My new Rebel XT focus problem.

I noticed some of my XT photos were out of focus so I did a test photo of 2 coffee cans from 66 inches away. The can I focused is the left one which is 66 inches away from the camera body. The right can is placed 15 inches back from the other can. The photo is much more focused on the right can plus the lens shows it is focused at just under 7 ft. on the lens barrel. Camera set to Av 2.8, 55mm.
Photo Link: http://www.pbase.com/image/48378414

I did this test of a chart placed on the table with the camera at 45 degrees. I used this test located here: http://md.co.za/d70/chart.html ; . Camera set to Av 2.8, 28mm . This test shows my camera has a back focusing problem.
Photo Link: http://www.pbase.com/qwe7/image/48378248

The camera and lens are brand new and I only have this one lens (Tamron 28-75mm 2.8). Could the problem be the camera, lens or operator error? Suggestions please.

Use the A-Dep mode or full manual.

I used the manual AF Point selection using the center AF lighting in red and centered over the subject for my tests.
This camera seems to be way off in focus. What could be the problem?

It's not a camera problem but a camera/lens combination. Front or back focus is very common among 3rd party lenses. You can't send it to Canon for calibration because they won't support a 3rd party lens. You can try Tamron, saying it backfocuses, but they'll want validation that other lenses work find on that body. Do you have another lens to verify?

BTW, ignore the other post about A-DEP and Manual - huh?!

qwe said:

The camera and lens are brand new and I only have this one lens
(Tamron 28-75mm 2.8). Could the problem be the camera, lens or
operator error? Suggestions please.

Click to expand...

I went to a store to purchase the Tamron 28-75 f/2.8 lens some time ago. The first copy I tried (let's all it copy A) gave horribly out of focus shots wide-open with my XT. Mind you, I've got Canon 17-85, Canon 85 f/1.8 and Sigma 150 f/2.8 lenses which work perfectly fine. Anyway, I returned to the store to exchange for copy B. This one worked out perfectly, i.e., sharp when wide-open.

Now, comes the weird part. The store has its own XT camera. We tried out both lenses on their camera. Guess what? Copy A was sharp when wide open but copy B was terrible. So, the results are just the reverse!

Conclusion? You should get the lens that matches your camera body (assuming your body is properly calibrated). If you bought it in a brick and mortar store, it's easy to get an exchange till you're satisfied. If you got it over the web... well, good luck.

I don't have another lens to verify, but I noticed my battery was very low. Hopefully a very low battery is the cause and I will report back tomorrow after the recharge.

My advice is this:
Try the camera with another lens (preferably canon).
You must find a friend or someone who has one. If not try at a photo store.
If it'll be the same thing, exchange your camera or send it for calibration.
Using a-dep or manual focus will NOT solve your problem.
Good luck.

I recharged the battery, but this was not the cause. I took the camera to Best Buy to do the focus test with the Canon EF-S 18-55 lens. I have the same out of focus results with this lens also. Test photo here: http://www.pbase.com/qwe7/image/48416591

The body appears to be defective or out of calibration. Since I purchased this body from Dell I can replace it with another since it has been under 21 days.

What kind of quality control does Canon have anyway?

Quite a few people have complained about this here.

I bought a body back in May and it was not focusing correctly. I sent it back and got another body and that was worse with AF. I sent that back and they calibrated it. This was slightly better but the AF was still failing and letting me down in a lot of cases. Its not that I do not know about camera shake or DOF. I am currently trying to arrange to send the body back to Canon for further calibration but I hear they take a few weeks. So I am going to send it in a few weeks after I have covered an event coming up.

These days, getting a body and lens that works first time is a matter of luck. Talk of QC!

Akkers said:

Quite a few people have complained about this here.

I bought a body back in May and it was not focusing correctly. I
sent it back and got another body and that was worse with AF. I
sent that back and they calibrated it. This was slightly better but
the AF was still failing and letting me down in a lot of cases. Its
not that I do not know about camera shake or DOF. I am currently
trying to arrange to send the body back to Canon for further
calibration but I hear they take a few weeks. So I am going to send
it in a few weeks after I have covered an event coming up.

These days, getting a body and lens that works first time is a
matter of luck. Talk of QC!

Click to expand...

Who did you send it back to for calibration the first time? It sounds by the way you written your paragraph that you haven't sent it in to Canon yet.

I am wondering instead of having another exchange with not knowing of what I will be getting - to instead send this body into Canon factory repair for recalibration. Maybe this will get me better quality.

What is front/back focusing?

I recommend you to try it with another lens made by Canon.

Calibration, Tamron lens is very good in focus,
most of the time, it is a Canon body problem.

I had 3 tamron lens, all focus tact sharp and correct,
very fast, just slower than the L.

