharpening in Photoshop Camera Raw.

In the Sharpen Panel with files from most cameras I generally set the Amount slider to about 50 and the Radius slider to 1.0 pixels.

But with the SX60 I find files from the wide end of the zoom range require a different treatment from those made with the long end of the zoom because the long telephoto shots have lower contrast and sharpness.

For the wide end I set an Amount of 50-60 and Radius of 1.2-1.4 pixels.

For the long end I experiment with an Amount of 60-100 and Radius of 1.5-2.5 pixels.

This aggressive sharpening is often useful. The downside is an increase in the already prominent luminance noise (grain).

On balance I find the sharpened-but-grainy pictures from converted RAW files more appealing than the watercolour look of the standard JPGs.

Performance

* Single autofocus generally works well. It is decently quick at the wide end of the zoom and acceptable at the long end and/or low light for subjects not moving quickly. Although not lightning fast the AF locks on smoothly without hunting back and forth. It is commendably accurate with very few misfocussed frames.

* With JPG capture ‘Continuous Shooting AF’ works surprisingly well in bright light and around mid zoom range. I photographed cars moving towards and away from the camera at about 30 kph. At 5 frames per second 85% of frames were acceptably sharp and only 10% completely out of focus.

There are three main problems which make the camera much more difficult to use on moving subjects at the long end of the zoom:

* The image you see in the viewfinder is not a preview of the next shot but a review of the previous one or the one before that.

* The diagonal angle of view is only about 2 degrees, so it is very difficult to keep in frame any subject moving across the line of sight.

* Autofocus slows as the lens is zoomed out.

Birds in flight ? Not likely.

* There is a manual focus function which I did not find to be useful. As described on Page 79 of the

User Guide there is a rigmarole of button presses on the badly designed 4 way pad to bring up and activate manual focus all of which gets you to the “general focal position”. Then you activate “Safety MF” by half pressing the shutter button which activates autofocus to “fine tune” the focal position which you could have done simply by half pressing the shutter button in the first place.

* In single shot mode and RAW capture with AF and AE on each frame, shot to shot time is 1.4 seconds. The EVF or monitor black out for about 0.6 seconds after each single shot exposure.

* The lens takes 2.5 seconds to traverse the full zoom range.

Next post- Ergonomics and summary

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Why have MILCs been slow to gain popularity ?

Mẹo sử dụng đồ gia dụng 18:10

Braldu River Northern Pakisan This photo was made a few years ago with a Mamiya 7 manual focus, manual everything medium format rollfilm camera. A reminder that photographers managed just fine for many years without autofocus or auto anything.

This is a follow on from the previous post, DSLR-vs-MILC-vs-FZLC.

Some people, I was one of them, imagined that the MILC as a camera type would overtake the DSLR in popularity soon after it first appeared in 2008. We were wrong.

I guess the global financial crisis of 2008/9 didn’t help. Maybe the GFC prompted lots of camera buyers to take a cautious approach to their purchase decisions.

But I suspect the main reason is just that Canon and Nikon have not fully embraced the MILC concept.

These two manufacturers make most cameras. If they did shift to MILCs as their dominant offering then MILCs would sell more than DSLRs.

So why have Canon and Nikon not embraced the MILC category more fully ?

I don’t know of course, being nowhere near the corridors of power in the camera world, so I have to guess and I think there might be two reasons.

1. The first is about sales. I think that while Canon and Nikon are doing well with DSLRs that is what they will continue to make. I think that if DSLR sales fall even further than they have done then maybe CanoNikon will ramp up their MILC designs to a more prosumer level and increase output. Maybe: but see below.

2. The second is about lenses and focussing technology.

In the previous post I talked about the focussing problems experienced when a lens designed for PDAF is mounted on a camera which relies on CDAF.

Canon and Nikon each have a huge inventory of lenses designed for PDAF.

Obviously they want their existing DSLR lens inventory to work properly via an adapter on their MILC bodies. This would allow existing lens owners to transition to MILC without having to change their kit of expensive DSLR lenses.

So they need MILCs with PDAF. In fact they do have MILCs which have both PDAF and CDAF on the imaging sensor.

But apparently DSLR style PDAF using dedicated sensors in the base of the mirror box is more sensitive, more accurate (if the hardware is in correct alignment) and faster than the on sensor style PDAF of mirrorless cameras.

The technical reasons for this are over my head. I read about it on photo.stackexchange.com, Wikipedia and cambridgeincolour.com. I don’t understand the technical exposition but I do get the message: on sensor PDAF is not as good as DSLR type PDAF.

Canon appears to be trying to manage this in two ways simultaneously.

Some EOS DSLRs utilise Canon’s ‘Dual pixel CMOS AF’ which allows every effective pixel to participate in PDAF as well as image capture.

