p.1 #1 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
What would the sharpest aperture be on the 300mm 2.8 is,the 200 2.0 is, and the new 70/200 Mark 2
You read a lot how sharp they are at f.2.8 and f 2.0,but stepping down are they still as sharp up to f11 or f13 or higher,do you loose any IQ,i know most use at f2.8 or f2.0 for the bokeh.
And if you wanted to use in studio and get some DOF for heads shots or portraits,would would be the best aperture for this ? Thank you.
p.1 #2 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
The 300 2.8 IS is definitely very sharp from f/2.8 to f/11, so it's really up to you how blurred you want your background to be. Shooting in a studio, you probably want things more in focus, so just set the lens to f/8 and leave it there unless you need to let some more light in.
p.1 #4 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
Superteles are designed to be pretty freakin' sharp wide open. Not much is gained stopping down beyond 2/3 to 1 full stop.
My experience is limited to Canon's/Nikon's 300 f2.8 and 200 f2 offerings, but my friends with the 400 f2.8's agree
with my findings on their glass too. YMMV on f2.8 zooms, I've found f5.6 still pretty darn sharp.
Sep 06, 2010 at 11:56 AM
AmbientMike Offline • • • • • • [X]
p.1 #5 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
Usually lenses are sharpest around f/8. Sometimes f/11, sometimes f/5.6.Have seen graphs of the sharpness of 300/2.8, I think non-is, on the web. With lenses, usually you lose some by f/16 but not always, and will you see it anyway? Canon's 300/2.8's are great but I doubt they'll be sharpest wide open. 2.8 is probably their worst aperture until 16 or 22. My old Tamron got 51 lp/mm wide open, the 300 2.8 is probably above 60 wide open and 80 stopped down in the center.
p.1 #8 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
60lp/mm or 80, it's sharp as hell no matter what aperture.
Sep 06, 2010 at 12:13 PM
AmbientMike Offline • • • • • • [X]
p.1 #9 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
The big advantage of the 200/2 and 300/2.8 lens for portraits is to use it wide open to throw stuff out of focus. If you stop it down, you'll get more depth of field, haven't done any studio stuff with this length, though. f/8 or f/11, but that's just a guess. Perhaps try it and see what you like. 200 depth of field will be the same with zoom or prime. 200 prime should be sharper, but whether you'll see the sharpness compared to a good zoom or even want it for a portrait is another matter.
p.1 #12 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
AmbientMike wrote:
Usually lenses are sharpest around f/8. Sometimes f/11, sometimes f/5.6.Have seen graphs of the sharpness of 300/2.8, I think non-is, on the web. With lenses, usually you lose some by f/16 but not always, and will you see it anyway? Canon's 300/2.8's are great but I doubt they'll be sharpest wide open. 2.8 is probably their worst aperture until 16 or 22. My old Tamron got 51 lp/mm wide open, the 300 2.8 is probably above 60 wide open and 80 stopped down in the center.
relatively few lenses are sharpest at f/8 these days
fast lenses are often sharpest at f/4-f/5.6
and slower ones at f/5-f/6.3
(although it gets tricky if you count corners/edges and sometimes corners may peak at f/5.6-f/11 while the center does at f/4-f/5.6)
although some consumer f/5.6 lenses, like a 70-300 IS at 300mm probably don't reach peak until f/8
I think that you are way wrong in saying that the 300 2.8 IS is worst at f/2.8 until f/16-22! My guess is that it peaks at f/3.5-4 and would already be no better than f/2.8 by f/8.
p.1 #13 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
The only reason to stop down beyond f3.5 is for add'l DOF. My 200 f2 right at f2.5 Real world, in my fat hands results.
Who ya gonna believe For the MTF parrots we're talking center sharpness AND actual images.
Sep 06, 2010 at 04:06 PM
AmbientMike Offline • • • • • • [X]
p.1 #14 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
Faster lenses tend to get sharper at a wider aperture, yes. You'll notice I said "sometimes 5.6." Yeah, I guess the newer lenses do get sharper quicker in the center, have tested a couple of macros that seem to do this or close, forgot about those earlier. Been looking at test reports for older lenses and trying to get good corners in scenics a lot lately. But as two people said above, it needs to be stopped down a stop for sharpest performance. The kit lens was quite sharp wide open or close in the center, but needed to be stopped down in the corners. Used the 50/1.8 at f/11 and was happy to get good corners.
The guy posted photos of f/8 being better than 2.8. Iif the above photos are to be believed, f/8 is better than 2.8, and you will have to stop down more to decrease sharpness, and that's getting close to f/16. The mtf charts from canon say the same thing, f/8 vs. f/2.8 if I read them right.
The guy asked for the sharpest aperture, not how far until you couldn't see the difference. If we're talking real world, it might get interesting what sort less expensive lens looked similar to a 300/2.8 in images, esp. stopped down. Not sure how noticable 10-15lp/mm advantage is in real photos, although I would certainly prefer it.
p.1 #15 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
morrismediagro wrote:
What would the sharpest aperture be on the 300mm 2.8 is,the 200 2.0 is, ....
And if you wanted to use in studio and get some DOF for heads shots or portraits,would would be the best aperture for this ? Thank you.
I don't believe 300 f/2.8 and 200 f/2 IS see much studio use. One can do very viable studio photography with much much cheaper lenses.
One key factor in choosing those lenses is not to have to worry about their optimum sharpness point. The lenses are sufficiently sharp for all aperture values of interest in practical photography. Therefore, instead of having to worry about the lens intrinsic sharpness, one can manipulate the aperture in order to achieve required shutter speed as well as other IQ objectives such as subject isolation/background blurring, DoF, ISO noise reduction etc.
p.1 #19 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
I own the EF 300/2.8L IS, so I can tell you from first-hand experience that from f/2.8 - f/8, anything at critical focus is equally sharp on a 5D2. There is just the very slightest, tiniest hint of diffraction beginning to affect sharpness at f/8 that you can see in a test chart, but in practice, you would find it extremely hard to see any difference from f/5.6 to f/8. However, diffraction does become noticeable at f/11 and slower.
The only difference is some loss of contrast due to vignetting wide open, which disappears by f/5.6.
You can certainly use this lens for studio portraiture, but only if you have a lot of space, or if you only want headshots. The DOF is really thin wide open and near MFD--thin enough that if the subject's face is not perfectly parallel to the camera, you will find it difficult to get both eyes in focus.
Full-body portraiture is possible but you would need a good 50-80 feet of distance between you and your subject. The effect is really nice, though. The EF 200/2L IS is a better choice in this regard, as well as the 135/2L.
p.1 #20 · Canon EF 300mm f/2.8 L IS USM Sharpest Aperture
You see, there is a consensus among 300 2.8 IS owners regarding center sharpness in the plane of focus:
f/2.8 and f/8 are about equally sharp
stopping down to f/3.5 improves a little, but hardly visible on FF cameras
The peak sharpness is reached at about f/4.5, but the difference from f/3.5 is really really hard to find, even on the highest pixel density camera.
From around f/11 diffraction will make it less sharp than f/2.8
But as already mentioned many times, the wide open sharpness is still remarkable.
Take a near perfect lens like the 135/2 L. You need to stop that one down to stops to about f/4 to match the sharpness of the 300 2.8 IS wide open. That speaks volumes and should sum it up:
For real world use, the relationship between aperture and sharpness is the least important thing to consider when selecting aperture. If you want thin DoF, don't be afraid to use 2.8 all the time.
Unbelievable!
For the MTF parrots we're talking center sharpness AND actual images. 
