70-200 F4 IS

[ultima16888]

well, the point i'm trying to make is that during regular shots, the image still looks like this... ie shutter speed 400th of a sec.


as for autofocus, I do need it to perform because I never quite get to learn how to manual focus without it being too soft, probably just me and my glasses thing.


the lens at F8 if you look at the ISO chart Bryan made, is softer, and I've made tests before same result, it becomes softer due to defraction or some oddity reason.


it is iso 100, RAW, contrast +1, sharpness +1, awb.


distance from sensor to target is 2m





but i thought the idea is that the lens is canautofocus reasonably, hand hold at slower shutter speed whilemaintainingit's sharpness reasonably well. Anyways.


Here is another one.(and DOH I guess I introduced another change, different block of type, but anyways it's just few lines down, I'm not trying to do a review so here we go, a round of applause for Bryan and his relentless testings, it'strulyaxxl to perform such test.)


mirror lock up, autofocus, 1 sec exposure (well because of F8) F8, 200mm 2 meters away from test sheet, ISO 100, RAWcontrast +1, sharpness +1, awb. (and as oddly expected of f8 for this lens, it's softer) again, if the lens can't take a sharp image with these settings, is it a lemon(I guess at least a mushy one)? this is the 2nd lens that I got and it's already gone back to canon once. it's mysterious to me how you prosdetermineif you have sharp copy and go about replacing it if it's not.


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[cian3307]

Hi, this might be a stating the obvious, but have you used the lens without a filter attached? I had terrible trouble with unsharp pics from my 300L that turned out to be caused by a counterfeit UV filter!

[ultima16888]

I got my filter from Sammy's they are Heliopan from Germany, cost around $100 if I remember correctly, but I'll give it a try.


same setting as above, sharpness seems to improve. a little F8 without filter


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here's F4 without filter. seems much much better. I didn't think the filter would make that much difference.


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the results seems to be in reverse of the earlier sample shot, could it be with the filter on the F8 amplified the imperfection of the filter? but at F4, the image is still a bit to soft compare to Bryan's ISO crop.

[cian3307]

The filter that caused my problems was a definite counterfeit. A good quality filter shouldn't degrade image quality that noticeably. Perhaps some one who knows more about this sort of thing can advise?

[peety3]

Could we see some shots with shutter speeds faster than 1/250th?

[Ian McFarlane]

Hi


I recently bought the 70-200 F4 L IS and I'm also experiencing "soft" images in certain situations, particularly when taking portraits of animals (my dogs, horses, etc). I'm finding that the pictures have a general "softness" to them, but most disturbing is the fact that I'm not getting the pin-sharp pics I expected from a L series lens.


Most of the pics I've taken have been at fast shutter speeds (so probably at F4 or F5.6), with the image stabiliser on. When I do get a sharp picture, the depth of field seems to be very shallow, or the area in focus isn't exactly where I expected (when taking a dog's picture, I always focus on the eyes, but I've found that the area that is in focus in many of the picsseems to be just in front of the eyes).


I don't know ifa shallow depth of fieldis a characteristic of the L series lens. I'm taking most of the pictures from a distance of about 5 - 8 metres, so it's not like I'm having problems with the minimum focussing distance. Most of the pictures have been taken next to my house in the shade, or in slightly overcast conditions.


This is happening both with my 20D body and anew 450D body. I'm getting much sharper pics from my old 28-200 lens (without IS) and the 18-55 IS kit lens that I got with the 450D.


I suspected that the auto focus was faulty, but I took several pictures at a horse show jumping event and test shots of other subjects around the garden and got much more acceptableresults.


I read with interest thatan inferiorUV filter could cause problems, so I will be doing sometests this weekend without the filter.


Ian