My 70-200 f4L backfocuses, what can i do?

personally, i think you're missing out as the 70-200mm f/4L is a great lens and worth the trouble...there really isn't anything else out there like it in terms of great handling, fast focusing, sharpness, colors and light weight. canon is really fast about fixing things; i've gotten my stuff back in less than 10 days from the day i sent it in each time. i find it worth keeping even though i have another lens with the same range but with the f/2.8 aperture.

as for the 100mm macro USM...great images but not without it's own quirks. it can hunt throughout it's focus range and still never lock on...it does this more than any other lens i own.

good luck.

-norm

PaulyOly said:

NKH said:

hmmmm, most reported backfocusing problems with the 70-200 f/4L are
at the wide end. despite all my efforts to get a new
batch/never-before-opened copy of this lens, mine backfocused
horribly at 70mm but was absolutely spot-on at 200mm. how is yours
at 70mm? at 135mm?

looking at your test shots, are you sure you were beyond the lens'
minimum focus distance? looks pretty darn close there.

when i corresponded with chuck westfall of canon about this lens
and the BF problem, he said they could indeed fix the lens without
the camera. it took 2 visits to the canon factory service center
for mine but it works great now. the first time, i sent it in with
the camera...the second time (when it was finally fixed right), it
was sent in alone.

--
NKH

Click to expand...

I only tested it at 135mm and 200mm, it backfocused at both. Mine
had another problem that may have been related to the focus
problem. When i would refocus without moving the camera the image
in the viewfinder would jerk as if the element that moves was
loose, very unnerving. The lens is on it's way back to 17 street
photo for exchange for a canon 100mm macro (another lens on my list
to purchase). I will wait on my midrange zoom purchase. I was 5-6
feet from the test chart, it was printed on 8 1/2 x 11 paper and
was a crop from the original photo which is why it looks so large.
I really liked the lens, but was not willing to try to exchange for
another and take the chance of having to send it back again.
--
http://www.pbase.com/paulyoly/root

Click to expand...

--
NKH

Hi guys,

Just want to tell you guys, my 70-200mm f4/L is back! I have try some shoot even in the Canon Service center, it look "good" or big screen at 70mm and 200mm f4!!! everything work perfect from 70-200mm( will i said it to early) at this moment. I am going for a out door shoot soon. Will post some picture here.

For those still waiting or exchange their L lens with the seller, don't! go straight to your canon nearest center(I mean main office), cos the seller will have to redirect your lens to the Canon enter as well. Seller can't do anything...

As i ask them what have happen on this lens and the 300D, their said that 300D is newest version then the L lens, so need some adjustment. Another thing their also said, my L lens 'really" have back-focus problem.
Well, I am going to stop here and go to take more photo.......

Seeya

NKH said:

as for the 100mm macro USM...great images but not without it's own
quirks. it can hunt throughout it's focus range and still never
lock on...it does this more than any other lens i own.

good luck.

-norm

PaulyOly said:

NKH said:

hmmmm, most reported backfocusing problems with the 70-200 f/4L are
at the wide end. despite all my efforts to get a new
batch/never-before-opened copy of this lens, mine backfocused
horribly at 70mm but was absolutely spot-on at 200mm. how is yours
at 70mm? at 135mm?

looking at your test shots, are you sure you were beyond the lens'
minimum focus distance? looks pretty darn close there.

when i corresponded with chuck westfall of canon about this lens
and the BF problem, he said they could indeed fix the lens without
the camera. it took 2 visits to the canon factory service center
for mine but it works great now. the first time, i sent it in with
the camera...the second time (when it was finally fixed right), it
was sent in alone.

--
NKH

Click to expand...

I only tested it at 135mm and 200mm, it backfocused at both. Mine
had another problem that may have been related to the focus
problem. When i would refocus without moving the camera the image
in the viewfinder would jerk as if the element that moves was
loose, very unnerving. The lens is on it's way back to 17 street
photo for exchange for a canon 100mm macro (another lens on my list
to purchase). I will wait on my midrange zoom purchase. I was 5-6
feet from the test chart, it was printed on 8 1/2 x 11 paper and
was a crop from the original photo which is why it looks so large.
I really liked the lens, but was not willing to try to exchange for
another and take the chance of having to send it back again.
--
http://www.pbase.com/paulyoly/root

Click to expand...

--
NKH

Click to expand...

So this means that Canon lenses and DSLR's are often mutually incompatible. Heck, this sounds like Sigma. If this is acknowledged by Canon they they have skrewd themselves and shot themselves on the foot at the same time. Go back and ask them about their marketing propoganda about the EF lens mount after they dumped FD... all their claims of 100% future compatibility etc.

