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Archive 2013 · Questions re 200 1.8 with extension tubes
  
 
Tenn.Jer
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p.1 #1 · Questions re 200 1.8 with extension tubes


I'm in the process of evaluating a 200 1.8L for hopeful purchase; 'J' date code (1995), it looks great, focusses fast, is quite sharp wide open, and seems a good buy except...

I used a 36mm extension tube with it some this last weekend and found that there were fuzzy haloes around objects at wide-open apertures. I figured that, since depth-of-focus at 1.8 with tubes is hair-thin at most, that it was a focus problem, and needed some micro-focus adjustment. So, I've done that - with a Lens-Align - but I'm still getting the haloes. Today I set up the ubiquitous batteries and got out the old focus chart. I used a tripod, mirror-lockup, remote release, and 10x live-view manual focus, then looked at a few frames...

Below are three from each sequence, one full stop apart (I shot at 1/3 intervals). The fuzziness disappears completely by about f/3.2 in both batteries and chart. Also are a couple of "real-world" f/1.8 flowers from earlier in the week (today it's poured all day long, no outdoor time for me).

I've never heard of extension tubes causing such a thing; my understanding is that they shouldn't affect image quality at all. I feel like I've taken the focussing variable out of the question, and now I'm stymied...Anyone have any ideas? Is this a normal "issue" (for lack of a better term) with the lens?

Of course I would probably never use a 1.8 aperture for tube-assisted macro, but I'm wondering if this could be indicative of a problem that could surface later in some other way...and, naturally, I REALLY want to have no doubts about keeping this one...

Thanks,
Jerry

(edit - I have to use two posts to get all the examples up)
(oh, and all these are 100% crops)





with 36mm extension tube

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/1.8    1/30s    200 ISO    +0.7 EV  







same as above

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/2.5    1/15s    200 ISO    +0.7 EV  







and again

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/3.5    1/8s    200 ISO    +0.7 EV  







also with 36mm tube

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/1.8    1/40s    200 ISO    +0.7 EV  






  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/2.5    1/25s    200 ISO    +0.7 EV  



Edited on Apr 04, 2013 at 11:28 PM · View previous versions



Apr 04, 2013 at 11:25 PM
Tenn.Jer
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p.1 #2 · Questions re 200 1.8 with extension tubes


...And the rest..
Jerry





with 36mm tube

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/3.5    1/13s    200 ISO    +0.7 EV  







with 36mm tube

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/1.8    1/2000s    100 ISO    0.0 EV  







with tube, upper right quandrant of the frame

  Canon EOS 5D Mark III    EF200mm f/1.8L USM lens    200mm    f/1.8    1/1000s    100 ISO    +1.3 EV  




Apr 04, 2013 at 11:27 PM
Kenneth Farver
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p.1 #3 · Questions re 200 1.8 with extension tubes


are you sure your problem isn't mirror slap with such a slow shutter speed?
I can't comment on the tubes since I've never used any but I would think you would still have a minimum focusing distance. How close are you?



Apr 04, 2013 at 11:29 PM
Tenn.Jer
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p.1 #4 · Questions re 200 1.8 with extension tubes


With tubes, I'm about three feet away; the space in which I can attain focus is only about six inches, so I don't have much choice in distance at that time...
and, mirror-lockup (with pause before shutter) or shooting out of live-view eliminates mirror-slap vibrations...

Edited on Apr 04, 2013 at 11:40 PM · View previous versions



Apr 04, 2013 at 11:32 PM
jcolwell
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p.1 #5 · Questions re 200 1.8 with extension tubes


Hi Jerry,

I can't help you with this specific problem, but I can share some of my experiences with the 200/1.8L and extension tubes, and extenders.

The Canon EF12 tube reduces the focus range on my 200/1.8L from infinity to 2.5m, to about 3.7m to 1.6m.

When doing AFMA tests with the 200/1.8L and 2X II on my 1DsIII, I noticed significant coma, and made a note to self to not use this combo. This is not a problem on my 1DX or 1DIV.

In general, extension tubes cause the image circle to expand, and so any imperfections in the image will be magnified. I explored the combination of 200/1.8L and EF12 tube to get reduced MFD. As noted, the 12mm tube provides a MFD of about 1.6m, which compares well to the EF 200/2.8L II MFD of 1.5m.

With the 200/1.8L, I figure you're close enough at 1.6m. If I want to get closer (i.e. higher magnification) I use a different lens.

Cheers, Jim



Apr 04, 2013 at 11:39 PM
Tenn.Jer
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p.1 #6 · Questions re 200 1.8 with extension tubes


Thanks, Jim; yeah, I'd call this "significant coma", alright ...I think my 1.4x III extender is out-of-whack, so I haven't even tried it on this lens...
Of course I should use a macro lens for these types of things, but it was kinda fun just to walk around with the camera and lens with a couple of tubes in my pocket...
Jerry



Apr 04, 2013 at 11:44 PM
jcolwell
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p.1 #7 · Questions re 200 1.8 with extension tubes


It's all good. OTOH, you have to know where to draw the line.


