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03-08-2013, 06:57 PM - 1 Like   #1
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Problems with Super Takumar 50mm 1.4 on 5DmkII

Hello,

I recently bought a Asahi Super Takumar 50mm 1.4 (M42), after doing a lot of research and reading this forum, I decided for the non multicoated version. I'm very happy with the lens bokeh, how is built and how good is for pulling focus, so smooth... I got it from ebay so it's not mint, just a few dust specks that won't affect image quality.

I mainly shoot video, and while doing some test today form my window I realized that the lens (I hope is not my camera sensor) was producing a weird magenta/purple circle right in the middle of the frame. It usually produces one when it flares or pointing to a window or any very bright light source, but in this case I was pointing to the ground. I did the same shot with a 28-70mm Nikon AF-S 2.8 on 50mm and I couldn't see that magenta circle in it. I made a few more test and looks like that is more obvious in video mode than stills, but only happens with the Super Takumar.

Has anyone had a similar issue with this lens? The circle's color si very similar to the reflection's color that the lens make when you look straight through it. I was wondering if it is an internal reflection due to the M42-EOS adapter or something that this lens always does. Or maybe I got a bad copy of the lens, I don't know but is driving me crazy... I realized that is more obvious when shooting f8-f11, f8-f1.4 it's almost imperceptible.

I attached some screenshots of the effect/artifact/aberration/glare (I don't know how to call it). Stils are Super Takumar at f16,11,8,4and 1.4

NOTE: There is a soft focus effect in all the shots because the window I was shooting through had a screen that is in the foreground out of focus, and these are screen shots of video shot at 1/50, I have no complains about the lens sharpness.

Thanks you!

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03-08-2013, 07:43 PM - 1 Like   #2
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Do you use a hood for it?
03-08-2013, 07:47 PM   #3
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To me it looks like a reflection of the lens on the window.
03-08-2013, 07:48 PM   #4
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Found something similar: Spot problem with super-takumar 50/1.4: Pentax SLR Talk Forum: Digital Photography Review
Judging from other search results it seems correct. Old lenses seem to be prone to "purple spot" on some modern cameras when stopped down.

03-08-2013, 07:55 PM   #5
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QuoteOriginally posted by VisualDarkness Quote
Do you use a hood for it?
Hi!

I used a hood (look at attached pic). I also forgot to mention that it's the 8-element version and the lens had a Quantary Multi-Coated UV Protector filter on (I tried with filter on and off and there was no difference. I know that the early 8 element version tends to flare, that's one of the reason why I bought since I shoot video and I love flares (controlled flares). But I was pointing down, it snowed but the day was grey, no sun at all, and I still got flare/glare or whatever that is.

Should've I bought the SMC version? I read that this version is supposed to be the best one.

Thanks for your quick reply!
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03-08-2013, 08:02 PM   #6
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QuoteOriginally posted by VisualDarkness Quote
Found something similar: Spot problem with super-takumar 50/1.4: Pentax SLR Talk Forum: Digital Photography Review
Judging from other search results it seems correct. Old lenses seem to be prone to "purple spot" on some modern cameras when stopped down.
Thanks for the link, sounds extremely familiar (and disappointing). I was so exicted about this lens, I still love and I can just shot form f1.4 to f8, I bought to use it in low light situations, but it sucks that I can not use the entire f stops range...
03-08-2013, 08:34 PM   #7
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Does anyone know if the 7 elements version or the SMC versions have this problem too? I did a lot of research to make sure I was buying the early 8 elements, legendary, 60's... blablabla version.
03-08-2013, 09:08 PM - 1 Like   #8
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I have both the 7 elements and the SMC version but have not seen this with the K-5. On the other hand I rarely stop down bellow F10.

03-08-2013, 09:12 PM   #9
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QuoteOriginally posted by VisualDarkness Quote
I have both the 7 elements and the SMC version but have not seen this with the K-5. On the other hand I rarely stop down bellow F10.
Which one do you like better? Do they prone to flare (I don't know if you've tried the 8 elements version).

Thanks
03-08-2013, 10:47 PM   #10
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It is the out-of-focus reflection of the silhouetted iris opening on the sensor bounced off the rear element. I shoot a lot with vintage lenses and have heard of this phenomenon, but have never seen it with any of my gear combinations. My understanding is that it is most common with lenses having wide, flat rear elements. This was never a problem with film, but those sensors are soooo shiny!


Steve

(...has a few lenses with primitive coatings and wide, flat rears...time to see if the K10D's sensor is as shiny as a Canon's!)
03-08-2013, 10:52 PM   #11
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QuoteOriginally posted by stevebrot Quote
It is the out-of-focus reflection of the silhouetted iris opening on the sensor bounced off the rear element. I shoot a lot with vintage lenses and have heard of this phenomenon, but have never seen it with any of my gear combinations. My understanding is that it is most common with lenses having wide, flat rear elements. This was never a problem with film, but those sensors are soooo shiny!


Steve

(...has a few lenses with primitive coatings and wide, flat rears...time to see if the K10D's sensor is as shiny as a Canon's!)
Even Sigma pretty recently updated a couple of lenses with better coatings on the rear element so I guess there is a lot to win by coating it well, not just focus on the front element.
03-08-2013, 11:09 PM   #12
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QuoteOriginally posted by stevebrot Quote
It is the out-of-focus reflection of the silhouetted iris opening on the sensor bounced off the rear element. I shoot a lot with vintage lenses and have heard of this phenomenon, but have never seen it with any of my gear combinations. My understanding is that it is most common with lenses having wide, flat rear elements. This was never a problem with film, but those sensors are soooo shiny!


Steve

(...has a few lenses with primitive coatings and wide, flat rears...time to see if the K10D's sensor is as shiny as a Canon's!)
I'm going to try to test this same lens on a 5d mkIII, just curious to see it gets the same reflection. I read that the Super Takumar rear element actually passes the mount when focused to infinity inside the camera body(when the lens was on close focus I didn't see it), and that's what creates the reflection, I believe this won't happen with a 7 elements version or a SMC because the rear element doesn't go that far when focus to infinity.
03-08-2013, 11:16 PM   #13
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QuoteOriginally posted by rubender Quote
I read that the Super Takumar rear element actually passes the mount...
That may be. I used to have a ST 50/1.4, but don't have it anymore. I do have a Auto-Rikenon 55/1.4 with a large protruding flat rear element that goes so far back that it will not clear some rear caps. That one might do the trick.


Steve


(...that failing, there is always the Jupiter-9...)
03-09-2013, 01:51 AM   #14
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To the best of my knowledge, the rear element of the 8 element does not protrude further than the usual 7 element 50/1.4. It is just the protective rim that is bigger on the 7 element, so that the element is less exposed.
That being said, the 8 element grabs its high prices mainly because of it being a collector's item. Multi coating really makes a difference here, and I believe the coating on the 8 element is rather primitive by comparison (I've owned Super Takumars and I know that is the case with most of them).
03-09-2013, 07:45 AM   #15
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That looks exactly the same as the infamous blue spot on the Tamron 90 2.5 macro, which is a superb lens in every respect except this blue spot. Which as Steve says, is most likely a reflection of the sensor on the flat rear element.
With my Tamron I can see it in the viewfinder as it occurs and changing position so the flare through the lens doesn't reflect gets rid of the blue spot. I didn't finda hood a great deal of help - some help but not enough to get rid of it. I experimented with different hoods and apertures with the camera on a tripod.
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