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Author Topic: Overexposed streaks bottom of frame Sony A7 with Manual Lenses  (Read 972 times)

sharkowill

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Hello, I am using a first-generation Sony A7 with some adapted manual focus OM and M42 lenses with a cheaper K&F concept adapters and have noticed overexposed streaks of light along the bottom of the frame of varying size and severity. The effect seems reduced when stopping down and also when shooting in lower light scenarios or in varying angles to strong light sources. I have tried different shutter speeds and turning on and off the electronic first curtain with no consistent ability to remove the issue entirely. I am trying to figure out whether this is due to a light leak with the adapter, reflections off the sensor, or any other possible mechanical issue that I am not thinking of. Has anyone experienced any issues like this, or know of any solutions? I am wondering if a Rayqual, Novoflex, or Metabones adapter would mitigate or eliminate the issue.

Link to samples if issue:

http://www.evanwill.ca/blog/overexposed-streaks-bottom-of-frame-sony-a7-with-manual-lenses
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Paulo Bizarro

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Re: Overexposed streaks bottom of frame Sony A7 with Manual Lenses
« Reply #1 on: July 27, 2017, 04:27:16 AM »

I would suggest using a native E mount lens, to dismiss any camera problems. Then most likely it would be the adapter.

BartvanderWolf

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Re: Overexposed streaks bottom of frame Sony A7 with Manual Lenses
« Reply #2 on: July 27, 2017, 07:35:34 AM »

Hello, I am using a first-generation Sony A7 with some adapted manual focus OM and M42 lenses with a cheaper K&F concept adapters and have noticed overexposed streaks of light along the bottom of the frame of varying size and severity. The effect seems reduced when stopping down and also when shooting in lower light scenarios or in varying angles to strong light sources. I have tried different shutter speeds and turning on and off the electronic first curtain with no consistent ability to remove the issue entirely. I am trying to figure out whether this is due to a light leak with the adapter, reflections off the sensor, or any other possible mechanical issue that I am not thinking of. Has anyone experienced any issues like this, or know of any solutions? I am wondering if a Rayqual, Novoflex, or Metabones adapter would mitigate or eliminate the issue.

Link to samples if issue:

http://www.evanwill.ca/blog/overexposed-streaks-bottom-of-frame-sony-a7-with-manual-lenses

Hi,

My first thought was that it looked like shutter bounce, where the second shutter curtain is not functioning well. This would become less noticeable at narrower apertures because the edge shadow of the curtain is sharper. But if you also see it when using the electronic shutter, it might point to an adapter issue. It could be an internal reflection (inadequate flocking or mat paint for shallow ray angles).

When it changes with aperture, it must be something in the optical path rather than an electronic/sensor issue.

Cheers,
Bart
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