Weew said:

As i ask them what have happen on this lens and the 300D, their
said that 300D is newest version then the L lens, so need some
adjustment. Another thing their also said, my L lens 'really" have
back-focus problem.

Click to expand...

Did they do something to your camera or just the lens? I have the 300d and it works great with my 400mm f5.6L. I could just see me sending the camera in with the 70-200 f4L and then it front focusing with the 400 f5.6L. I will probably try another one in the future unless i buy the 100-400L and sell my 400 f5.6L. It's a shame though that a lens in this price range doesn't focus accurately right out of the box and the shake in the viewfinder is very disturbing if you've ever seen it happen, looks like something inside the lens is loose.

http://www.pbase.com/paulyoly/root

Yes, they do something on the lens not camera, 300D work well. Maybe you have to send the 400 f5.6L to them as well,cos without they techinically adjust something with the lens, you not be able to use it. Don't worry, if my local canon center can fix this problem, I believe yours can also.

400 f5.6L must cost you a lot, do you sell all the piture you try to take through this lens in future?

PaulyOly said:

Did they do something to your camera or just the lens? I have the
300d and it works great with my 400mm f5.6L. I could just see me
sending the camera in with the 70-200 f4L and then it front
focusing with the 400 f5.6L. I will probably try another one in
the future unless i buy the 100-400L and sell my 400 f5.6L. It's a
shame though that a lens in this price range doesn't focus
accurately right out of the box and the shake in the viewfinder is
very disturbing if you've ever seen it happen, looks like something
inside the lens is loose.

http://www.pbase.com/paulyoly/root

Click to expand...

Weew said:

Yes, they do something on the lens not camera, 300D work well.
Maybe you have to send the 400 f5.6L to them as well,cos without
they techinically adjust something with the lens, you not be able
to use it. Don't worry, if my local canon center can fix this
problem, I believe yours can also.

400 f5.6L must cost you a lot, do you sell all the piture you try
to take through this lens in future?

Click to expand...

Weew, so how do you think your lens is performing since receiving it back fron Canon? Is it still backfocusing or spot on now? It'd be great to see some pics posted

there are only two places at each coast of US where everyone has
to send the lenses/cameras except for very few of those who
are really local.

Do Canon has second tier service center in each bit city?

Thanks,

-shan

Weew said:

400 f5.6L must cost you a lot, do you sell all the piture you try
to take through this lens in future?

PaulyOly said:

Did they do something to your camera or just the lens? I have the
300d and it works great with my 400mm f5.6L. I could just see me
sending the camera in with the 70-200 f4L and then it front
focusing with the 400 f5.6L. I will probably try another one in
the future unless i buy the 100-400L and sell my 400 f5.6L. It's a
shame though that a lens in this price range doesn't focus
accurately right out of the box and the shake in the viewfinder is
very disturbing if you've ever seen it happen, looks like something
inside the lens is loose.

http://www.pbase.com/paulyoly/root

Click to expand...

Click to expand...

The lens just missed a hair

I got mine yesterday. I did some initial testing. The AF seems fine. I sure will do some more testing. I have heard too many complains of focus problem with this lens.

Kai

PaulyOly said:

chuso said:

PaulyOly said:

Well after getting consistently blurry pics of flowers at 200mm and
not at say 135mm i decided to test it using a focus chart at a 45
degree angle, it seems to be bacfocusing very bad at 200mm. There
is no way i'm sending my camera to canon with this lens so will
they try to fix it without my camera? Or will they simply test it
and say there is nothing wrong with it? Maybe 17 street photo will
take it back even though i've had it for 16 days. I'll follow this
up with the chart pics.
--
http://www.pbase.com/paulyoly/root

Click to expand...

--
Canon 300D
http://www.pbase.com/chuso

Click to expand...

This is shot wide open, this is a 100%crop. I posted the 100% crop
so you could see the dots on the paper, everything to the right of
the line is oof. I shot this on a tripod/outside and i used the
flash.
http://www.pbase.com/image/27376284/original

here's one shot at f8.

http://www.pbase.com/image/27376285

I like this lens, but if they let me send it back then i'm going to
ask for something else or just my money back. I've seen a lot of
posts talking about this lens and focus problems so the odds are i
will get another back focusing lens. My other three lens, rebel
kit lens, 400 f5.6L and 50 1.8 all seem to focus fine. I'm not
buying anymore $500 dollar lenses anymore, i don't have the stomach
for it.
http://www.pbase.com/paulyoly/root

Click to expand...

--
http://www.pbase.com/kaihui

Hi Bek,

Yes, I am still done have time go for a shooting of this lens, but i did try some "back yard" shoot, it look great, no back focus problem "at all".

