70-200L 4IS - shifting minimum focus distance

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Archive 2008 · 70-200L 4IS - shifting minimum focus distance

Daan B
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p.1 #1 · 70-200L 4IS - shifting minimum focus distance

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

Feb 19, 2008 at 07:19 PM

Steve Spencer
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p.1 #2 · 70-200L 4IS - shifting minimum focus distance

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.

Feb 19, 2008 at 07:53 PM

Leon Noel
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p.1 #3 · 70-200L 4IS - shifting minimum focus distance

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).

Feb 19, 2008 at 08:03 PM

Daan B
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p.1 #4 · 70-200L 4IS - shifting minimum focus distance

Steve, I found some reports by mfurman (and others) of the same shift in MFD. Funny you have no issues at all

Feb 19, 2008 at 08:12 PM

GeorgeM
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p.1 #5 · 70-200L 4IS - shifting minimum focus distance

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

Feb 19, 2008 at 08:25 PM

mfurman
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p.1 #6 · 70-200L 4IS - shifting minimum focus distance

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.

Edited on Feb 19, 2008 at 08:48 PM

Feb 19, 2008 at 08:36 PM

thedruid
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p.1 #7 · 70-200L 4IS - shifting minimum focus distance

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

Feb 19, 2008 at 08:55 PM

Steve Spencer
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p.1 #8 · 70-200L 4IS - shifting minimum focus distance

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:

This image is copyrighted by the owner

I think it turned out pretty sharp. This was shot from a tripod with remote release and mirror lock up.

Feb 19, 2008 at 09:07 PM

sirimiri
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p.1 #9 · 70-200L 4IS - shifting minimum focus distance

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.

Feb 19, 2008 at 09:17 PM

Daan B
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p.1 #10 · 70-200L 4IS - shifting minimum focus distance

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.

Feb 19, 2008 at 09:46 PM

Chris Dees
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p.1 #11 · 70-200L 4IS - shifting minimum focus distance

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?

Feb 19, 2008 at 09:49 PM

Daan B
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p.1 #12 · 70-200L 4IS - shifting minimum focus distance

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?

Feb 19, 2008 at 09:58 PM

Chris Dees
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p.1 #13 · 70-200L 4IS - shifting minimum focus distance

It's too late know

, I'll try tomorrow and let you know.

Feb 19, 2008 at 10:04 PM

Daan B
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p.1 #14 · 70-200L 4IS - shifting minimum focus distance

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...

Feb 19, 2008 at 10:14 PM

thedruid
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p.1 #15 · 70-200L 4IS - shifting minimum focus distance

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

good luck.

Feb 20, 2008 at 12:16 AM

mfurman
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p.1 #16 · 70-200L 4IS - shifting minimum focus distance

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)

This image is copyrighted by the owner

original
http://mfurman.smugmug.com/gallery/2842902_M92Lx#171559816_h2pN3-O-LB

or

This image is copyrighted by the owner

original
http://mfurman.smugmug.com/gallery/3119444_dvJvS#170817950_wKgYg-O-LB

in contrast, it is what I was getting for 200mm and MFD:

This image is copyrighted by the owner

original
http://mfurman.smugmug.com/gallery/2842902_M92Lx#171558177_ZMZBW-O-LB

Edited on Feb 20, 2008 at 12:38 AM

Feb 20, 2008 at 12:34 AM

Daan B
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p.1 #17 · 70-200L 4IS - shifting minimum focus distance

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.

Edited on Feb 20, 2008 at 07:47 AM

Feb 20, 2008 at 05:42 AM

DynoMoHum
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p.1 #18 · 70-200L 4IS - shifting minimum focus distance

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?

Feb 20, 2008 at 11:58 AM

mfurman
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p.1 #19 · 70-200L 4IS - shifting minimum focus distance

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)

Feb 20, 2008 at 12:17 PM

mfurman
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p.1 #20 · 70-200L 4IS - shifting minimum focus distance

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.

Edited on Feb 20, 2008 at 03:23 PM

Feb 20, 2008 at 12:26 PM

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