That is what I have, all lens focus correctly in the new Xt,
that all lens are focus right on in my old 20D also.

ef 50mm f1.8
ef-s 18-55mm
Tamron 28-80
Tamron 18-200
Tamron 70-300

Once you verified that is a body problem, send it back to Dell
and get a new one, and test it again.

I dont trust the calibration from Canon, because when they
calibrate, they calibrate with the test lens, which is Canon
for sure, and may not match the Tamron anyway.

my pennies

Good luck

alien

was the target big enough to be included in the focusing braket well enough? the camera will pick up contrasty subject slightly outside the braket.

did you use center focusing point or all point?

also you're shooting wide open so don,t expect tip top sharpness from that.

the first images at slow shutter speed looks like camera shake/mirror slap and that is the shutter speeds that is prone to this.

the best way to test that is outdoor with good light and on tripod, with center focusing point and to make sure that nothing slightly outside the focusign braket can fool the AF system.

qwe said:

I noticed some of my XT photos were out of focus so I did a test
photo of 2 coffee cans from 66 inches away. The can I focused is
the left one which is 66 inches away from the camera body. The
right can is placed 15 inches back from the other can. The photo
is much more focused on the right can plus the lens shows it is
focused at just under 7 ft. on the lens barrel. Camera set to Av
2.8, 55mm.
Photo Link: http://www.pbase.com/image/48378414

I did this test of a chart placed on the table with the camera at
45 degrees. I used this test located here:
http://md.co.za/d70/chart.html ; . Camera set to Av 2.8, 28mm .
This test shows my camera has a back focusing problem.
Photo Link: http://www.pbase.com/qwe7/image/48378248

The camera and lens are brand new and I only have this one lens
(Tamron 28-75mm 2.8). Could the problem be the camera, lens or
operator error? Suggestions please.

Click to expand...

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Please do not start new thread for private message to me but send them to me via email instead! thanks.

qwe said:

I am wondering instead of having another exchange with not knowing
of what I will be getting - to instead send this body into Canon
factory repair for recalibration. Maybe this will get me better
quality.

Click to expand...

Sorry your camera is not working correctly. I think you would be better off exchanging the camera. The 3 XTs I know of, including mine, focused very well right out of the box. So the odds are you will get a good camera.

Maybe I am extremely lucky, but here are the lenses I use with the XT, all perform AF well within specs:

EFS 18-55 kit lens
EF 28-105 zoom (12-years old)
EF 50/1.4
EF 85/1.8
Sigma 30/1.4

I don't know anything about Tamron lenses though.

Sal

I think it a high probability that this is the camera that is at fault for the simple reason that the problem seems to travel more with the camera. If the lens were bad, there would be a high probability that the kit lens then would operate fine. It is kind of hard to test it with only one lens for comparison.

There does seem to be some interaction between bodies and lenses. I have 5 lenses, and no problems except that I did have a tamron 28-75 (same as you) that front focused. I returned it for another copy and no worries - dead on. That was the ONLY lens I have ever had problems with - not to say it is Tamron, but that the defect rate is much much lower than one would get the feeling from reading here. If you pick any lens or any body there will be someone who claims that that mfg has a big problem with focussing issues or 'QC'. Point of fact, if there were as many bad units as claimed, all of the lens and camera guys would be out of business. Most of the time, i suspect test methodology. Little differnce can mean completely different results.

I think it is pretty likely that your camera is the culprit here since it sounds like you were pretty rigorous with this. The thing that is REALLY important, and what I might question about your Best Buy test is that the you need to make sure you have high contrast on your subject whether it be a chart or an object. You camera has a contrast based AF system and it matters for the test. The trap is that the human eye has a much larger dynamic range than the camera so what we see as still bright and usable is an order of magnitude dimmer for the hardware. My advice is to try this win sunlight so that you have shutter speeds of 1/1000 or so. On your chart, that pretty much guarantees good contrast.

I tested a lens (my sig 18-50 f2.8) and thought it had a problem. Then I tested my 70-200 f4L and it seemed to have the same problem. When I tested it in the morning (this was 11pm in the kitchen, but in what I thought was good light), both lenses were dead nuts right on. So, it was the lighting I chose, not the AF system. Just so you don't make the same mistake, might be a good test.

Here is a great source of information on your AF system:

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

The tam 28-75 has great optics. If you get it right with this, you should be very happy with that lens (great choice).

Let us know what happens!

J.

qwe said:

I recharged the battery, but this was not the cause. I took the
camera to Best Buy to do the focus test with the Canon EF-S 18-55
lens. I have the same out of focus results with this lens also.
Test photo here: http://www.pbase.com/qwe7/image/48416591

The body appears to be defective or out of calibration. Since I
purchased this body from Dell I can replace it with another since
it has been under 21 days.

