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Contax G 45mm Zeiss Planar f/2 weird ring

contax g 45mm planar zeiss techart golden eagle a7rII

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#1 felixeter

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Posted 07 March 2017 - 02:35 PM

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Hey all, made some pictures with today with my 45mm Contax lens and Techart adapter and this weird ring started appearing. It's not really vignetting in the way that I am familiar - it does not happen with my 55mm 1.8 or the 90mm Zeiss Sonnar mounted on the same adapter, so I'm inclined to think it's lens specific but not sure. I hadn't noticed this in previous use with this lens, and I don't know what could have changed it. It happens at all shutter speeds with efcs turned on and off and it gets a little more pronounced with a smaller f stop as you would expect things to come in to sharper focus. I tried removing the lens hood and UV filter just in case that was somehow showing up even though it never did on the film camera - but that didn't change anything. I'm aware it could be some bizarre refraction issue or something given the beach scene, but it happened last night and this morning on the beach and again not with the other lenses.  It's weird.... 

 

Any thoughts appreciated. 

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#2 felixeter

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Posted 11 March 2017 - 03:09 AM

Nothing - anyone ever seen anything like this before?



#3 Username

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Posted 11 March 2017 - 09:33 PM

Reflection. Adapter prolly not flocked.



#4 felixeter

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Posted 12 March 2017 - 01:39 AM

Is this possible to address DIY in any way? I generally use native lenses except with my Sony so I haven't come into these issues before. No problems of this nature with the other lenses on this adapter, even in crazy bright sun - weird. (I did have the EFCS issue with the 28) 

 

Thanks for replying. 



#5 felixeter

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Posted 12 March 2017 - 03:48 PM

Actually, adapter is flocked - you still think it's a reflection? If so what else could help?



#6 Username

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Posted 12 March 2017 - 05:42 PM

Actually, adapter is flocked - you still think it's a reflection?

If so what else could help?

 

Possibly edges of one or more elements is not well blacked. 

IOW this lens would very likely do this on any digital camera. 

There's an extra reflective bounce in digital gear that didn't 

happen with film gear ... film is not a "mirror" surface but the 

flat glass filter pack in front of the sensor is exactly that. 

 

Use of a lens hood and choice of aperture can offer some 

relief from this effect, but not in every shooting condition. 

There really are a few lenses that are close to hopeless for 

use on digital cameras :-( 


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#7 Username

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Posted 19 March 2017 - 06:57 PM

New possibility, just gleaned from another thread. 

If you've got in-camera vignetting relief engaged, 

cancel it and see if that helps. Good luck and do 

let us know if that helps ! 


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#8 felixeter

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Posted 23 March 2017 - 04:50 PM

Hmm - I don't think I did but I will check that out - honestly, I don't know my Sony super well as I set it up for my purposes when I got it and don't tend to mess with it, so that could be it. But not sure why that would only occur with this one lens. I had EFCS turned on for months without knowing, it never affected my pictures until it did (high shutter speed, wide angle, bright sun), and I had to figure that out haha.

 

Can you point me to that other thread so I can see if any other behavior was similar?

Thank you!

 

** Edit - can't find this option in the menu - but I only ever shoot RAW so I'm not sure this would apply? 



#9 slingers

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Posted 11 April 2017 - 06:36 AM

This adapter for electronic communication pretends to be a lens that has corrections. The setting to change is lens corrections. By default the lens corrections are set to auto. If you set to off the circle disappears.
Craig Slingsby

#10 vejo

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Posted 11 April 2017 - 07:16 AM

I had a somewhat similar problem with the old Minolta 2.8/50 macro lens.
Here it was a light spot in the middle of the frame on pictures with small entry pupil (f/8 or higher) against a bright background.
This was caused by the nearly flat back lens of the macro - it bounces the light reflected from the sensor back to the central spot.
Sony then changed the geometry of the back lens, and also the coatings are better nowadays.
 
Just an idea...


#11 vejo

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Posted 11 April 2017 - 08:49 AM

You're not alone...

http://www.fredmiran...255248/1413?b=2



#12 UnSean

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Posted 11 April 2017 - 12:08 PM

I use this lens with Metabones adapter, I can shoot directly into the sun with a Gobe Schott filter fitted, with no rings, no flair, excellent contrast, on both of my A7rm2's, the lens works perfectly.



#13 Landru

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Posted 11 April 2017 - 05:56 PM

I have the same combo of gear (Contax G 45 + Techart adapter + A7ii) but have never seen this phenomenon.

 

Grasping at straws a bit here ... how do you process your RAW files?  Is it possible, for example, that you have Lightroom set to apply lens correction on import, and that's the cause of what appears to be anti-vignetting?



#14 felixeter

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Posted 12 April 2017 - 02:25 AM

This adapter for electronic communication pretends to be a lens that has corrections. The setting to change is lens corrections. By default the lens corrections are set to auto. If you set to off the circle disappears.

You think this is it? In some situations the ring hasn't appeared, which is why I'm not sure.

I'll try it tomorrow in the daylight though and see if I can notice any difference. 

 

I have the same combo of gear (Contax G 45 + Techart adapter + A7ii) but have never seen this phenomenon.

 

Grasping at straws a bit here ... how do you process your RAW files?  Is it possible, for example, that you have Lightroom set to apply lens correction on import, and that's the cause of what appears to be anti-vignetting?

Nah, that's not it - I can actually see this happening in the viewfinder while I'm shooting and on image review on the camera back before the file even makes it to the computer. It's also different from an anti-vignette I think because it's a white ring - but the white doesn't go all the way to the corners, which I would think it would do if it were a vignette fix. Either way, in LR I have no lens correction applied on import for my Contax G + Sony combo. 



#15 Landru

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Posted 12 April 2017 - 10:36 PM

So, Felixeter, any progress, I hope?

 

Just as a side note of (possible) interest, the Techart Mark 3 (Golden Eagle) adapter does report the correct focal length and maximum aperture for the actual lens, and identifies it as full frame.  Older Techart adapters had the quirk of reporting the Contax lens as APS-C size. The adapter also identifies the lens (any lens mounted) as "0mm F0.0 SAM."  This appears to be the catch-all ID for any adapter with electronic contacts.  For example, a Canon lens on a Metabones adapter gets the same lens ID.  Lightroom does appear to have a builtin profile for this catch-all "SAM"  ID which applies minimal processing on import.



#16 felixeter

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Posted 18 April 2017 - 01:34 PM

So, Felixeter, any progress, I hope?

 

Just as a side note of (possible) interest, the Techart Mark 3 (Golden Eagle) adapter does report the correct focal length and maximum aperture for the actual lens, and identifies it as full frame.  Older Techart adapters had the quirk of reporting the Contax lens as APS-C size. The adapter also identifies the lens (any lens mounted) as "0mm F0.0 SAM."  This appears to be the catch-all ID for any adapter with electronic contacts.  For example, a Canon lens on a Metabones adapter gets the same lens ID.  Lightroom does appear to have a builtin profile for this catch-all "SAM"  ID which applies minimal processing on import.

I actually haven't been able to get out and shoot yet to reproduce this (doesn't seem to be a problem in indoor environments) - but given that it doesn't happen with my 28mm lens and I can see it in the viewfinder while I'm shooting I really am not sure how it would be a software correction issue - but when I shoot again I will try turning off lens correction and back on and see if I see any changes out in the field. Will report back when I get to it. I do use the techart 3 (golden eagle) version of the adapter. 





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