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  #1  
Old 19-10-2017, 01:01 PM
glend (Glen)
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Internal Reflections on CMOS Mono Sensors

Thread was high-jacked. Original discussion removed.

Last edited by glend; 20-10-2017 at 07:20 PM.
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  #2  
Old 19-10-2017, 02:17 PM
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billdan (Bill)
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Must be a similar issue with the QHY168, as QHY has asked the debayer company to return the camera with an anti-reflection cover glass installed.

This company is Chipmod in China who are selling the QHY168 Mono on special at the moment for $US 1850.00 ($350 more than the colour version)

https://www.facebook.com/chipmod.astrocn.org/
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  #3  
Old 19-10-2017, 05:04 PM
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I can confirm what Glen said that the original glass causes reflections on debayered cameras.

I have debayered Nikon D70 sensor for my self-made Cam86 camera and initially I put back the original glass. The reflections were quite obvious. Eventually I removed the glass and am using the sensor without anything in front of it. I may order the anti-reflection coated MC-clear glass from Astronomik for protection, but it works quite well without any glass.

Few other people who debayered the D70 sensor for the same camera build also commented about the reflections caused by the original glass.
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  #4  
Old 20-10-2017, 01:09 AM
ErwinL (Erwin)
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Quote:
Originally Posted by luka View Post
Eventually I removed the glass and am using the sensor without anything in front of it. I may order the anti-reflection coated MC-clear glass from Astronomik for protection, but it works quite well without any glass.
That's interesting to hear. How long did you use the sensor in unprotected state? And did you ever operate an unprotected sensor while it was fogged, maybe due to cooling?
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  #5  
Old 20-10-2017, 12:40 PM
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Originally Posted by ErwinL View Post
That's interesting to hear. How long did you use the sensor in unprotected state? And did you ever operate an unprotected sensor while it was fogged, maybe due to cooling?
I only started using it. About 4-5 nights only and it was all in the last few weeks. I think on the second night out it got fogged up before I realised what was going on. No problems after it warmed up and on the following nights. Few other guys have been using it for a few months longer, didn't hear about any issues.

I can see two potential issues when using the sensor without cover glass:
1. protection, the thin gold wires on sides are exposed and can be damaged VERY, VERY easily. Even looking at them the wrong way can break them
Having said that I accidentally cut one on my sensor and then repaired it by soldering across. I would say that the success of the repair was based on 99% luck.
Also compressed gas from a can is OK for cleaning dust, it won't break the wires.
2. Moisture from condensation creating an electrical connection between the gold wires. Can't really comment on this.

And if you are considering removing the protective glass, as Glen said it involves high heat and chances are you will kill the sensor and/or electronics. My sensors are from Nikon D70 which can be bought from ebay for <$50. ASI1600 on the other hand costs much, much more.
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  #6  
Old 20-10-2017, 05:57 PM
ErwinL (Erwin)
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... No problems after it warmed up and on the following nights. Few other guys have been using it for a few months longer, didn't hear about any issues.
Sounds good. I'm thinking about using an open sensor together with a photo lens as a kind of basic protection.

Quote:
... the thin gold wires .. can be damaged VERY, VERY easily.
I apply a resin shield as already suggested by famous Gina. To avoid the thermal stress Gina reported, I use Pattex repair gel which remains flexible but still protects sufficiently.

Quote:
... repaired it by soldering across.
Congratulations!

I'm modding 1100Ds which are said to be very difficult to open - what I can confirm. But I found a way to remove the protective glass with quite little risk by use of a soldering iron. The trick is to regulate the temperature to at least 450C and - very important - to bring yourself to apply plenty of tin to the front glass to improve the thermal contact. This way one can introduce sufficient heat locally without endangering the CMOS.
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  #7  
Old 20-10-2017, 06:51 PM
glend (Glen)
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Thanks for high-jacking this thread guys.

My original post removed. Its all yours.

Last edited by glend; 20-10-2017 at 07:22 PM.
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  #8  
Old 20-10-2017, 07:09 PM
ErwinL (Erwin)
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Oh, I'm sorry, please accept my apologies.
Erwin
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  #9  
Old 20-10-2017, 09:54 PM
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multiweb (Marc)
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Thanks for high-jacking this thread guys.

My original post removed. Its all yours.
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