My new 70-200 f2.8L IS compared to my old 28-135 IS

[Radtech1]

These are full resolution crops without any manipulation, shot with my 10D, in Large JPG mode.

The camera was tripod mounted. 28-135 was mounted tripod to camera, 70-200 was mounted tripod to lens ring, therefor, the subject to lens distance remained the same.

Focal lengths were verified to be identical through the EXIF data, specifically, comparing 75mm to 75mm and 135mm to 135mm. ( Then why the different FOVs? http://photography-on-the.net/forum/showthread.php?t=34229 )

All exposures were done using only the center focus point, aiming at the pink nose. All exposures were first set "out of focus" and the AF was allowed to find the focus itself.

To me, it looks as though that at 75mm focal length the L glass just barely has the sharpness edge. At 135mm, the 28-135 is clearly sharper. Am I being too picky, or would you feel the same about shelling out a months salary for a lens and then it does not stomp the one that you only had to work a week for?

28-135 IS at 75mm
http://users.adelphia.net/~radtech1/Photos/75lensX.jpg


70-200 L at 75mm
http://users.adelphia.net/~radtech1/Photos/75lensY.jpg

28-135 IS at 135mm
http://users.adelphia.net/~radtech1/Photos/135lensX.jpg


70-200 L at 135mm
http://users.adelphia.net/~radtech1/Photos/135lensY.jpg

[ron chappel]

Odd results but there could be explanations.
The first ones that come to mind are what aperture was the 70-200 set at?
The 28-135 is no real slouch and could easily be normally sharper wide open than the f2.8 lens is wide open

[maderito]

The 28-135 is a rear focusing lens whereas the focusing group for the 70-200 is internal to the lens body. Thus the field of view (FOV) is wider for the 28-135, a difference that is magnified when focusing at close range.

For more, see this thread: http://photography-on-the.net/forum/showthread.php?t=29357

Your subject is not a good one for checking image resolution. You are very close and the depth of field will be very small. Given your fuzzy subject, it is hard to know exactly what the lens is actually focusing on.

[Radtech1]

The 28-135 is a rear focusing lens whereas the focusing group for the 70-200 is internal to the lens body. Thus the field of view (FOV) is wider for the 28-135, a difference that is magnified when focusing at close range..

Well that is interesting. Thank you for the heads up there. Anyone know if the 28-70L focuses in the same manner?

Your subject is not a good one for checking image resolution. You are very close and the depth of field will be very small. Given your fuzzy subject, it is hard to know exactly what the lens is actually focusing on

Hmmm...

I would have thought that hair would be an excellent test. As far as being that close, those are crops showing 1/16 of the full frame. I was actully about 8 feet away. I saw no need to post 3 megs x 4 shots. This is what the full field looked like at 70mm.

http://users.adelphia.net/~radtech1/Photos/Full.jpg

[ron chappel]

Hangon....The 70-200's not front focusing is it?!

[DocFrankenstein]

From what I've seen in movies shooting, they always measure the distance to the subject from the camera body... or the "sensor" in this case.

Maybe if you mounted it in such a way that the BODY is the same distance to the subject, the results would be "better"

On the sharpness subject... One lens has an aperture of about 4.5 and the other 2.8 Of course you're gonna have a shallower DOF with 2.8

[JZaun]

Go back to your 135mm shot and crop the same for both pic's... they are crop'd or filling the frame different..


JZ

[Radtech1]

Go back to your 135mm shot and crop the same for both pic's... they are crop'd or filling the frame different..


JZ

The crop is exactly the same 768 pixels by 512 pixels, or exactly 1/16 of the original frame. Please go back up and re-read my original post, this time paying attention to the third paragraph.

Rad

[JZaun]

I did read your post but the pic's are a different size on the screen. You did ask for help and I gave you a opinion. It appears that the last pic is cropped closer. You go back and lookand pay attention to the pictures you posted! They are different!!

Just my thoughts take them or leave them but don't be touchy if you don't agree..

JZ