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Old Jul 27, 2005, 8:32 AM   #1
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Posted: Wed Jul 27th, 2005 01:25 pm
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I am reading about this problem everywhere, and though i hate to say it as i own a 20D, they must have a design fault or at the very least bad production standards. I have been a pro photographer for years for a music magazine, working under demanding low light conditions, we are given 3 songs to get our shots often without flash.
I used to work on Nikon F100s and Fuji 400 transparency film. I would use everything from fast pro primes and zooms wide open to cheaper prosumer zoom lenses. I know for a fact that over 95% of my shots were razor sharp, if they weren't i'd never work again. I have not changed, only my system has from Nikon film to Canon digital which i did as often the speed of digital was being demanded by my clients and canons digital high iso noise was far better than nikons at that time. Dont get me wrong, i love digital and want to embrace it, but there are problems.
Over the past past few years I've shot on Canon 1Vs , and still own an Eos 3, 24-70L, 70-200L IS, 50f1.4, 20F2.8. I have often hired Eos 1D's mk 1&2, and have found their focusing systems to be very good. The 1D mk2 with a 70 - 200 wide open is exceptional! but its not the same across the board. I bought a 20D to play with last year, as i will wait until a 12mp 1D mk3 arrives, on paper it looks a bargain. In reality its erratic and unreliable, i am on my third one, the first 1 was fine at first then after 6000 shots just stopped focussing altogether, the second hunted continually and my current 1 has just started to miss focus at 12ft away!.
I dont even want to go into discussions of accepted digital image quality, camera handling techniques etc. I know what to expect with digital and its differencies to film. When i use an Eos 3 or 1D with my lenses, they are sharp, when i use them on my 20D they are not.
To prove the point i got a few of my friends together, all pro photographers (see http://www.andrewkendall.com). We tried each others lenses on a 1D mk2 , 20D, 300D and D60 to see the difference. The most startling result was with the 20D and 24-70L. We tried 3 separate copies of the 24-70L' at 24mm end f2.8 on single shot/ central sensor/ iso 400/ 12ft away in bright conditions and with 580ex flash. To rule out operator error we each took it in turn with each others lenses on our cameras. The 20D was the worst by far, focusing some 16 inches behind our subjects face, the 300D was a little better but not much, and the 1Dmk2 was very good but not perfect. The D60 was perfect, stunningly sharp. WHY? Because the photographer had adjusted his bodies AF with the Canon service software available some time back. If anyone can suggest where i can get hold of this software for a 20D or 1D's please let me know. I was amazed! I know i can take my camera to Canons CPS Pro? service. However their service takes over 2 weeks and they do not loan out any equipment to cover me. Why these cameras are not checked, or calibrated, before they're shipped must be due to economics of time delays and delivery to a competitive and fast moving market. And as my experience suggests they are sometimes supplied with faults or drift out of focus to an unusable degree Why isnt this calibration software available to the end user? If you or anyone reading this can help! Meantime maybe we should compile a list of unsatisfied customers, canon will not admit a fault but might accidentally leak a software solution?
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Old Jul 27, 2005, 8:57 PM   #2
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Did you do the same test with the 70-200? I'm just wondering if you will see the same calibration problem no-matter what lens you put on the 20D, or are you having a problem just with the 24-70 2.8L.

I have the 24-70, and found that at 70mm the focus is spot on (tested at f2.8 and f 2.8 , but I have a small amount of front focus at 24mm and f2.8 (about 1 1/4" with the camera about 3' from the subject). With my 70-200 f4 I get perfect focus at f4 for both 70 and 200mm, but at f8 I get a bit of back focus (7/8" at close to the minimum focusing distance).

The calibration problem isn't bothering me right now, but I plan on sending my equipment in to Canon service before my warrantee is up.
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Old Jul 28, 2005, 11:54 AM   #3
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Ive tried various lenses on both my 20D and Eos 3, as well as giving them to my other pro friends to try. They all seem off focus on the 20D and fine on the Eos 3 and 1Dmk2, the 24-70 is the worst at its wide end and better but not right at 70, the 20mm 2.8 is also bad. I get the impression that wide angles are affected far more. I shot rolls on 24 end of 24-70 at 2.8 and the focus, resolution & Dof are very good with that lens- at least on film. When i shoot the same thing on the 20D in exactly the same manner it misses massively. I have had the same problem with all my lenses! Mostly at distances over 12ft on the wideangles and over 20ft on the 50mm, and 70-200L, however the longer the lens the less of a problem it seems to be.

It has to be something to do with front or rear focusing lens elements? or the amount of focus travel within a lens ? or the distance of the rear elements to the sensor and that sensors relative size? (I converted a 30's 120 bellows camera a few years back to take a 3x4" polaroid back. As you would expect moving the film plane meant i had to remap the focus points on the bellows rail as they had no relation to the new back. I did this with some ground glass and candles at various key distances, remarking the new distances. The depth of field was critically shallow, but i did it and used it with 665 neg/pos polaroid to make 20x16 prints perfectly, however that was a fixed lens!. )

My point is this, Canon's current complex wide angle zoom lenses and the majority of their fixed lenses work within narrow ranges and at a set distance to focus/film plane for which they were designed! Changing the film/focus plane changes everything, and possibly these lenses cant stretch their old focus travel range to accurately be effective across the entire range in relation to the new sensor position. Perhaps canon have placed this sensor so that it works best on a popular combination say 35mm @ 6ft, knowing that an aperture of 5.6/8 should cover any slight focus errors. Wideangle Zooms are particularly complex, with a huge demand placed on them as they shift from wide to tele and have to focus from extreme closeup to infinity. I think they just never foresaw they might have to build in some slack for a digital future, so the older wide angle lenses are suffering. Standard lenses are simpler and telephoto lenses have less work to do, or at least focus travel to shift.

I know you can calibrate a lens to work at a certain distance, i just hope you can stretch it's range to focus across the entire zoom and focus range . You can calibrate a body as i've seen, but i think the answer lies ahead in a redesign. The smaller sensor cameras are less compatible with the old film lenses and show this shortfall. The larger sensors seem to be in the right place and are more compatible. Once they decide on 1 sensor size and position, instead of 3 then they can introduce new lenses which will be stunning. Digital resolution is fantastic compared to film and i want it but until then i will either have to get a larger sensor camera, which i intend to ,or buy the EFS lenses which were specifically designed to suit this camera, thats probably why the first few were wideangle zooms. It solved the problem of the crop 1.6 factor and hid the incompatibility problem in one swoop.
,( shame they don't do L EFS lenses ) I'll think about it some more, but i think i'm right!

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Old Jan 11, 2007, 7:32 PM   #4
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Yep just to say i have had the same experience wi th the 20d. I used to shoot gigs and clubs for magazines in the uk ( NME MIxmag Select ) and always shot on tranny. since I've got old and nealry a dad that line of of work has dropped away have since gone digi with first the 10d then 20d. I goto a call the other fay to go and shoot the band Feeder live and after the gig I was amazed how some shots were totaly out of focus. The drummer was coming crips but who wants the drummer! It was A real shock to find out how crapo this camera is at low light. for still shot sin the studio i'm really going even Manual focus.

just waiting on that 1d mk3 due in March. Roll on.

all the best to the new generation of music photographers as think we might of had it easy on film!

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Old Jan 11, 2007, 11:13 PM   #5
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Have you done the ruler test to see if its front or back focusing?
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