But apparently dual pixel AF, while suitable for video, is still not very good for predictive continuous AF on moving subjects with still photos, which might explain why the EOS M3 MILC does not have this technology, utilising instead ‘Hybrid CMOS AF III’.

I suspect this issue is actually a very big deal and possibly the main rate limiting factor affecting CanoNikon’s progress on MILC development.

In a recent interview with staff from Digital Photography Review, Mr Masaya Maeda, a senior Canon imaging executive is quoted as saying “ ..every day I’m saying, speed up, make it faster…” .

FZLC

Both companies are also in the FZLC market and I am guessing they will upgrade their design and production in this sector if sales figures tell them that is where buyers want to go.

Trailblazing

CanoNikon are allowing Sony, Panasonic, Olympus and others do the trail blazing and market making with new camera types, planning, I suppose, to move in when they are ready.

The danger is of course, that previously faithful CanoNikon buyers will drift away to other brands in the meantime and fail to return to the fold.

Maybe Apple will do a run around all of them and collapse the established camera industry completely.

The buyers will decide.

We live in interesting times.

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DSLR vs MILC vs FZLC What's the difference ?

Mẹo sử dụng đồ gia dụng 02:23

Rainbow Lorikeet photographed with a Canon SX60, a FZLC

Last week someone posted a question on a photo user forum asking about the difference between cameras with and those without a mirror.

Old guys like me who have been using cameras for 60 years need to be reminded occasionally that not everybody has a long personal history of camera use and that many people wonder what all the mirrorless debate is about.

So I put together this brief summary of the characteristics of each type, with a third one thrown in for good measure.

Let’s start with a little acronym entrée:

ILC: Interchangeable Lens Camera

SLR: Single Lens Reflex (Camera)

DSLR: Digital Single Lens Reflex (Camera)

MILC: Mirrorless Interchangeable Lens Camera

FZLC: Fixed Zoom Lens Camera

PDAF: Phase Detect Autofocus

CDAF: Contrast Detect Autofocus

OVF: Optical Viewfinder

EVF: Electronic Viewfinder

The SLR Camera This is a type of ILC which arose in the mid part of the 20^th Century. It was and to some extent still is, an elegant solution to several photographic problems:

* How to provide a range of lens focal lengths from wide to long, there being no zooms when the SLR was invented.

* How to preview the subject correctly oriented in a viewfinder then focus and frame accurately.

* How to achieve accurate exposure metering through any lens mounted.

* How to package all this in a compact device at a price point accessible to ordinary people.

The SLR is a quintessentially 20^th Century invention. It relies on mechanical and optical solutions to the problems presented.

In due course camera makers replaced the film with a digital sensor and added electronic operation but otherwise kept the same basic design, thus creating the DSLR.

DSLR Schematic

This is a very basic schematic of a DSLR.

When the flipping mirror is down, as shown here, light comes from the subject through the lens and strikes the mirror. Most of the light is reflected up to the focussing screen where it forms a visible image which is inverted laterally. Some light is passed through to the sub mirror and thence to the Phase Detect autofocus module.

Light passing upwards from the focussing screen bounces around the pentaprism (or mirrors in some models) and in the process the preview image becomes correctly oriented laterally and vertically.

Some of the light is picked up by another little mirror and deflected to the metering sensor.

The user looks in the eyepiece of the optical viewfinder to see a preview of the subject, with adjacent camera data which adds further complexity not shown in the diagram. The focal plane shutter is closed.

In this mirror position, image preview, exposure metering and (auto) focussing take place.

When the user presses the shutter button several things happen very quickly.

The flipping mirror lifts up, the sub mirror flips up with the main mirror and the operator’s view is blacked out for a short time.

The shutter opens, the imaging sensor is exposed to light.

Then the shutter closes to end the exposure and the flipping mirror drops down again, allowing the cycle to repeat.

A DSLR can also operate in monitor view mode with the mirror held up, the shutter open and light passing directly to the imaging sensor. In this mode a DSLR works very much like a MILC. The image preview, metering and focussing are all generated directly on the imaging sensor. Image preview data is fed electronically to the rear monitor.

You can think of a DSLR as in effect two camera types in one body, one with an optical viewfinder, the other with an electronic viewfinder (the monitor).

DSLR Variant: Sony SLT

Sony is the only manufacturer to offer this type of camera. It is a DSLR but some of the inner workings are different from the standard version.

The main mirror is a fixed pellicle type, not flipping. It transmits about 70% of the incoming light to the imaging sensor and reflects the remaining 30% up to a Phase Detect autofocus module located about where the front of the pentaprism would be on a conventional DSLR. There is no focussing screen. Autofocus can operate continuously with no interruption for image capture.

