Canon 400mm f5.6 vs f2.8?

Shoreline

Shoreline

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Martin
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Hi, please forgive me if this is a dumb question but could someone give me a definitive answer to the following question please? I currently use a 7D + 400mm f5.6 for wildlife shots. I can get great images in good light if the subject distance isn't too far away (obviously). My question is, given identical shooting conditions + identical camera settings etc, would the 400mm f2.8 resolve more detail than the 400mm f5.6 at the same distance? I appreciate that detail falls off as distance increases, but would the fall off in detail be less with the 400mm f2.8 than with the 400mm f5.6?

Thanks in advance for any help with this.

Martin
 
If you look at the MTF charts on the Canon website then yes, the 400mm F2.8 is capable of resolving more detail for the same distance.

I'm not sure what you mean by falloff in detail though...
 
f/2.8 is almost 10x more expensive (Ok slightly less but you get the idea). The first question is could you realistically invest that money in one.
Then in theory f/2.8 would resolve better, particularly at f/5.6. There are other factors like software used, and technique. This could add up to perceptible difference, but presuming you have exhausted it it's a huge bill to pay.
 
The resolving power of the lens plays a valid part in the equation but environmental factors come more into play as your subject distance increases. Heat haze and humidity in the air can nullify the benefits of having a lens that gives you the potential for more distance.

Bob
 
Thanks for the replies everyone. I think the bottom line is that I just need to find a way to get closer to some of my subjects but there are so many places where I can see the birds but where it is impossible to get any closer due to the laws of trespass etc :nono: It is so frustrating! Consequently I end up heavily cropping a lot of my shots and of course there are limits to how far you can go. I just thought that if the difference in detail resolution, between the two lenses, was going to be night and day then it might just be worth the expense and the effort of lugging the f2.8 around. However, I do take the point about atmospherics because I've seen the effects of that very clearly.

Thanks again for the replies.
 
the main benefit for getting closer with a 400f2.8 is to stick a doubler on it and have an effective 800 f5.6

for a slightly more affordable option you could look at the sigma 120-300 f2.8
 
The 400 F2.8 is awsome glass and something which hasn't been mentioned is that it allows you to use the 1.4x or 2x convertors whilst retaining autofocus. Neither of these can be used with the 400 F5.6 to enjoy the same benefit.

My 400 F5.6 is never used..... If ... When I get a 2.8, it will be used all the time!!

:D

Edit: ok, it has now been mentioned as bsm beat me to it.
 
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