are these acceptable from 70-200(last time i ask)

[summerwind4]

i think it has more to do with the 20D's AF system but i'd like your opinions please.

now i am posting these sample i shot this morning at 70mm where i see the only problem with my new 70-200 f/4L.

first i did another shot at a focus chart, but not sure if i did it right (feel free to kick me)

http://www.pbase.com/image/45666389/original (http://www.pbase.com/image/45666389/original)

then i shot this sign and got 2 different results

http://www.pbase.com/image/45666157/original (http://www.pbase.com/image/45666157/original)

http://www.pbase.com/image/45666270/original (http://www.pbase.com/image/45666270/original)

then these random shots.........

http://www.pbase.com/image/45665560/original (http://www.pbase.com/image/45665560/original)

http://www.pbase.com/image/45665883/original (http://www.pbase.com/image/45665883/original)

http://www.pbase.com/image/45665943/original (http://www.pbase.com/image/45665943/original)

http://www.pbase.com/image/45666241/original (http://www.pbase.com/image/45666241/original)

http://www.pbase.com/image/45666318/original (http://www.pbase.com/image/45666318/original)

they don't look like there is a problem, but i'd like your opinions.
it may just have to do with what is said in this article

http://www.fredmiranda.com/forum/topic/241524 (http://www.fredmiranda.com/forum/topic/241524)

[tim]

Looks to me like it's focusing where it should on the focus chart. Remember the area behind the focus point will be in focus for longer than in front of the focus point because of the way things work - usually 1/3 in front and 2/3 behind, but that's just a rule of thumb. It doesn't look particularly sharp, but wide open that's probably not unusual.

[Pekka]

The lens output looks fine.

[Keiffer]

Well the second sign shot is more in focus. But is that you or the lens?

[summerwind4]

Well the second sign shot is more in focus. But is that you or the lens?

it was the lens, autofocused by the 20D using all AF points activated.

i just did another focus chart tests and then a ruler test. the ruler shows everything to be in order.
i'm starting to think it may be the focus square (being larger than the square itself) is the culprit.

[Phil V]

it was the lens, autofocused by the 20D using all AF points activated.

i just did another focus chart tests and then a ruler test. the ruler shows everything to be in order.
i'm starting to think it may be the focus square (being larger than the square itself) is the culprit.

I'm beginning to think it's the operator that's the culprit, ;) allowing the camera to select the AF point and then complaining it didn't do what you wanted is a little naive. No camera yet invented can mind-read, you have to tell it what you want it to do, then it'll do it; if it doesn't there's a problem. But don't keep inventing impossible tests for equipment then questioning why they failed.

Read a few photography books, then go out and take some pictures, the kind of pictures you'll be happy to show your grandchildren. Not the kind of pictures you can post on the internet to show how good/bad/expensive/cheap your gear is.:)

[summerwind4]

I'm beginning to think it's the operator that's the culprit, ;) allowing the camera to select the AF point and then complaining it didn't do what you wanted is a little naive. No camera yet invented can mind-read, you have to tell it what you want it to do, then it'll do it; if it doesn't there's a problem. But don't keep inventing impossible tests for equipment then questioning why they failed.

Read a few photography books, then go out and take some pictures, the kind of pictures you'll be happy to show your grandchildren. Not the kind of pictures you can post on the internet to show how good/bad/expensive/cheap your gear is.:)

OMG!!
i shot original test pics with AF set to center (with me so far?) ,these came out really soft, and then did the same shots again letting the 1 of (or all) AF points select the point of focus............in each case, the shots where the camera AF points were activated, the 70-200 @70mm (which is where the problem is) and at f/4 (still with us?) the shots came out perfectly focused.
where do i need a book to tell me what i did wrong?
i have been in photography for at least 15 years, but never encountered a lens that would focus absolutely perfect at 200mm and then backfocus at 70mm (the wide end).
so you say i should go out and shoot pictures with this lens and then tell the kids that they really were the target when the kids in the background were sharper?
show me the book that shows this technique and i'll buy it.:rolleyes:

[Phil V]

OMG!!
i shot original test pics with AF set to center (with me so far?) ,these came out really soft, and then did the same shots again letting the 1 of (or all) AF points select the point of focus............in each case, the shots where the camera AF points were activated, the 70-200 @70mm (which is where the problem is) and at f/4 (still with us?) the shots came out perfectly focused.
where do i need a book to tell me what i did wrong?
i have been in photography for at least 15 years, but never encountered a lens that would focus absolutely perfect at 200mm and then backfocus at 70mm (the wide end).
so you say i should go out and shoot pictures with this lens and then tell the kids that they really were the target when the kids in the background were sharper?
show me the book that shows this technique and i'll buy it.:rolleyes:

So;
You know what you are doing, you tested the lens, you know it's bad, why are you asking our opinion and not shipping it to Canon to have it fixed?