What kind of quality control does Canon have anyway?

Click to expand...

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--
'Get your facts first, and then you can distort them as much as you please.' -
Mark Twain

(equip in profile)

Have most of the people here who have had a focusing problem sent the camera in for calibration or just ordered a new camera.

I ordered the camera with the kit lens, and was running up against my 30 day return period, panicked, and returned the camera, believing that most of the problems I was having(softness) were my fault. I still believe that is the case, and with more time I could have worked that out.

I ordered the body only with the 50mm 1.8 and have had it for a week. I set up the 45 degree angle test with the lines front and back, and the center line was not in focus, but the 8 and 10mm lines and text behind the focus point were.

I set up the test only after I was photographing a baby, and in almost every shot her eyes were a little fuzzy, but her ears were perfectly focused.

This test always seemed a little artificial to me, but I was getting the same result almost every time. Then I put my father in front of the garage and focused on him(his eye to be exact). In every picture, he was out of focus, but the shingle on the garage behind him were right on.

I know all about the depth of field problems new people like me have, but I was shooting at an aperture of 7.1 at about 8-10 feet which should give me something just short of a foot in front of the subject in focus. Yet on almost every shot, the wall behind him was clear as could be.

I am committed to making this relationship work out, and I would like to know, for those who have had a problem, what course of action did you take, return or calibration.

In any case did someone have a camera they sent in that was sent back to them with the claim from canon that it was fine? That would be a concern in that it would put me beyond the return period.

Sal Baker said:

qwe said:

I am wondering instead of having another exchange with not knowing
of what I will be getting - to instead send this body into Canon
factory repair for recalibration. Maybe this will get me better
quality.

Click to expand...

Sorry your camera is not working correctly. I think you would be
better off exchanging the camera. The 3 XTs I know of, including
mine, focused very well right out of the box. So the odds are you
will get a good camera.

Maybe I am extremely lucky, but here are the lenses I use with the
XT, all perform AF well within specs:

EFS 18-55 kit lens
EF 28-105 zoom (12-years old)
EF 50/1.4
EF 85/1.8
Sigma 30/1.4

I don't know anything about Tamron lenses though.

Sal

Click to expand...

Actually the 2nd body was sent back to the shop who sent it onto their own appointed workshop. They carried out variuous checks and calibration.

It seems that Canon UK take some time in returning cameras and I need it for an important event in Sept. Ok, I will not get perfect pics but anything will do. I intend to send it to Canon after the event.

http://www.canon-dslr.com/

proper test charts to print out and verify if you have a front or rear focus problem

Here's how it went for me:

I went into a local camera store and asked if they carried the Tamron 28-75. They did, but unfortunately they were out of stock on the EF mount lens. They called their sister store (about 15 miles away). They didn't have any in stock either. First of all I am thinking how they can be out of stock at two stores. Anyway, they said they were supposed to get a shipment in about a week. However, they wouldn't guarantee they would receive any Tamron 28-75's. Therefore I ordered online. I received the lens and tried it on my 300 (at the time I didn't own the XT). The lens worked very well; no problems. Six months later I bought the XT, and lo and behold, the lens didn't work well at all. I went through the rest of my lenses, and found only one other that didn't work with the XT, this was my kit lens. On my 300, my kit lens was actually quite good. The problem with both lenses was significant front focus.

I would like to buy from my local store, but they just don't stock much of anything anymore. I have bought two camera bodies, and other equipment from them, but I no longer patronize them because they are either don't carry what I am looking for, or they are "temporarily out of stock". The prices too, are far higher than internet prices. I don't see how this store will remain viable in the long term.

Since this time, I have purchased a split prism focus screen, and now can use all my lenses.

jgb

thw said:

thw said:

The camera and lens are brand new and I only have this one lens
(Tamron 28-75mm 2.8). Could the problem be the camera, lens or
operator error? Suggestions please.

Click to expand...

I went to a store to purchase the Tamron 28-75 f/2.8 lens some time
ago. The first copy I tried (let's all it copy A) gave horribly out
of focus shots wide-open with my XT. Mind you, I've got Canon
17-85, Canon 85 f/1.8 and Sigma 150 f/2.8 lenses which work
perfectly fine. Anyway, I returned to the store to exchange for
copy B. This one worked out perfectly, i.e., sharp when wide-open.

Now, comes the weird part. The store has its own XT camera. We
tried out both lenses on their camera. Guess what? Copy A was sharp
when wide open but copy B was terrible. So, the results are just
the reverse!

Conclusion? You should get the lens that matches your camera body
(assuming your body is properly calibrated). If you bought it in a
brick and mortar store, it's easy to get an exchange till you're
satisfied. If you got it over the web... well, good luck.

Click to expand...

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