Today I bought a Canon 70-200L f/4 IS. Excellent IQ. I love the IS. I am really happy with it

Going through my usual testing routine (nothing fancy, just a whole lot of shooting), I noticed something funny and familiar at the same time.

It seems like the minimum focus distance changes when I zoom in beyond 135mm. I had a Nikkor 80-200mm f/2.8 that showed the same behaviour:

At and under 135mm I get (very) sharp pics when focusing between 1.2m/4ft and infinity. Beyond 135mm I can only get sharp pics when focusing between 3m/10ft and infinity. For example: the AF will give a confirmation when shooting at 200mm at 1.5m, but the pic is totally soft. When shooting at 200mm at 3m the pic is very sharp.

So, I was wondering if any of you owners of this lens has seen the same shift of the minimum focus distance beyond 135mm?

And of course what it really boils down to is: do I have a "bad" copy or is 70-200L 4IS designed this way?

Thanks

Hi Daan,

My 70-200 f/4L IS doesn't show that shift in minimum focus distance, but I have seen others talk about this issue and report the same thing. Notably mfurman had a post several months back that described this exact problem--you might search for it in the archives. I am not sure why some lenses seem to have this problem and others don't. I bought mine half expecting it to have the problem and was pleasantly surprised when it didn't. I personally would not have been too bothered by it. I don't shoot a lot at MFD, but occasionally do. I hope this helps.

I will test mine as soon as I got time. Well I just found out my copy backfocuses a tad with 5D (not sure lens or camera), pretty frustrated because I don't want to send things to Canon (sometimes people report things come back worse than before they got sent).

Steve, I found some reports by mfurman (and others) of the same shift in MFD. Funny you have no issues at all Back in the days when I owned the Nikkor 80-200mm there were also people who had these problems and people who didn't. Makes you wonder doesn't it?

It is also funny that Canon placed a focus limiter at 3m...

Now what to do? Phone Canon tomorrow morning about it I guess... I am confused: do I have a bad copy or is the lens designed this way? If it is a bad copy, I can take it back to the shop and try another one...

Leon, I would appreciate it if you would do some testing.

I've a Nikon 80-200 2.8 that exhibits this 'feature' as well. Doesn't bother me. I just work with it and use it to my advantage when I can.

George

Hello,

I have had this problem with 2 lenses. At 135 mm, the lens is sharp at MFD of 1.2 m and I could have sharp image up to 155-160 mm. At 200 mm, I need at least 2.6-2.8 m to have a decent sharpness. I also noticed that if IS is off, the image at 200 mm looks better.

Here are a few links:

http://forums.dpreview.com/forums/read.asp?forum=1029&message=23193922
this is an important one
http://www.fredmiranda.com/forum/topic2/551878
http://www.fredmiranda.com/forum/topic2/536912
http://forums.dpreview.com/forums/read.asp?forum=1029&message=23237903
http://forums.dpreview.com/forums/read.asp?forum=1029&message=23658406
http://forums.dpreview.com/forums/read.asp?forum=1029&message=23956510

Some of the older threads seem to be gone.

Are you shooting handheld and if so at what shutter speed?

Daan B wrote:
Steve, I found some reports by mfurman (and others) of the same shift in MFD. Funny you have no issues at all Back in the days when I owned the Nikkor 80-200mm there were also people who had these problems and people who didn't. Makes you wonder doesn't it?

It is also funny that Canon placed a focus limiter at 3m...

Now what to do? Phone Canon tomorrow morning about it I guess... I am confused: do I have a bad copy or is the lens designed this way? If it is a bad copy, I can take it back to the shop and try another one...

Leon, I would appreciate it if you would do some testing.

I think what you do depends on how often you shoot a MFD and 200mm. If you shoot at it a lot then I would consider exchanging your lens or perhaps going with a different lens (maybe the 200 f/2.8L is better). If you don't and are willing to work around this issue it is still a great lens and this is about the only defect. By the way here is an example of my 70-200 at about 185mm and 4 feet:

You've got some ghosting in that image...but it's not that bad.

My 70-200 has a pretty serious amount of internal reflections, when shooting at night.

Not sure I've noticed the MFD thing yet, usually I use a macro for the closeups.

mfurman, thanks for the links. I wish I had read those before I purchased the 70-200L 4 IS...