Apr 04, 2013 at 11:47 PM
 

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gasrocks
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p.1 #8 · Questions re 200 1.8 with extension tubes


36mm of extension is very drastic for any lens. Something I would never dream of using, myself. In fact if I feel the need to go over 12mm, I know I am using the wrong lens to attach it to. I have the Leica 180/2 APO lens. It can eat TCs for lunch with little IQ loss. However, so much as 12mm of extension and I get fuzzy pix like you are showing us - wide open. I have to stop it doen one stop to clear it up. Conclusion the very long fast lenses optical design was not made with ext. tubes in mind.


Apr 07, 2013 at 03:14 AM
Tenn.Jer
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p.1 #9 · Questions re 200 1.8 with extension tubes


Thanks for that, gasrocks; I've never heard it before. There's not much ..."literature", or discussion, or whatever, about extension tubes, so I just thought that if Kenko sells them in packages of three (36, 24, and 12mm), I could use them with impunity... Ignorance is not always bliss!

Your comments make sense; as I mentioned above, it was only the convenience of sticking a tube or two in my pocket, enabling me to have a 200mm macro lens whenever the urge struck me, that prompted the experiment anyway...its a relief to learn that whatever malfunction exists in the setup is behind the camera, not in front of it...

Many thanks,
Jerry



Apr 07, 2013 at 04:08 AM
Pixel Perfect
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p.1 #10 · Questions re 200 1.8 with extension tubes


Don't forget a 200 f/1.8 at mfd has very thibn DoF and extension only exacerbates that and will also magnify any aberrations. You would only shoot wide open if you were after a very dreamy effect.

These are all taken with 25mm or 36mm tubes.




      100.0-400.0 mm lens    2mm    f/1.0    1/1s    800 ISO    +1/0 EV  






      100.0-400.0 mm lens    2mm    f/1.0    1/1s    800 ISO    +1/0 EV  






  Canon EOS-1D Mark II    135mm    f/16.0    6s    200 ISO    0.0 EV  






  Canon EOS 20D    100.0-400.0 mm lens    0mm    f/0.1    1/115s    200 ISO    +0.3 EV  






  Canon EOS 20D    100.0-400.0 mm lens    0mm    f/0.1    1/110s    200 ISO    +0.3 EV  




Apr 07, 2013 at 09:55 AM
Tenn.Jer
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p.1 #11 · Questions re 200 1.8 with extension tubes


Thanks, Whayne...
Flowers (or bugs) with a vanishing background (like your first example above) are the type of effect I was looking for when I mounted an extension tube on the 200 1.8.

Beautiful work, here, catching that paper-thin DOF like you did - especially when apertures were as large as f/0.1!

Since stopping down did eliminate my "problem", I think that (and not so much pixel-peeking at 100%) are the answers...

Jerry



Apr 07, 2013 at 10:37 AM
15Bit
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p.1 #12 · Questions re 200 1.8 with extension tubes


Jerry,

Though i am not fortunate enough to own a 200/1.8 i have experienced similar (though not so serious) "glow" with both my 50mm f/1.4 and Samyang 85mm f/1.4 when using tubes. As others have mentioned though, it is unusual to shoot wide open with tubes attached so it's a problem that i only rarely encounter. In most cases i think i have assumed user error anyway, as DOF is so thin with tubes plus big apertures that there is only a mm or two of focus depth to play with.



Apr 07, 2013 at 10:39 AM
Access
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p.1 #13 · Questions re 200 1.8 with extension tubes


I posted about a similar issue a while back, what was found was that extension tubes sometimes can have a effect on the image (though often quite subtle). Depends at least partly on whether the lens focusses by moving the front element, the back element, or some internal element(s). I had a lens that was internal focus and could notice a subtle effect at shots taken at similar distances with or without extension tubes.

http://www.fredmiranda.com/forum/topic/1200573/



Apr 07, 2013 at 11:01 AM
Tenn.Jer
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p.1 #14 · Questions re 200 1.8 with extension tubes


Thanks, 15Bit and Access; the coma/halo/blurry outline I've come across is apparently a well-known and expected occurrence. I used to think that, containing no glass elements, that extension tubes merely enlarged the image circle cast by the lens with no effect on image quality...well, I was mistaken...

So it goes...

I remember your thread, Access, and I remember how baffled I was by the whole internal movement thing, DOF calculations, etc...your observations on 70-300 DO bokeh were clear and accurate, though; I used one for years...

Honestly, though, what I remember best from the thread is the picture of Sheldon N's daughter...

Thanks, guys...
Jerry



Apr 08, 2013 at 12:31 AM





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