70-200 F4 IS sharpness issues

[KRobA]

This may or may not help but I find that the point of max contrast (although as someone corrected me) not max resolution is further forward at f/4 than f/8 at 200mm & 1.2m. If you have not already tried, check out the lens with some 45 degree angle shots of a newspaper. My lens gives acceptable if not stunning pictures at 1.2m/200mm if I stop down and then move backwards slightly to overcome the lens's apparent back focus problem. (Note this back focus is not apparent at f/4 & 1.2m just on stopping down).

Has anyone that has sharpness issues at close distances (1.2-2m or
so) with 180-200mm focal lengths (especially 200mm) tried sending
it in to Canon?

It seems that some claim that stopping down solved the problem (if
i understood), but mine actually gets worse, especially at f7.1. i
get different results at every aperture, none of them pretty. It
generally performs fine elsewhere, at distance, and even close at
lower focal lengths, so i don't believe it's focus or depth of
field.

tests done - setting (no tripod, but equivalent) on steady surface,
mirror lockup, measured distance, AF, IS off, shutter speeds of
1/320 or so, decent light, little if any wind. ( i think the tests
were well enough controlled).

 

[Conradm]

I will try this, maybe tomorrow, but i must ask, if this is the case, can this be fixed, is it normal? If sent to canon, will the 'problem' be corrected (by other's experiences)? it doesn't seem normal that the focus point would change (even if explainable by something like SA), but then i get the impression that the 'threshold of visible errors' might be much more noticeable with this lens, at that focal length and distance to subject, then maybe with others.

it seems concerning that i must accept any problem with a lens operating within its specified domain for $1k.

in the end, maybe one must consider what the lens would be like if specs were 70-200mm, min distance of 2m, as a product. sure, having the extra .8m would be a treat, a bonus, even if not sharp. but it says 1.2, and by 1.5, meeting others minimums, i think it should have its problems resolved, regardless of what they are. for $500 dollars, i would easily let it slide, especially with no red strip.

 

[Mike.]

Hi mfurman,

Actually I didnt realise this at all, but related my experience with the 'old' 70-200 F4L (non-IS) - it was boxed brand new and opened in front of me, as were the F2.8 and F2.8IS, I opted for the F4 simply due to its size and lack of pocket money - I later found it was backfocusing pretty badly and had Canon take a look at it. It came back with spot on focus. For me the Service center is fairly close, drop the camera in and with a day or two turnaround quicker than sending it back to the store..

-Mike.

Do you realize that there have been already a few people with less
than perfect 70-200 f/4.0 L IS? It was supposed to be almost an
ideal lens

http://www.photozone.de/8Reviews/lenses/canon_70200_4is/index.htm

--
Michael

'People are crazy and times are strange, I'm locked in tight, I'm
out of range, I used to care, but things have changed' - Bob Dylan

--
-Mike

 

[cityphotog]

this lens is capable of producing never seen before sharpness but it shows a couple of problems already. My idea is that we should wait a little before sending it to Canon since I don't believe that the fix will be so easy . But Canon gave us (during the recent months) some outstanding support with other items like the 70-300IS and the 24-105.
I am confident that they'll find a solution soon.

And we (the users, customers whatever we are) must report about it and put some pressure on Canon as well even if I believe that they know all about it already.

For now let's use the lens trying to avoid the problems because we all know how good that lens can be.

Just like the 70-300IS vertical issue many canon-fanatics here didn't want to admit the problem: thank God Canon didn't listen to them and made the recall on that lens anyway

LOL