Quote:
Originally Posted by duncan22
Can anyone point me in the direction of photographs taken with a Canon full frame and a cropped frame camera with similar lens and lighting conditions and where these can be compared side to side along with additional data if available ?
What I am trying to work out and it's purely a personal decision is if the additional cost of going full frame is worth it.
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Well here's a little advice from someone using FF. I don't think you're asking about the effect of the crop factor, you're just wanting a like for like comparison, so based on that here's my take on it all.
If you compare crop frame against FF with a top quality lens or a prime or lesser quality, the FF will give you better image quality, with smoother gradients and nicer colours, but if you can't afford the camera body and a set of top end lenses you're going to be in for a cruel surprise, because the camera capable of returning such fine images simply won't produce them for you. Problems which are not visible on a crop frame sensor will conspire to degrade the Image, these are usually seen towards the edges of the image.
Distortion, vignetting, and resolution fall off are just some of the issues which you are likely to see, plus if there are any optical faults in the lens it can go from an irritation to unuseable on FF.
Even with good quality optics you are still going to have this effect, only not quite as noticeable:
Canon 24 -105mm IS L f/4 distortion on crop 1.8% and not a problem, on FF is a rather more visible 4.3% Vignetting wide open at .4 EV and a huge 2.4 EV on FF Resolution is more difficult to describe because of the difference in sensor resolution, however there is a much more marked fall of towards the edges. Of course stopping down improves most parameters.
Nikons 24 - 70mm f/2.8 G ED is no exception either distortion at 1.1% on crop and unnoticeable, while on FF it's a rather more visible 3% Vignetting wide open is .45EV on FF it's 1.55EV again border resolution falls markedly.
This is to illustrate what happens when top end lenses are used poorer quality ones start off with worse figures which might be acceptable on crop, but simply aren't on FF.
Aside from those considerations, crop cameras are better suited for some kinds of photography, such as sports wildlife and macro, because of the reduced FOV, greater depth of field, and higher pixel density. Full frame is better for landscape some architechture and portrait photography.
I don't think the FF camera should be regarded as some kind of holy grail to aspire towards, they do become more diffcult to use, will show up mistakes mercilessly, and won't return good results unless they are paired with the best lenses. Be prepared to spend a lot of lenses if you do buy one.
30-10-09, 02:44 PM
You start off by giving the correct answer and then go on to contradict yourself. A 50 mm lens used on a sensor with a 1.6X crop factor would produce the same field of view as a 1.6 x 50 = 80 mm lens on a 35 mm full frame sensor. The focal length however, does not and cannot change, just it's field of view (FOV). A 50mm lens is always a 50mm lens, regardless of the sensor type. As a result of the somewhat smaller FOV the illusion is that one has zoomed in but this is only an illusion and using words such as magnification is misleading - focal length has not changed. As I've already said, a 50mm lens or indeed a 300mm lens will always be a 50mm lens or 300mm lens. Don't think that owning a camera with a sensor having a crop factor means you only need to go out and buy a 300mm lens to achieve the same magnification as a 600mm lens thereby saving money, it simply doesn't work that way. 
