Full-frame or brighter lens?

[Jitendra Katre]

hello,
What will have greater impact on images quality, particularly in low light situations? Upgrading to full-frame camera or buying brighter lens (like Sigma 18-35, f/1.8) for my Canon 7d?..And logically if full-frame is 1.6 times bigger than crop-sensor, noise performance of full-frame should be 1.6 times better. ..is this true?
Regards and thanks,
Jitendra

[Rajan Kanagasabai]

Hi

In my opinion, though not a true Full Frame, the 7D has enough pixels and decent size of photosites to produce some brilliant images. It is right at the door of the professional league and the difference from a full frame, that too in just a few conditions like wide angle, low light etc, can at the best be a little – nothing dramatically different. Of course, the noise on a full frame – especially on high ISO’s is a lot better (Bigger individual light sensors capture more light – and this means that less electronic noise is created), but that is about that.

What really makes a difference is the quality of the lenses that get hooked to the body. In my view a good lens with low light handling capabilities would make much more difference to the quality of the image.

regards
Rajan

[Jitendra Katre]

Hi

In my opinion, though not a true Full Frame, the 7D has enough pixels and decent size of photosites to produce some brilliant images. It is right at the door of the professional league and the difference from a full frame, that too in just a few conditions like wide angle, low light etc, can at the best be a little – nothing dramatically different. Of course, the noise on a full frame – especially on high ISO’s is a lot better (Bigger individual light sensors capture more light – and this means that less electronic noise is created), but that is about that.

What really makes a difference is the quality of the lenses that get hooked to the body. In my view a good lens with low light handling capabilities would make much more difference to the quality of the image.

regards
Rajan

Thanks Rajan for quick and very logical reply. I am concerned with low light shooting. And the problem is that, for crop sensor there is hardly any choice other than the one I mentioned, and I am little apprehensive about Sigma.. Regards

[Rajan Kanagasabai]

Apart from the regular aspects that address low light (high ISO capability, high Exposure compensation capability, high aperture capability, sturdy support, AV mode of shooting etc) you probably need to look for a 'Fast Lens' as well, which can make a real difference in low light.

The only Sigma i had (and still have) is the 150-500 APO USM. It is a good lens, provided you give it good light. The minute the light drops, the hunting begins and the quality of the image drops dramatically. Compare this with the 100 - 400 of Canon, there is a world of difference in performance under the same conditions. So, i am on your side, with my apprehensions with the Sigma . . . .

regards
Rajan

[Sabyasachi Patra]

There is no simple answer. The fact is Full frame will have bigger pixels, so better light gathering capacity and hence better low ISO ability.

If you are able to shoot with a wider f stop and hence able to use a lower ISO, then the noise will be better. You can get f1.8 or wider f stops in lenses in the wide angles. Else f2.8 is the widest for telephoto lenses.

There is ofcourse a 200mm f2 lens. F2 is one stop wider than f2.8

So if you are shooting at f2 instead of f2.8, then you will be able to use one stop lower ISO. f1.8 is one third stop faster than f2.

Remember that the depth of field would be extremely shallow at those wide apertures so unless you are extremely careful in focusing, the image will be soft due to lack of focus.

I find my 5D III (full frame) and 1D Mark IV (1.3 crop) better in its low light ability than the 7D. Just check the kabini leopard images shot with 1D Mark IV and the ones shot by others with 7D and you get a rough idea about noise.

However, remember that if you want to shoot in very low light situations even the f1.8 won't be sufficient. I was waiting for a leopard to appear in the night and the scene needed 40,000 ISO at f2.8. So you have to tell us which scene you are planning to shoot and then we can tell if it is practical or not.

Canon has a 50mm f1.4 which is cheap. The 50mm 1.2 is around a lakh and then there are cinema lenses which are pretty costly.

I have been bitten by Sigma before. Their lenses didn't work with the new Canon firmware. Every time you use a new camera body, there would be a potential chance of mismatch. Canon and Nikon don't reveal the full specs to the third party lens manufacturers. So not always they get it right. The new Sigma 24-105 f4 didn't autofocus well with Canon cinema lenses. Then Sigma changed the firmware and I am told it works now. However, I have decided to only stick with Canon lenses, so all colours match even though different canon lenses were used.

[Jitendra Katre]

Any opinion about Samyang 14,f/2.8?

[Jitendra Katre]

Thanks Sabyasachi for the detailed answer. Actually doing landscapes during night is in my mind... Even 50mm on a crop body will be too much for this work. Only widest Canon lens I know is 20 mm, 2.8.(of course there is 16 35, but right now i am not prepared to pay so much) ...maybe Samyang 14 mm, 2.8?

[Sabyasachi Patra]

Samyang (branded Rokinon in US) are low cost lenses and are fine for normal shooting. Recently the Samyang has become popular among budget shooters. The Canon 14mm f2.8 L II USM lens is actually very good. Unfortunately, the Canon is costly as well. However, if you want to really put up poster size prints, the Canon should be the one to go for. However, all of us struggle with budgets. I am also trying to get an even costlier Canon 14mm cinema lens. So the Samyang at 1/7th the price of the Canon EF 14mm f2.8 L II USM lens is an easier option.