70-200L f/2.8 vs 70-200L f/4: The battle @ f/4

thaking wrote in post #9251657
if you're referring to his overuse of LOL, then i can't help ya there...

here ill add something new... hehe...

zshaft wrote in post #9251615
your statement doesnt make sense. where did u learn that ?

it absolutely makes sense... google "photo rotation degradation"

i dunno its just me but i see more CA in f/4.

canonnoob wrote in post #9251674
here ill add something new... hehe...

just givin ya a hard time..

just_a_hobby wrote in post #9251050
yes, dusk and dawn issue because of the low lighting, but not strictly. you can also use f/2.8 over f/4 when you want narrower DOF as well. And, also if you feel like working your arm a little too.

One other thing I didn't think about is the added AF precision, with my T1i, by using f/2.8.

OK, but how's the f/4 at f/2.8?

rijndael wrote in post #9250974
If your primary use for the 70-200 would be outdoor events for kids, when would you need the f/2.8 over the f/4? Strictly a dusk and dawn issue?

Read up on depth of field.

nphsbuckeye wrote in post #9252068
OK, but how's the f/4 at f/2.8?

Thanks. I'm familiar with the numbers @ the distances I want to shoot at. f/4 will suite my needs. For a quick and dirty look at the numbers I use this: http://www.dofmaster.c​om/doftable.html

Other than the added AF precision, I'm struggling to significantly nudge myself in either direction.

thaking wrote in post #9251657
do a quick google search for "photo rotation degradation photoshop" or something similar...you'll see that this can, and does, degrade the photo...

Keep in mind that the 5D mark II has 21 Msubpixels, that is much less information than 21 real RGB pixels (blame marketing, but saying the 5D mark II has 21 Mpixels is like saying that a 1280x1024 display has 4 Mpixels).

RGGB sensors favor spatial information at the cost of color information.
The optimistic will say that this helps a lot with spatial transformations like rotation.
The pessimistic will say that you do not lose much information because it is not there in the first place

I will just say I cannot notice any difference between the original and the rotated image.

crn3371 wrote in post #9251552
Maybe I'm just missing something here. I don't see really what this test proves, or disproves. One lens is stopped down, the other wide open. Either compare them both wide open, or both stopped down. To me, debating the sharpness of the 70-200 L's is kind of like debating the sharpness of Bic razors vs Gillette razors, they're all sharp.

Comparing these two lens is pointless simply because one is a f/2.8 lense with a metal rather than plastic barrel that has almost double the light gathering capability as well as a shallower DOF.

It's like comparing apples to oranges. Depends on what your cooking.

CheshireCat wrote in post #9253527
I will just say I cannot notice any difference between the original and the rotated image.

you may not notice any difference, but try this...rotate, save, open saved image...repeat...repea​t....repeat....repeat.​..repeat...you get the idea...after a while you'll notice degradation...just because you don't notice it doesn't mean it's not true...

blackhawk wrote in post #9254008
Comparing these two lens is pointless simply because one is a f/2.8 lense with a metal rather than plastic barrel that has almost double the light gathering capability as well as a shallower DOF.

This actually is the point.
The test is here to demonstrate that the f/2.8 IQ is almost identical to the f/4, so users should just decide if they need the extra stop, metal barrel, [you name it], instead of worrying about IQ.

And of course the f/2.8 has downsides too, but these are already discussed in other threads. The problems with most of these threads is there is always someone saying "don't buy the f/2.8 because IQ sucks"... and that is not going to help people choose the right lens for their needs.

thaking wrote in post #9254252
you may not notice any difference, but try this...rotate, save, open saved image...repeat...repea​t....repeat....repeat.​..repeat...you get the idea...after a while you'll notice degradation...just because you don't notice it doesn't mean it's not true...

Just because it is true it doesn't mean you will notice it if I do that only one time on a raw image

MHO wrote in post #9247306
. . . a little better sharpness (marginal!) from the f4 . . .

Lowner wrote in post #9250164
I see a very slightly sharper shot from the f/2.8.

And there you have it.

If you need the f/2.8, get the f/2.8. If you don't, don't. The f/2.8 gives you the one stop advantage, better low-light focusing, shallower DOF when needed. You can still shoot it at f/4.

All 4 of the lenses are great; you just have to get the one you need and can afford. If the price difference is not the deciding factor, ask yourself if all 4 lenses were on the counter and the clerk said "take the one you want" which would you take?

For me, with low-light applications for shooting ice hockey, it was the f/2.8.

f/2.8 rocks.

CheshireCat wrote in post #9256009
This actually is the point.
The test is here to demonstrate that the f/2.8 IQ is almost identical to the f/4, so users should just decide if they need the extra stop, metal barrel, [you name it], instead of worrying about IQ.

And of course the f/2.8 has downsides too, but these are already discussed in other threads. The problems with most of these threads is there is always someone saying "don't buy the f/2.8 because IQ sucks"... and that is not going to help people choose the right lens for their needs.

I'm being sarcastic, and agree with you. IQ was never an issue with this lense, and even the way it flares light is beautiful.
The 2.8 is Canon's most versatile, well balanced zoom, still even after all these years. It's very hard to fault.

The trade offs between these two, what you loose versus what you gain should more than justifies using the 2.8 version for most without a second thought.