Should post some photos as soon as possbile when I take some great shoot!"bakc yard" shoot is terrible composition... can not be present here....

bektravels said:

Weew said:

Yes, they do something on the lens not camera, 300D work well.
Maybe you have to send the 400 f5.6L to them as well,cos without
they techinically adjust something with the lens, you not be able
to use it. Don't worry, if my local canon center can fix this
problem, I believe yours can also.

400 f5.6L must cost you a lot, do you sell all the piture you try
to take through this lens in future?

Click to expand...

Weew, so how do you think your lens is performing since receiving
it back fron Canon? Is it still backfocusing or spot on now? It'd
be great to see some pics posted

Click to expand...

Here you go

http://www.pbase.com/weew/l_lens_ok

It work fine, but I need to train to steady my hands, cos i shoot quite numbers of picture with handshake(1/320s)..sigh....

anyone have ideal how to "train" the hands to be more steady when hold the this combo(300D+70-200mm f4)

Shan Zhu said:

Do Canon has second tier service center in each bit city?

Thanks,

-shan

Weew said:

400 f5.6L must cost you a lot, do you sell all the piture you try
to take through this lens in future?

PaulyOly said:

Did they do something to your camera or just the lens? I have the
300d and it works great with my 400mm f5.6L. I could just see me
sending the camera in with the 70-200 f4L and then it front
focusing with the 400 f5.6L. I will probably try another one in
the future unless i buy the 100-400L and sell my 400 f5.6L. It's a
shame though that a lens in this price range doesn't focus
accurately right out of the box and the shake in the viewfinder is
very disturbing if you've ever seen it happen, looks like something
inside the lens is loose.

http://www.pbase.com/paulyoly/root

Click to expand...

Click to expand...

Click to expand...

I have similar problem. But mine has a problem at 70mm.

I called the customer service today and they were extremely nice and professional. I described them my problem and they told me to send in just the lens. I will send it on Monday.
My other three lenses are just fine (I have 10D).

The guy said that it should take 10-15 bussiness days after it gets there.

I will let you know when it gets back.

It really missed by a mile, the focus should be the same on both sides of the focus line, but clearly nothing on the right side of the line is in focus and if you look closely between the focus line and the 1 to the left, the dots on the paper aren't properly focused until the middle, this is why all my daisy(yellow flower) pics that i shot straight on appeared oof. This would be missing by a mile as far as a dslr's depth of field goes. I hope yours is good, but this one was clearly off.

It's more noticeable on the F8 example because of the added depth of field.

--
http://www.pbase.com/paulyoly/root

As far as i know you have to send it to New Jersey or California.

because i just spent the last 20 minutes looking at your gallery ...it's fantastic .. I really enjoyed it and i can't wait to see what you add with the F4..
good luck

drbailey said:

because i just spent the last 20 minutes looking at your gallery
...it's fantastic .. I really enjoyed it and i can't wait to see
what you add with the F4..
good luck

Click to expand...

I have allready sent it back in exchange for a 100mm f2.8 macro. I will try another copy at a later time or possibly a 100-400L and sell my 400 prime if the zoom proves worthy.
--
http://www.pbase.com/paulyoly/root

Yeah, I was kidding. I sure understand that after you paid that much moeny you'd expect a functional lens.

I tried few shots indoor. It seems OK. Tomorrow I will bring it out for some real shots.

Kai

PaulyOly said:

It really missed by a mile, the focus should be the same on both
sides of the focus line, but clearly nothing on the right side of
the line is in focus and if you look closely between the focus line
and the 1 to the left, the dots on the paper aren't properly
focused until the middle, this is why all my daisy(yellow flower)
pics that i shot straight on appeared oof. This would be missing
by a mile as far as a dslr's depth of field goes. I hope yours is
good, but this one was clearly off.

It's more noticeable on the F8 example because of the added depth
of field.

--
http://www.pbase.com/paulyoly/root

Click to expand...

--
http://www.pbase.com/kaihui

I just ordered EF 70-200mm/f4L two days ago, and it is on its way to my home. I am wondering what is the best (may be just the easiest) way to test the lens to see if it is normal.

Any help on how to test this lens will be appreciated. But simple less time consuming method is prefered, since I am still learning the rope,

--- wuchou.

PaulyOly said:

Well after getting consistently blurry pics of flowers at 200mm and
not at say 135mm i decided to test it using a focus chart at a 45
degree angle, it seems to be bacfocusing very bad at 200mm. There
is no way i'm sending my camera to canon with this lens so will
they try to fix it without my camera? Or will they simply test it
and say there is nothing wrong with it? Maybe 17 street photo will
take it back even though i've had it for 16 days. I'll follow this
up with the chart pics.
--
http://www.pbase.com/paulyoly/root

Click to expand...

