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DPChallenge Forums >> Tips, Tricks, and Q&A >> 100-400L IS Lens Quality
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Showing posts 1 - 19 of 19, (reverse)
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 08/03/2005 01:14:33 PM · #1
I have a couple of questions. First do you know what type of hawk this is? There are four of them that have decided to hang out together atop a tree in my back yard. Second, this photo was take with a canon rebel body and a 100-400L IS lens at about 100 feet up. What is your opinion about the quality of this image?

08/03/2005 01:42:52 PM · #2
No Replies???
 08/03/2005 01:48:07 PM · #3
Looks pretty sharp to me. But the features are pretty small. How about showing a 100% crop of the bottom hawk?
 08/03/2005 01:48:42 PM · #4
Looks pretty sharp, oversharp even...did you sharpen in PS?
 08/03/2005 01:56:08 PM · #5
On a purely technical note, it's utterly useless to check the sharpness of a lens with a resized image -- what you end up checking is the sharpening or softening effects of the resizing algorithm.

I did zoom it in a bit to look for any signs of CA, since this is a shot just about perfect for trying to find it (dark branch against a very bright sky), and didn't see anything, but again, it may be obscured by the resize.
 08/03/2005 01:56:34 PM · #6
Yes I did sharpen in PS. I just thought I could have gotten more detail from a 400L lens
 08/03/2005 01:58:11 PM · #7
Definitely looks over sharpened to me.
 08/03/2005 02:00:59 PM · #8
Originally posted by PhotoRyno:
Yes I did sharpen in PS. I just thought I could have gotten more detail from a 400L lens


More detail? what do you mean? That shot is a tough lighting situation , you are shooting dark subjects in a backlit situation...
 08/03/2005 02:02:06 PM · #9
...and without knowing exposure settings it's hard to say anything about the lens quality.

P.S. My wife has this lens and it is a fantastic lens.
 08/03/2005 02:27:43 PM · #10
Originally posted by PhotoRyno:
Yes I did sharpen in PS. I just thought I could have gotten more detail from a 400L lens

It's not a "400L lens" it's a 100-400L, which is quite a wide range, and fairly telephoto too. This coupled with the fact the lens design is pretty old means it's not going to be has hot as, say, a 70-200L. That said for the range the lens should be pretty good. You really need to post unsharpened full size images to get a reasonable evaluation. From reading reviews (as others may have said), between 300-400 the lens does get somewhat softer.
 08/03/2005 03:05:02 PM · #11
OK here is the full size photo, only reduced for web upload.
exposure settings
FL=360
ISO=100
Speed= 1/400
F Stop=6.3
Manual

...and how do I look for signs of CA?
08/03/2005 03:15:17 PM · #12
Originally posted by PhotoRyno:
OK here is the full size photo, only reduced for web upload.

This still doesn't help. What you need to do is crop a 640x640 chunk out of the photo so that no resizing happens. Try to get a crop that shows two things: the head of a hawk, and a length of relatively straight, unadorned dark branch against bright sky. Don't do any sharpening at all.

Originally posted by PhotoRyno:
...and how do I look for signs of CA?

Look for a strange color fringe along a high contrast edge. Most common are red, cyan, or purple edges along a line where dark pixels meet light pixels.
 08/03/2005 03:24:05 PM · #13
On that pic, did the focus point beep before you took the picture? (IE. did auto focus confirm you were in focus?)
 08/03/2005 03:41:50 PM · #14


Yes the focus point did beep

I also did not notice a strange color fringe along a high contrast edge
when I zoomed in

Also what about the bird ID, anyone know?

Message edited by author 2005-08-03 15:46:01.
 08/03/2005 03:50:01 PM · #15
Looks like you focused on the leaves.
 08/03/2005 04:25:19 PM · #16
Just to hard to tell the ID of the bird based on this shot. Without more facial detail or better light it would be a guess. this time of the year there cna be many juvenile birds out there that complcate matters even more.
 08/03/2005 04:39:05 PM · #17
They look like a typical chicken hawk to me.
 08/03/2005 04:59:19 PM · #18
Originally posted by PhotoRyno:


Yes the focus point did beep

I also did not notice a strange color fringe along a high contrast edge
when I zoomed in

There is a very, very slight blue/yellow CA line along the branch (blue below, yellow above), but you have to be looking at 400% to see it. In other words, nothing to worry about.

Did you use all-points autofocus, or a single point focusing on the bird? As someone else suggested, it looks like the image is focused on the leaves behind the birds, not the birds themselves.
08/03/2005 05:01:03 PM · #19
As a second question, did you have IS on? There may be slight motion blur involved as well, though I would have expected you to be okay at 1/400 for a 360mm focal length.
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