The viewfinder is Electronic, receiving data from the imaging sensor just like a MILC.

MILC Schematic

The MILC is a creature of the 21^st Century. It replaces the fixed and moving mirrors and other optical parts of a DSLR with electronic data processing and transfer.

You can see the MILC has fewer mechanical and optical parts than the DSLR, but it is more reliant on electronic data transfer and processing.

The body has less depth because the back focus distance is less, there being no need to accommodate the flipping mirror and focussing screen.

It may also be possible to reduce the height a bit as many EVFs are smaller than a pentaprism or mirror and there is no need to find room for the PDAF module in the base of the camera.

Image preview can be fed to the EVF and monitor simultaneously although the camera is usually set to display one or the other to save power.

All metering, CDAF and/or PDAF and image capture take place on the imaging sensor.

The focal plane shutter is open when previewing the subject. If the shutter is of all mechanical type it closes when you press the shutter button then opens to make the exposure and closes to end the exposure. Some shutters have an electronic exposure commencement (a.k.a. electronic first curtain) and mechanical exposure termination. This is desirable to prevent shutter shock, see below.

Mirrorless variant: The FZLC

In this style of camera the zoom lens is not interchangeable. There is no need for a lens mount. The rear element of the lens can be quite large with a diameter equal to or greater than the imaging sensor, providing some optical advantages. This rear element can be very close to the sensor allowing further reduction in the overall depth of the camera.

The shutter is usually a diaphragm leaf type located inside the lens. This allows for further reduction in bulk of the unit.

Which is best ? Each type has advantages and disadvantages.

DSLR Advantages:

* For most non professional photographers I suspect the main advantage of the DSLR is incumbency. It is an established and widely recognised camera type. I suspect lots of people ‘know’ or think they do, that the DSLR is the camera type to get if good quality pictures are desired.

* Pro-Am and Pro level DSLRs can effectively follow focus on a moving subject with an appropriate lens fitted. Entry level DSLRs and many MILCs are less competent at follow focus, although MILCs are catching up with every new model generation. The situation is not static.

* The long established DSLR makers have a huge inventory of lenses and other accessories from which consumers can choose.

* Some users still insist that the OVF of a DSLR is preferable to the EVF of a MILC. That was true a few years ago but the new EVFs are now so good that in several respects the better ones have the advantage.

DSLR Disadvantages

* A DSLR requires extremely accurate location of several moving and still optical components. There is a manufacturing cost to this and also variation between samples. This leads for example, to each lens requiring AF micro adjustment on each separate body. This adjustment is not offered on entry/upper entry models.

This is a problem with accuracy which is the degree of closeness of a measurement to the true value, or in this case the closeness of the focus point to the correct one.

No such adjustment is required on a MILC or FZLC which measure focus directly on the imaging sensor.

* The PDAF system used on a DSLR is inherently faster but delivers more variable results than the CDAF used on MILCs.

This is a problem with precision which is the degree to which repeated measurements give the same result.

The CDAF system on MILCs and FZLCs is inherently more accurate and more precise than the PDAF system used on DSLRs.

That, by the way, does not mean every MILC and FZLC has more accurate and more precise autofocus than every DSLR. Some MILCs have CDAF implemented badly which is no use to anyone.

* Mirror slap. The flipping mirror can cause vibrations which can lead to blurred images at some shutter speeds, usually around 1/8 second and therefore not usually seen with hand held pictures.

* Cost: (soon) For the moment, MILCs are either equal in price to the consumer or even more expensive than DSLRs. Makers of MILCs are playing catch up in several areas of technology at present, adding to R&D costs but I expect that in due course it will be less expensive to make a MILC than an equivalent DSLR as there are fewer parts.

* Much has been made by manufacturers and users of the size/mass advantage which MILCs have over DSLRs. This is real but not as great as some MILC enthusiasts might have you believe. MILC bodies can definitely be smaller for any given sensor size, but the lenses are generally not and lenses make up the bulk of a multi lens kit.

Sony SLT advantages/disadvantages

* The main advantage would be the ability to perform continuous PDAF. This should benefit follow focus with continuous autofocus and high frame rates. There is no mirror slap.

There are also fewer moving parts than a DSLR.

* I can think of several disadvantages though.

That pellicle mirror is always between the subject and the sensor, collecting dust and potentially degrading image quality.

There is little if any size/mass advantage over a DSLR.

But perhaps the main one is ongoing uncertainty regarding Sony’s intentions about the SLT type and about the A mount in general.

MILC advantages

* I expect that in due course mirrorless cameras will be less expensive to make and buy.

* Size/mass is a minor advantage as pointed out above.

* Advantages of the EVF and the ability to configure the monitor and EVF to display the same information in the same way making for a seamless segue from one to the other.