Put your camera on a tripod, or set it on a table and prop it... get a measuring tape... put it in front of the lens 45% (at least 1.2m as thats the lens' min focus distance)... use the middle focusing point... focus on a given value on the tape (lets say 30cm or whatever is that in inches... take 4 shots.... 70mm, 100mm, 135mm, 200mm,

take out your CF.... bring it to Computer... view full resolution and Hopefully you will not see what I saw I try to get an exchange, but my stomach will be cramping for a week, fearing I will get another one that does the same thing.. (backfocusing at 70 the most, at 100 less and 135 the least)

@
/
/ -----Measuring tape at 45% to the camera
/
/
.

.

. ------ at least 1.2 m focus distance

.

II ---- 70-200 f4L
II
--camera

Sorry if I am reapeating someone, and sorry if it looks crapy...

wu chou said:

I just ordered EF 70-200mm/f4L two days ago, and it is on its way
to my home. I am wondering what is the best (may be just the
easiest) way to test the lens to see if it is normal.

Any help on how to test this lens will be appreciated. But simple
less time consuming method is prefered, since I am still learning
the rope,

--- wuchou.
--

Click to expand...

Roland Pallagi

Roland,

Thanks a lot for the information, and I will try it when my lens arrives. You might consider to send the lens to Canon service center to get it fixed. Someone did that with good result.

---wuchou.

roland pallagi said:

take out your CF.... bring it to Computer... view full resolution
and Hopefully you will not see what I saw I try to get an
exchange, but my stomach will be cramping for a week, fearing I
will get another one that does the same thing.. (backfocusing at 70
the most, at 100 less and 135 the least)

@
/
/ -----Measuring tape at 45% to the camera
/
/
.

.

. ------ at least 1.2 m focus distance

.

II ---- 70-200 f4L
II
--camera

Sorry if I am reapeating someone, and sorry if it looks crapy...

wu chou said:

I just ordered EF 70-200mm/f4L two days ago, and it is on its way
to my home. I am wondering what is the best (may be just the
easiest) way to test the lens to see if it is normal.

Any help on how to test this lens will be appreciated. But simple
less time consuming method is prefered, since I am still learning
the rope,

--- wuchou.
--

Click to expand...

Roland Pallagi

Click to expand...

wu chou said:

I just ordered EF 70-200mm/f4L two days ago, and it is on its way
to my home. I am wondering what is the best (may be just the
easiest) way to test the lens to see if it is normal.

Any help on how to test this lens will be appreciated. But simple
less time consuming method is prefered, since I am still learning
the rope,

--- wuchou.

--

Click to expand...

Shooting at rulers or flat test charts held at an angle does not always work consistently. The AF points in the camera cover a much wider area than that represented by a single line on a ruler or test chart. You need a good high-contrast target for the AF point. The best target is a flat surface at 90 degrees to the camera wide enough to give the camera's focus point a solid target with good contrast and good lighting - then the AF system should give consistent results.

Using a small AF target like a line on a ruler or test chart is why most of these 70-200 lenses backfocus at 70mm and less so at 200mm or even work ok at 200mm. At 70mm you have low magnification and the AF system sees a small target so the system misses and generally backfocuses. At 200mm you have much more magnification and the target line is more distinct and the AF system gets better contrast and will generally focus better. Oly's lens was the opposite (better at lower end) and the image jumped in the viewfinder which is weird and probably indicates a real problem.

Check out this webpage:

http://www.hkdotnet.com/FrancisPhotographyChannel/AF_Test/index.htm

You can also look at my test target which works well. I have since made a bigger test chart with a wider center target that works even better and gives very consistent results with all my lenses:

http://www.pbase.com/wrwood/test_images

Another good method is to line up 7 coke cans or something similar in a straight line and shoot at the middle can from a 45 degree angle. This also gives the AF point a good solid target and will immediately show you misfocusing.

Another critical test in my opinion is to shoot at text to be sure the lens focuses consistently up/down and left/right all the way across the entire image. Find a big poster or open a good quality magazine full width and attach it to a flat board. Shoot at 90 degrees to the camera. The text should be equally sharp top/bottom and left/right. I had one 70-200L that showed blurry text on the left 1/3 of the image. This problem is very hard to see in real life photos because you can miss it thinking the blur is due to the DOF.

On all tests shoot off a solid tripod in good light, preferrably outside. Poor lighting will also produce inconsistent results. One test is not enough to conclude that your lens is defective. Test several times in different lighting.

Regards,

Bill Wood
Fountain Hills, AZ