Buying a 1.4 vs. 2.8 lens
For the purpose of discussion; Let’s say you would be happy to buy a f2.8 lens and think you will want to shoot at f2.8 shouldn’t you still consider a faster lens since most tend to shoot sharper two or so stops over open?
Cost might be a reason. Whether the lens is IS / VR enabled might be consideration. Whether the options are from the manufacturer or include third-party lenses.
par4fore wrote:
For the purpose of discussion; Let’s say you would be happy to buy a f2.8 lens and think you will want to shoot at f2.8 shouldn’t you still consider a faster lens since most tend to shoot sharper two or so stops over open?
The question is now, is the f/1.4 lens sharper at f/2.8 than the f/2.8 lens? You really wouldn't know unless you test them or have some trusted lab test them.
BebuLamar wrote:
The question is now, is the f/1.4 lens sharper at f/2.8 than the f/2.8 lens? You really wouldn't know unless you test them or have some trusted lab test them.
If lenses are sharper away from their maximum aperture, wouldn't logic dictate that the 1.4 would be somewhat sharper at 2.8?
Price is usually the reason for me. Yes, I would rather have a f1.4 over a f1.8. But if a f1.8 is satisfactory, it generally is OK to many of us. Nikon makes a 105mm f1.4 for $2200. The 105mm f2.8 is far less expensive. Or any other Third Party lenses in that category. And, another thing to consider. Will you always need f1.4?
Longshadow wrote:
If lenses are sharper away from their maximum aperture, wouldn't logic dictate that the 1.4 would be somewhat sharper at 2.8?
Yes that's what people said and that's what the OP mentioned too but is really true? Is my Nikon 50mm f/1.4 is any sharper than the 50mm f/1.8 version with both at f/2? I can't be sure as they don't look that much different but tend to think that the f/1.8 is a bit sharper.
BebuLamar wrote:
The question is now, is the f/1.4 lens sharper at f/2.8 than the f/2.8 lens? You really wouldn't know unless you test them or have some trusted lab test them.
It might be more relevant if the 1.4 lens is just as sharp / shaper at f/2 as the f/2.8 lens is at f/2.8. That's a stop more light with no image quality penalty, other than maybe composition challenges due to the narrow depth of field, assuming both are primes. An f/2.8 zoom could provide more flexibility at different focal lengths, that are maybe more useful, than sharpness at a given aperture and focal length.
In this example the difference in sharpness would be so minuscule that your shooting technique or post processing technique would completely override it. This applies to most discussions about minute differences of sharpness in general, IMO. Theoretical but not very practical.
par4fore wrote:
For the purpose of discussion; Let’s say you would be happy to buy a f2.8 lens and think you will want to shoot at f2.8 shouldn’t you still consider a faster lens since most tend to shoot sharper two or so stops over open?
I don't think it's a matter of sharpness when wide open verses stopped down a stop or two. Todays lenses are very sharp wide open and not as much when stopped way down past f/22. My 300mm f/2.8 and my 70-200 f/2.8 are tack sharp wide open. You don't get any sharper than that.
Longshadow wrote:
If lenses are sharper away from their maximum aperture, wouldn't logic dictate that the 1.4 would be somewhat sharper at 2.8?
This is a big "if" that is a useful generalization, but maybe not applicable when you get to the high-end models where the max aperture is already perfection. And where sharpness intersects between two models is a case by case comparative analysis, not a linear relation with universal application.
Great feedback, Thanks! I was going for theoretical but not practical.
par4fore wrote:
For the purpose of discussion; Let’s say you would be happy to buy a f2.8 lens and think you will want to shoot at f2.8 shouldn’t you still consider a faster lens since most tend to shoot sharper two or so stops over open?
As a quite general rule, Yes, and it will focus better too ......
All general consumer grade lenses get sharper stopped down and expensive 1.4/1.8 lenses are designed to be sharper at all f stops - but especially stopped down ! ( within reason) - one reason they are expensive.
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par4fore wrote:
For the purpose of discussion; Let’s say you would be happy to buy a f2.8 lens and think you will want to shoot at f2.8 shouldn’t you still consider a faster lens since most tend to shoot sharper two or so stops over open?
The problem with that is not every F 2.8 lens has a 1.4 option... the 17-50mm Sigma the 24-70mm or the 70-200, the most glass that you find this F2.8 -1.4 option in, are Prime lens.
mrpentaxk5ii wrote:
The problem with that is not every F 2.8 lens has a 1.4 option... the 17-50mm Sigma the 24-70mm or the 70-200, the most glass that you find this F2.8 -1.4 option in, are Prime lens.
If a 2.8 lens has a 1.4 option, wouldn't it be a 1.4 lens???
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