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Old 30th November 2016
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Mirrorless vs DSLR resource?

No, this isn't another salvo in this daft debate!

A load of members of my camera club are now asking about switching to or adding mirrorless cameras, so I put together some thoughts with input from a couple of others. So, I hope this might be useful to other members here as a summary resource to give to others, modified as you wish.

I've covered what is usually asked (mirrorless vs DSLR) plus what I believe to be much more important questions (how big a sensor do you need, and what are the important differences between manufacturers' products).

I've edited it slightly since I'm preaching to the converted on this forum, but I've left in the bits about my own experience, because I think that's relevant.

It's aimed at pretty basic photographers: others either genuinely know it all already or think they do and won't ask in the first place.

I'd be really interested if anyone has any other points that could usefully be made, or any disagreements!

Here we go:

>> FIRST, before choosing DSLR or mirrorless, I'd say you absolutely must decide what you mainly want to use your camera for.

All current cameras are excellent and can do almost any type of shooting and get award-winning results, but all have their strengths and weaknesses and a few of these are affected by whether you're using a DSLR or a mirrorless body.

Looking at current DSLR & mirrorless models, I'd say the only really significant point influencing that particular decision is whether you intend to do a lot of bird images, or a lot of fast sports (and maybe fast wildlife) photography. If so, DSLRs are still much better at continuous autofocus and tracking than almost all mirrorless bodies, and they also have direct vision viewfinders that are much better for following fast action at high frame rates.

"How much better CA focusing in real life?", I hear you say.

Well, I only have personal comparative experience of this in motorsports, but with 400mm (full-frame equivalent) f4 lenses, following cars coming towards me downhill from Paddock Hill Bend at Brands Hatch (a fairly tough test, but a medium-sized subject) from the same viewpoint I got around 90% frames in focus with my 2007 Nikon D300, compared with around 60 - 70% with my 2013 Olympus E-M1. Smaller targets accentuate the difference further, although some experts do seem to achieve nice images of birds in flight with mirrorless cameras (not me!). The Sony 6300 and 6500 crop-sensor bodies are favoured by mirrorless sports and bird photographers as best of the bunch for this, and the brand new Olympus E-M1 mk2 looks to have as good CAF as basic DSLRs in early reviews (watch this space, though).

What the DSLR fanboys on internet forums (!) won't tell you is that, when it comes to single autofocus, the average current mirrorless camera is usually faster than the average current DSLR to acquire focus, in part because the smaller-sensor lenses are smaller and lighter to move. (They also go on and on about low-light performance and noise: well, it's the end result that matters, and with a bit of careful exposure and post-production noise-reduction you won't often see a significant difference in noise between FF and micro 4/3 sensors at up to 12 x 16" prints. The fanboys only publish images on the web, of course, and in real life they might as well all use Sony RX100s, but they obsessively examine all the images on screen at 100%+...).

Similarly, mirrorless camera bodies are mostly a bit smaller, lighter and cheaper than their DSLR equivalents because it's a bit smaller, lighter and cheaper to replace those complex mirror assemblies (plus the problems they cause by moving) with electronics. However this is NOT a big factor compared to others which explain why I usually carry round lighter/smaller camera gear than I used to (see below).

The electronic systems in mirrorless bodies allow the viewfinder and rear screen to show a excellent 'live view', and you can set this to show accurate over-and under-exposure information and highlight over- and under-exposed areas so you don't need a meter, and (mainly on micro 4/3 cameras) you can tap on the rear screen to set focus, which is great for street, macro and a lot of tripod-mounted landscape photography. You can also set 'focus peaking' and focus magnification on screen or viewfinder which are wonderful for manually focusing any lens and correcting focus when AF has locked on to, say, the grass in front of the leopard. You can show a histogram and a level indicator in the viewfinder, on the rear screen, or both, and switch them on and off easily.

To set against these advantages, the computer-like abilities bring complex menu systems which I have called 'the spawn of the devil'! The best mirrorless bodies do provide plenty of well-positioned dials, switches and buttons which, once you've set the camera up, allow extremely fast and logical operation (this applies to all the Fuji and some of the Olympus cameras (especially the E-M1), but much less to Sony).

SECONDLY, and to come to the real nub, I'd say that a much more important decision for most people is SIZE OF THE SENSOR, not whether there's a mirror in front of it or not. Some further thinking about your main type of usage is needed before making this particular choice: e.g. do you want to print, and how big? Do you want to do a lot of low-light photography? How good are your intervertebral disks (i.e. can you carry heavy kit) and do you do a lot of travel and light plane flights with your gear? How rich are you?