Since there are 70-200L 4 IS copies out there that seem to be performing good at MFD beyond 135mm, I can only conclude my copy is a "bad" one. Can I accept this "flaw"? Well, you are right Steve, it all depends if I am going to shoot a lot at MFD beyond 135mm. In any case, I will have to be aware there is an issue beyond 135mm. I think that the flexibilty of a zoom looses some of it's attraction this way.

I think I will try some more samples at the store tomorrow... See if there is one that performs OK at MFD over the whole focal range.

I didn't noticed this with my copy, but I don't use it that often at MFD.
Did we tried it at MFD yesterday?

Chris Dees wrote:
I didn't noticed this with my copy, but I don't use it that often at MFD.
Did we tried it at MFD yesterday?

Hi Chris,

I shot a few at 200mm with your copy within a few meters yesterday. They were rather soft. I thought I messed up with the IS. In any case, the softness isn't nearly as much as with my sample. Maybe yours is fine... But maybe you can take a few test shots at MFD beyond 135mm just to be sure?

It's too late know , I'll try tomorrow and let you know.

Chris Dees wrote:
It's too late know , I'll try tomorrow and let you know.

Understood I think I'll get some sleep over it too...

Don't know if it helps but ran a test on mine and it is sharp at the MFD @ 200mm,

good luck.

thedruid:
Don't know if it helps but ran a test on mine and it is sharp at the MFD @ 200mm

I find it very interesting! I had two copies of 70-200 f/4.0 L IS and they were identical. I also tested another copy and it was soft at 200 mm and MFD.

Are we talking about this type of sharpness (please check originals):

(at 135 mm f/4.0 and MFD)

mfurman, my copy shows exactly the same bluriness at 200mm MFD as yours. However, it already starts at 160mm MFD and the bluriness increases gradually when I zoom in to 200mm MFD. Thanks for posting these sample pics. I was wondering: did you have your lens checked by Canon Service?

thedruid, is it possible that you show a 100% crop of a pic taken at 200mm MFD?

I had a chat with Canon Service this morning. I explained the MFD issue to them. According to their specs, the MFD at 70mm is 1.2m and the MFD at 200mm is 3.9m!!! These are the tolerances that Canon finds acceptable. In my case the MFD at 200mm is about 3m. The cause of the shifting MFD lies in the shifting of the focal point when zooming in according to the tech.

So, according to Canon the shifting MFD is part of the lens design.

For me it's no big problem. When I am going to shoot exclisively at 200mm I set the focus limiter to 3m. When setting the focus limiter to 1.2m I simply have to be more aware.

Anyway, I have Canon Service have a look at my copy next week.

About this softness issue at or near MFD... I read the entire first thread that mfurman linked to at dpreview, and some of the threads that were linked to within that thread, I want to make sure I understand what the end findings are...

It seems that the softness is somehow related to IS and that if/when you turn off IS and use a tripod or shoot with fast shutter speed, the softness is not there? Is this a correct description of the issue being discussed?

DynoMoHum:
It seems that the softness is somehow related to IS and that if/when you turn off IS and use a tripod or shoot with fast shutter speed, the softness is not there? Is this a correct description of the issue being discussed?

I have to admit that I am still not certain about it. I thought that switching IS off may have helped but images at 200 mm and MFD were still far less sharp than at 135 mm (and MFD)

to Daan B

I am in a sense glad that you are experiencing the problem I was trying to interest others in, for quite a long time. As I mentioned, the problem (for my lenses) was also starting at 160 mm. I am still not sure if the issue is confined only to some copies or other users are more tolerant of softness.

I bought this lens (it is by the way absolutely excellent outside its limitations) for its maximum magnification (0.21), which can be only achieved at 200 mm.

According to their specs, the MFD at 70mm is 1.2m and the MFD at 200mm is 3.9m!!!

This is a shocking statement. Where is it listed or even mentioned in their data sheets?
What about the maximum magnification. I think that Canon is crossing any boundaries of decency recently.

Thank you for your post and findings.

I did a quick but unscientific test but I could see the diffference between 135mm and 200mm at about the MFD. In both cases I got AF confirmation.

mfurman wrote:
I am in a sense glad that you are experiencing the problem I was trying to interest others in, for quite a long time. As I mentioned, the problem (for my lenses) was also starting at 160 mm. I am still not sure if the issue is confined only to some copies or other users are more tolerant of softness.

I understand... There were many times I felt the same during my Nikon days when I found out my 80-200mm f/2.8 had the same problems.


I bought this lens (it is by the way absolutely excellent outside its limitations) for its maximum magnification (0.21), which can be only achieved at 200 mm.

