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UltravioletPhotography

Gx85 IR Shutter Monitor Contamination Test


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I have a full spectrum converted Panasonic Gx85. It is on the list of cameras that have the dreaded IR shutter monitor, both here and on the Kolari site, so I decided to run some tests. I assumed that longer exposures and higher ISO settings would show any IR contamination better. I ran a series of tests with a body cap mounted instead of a lens: ISO 200 to 25600 @ 60 seconds, and 5 to 60 seconds @ ISO 3200, which I thought was the upper end of practical ISOs

 

The camera settings were as follows:

Aspect Ratio: 4:3

Picture Size 4592x3448

Quality: RAW + fine JPEG

Shutter Type: MSHTR

Extended ISO: OFF

Color Space: sRGB

Silent Mode: OFF

iDynamic: OFF

iResolution: OFF

Shading Comp: OFF

Diffraction Compensation: OFF

White Balance: Daylight

Mode: M

 

I then examined the raw files in RawTherapee, and used ShareX to capture screen shots of the RawTherapee display to post here. The black border is there to show the lighter band along the edge, which is almost imposible to perceive on a white background.

 

60 seconds ISO 25600 with Long Shutter NR: OFF and the Neutral profile in RawTherapee:

post-243-0-98333200-1558635110.png

 

The lighter band along the upper and right edges can be seen more clearly using Raw Therapee's Auto Matched ISO High profile

60 seconds ISO 25600 with Long Shutter NR: OFF and the Auto Matched ISO High profile in RawTherapee:

post-243-0-12908400-1558635275.png

 

Turning on Long Shutter NR, which subtracts an identical frame taken with the shutter closed gives a nice even field:

60 seconds ISO 25600 with Long Shutter NR: ON and the Auto Matched ISO High profile in RawTherapee:

post-243-0-33085800-1558635548.png

 

It looks to me like this camera does not exhibit any IR shutter monitor contamination, unless my test methodology is flawed somehow?

An unmodified G85 produces almost identical results.

 

Steve

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Interesting,

Take an image at 2 seconds, ISO 200, 400, 800, 1600.

If nothing, you may have a winner. I read that the previous model, gx7 was only good using silent shutter mode which is limited. You would have to use electronic shutter. Only way I could think your testing was flawed is if the camera was somehow using electronic shutter rather than the mechanical shutter.

Who converted your camera?

Enrico had a recent conversion done where they also changed the internal led to a SWIR one. Its possible this may have been done for your camera as well.

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On a whim, I bought it preconverted from eeassa on eBay before I found this site and had much of any idea what I was doing. I too thought the shutter sensor might have been modified, so I messaged him about it and he said he did not modify the shutter sensor in any way, and further that he had never encountered IR shutter sensor problems with any micro four thirds camera that he had converted. He did not indicate how extensive that experience is.

 

I am reasonably certain that it is using the mechanical shutter. When you set the Shutter Type setting to ESHTR, the slowest the shutter will go is 1 second. With the Shutter Type at MSHTR and the electronic shutter sound turned off, you can clearly hear the shutter actuation.

 

I'll try your suggestion this weekend.

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Andy Perrin
Interesting, what was your experience with eeassa? I also bought my previous camera (NEX-7) from him. Aside from some dust in the case when I first got it, I never had an issue.
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  • 2 years later...

Steve, thank you for contributing this test ! I will link to it in the recent write up. HERE

 

I scarcely know what to write anymore about this IR shutter monitor thing !! 🤪

 

Some cameras which have it are almost useless, some cameras which have it only show the contamination occasionally and some which have it seem not to have any contamination at all (like your G85).

 

When testing for this by making long, high ISO exposures, it might be useful to verify that it does not happen when Live VIew is being used and also that it does not happen when using the electronic shutter. This suggestion is mostly me being curious, but it's possible alternate exposure modes could trigger the problem.

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