DSLRs only come with either full frame (FF, FX) or crop (APSC, DX) sensors.

Mirrorless bodies are more widely available, as FF (Sony), crop (mainly Sony & Fuji), micro 4/3 (Olympus & Panasonic), 1" (e.g. the Sony RX100 series and the Panasonic LX100 and Canon G1 etc.) and the vast number of yet-smaller point-and-shoots. Canon & Nikon have made various mirrorless bodies with crop or smaller sensors, but as far as I know they haven't sold many yet, and there are some left-field manufacturers like Samsung and Leica, of which I have no experience.

Over the last 3-4 years I've owned examples of all of those sensor sizes (currently I have micro 4/3 by Olympus, crop by Fuji, and FF by Sony, all mirrorless), and in the past I had a Nikon D300.

The key effects as the size of the sensor shrinks are (as ever) a mix of advantages and disadvantages, and my views and personal experience related to the questions above follow: I've put the length, weight and current Wex price of an example 600mm f4 lens by the sensor sizes as a guide:

Full Frame (448mm, 3920g, 9600)
Advantages: low image noise, especially at high ISO (my FF mirrorless Sony A7S produces usable PDIs at 25600ASA, and this is a unique camera for low light and video work); fast focus in low light; some are great for video; some models have high-definition sensors producing massively detailed files that allow lovely, huge prints (or massive cropping, which allows you to get away with carrying shorter focal length lenses, of course). Lenses in the 21 - 100mm range are generally quite compact and light as long as you don't go for the f1.4 behemoths (how often are you going to use the range below f2.8? Really???)

Disadvantages: price, size and weight, especially of telephoto lenses; huge files swallow hard disk space and slow post-processing, so you also need to spend more on these areas; poor image stabilization because of the heavy sensor and/or lenses.

Crop-sensor (Loads of lenses are available for crop DSLRs, but for a mirrorless example - 210mm, 1375g, 1499 - only zoom lenses currently cover this focal length for Fujis, and max f5.6 only)
For most variables I'd say the results are "intermediate between FF and m4/3", although of the mirrorless bodies the Fujis do punch above their weight in optimal image quality while the Sony 6xxx series have relatively excellent continuous autofocus. As shown by my being unable to find a 600mm f4 to compare, there's relatively much less lens choice for Fuji and Sony (although you can adapt some full frame Canon autofocus lenses to Sonys with good results). I'm happy up to ASA3200 with my X70 X-Trans sensored Fuji for street photography.

Micro 4/3 (227mm, 1270g, 2199)
Advantages: some of the bodies and lenses are weather and dust-sealed; price, size and weight; the best image-stabilization available; extremely high frame rates in relatively cheap cameras; wide depth of field suits some types of image; rear touch-screen focus and shooting; some are great for video; the wide lens choice from Olympus, Panasonic and independents, and the clever image-stacking, Live Bulb, high-definition file and other processing tricks.

Disadvantages: getting narrow depth of field - yes, you can get m4/3 f0.95 lenses, but then you lose the size and weight advantage; I don't use them above ISO 2000 even for 'street' images; I try not to crop the frame too much (to maintain image quality); some people find the loss of viewfinder image continuity distracting at high frame rates (although this has actually never bothered me, and Olympus are better in general than others for this); I use image blending or HDR more often than with my FF and crop camera bodies to maintain dynamic range, and this takes time.

1" and smaller sensors.
Wonderful and unique for having a camera always available in a small pocket, but the main disadvantages are low-light focusing and image noise, plus poor, frustrating handling (because the controls are so small & fiddly or mostly menu-based). Personal tip: take a look at the Fuji X70 for a genuinely pocketable crop-sensor body with great handling, a tilt touch-screen and top X-trans image quality (disadvantages: no viewfinder, and a fixed 28mm FF equivalent lens).

Having said all that, you can produce 16 x 20 prints from micro 4/3 cameras and win competitions and achieve distinctions, and an increasing number of club members are doing just that. Current PDI projection standards mean that it's usually impossible to tell whether an image was taken on a 1" sensor or full frame, although that's not true for shots taken under challenging lighting, and the forthcoming increased PDI resolution in competitions might make at least micro 4/3 a necessity.

Disclaimer: these are only my opinions (but they are based on some personal experience), and I'm sure others will have differing views!

I hope this is a helpful resource. <<

Too much Oly gear.
Panasonic GM5, 12-32, 12-35, 15. Laowa 7.5.
Assorted legacy lenses, plus a Fuji X70 & a Sony A7S.
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