I don't find this lens particularly good at micro level sharpness (over the entire range). For example, my 135L renders detail in a more delicate manner. I expect a macro lens would be better suited. But I agree, Canon advertises the lens has a MFD of 1.2m over it's entire focal range and a max magnification of 0.21 at 200mm provided you can get sharp pics at it's MFD

According to their specs, the MFD at 70mm is 1.2m and the MFD at 200mm is 3.9m!!!

This is a shocking statement. Where is it listed or even mentioned in their data sheets?
What about the maximum magnification. I think that Canon is crossing any boundaries of decency recently.

The tech had to look it up. But I also talked to a Canon rep today. He said he had never heard of this problem. Don't you hate how Canon reps try to make you think you are the dumb ass, instead of that there could be something wrong with the gear. Anyway, next week I let Canon Service take a look at my lens.

I also tested a little further today and got some decent sharp pics at 200mm / 1.4m FD :
REMOVED LINK (warning: big file - low JPEG quality)

and at 200mm / 2m FD:
REMOVED LINK (also big file - low JPEG quality)

In both pics I had flash and IS on. Both samples are rendered through Lightroom with no sharpening or any PP at all. Seems like there is a little backfocus going on. I focused on the nose (in very low light) and the hairs on top are the sharpest. In any case my initial findings of a MFD of 3m at 200mm were not accurate. I would say the pic shot at 2m FD is usable for large prints. The pic at 1.4m FD is suitable for medium sized prints.

Sometimes I think there is something not operating as it should be in the relation between the 5D's AF and the AF algorythms the lens uses. But this is pure speculation.

Anyway, to be continued.

Edited by Daan B on Feb 28, 2008 at 03:47 PM GMT (Reason: Removed links)

Interesting - and disappointing...

Curiosity got the better of me since I have a 70-200 f4 NON IS, and was seriously considering an upgrade to the IS version.

A quick test (tripod based, mirror locked up) says my NON IS version exhibits the same behaviour.

I get soft images at 160mm + FL when focused in the 1.2m (MFD) to 2m range.
Images are noticeably sharper at less than 160mm FL at the same lens to subject distance.

At 4m+ lens to subject distances this is a lens I would consider sharp -and I have a 200mm / 2.8 prime for comparison.

The prime has a 1.5m MFD and I shot the same test subject at this distance - the prime and zoom are comparable in sharpness when the zoom is at less than 160mm FL.

Mike A.

Ok Daan I ran a few simple test shots (IS off, ~ MFD, on tripod, triggered with wired remote), here's my findings (bear in mind I believe my copy backfocuses a little, a few mm for short focus distances)

- At 70mm it beeps if I half press the shutter on remote. Picture came out sharp.
- At 100mm it flashes but no beeping, shutter would not trip (no AF obtained), so I moved the tripod back away from the subject, about 1-2cm, then it beeped. So there was a tiny shift here. Picture came out sharp.
- At 135mm it beeped again, sharp result.
- At 200mm it beeped also, sharp result.

So the only MFD shift I experienced was from 70mm jumping to 100mm, and even so it was only 1-2cm. I don't know why Canon says MFD at 200mm can be about 3.9m !!!

Hope that helps , good luck and happy shooting.

Leon Noel wrote:
Ok Daan I ran a few simple test shots (IS off, ~ MFD, on tripod, triggered with wired remote), here's my findings (bear in mind I believe my copy backfocuses a little, a few mm for short focus distances)

- At 70mm it beeps if I half press the shutter on remote. Picture came out sharp.
- At 100mm it flashes but no beeping, shutter would not trip (no AF obtained), so I moved the tripod back away from the subject, about 1-2cm, then it beeped. So there was a tiny shift here. Picture came out sharp.
- At 135mm it beeped again, sharp result.
- At 200mm it beeped also, sharp result.

So the only MFD shift I experienced was from 70mm jumping to 100mm, and even so it was only 1-2cm. I don't know why Canon says MFD at 200mm can be about 3.9m !!!

Hope that helps , good luck and happy shooting.


Leon,

Thanks for sharing your test results Any change to post (or link to) some 100% crops?

I think a focus shift of 1-2cm can be considered normal.

About a 3.9m MFD at 200mm... I think he meant to say that MFD tolerances are between 1.2m at 70mm and 3.9m at 200mm. As we are seeing, it actually lies somewhere in between. With a lot of variation between samples I might add

Maybe we should start a poll to check who has the MFD problems and who doesn't. Even non-IS versions seem to suffer...