Ten Years of Digital Imaging or “How Many Megapixels Do You Need?”

A while ago I did a post on how much imaging technology had improved over the last decades from 35mm film to digital and concluded that within limited parameters (low ISO, good exposure etc) it wasn’t a massive difference. Then I found my first digital camera in a drawer – a Sony 5.1 Mp Cybershot from 2005 and thought “You really must test how well this will stand up against a 15Mp Oly EPL5, an 18Mp Canon 60D and a 36Mp Sony A7R”. So here we are.

Insanity? Probably, but if you don’t test assumptions you’ll never know if they’re right! And it sounded like fun. This post has turned out longer than I planned – sorry!

AA1379133

This shot has nothing to do with this post – I just needed something to look good on the reader page – no-one is interested in my bookshelf…. A7R, Zuiko 50mm f1.8

Before we start I’m not bashing or promoting any particular camera. I’ve bought all of these and still use them – with the exception of the old  Cybershot 5 Mp compact. The EPL5, 60D and A7R are all great cameras.

A high tech test scene was organised (my bookshelf and some bits and pieces) and to equalise the test the same Zuiko OM 50mm f3.5 macro lens was used on all the cameras except the tiny Sony Cybershot which has a fixed zoom lens. All shot at base ISO at f11, manually focussed on a tripod, straight RAW development in DXO Optics 9 (except the Cybershot jpg) and ‘auto levels’ applied to all in Photoshop. As there are variable camera crop factors involved, the distance to the subject was changed to keep – approximately – the same shot.

As a preamble to the shots here are the frame dimensions and file sizes :-

Cybershot 5.1 Mp    2592 x 1944 pixels, 1.7 Mb. Sensor will be tiny and is now ‘obsolete’. This camera would be worth around £5 now.

Olympus EPL5        4608 x 3456 pixels, 15.5 Mb. Micro Four Thirds. Around £500 when new, about £200 now second hand.

Canon 60D              5185 x 3456 pixels, 17.8 Mb. APSC DSLR. Around £800 when new, about £300 now second hand.

Sony A7R                 7360 x 4912 pixels, 33.6 Mb. Full frame mirrorless. The only camera without an anti alias filter. £1300 new, about £1000 second hand now.

frame

Onto the crops then – they get larger on-screen as we’re cropping out of progressively larger images.

Sony Cybershot 5.1Mp Crops – first the centre then the lower left. The card in this camera was a Sony Memory Stick of 128Mb (Yes MB!)

wsc100b

wsc100a

Then the EPL5 15Mp –

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Now the 18Mp Canon 60D

60db

60da

And finally the 36Mp Sony A7R

a7ra

a7rb

Well let’s get the bleeding obvious out of the way first – a 10 year old 5Mp camera doesn’t compare that well to mid range or top of the range sensors. However when looking at all the shots at around 8×6 inches on the screen the differences are quite subtle. I doubt I could tell the difference from the humble 5.1 ‘jpeg only’ image and the RAW processed 36Mp A7R image in a consumer print of the same size (i.e. 8×6 inches).

The EPL5 and 60D are very roughly the same frame dimensions, but the 60D looks slightly better in these enlargements – not much but it’s noticeable. There is obviously a big difference between 15Mp/18Mp and 5Mp sensors, but not between 15Mp and 18Mp sensors.

The A7R – not surprisingly – is resolving more detail than the 60D and the EPL5. However, all those extra megapixels aren’t adding that much extra so a bit more of a zoom in with the test ‘how far can I enlarge before I can see pixels?’.

60D

60dhuge

A7R

a7huge

Well – if you really look closely enough there’s a definite difference, but pixel peeping such a tiny section of a frame seems extreme. The 60D has an anti-alias filter, the A7R doesn’t, which, along with its extra pixels accounts for the extra sharpness.

Finally what happens if you downsample the A7R to 18Mp. This is a bit sharper that the 60d – if you can be bothered to go to so much effort.

a7rhugerescale

What conclusions regarding resolution then at base ISO? IMHO :-

If you never crop, never print more that 8×6 inches or only use your shots on the web – 5Mp is fine and anything more is just clogging up your disk drive and increasing your credit card bill. The same would apply to camera or tablet phones.

If you want to crop or print larger than 8×6 inches then 15 to 18Mp is fine – even for large prints like 22 x 15 inches (which I’ve done and sold!). These Oly/Canon cameras are useful all rounders which are well evolved, easy to use and can cope with most photographic subjects. They are very good value.

Cameras like the A7R are really only practically needed if you either want to print to huge sizes, or you wish to sell your work (as I do) when clients/agencies value larger file sizes as the extra resolution gives them more flexibility. Of course if you just want that extra resolution because you’re a perfectionist – and that’s fine by me as I’m one too – it’s there, and the Sony sensor is superb. It’s just that the improvement in image quality might not be as great as you expect. You’ll need to use the best lenses (ideally primes) at optimal apertures and the best technique to really make the most of the new sensors. The A7R Mk2 looks like it will be more forgiving that the A7R but it’s not cheap!

At higher ISOs it’s a different story of course, and this doesn’t take into account other variables like dynamic range (excellent on the A7R), image stabilisation, noise or colour rendition. Also video from older cameras is often very poor compared to more up to date models – an area where progress has been even more rapid.

It’s fair to say that ten years of digital imaging improvements have made a huge difference – though whether moving past around 20Mp is worth it is up to you. I’m sure in two or three years time 36Mp will be the ‘standard’ sensor resolution with the cutting edge sensors topping 80Mp! It’s worth pointing out that the very best, very expensive prime lenses resolve around 30Mp of detail, the best zooms around 25Mp on high resolution sensors according to DXO……

Oh – and that 30 year old Zuiko 5omm f3.5 lens is still excellent!

Hope you find this useful, thanks for looking (and for reading this far!).

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