However; of the shot's I saw ( I admit I haven't read all your threads or examined all your photo's), the test chart appears to be in focus, the sign shots have obviously different areas of focus (as I would expect from shots where the camera is allowed to choose the focus point). But if you're convinced you are right send it back to Canon.

[summerwind4]

Phil,

i'm not trying to waste anyones time, and while i do know what i'm doing and have tried various settings, time of day with various daylight, i am worried about sending it in and having it screwed up. call me a worry wart (i would agree) but i see more trustworthy knowledge here on this site than i have faith in Canon. example, they recently fixed my Pro1 but i had to send it back because the new sensor they installed came back looking like a Christmas tree.

having shot a bunch more shots of various scenes today and then with flash showed me something i really can't figure out.
let's forget all the test shots i have up at this time, and consider this.
all the shots i did at 70mm@f/4 showed me that the focus would be on/off in about a 40/60% ratio. some of those shots indoors were not bad, but were dead on accurate when done with flash...i mean no back focusing whatsoever. now if i have the lens calibrated on the 70mm end, will i then lose accuracy with flash shots?
i'm starting to believe the article that is posted here

http://www.fredmiranda.com/forum/topic/241524

about the 20D's AF system as this looks to be whats going on.

feel free to give me your thoughts on the calibration and what may happen when using flash.

[Tom W]

I wonder if there's a low-light focus issue - that is, with flash, you get the focus assist light (assuming that it isn't disabled) from the flash, while other indoor shots don't quite have enough light to work as consistently.

As you've noted (and is pointed out in RDKirk's explanation on the FM link), the focus sensors are a good deal larger than the indicators and will react to any high-contrast boundary they find. With less light, maybe it's finding a target other than that which you intend, even if you have the active focus point on the subject.

Just some thoughts for a little more experimenting.

[93octane]

I have been following summerwind4 post because I myself have 70-200 F4L I haven't been able to use because of my 300D in the shop. Anyways I have read that the problem he is having seems to happend with 20D more often. Other people with 300D and 10D have no problem with this lens camera combo. There are so many variables its hard to determine Camera, focusing points larger then shown on viewer, lens,etc... I'm curious to find out.

[summerwind4]

I wonder if there's a low-light focus issue - that is, with flash, you get the focus assist light (assuming that it isn't disabled) from the flash, while other indoor shots don't quite have enough light to work as consistently.

As you've noted (and is pointed out in RDKirk's explanation on the FM link), the focus sensors are a good deal larger than the indicators and will react to any high-contrast boundary they find. With less light, maybe it's finding a target other than that which you intend, even if you have the active focus point on the subject.

Just some thoughts for a little more experimenting.

Tom, this is exactly what it is.
DavidP over at Fred's pointed out a technique that i had forgotton all about.
focusing at 200mm and then zooming back to 70mm.
i redid several shots this way and in good light and being very careful of where the focus point hit, it made no difference. in shadowed scenes however, it made little difference at f/8, but the f/4 shots resulted in quite a difference.
further test shots on the same scenes where i used flash, only this time i enhanced the lighting, showed no backfocusing at all.
i feel so stupid for having not remembered this technique, but alas it's over.......i will no longer agonize over this.
i new this lens was a keeper from the very first shot, but it seems L glass brings out the mad scientist in some of us:lol:

[summerwind4]

I have been following summerwind4 post because I myself have 70-200 F4L I haven't been able to use because of my 300D in the shop. Anyways I have read that the problem he is having seems to happend with 20D more often. Other people with 300D and 10D have no problem with this lens camera combo. There are so many variables its hard to determine Camera, focusing points larger then shown on viewer, lens,etc... I'm curious to find out.

you'll know if it's working right then..LOL

don't worry over it, i'm sure it'll be fine.
mine is every bit as sharp (even sharper) as i expected.
the first one i tried wouldn't focus properly to save it's life, so this is what led me to all this agony.:rolleyes: