Full Frame, APS-C, APS-H and resolution?

Kilree

Just got to thinking about full frame digital SLR photography and wondered if anyone could shed some light on the following. I hope that I can explain the query properly.
If a 10.2 MP camera produces a particular image on an APS-C size sensor will the same Megapixel (10.2) full frame camera produce an inferior image because the pixels have to spread themselves across a larger sensor? If that is the case then what size megapixel full frame camera would be required to produce a comparable resolution to the APS-C sensor. Equally, leaving aside things like FPS, 45 focussing points etc. What would be the point of changing to a full frame camera unless there was a considerable increase in MP value?

ThOnda

I am not the best to answer that, however size of sensor shouldn't have any effect on focusing elements - that is only marketing decision.
The larger sensor - the bigger distances between pixels - the less noise.

Borderfox

The improvement in my eyes is less noise and the full frame aspect.

rahtkennades

Not an expert, but if you have a larger sensor with the same number of receptors, it means they can be larger. Larger individual sensors can capture more light, so you get better low light performance for one, and also the saturation of colour should be better*.
Also, a full frame sensor allows lenses to work at the focal length they're designed fo(ie no crop factor).

Have a look at http://www.dpreview.com/learn/?/key=Pixel_Quality it might explain better.

*health warning - I'm straying into speculation here!

bluepencilcase

Probably most significantly, where the photosites are bigger, there's much less noise. It's almost the opposite of what you were saying about "spreading out pixels"- in fact, you're just giving them enough space. the reason the noise is so high on P&S cameras with lots of megapixels is because they're all squashed into a tiny space.

full frame obviously being the other big one. expensive to get good wide angle lenses for cropped sensors.

basically, I agree with borderfox.

ThOnda

I'd love to have fulframe, but 5D is not in my league and it doesn't have a flash. I've just realised that more than 50% of my last shots (in bright daylight) were with flash.

sunny2004

rahtkennades wrote: »

*health warning - I'm straying into speculation here!

Brilliant

Borderfox

The 5d is not for everybody but I shot a wedding last Saturday and I would reccomend you have a few shots with one. Stunning image quality when paired with good glass and it is my weapon of choice when shooting indoor showjumping. To answer Kilree's question I think that a 10.2mp on full frame will produce a better picture than 10.2mp on an APS-c crop factor

pete4130

I'll let you know the score with Nikon's full frame in 2-3 weeks (hopefully) when I get my hands on my D3!

Kilree

Thanks for all the responses guys. I'm sure that Borderfox is correct when he says that the a 5D full frame will produce a superior shot than my 400D as otherwise why would manufacturers bother to produce them. Thanks for the link Rahtkennades. I've had a look and probably confused myself even more. I suppose the query arose from a basic lack of understanding about sensors and how they work. In film terms I know, for example that a medium format negative will produce a better image than 35mm (bigger area - more emulsion) and in turn 135 will do better than 126 but since I don't understand the basic concept of sensors and how they work I couldn't relate digital to film.

TJM

Full frame cameras have a massive advantage when it comes to natural light / low light shots as you can bump up the ISO with much less loss of quality.

ThOnda

Kilree wrote: »

... medium format negative will produce a better image than 35mm (bigger area - more emulsion)...

Well, not exactly. There is the same sensitivity = grain, but you don't have to magnify it so much. so you're getting better quality prints.

dhaslam

The extra pixels make no difference to the image quality except to make the picture more noisy. I have two almost identical cameras the 6Mp KM 5D and Sony 10 Megapixel Sony 100A. Pictures up to 400 ISO are similar but above that the 6Mp camera is much better. Lenses have the biggest effect on picture quality and the advantage of the full frame sensor is that for a given print size less magnification is required. The APS cameras using cheaper full frame lenses avoid some resolution problems at the edge by clipping the image but the better lenses should not have these problems. The Nikon D3 looks close to the optimum as a compromise between resolution and good low light performance. The D200, particularly, was not good at high ISO.

mloc

A full-frame sensor is generally better than a smaller sensor for a few reasons

a) a larger sensor has larger pixel elements: this means each pixel on the sensor is larger and has more space for light to "fall" on it, resulting in less of a need for over-sensitivity and less noise.

b) larger sensor means less enlargement: this is more a theoretical point, but a larger sensor (at least from a light point of view) means that when pictures are viewed or printed in a larger size, there is less of a enlargement ratio

c) greater availability of wide angle lenses: important to landscape photography, even a 18mm lens on a APS-C camera gives you a 27mm effective length. This means if you want a really wide angle view like 18mm effective you'd need a 12mm lens, which are hard to come by and quite expensive. And if you need a 12mm effective, you'd need to find a 8mm lens; apart from fisheyes, good luck with that!

Kilree

Thanks mloc and dhaslam. I think I understand the matter a bit better now. The main thing seems to be the pixel size on a full frame sensor which as mloc has pointed out is bigger. This makes more sense and explains why the full frame camera will produce the better quality picture. I hadn't realised that there was a difference in pixel size between full and aps.:)

mloc

Kilree wrote: »

I hadn't realised that there was a difference in pixel size between full and aps.:)

Well, technically only between sensors of the same megapixel value... e.g. the pixels on a 10 mp full frame will be bigger than a 10 mp aps-c