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Messages - johnrogerjennings

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Mechanical Q&A / Re: Can't focus QHY268M & QHY174M with OAG
« on: February 27, 2021, 10:11:51 AM »
I had a similar problem. I think the issue is that the minimum back focus distance for the guide camera is really about 61mm to the center of the off axis guider. That's 47mm to the base of the guider (Manual diagram), plus 12mm back focus (QHY462C), plus 2mm extra for focusing.

Lets assume the best case that you remove the front screw on AR window (-5mm) from the 462C guider. That means you have 7mm+2mm+47mm=56mm, not an idea situation, but the chip is still covered in the focuser from dust.

That means the back focus to the main sensor from the center of the off axis guider must be exactly 56mm for the two cameras to be in focus at the same time.

To get the calculation to the front of the OAG, add 8mm to the front of the OAG. (OAG 5mm, M54 plate adapter 3mm)  The total back focus to the main camera from the front of the OAG adapter is now 64mm.

Unfortunately that means that the 55mm back space requirement from the front of the OAG adapter to the main camera sensor plane can not be reached if the 2 cameras are parfocal. That's the issue with the diagrams on the QHY adapters website. The different back space adapters at the camera for the 268M or 268C is a red herring for this issue.

I'm using an astro-physics TCC Quad reducer/flattener on my AP130GT. It has 102.9mm back focus so I have a lot to play with. I use the full 69mm for my reducer/flattener spacer calculations and it should work ok.

There may be other quider/focuser housings that could be attached to the top of the OAG that would reduce the 47mm from the center of the OAG to the base of the focuser, or other guide cameras with less back focus, but I'm not aware of that. In reality, the stalk of the OAG may be too long. I also think other manufactures may have issues too. The real issue is the back focus of the OAG guider and camera.

I hope there is something I missed here and I'm wrong.


Image Issue Q&A / QHY12 - Bad bias frame
« on: August 27, 2020, 10:10:21 AM »
I have 2 QHY12 cameras. The first one operates perfect. The second QHY12 has an issue with the bias frame. The frame shows a dark area at one edge of the frame of about 20 percent of the sensor height. It is NOT the over scan area problem. I have checked the "remove over scan" checkbox in the driver and it makes no difference. The frame is darker in the final stacked image too requiring me to crop out the bad area.  I have tried various gain and offset values and the results are always the same. The attached picture had gain set to 0 and offset to 118. The offset seems very unlinear. I tested this camera with the most recent "classic drivers" and "original release drivers on my other computer that is setup for another QHY12. The result is the same on the old and new drivers: this bad area always appears.

teamviewer is installed. I can send you an invitation. Please give me an email address to send to. I will send the details of the system.

Any suggestions from anyone?

I have uninstalled and reinstalled the WINUSB and starsense drivers and I always get the same result. In maximdl 5 it always goes to immediate download with an image with no data.  In EZCAP at least it counts down the image exposure, but returns a black or empty image too with no data.


Thanks for the offer to help. How do you want to proceed? This may be difficult because my observatory is remotely located and I am not there.

I meant to say

I checked the dates on the c:\program files\QHY8_Drivers\driver\QHY8BASE.sys    (date 12/2/2009) (filesize 23KB)


I ran the driver detector and it identified the installed drivers as:

Found QHY8.Fireware Version:9-1-23
System Driver: x64/32 WINUSB driver

I checked my "programs and features" in the control panel and is says "Qhy8 Ascom Driver 2.0.0

I checked the original install file and it said ****starsense-v20

I checked the dates on the c:\program files\QHY9_Drivers\driver\QHY8BASE.sys    (date 12/2/2009) (filesize 23KB)

What else do I need to check?


Did anyone ever solve this problem? I've had my QHY8 since 2007 and never had any problems. I just completed a remote observatory in the desert 1200 miles distant and I had to build new computers and  install Win7 32bit. Apparently I had to use the WINUSB and ascom drivers because of WIN7.  I used to run on WinXP. I have the same issue as others here that when I press the expose button, the download starts immediately, but my exposure results in a black non exposed image. This is the latest ASCOM driver and latest maxim DL5 with all updates. I'm frustrated to the point of changing cameras and going to an FLI microline 8300. I'm very tired of dealing with these issues. The problem is that I'm having to deal with these issues remotely via my internet link. I'm not onsite at the observatory. I just installed the drivers at home and thought everything was ok before I left to install all my equipment.

I ran the driver detector and it identified the installed drivers as:

Found QHY8.Fireware Version:9-1-23
System Driver: x64/32 WINUSB driver

Maxim DL 5.18 with latest updates

Operating System:
Windows 7 Ultimate 32 bit SP1

Any help would be appreciated. I hate to trash this camera as obsolete for my setup after using it for years, but this driver nonsense is making me crazy.

John Jennings

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