* More accurate and precise single shot AF.

* In the end I suspect that mirrorless cameras will prevail at least for amateur buyers simply because gadgets in the 21^stcentury are characteristically electronic and DSLRs are at the core mechanical devices with their roots in the 20^th Century.

MILC disadvantages

* Mirrorless cameras are still playing catch up to pro level DSLRs for follow focus on moving subjects.

* Refresh rates on even the best EVFs have still not quite caught up to the DSLR OVF.

These issues still make Pro and Pro-Am DSLRs preferred for sport/action/wildlife/bird photography.

The gap is closing however as rates of electronic data processing and transfer increase with each new generation of mirrorless camera.

* ‘Shutter Shock’. Some cameras with an all mechanical shutter display blurring of the image, sometimes with double imaging, with some lenses at some focal lengths and some shutter speeds, usually in the range 1/20 to 1/200 second. This is caused by the first ‘shutter close’ action vibrating the camera/lens unit.

What about the FZLC ?

With recent developments in the technology of small imaging sensors and high range zoom lenses using aspheric elements some of the latest FZLCs are starting to look like an attractive alternative to an entry/upper entry DSLR.

The main advantage of this type is that it represents an ‘all-in-one’ solution to many users’ desire for a go-anywhere-do-anything camera with no need to carry or change lenses.

FZLCs typically have a greater zoom range in a more compact, lighter, less expensive package than any superzoom lens on a DSLR or MILC.

The leaf shutter is compatible with flash at all speeds, is usually very quiet (most of the ‘shutter sound’ you hear is electronic and artificial) and does not cause shutter shock.

The disadvantages are that there is no option to change lenses and high ISO image quality of FZLCs is not as good as that available from many ILCs, due to the smaller sensors required.

But FZLCs are improving with every generation.

What about lenses ?

In the ‘good old days’ lenses were focussed manually by turning a ring on the lens barrel. This moved the whole optical group back and forth on a helical mount.

When autofocus was invented, lens makers kept the same basic helical mount but the user’s fingers were replaced by a little motor. Some lenses appeared using just the inner/rear group of elements for focussing but still using a helical action.

This worked (and still does) just fine with PDAF.

But cameras with CDAF are a very poor match for lenses with a helical focus action.

PDAF vs CDAF Schematic

The diagram above relates to the discussion below.

With PDAF the AF module measures some light rays and figures out:

a) which direction the focus elements in the lens need to move

b) how far the focus group needs to move in order to achieve correct focus.

Having done that the AF system says to the lens “go there” and it does. With a basic PDAF system the camera doesn’t check whether the lens is actually in focus at the ‘go to’ point. I believe the more sophisticated (=expensive) systems may have a final ‘are we really there’ check before the shutter fires.

A basic CDAF system cannot tell if the lens needs to move one way or the other to achieve focus.

So it moves the lens and repeatedly asks ‘are we getting closer’ until the focus action overshoots the mark and the camera detects the focus action has to reverse. As indicated in the diagram above the process of finding correct focus involves several back and forth movements of the focus elements.

This back and forth movement requires the focussing parts of the lens to accelerate, stop then reverse extremely fast.

A helical mount is simply too slow even with a powerful motor.

So most lenses particularly zooms, designed for CDAF have a different design. They

a) utilise a few small optical elements in the interior of the lens for focussing and

b) those elements, in a lightweight housing, are driven directly back and forth on rails.

This is much faster and has allowed cameras with CDAF to match or better those with PDAF for single shot autofocus speed.

But basic CDAF is still not good for follow focus on moving subjects as it has no predictive capability.

Camera makers have tried to deal with this problem in two ways.

Most have converted some pixels (about 10,000 or thereabouts) on the imaging sensor to PDAF sensors. The idea is to use the PDAF function to drive the lens to where it estimates the correct focus point to be then fine tune with the CDAF.

MILCs from Canon, Nikon, Sony, Olympus, Samsung, Fujifilm and Olympus have this technology.

Panasonic uses a technology which it calls DFD (Depth from defocus) which uses data about the optical characteristics of out of focus images to estimate the direction and amount by which the focus lens must be moved. It is a way by which CDAF might emulate the best feature of PDAF.

For a first generation new technology it seems to work pretty well. My GH4 and FZ1000 with DFD are better at follow focus than my GH3 (without DFD), but still not up to the standard of a high end DSLR. Maybe the second generation of DFD will boost follow focus even further.

Which system will prevail ?

In a recent interview a very senior Canon executive said he did not know whether DSLR, MILC or ‘Compact’ by which I think he probably meant FZLC, would the dominant technology for most camera buyers in the future.

If he doesn’t know then I guess nobody does. The buyers will decide, as usual.

We live in interesting times.

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