Hello,
I just started using my QHY 268M, and I was surprised how noisy the images were, and full of square artefacts. These are screenshots from the Voyager FITS viewer. I guess I am doing something wrong, so I would love to hear what others have to say about the camera.
Conditions
600sec subs
DSO setting (Gain 30 / Offset 76)
Bortle 1
Narrow band (Chroma)
Veil Nebula
Note that my flats are fine and my Clear filter shots are not noisy and look good. (Shot at 180sec).
First make sure the Voyager Fits viewer is set to its highest quality setting. But most likely, you need a larger offset. Try 50 and work up from there. Narrow band filters usually require a larger offset.
📷 PIHQ Sub.jpg
There is one of mine from last nights session on an extremely faint target. Make sure the HQ button is selected and the PI stretch immediately to the right of the HQ button is also selected. I agree with the previous comment about camera settings. I have used one of these cameras since they first came out and seen many changes over the years. I only use two operating points/modes now and feel they work the best, at least for me. High Gain 2CMS with Gain 56 Offset 25 is my main mode and used for everything except bright nebula like Orion or RGB Stars to go with my NB images. For those brighter things I use High Gain 2CMS with Gain 0 Offset 15. These are great choices of where to start operating this camera but it is personal preference. Use the camera curves on the QHY website to help guide you if you want to try some different settings. You may find something you like better with your specific gear.
Let me add a note here on the HCG switch/modes. The HCG switch for this camera activates at Gain 26 in Photographic DSO mode and Gain 56 in High Gain mode. The newer 2CMS modes do not change this switch setting and are recommended by QHY. There is really no benefit to selecting higher gain settings using either of these modes. You may wish to choose lower gain settings in some special cases like I mentioned to maximize full well capacity and dynamic range. Some people use the Extended Full Well mode in these situations. I personally do not recommend it nor have I ever found a place I felt it was really needed. It has much more noise and no HCG switch.
CS,
Jeff
Jeff Reitzel · Sep 23, 2025, 12:44 PM
📷 PIHQ Sub.jpg
Let me add a note here on the HCG switch/modes. The HCG switch for this camera activates at Gain 26 in Photographic DSO mode and Gain 56 in High Gain mode. The newer 2CMS modes do not change this switch setting and are recommended by QHY. There is really no benefit to selecting higher gain settings using either of these modes. You may wish to choose lower gain settings in some special cases like I mentioned to maximize full well capacity and dynamic range. Some people use the Extended Full Well mode in these situations. I personally do not recommend it nor have I ever found a place I felt it was really needed. It has much more noise and no HCG switch.
CS,
Jeff
Hi,
Thank you for the quick replies and helpful insights.
I found out what happened. I read in the fits header that my gain and offset was 0. I have somehow forgotten to set the gain and offset values in the base sequence in Voyager. I expect to see different results tonight.
Clear skies
Roger Renberg · Sep 23, 2025, 06:36 PM
Jeff Reitzel · Sep 23, 2025, 12:44 PM
📷 PIHQ Sub.jpg
Let me add a note here on the HCG switch/modes. The HCG switch for this camera activates at Gain 26 in Photographic DSO mode and Gain 56 in High Gain mode. The newer 2CMS modes do not change this switch setting and are recommended by QHY. There is really no benefit to selecting higher gain settings using either of these modes. You may wish to choose lower gain settings in some special cases like I mentioned to maximize full well capacity and dynamic range. Some people use the Extended Full Well mode in these situations. I personally do not recommend it nor have I ever found a place I felt it was really needed. It has much more noise and no HCG switch.
CS,
Jeff
Hi,
Thank you for the quick replies and helpful insights.
I found out what happened. I read in the fits header that my gain and offset was 0. I have somehow forgotten to set the gain and offset values in the base sequence in Voyager. I expect to see different results tonight.
Clear skies
And that was a complete fail. I set the Gains and the offsets in the pre-setup, in the base sequence. But when I runt dragscript and robotarget it doesn’t add gain or offset. I saw had a look in the log folder and it said DEBUG next to setting Gain and Offset.
Anyone else ran into this issue with this camera using Voyager?
Hi Roger,
I have never used Voyager, NINA, or The SkyX to control my QHY camera gain or offset like you seem to be trying to do. I have never had it work consistently, if at all, with any of those programs using the native or X2 drivers that are required for that type of control. The ASCOM drivers have always worked perfectly with all my cameras so that is what I use regardless of the imaging program controlling the session. You can set up the gain, offset, and operating modes with the ASCOM drivers any way you want it. You just can’t change it without rebooting the camera. For initial setup like this in most programs including Voyager you would select ASCOM Camera and not QHY imaging camera then follow the prompts to set up the ASCOM control. In Voyager that will disable the fields to enter gain/offset since it is now being controlled with ASCOM. I use a pair of QHY268M cams, a QHY410C cam, and a Player One Zeus Cam. I have found this to be true for all of them. Someone else may know of a workaround to do what you are trying to do. In my experience each company you contact related to this will blame the others software and nothing changes. :)
CS,
Jeff
I somehow think that Mode 0 combined with Bortle 1 sky with 600s subs is not optimal. The read noise is relatively high , and simply not swamped in very low (Bortle 1, narrow filters) overall background.
So the read noise might be dominating in your case.
I am always using high gain mode with gain set to 56 . Usually I have 300s subs (Bortle 4/5) and all is OK with NINA.
Jeff Reitzel · Sep 24, 2025, 12:59 PM
Hi Roger,
I have never used Voyager, NINA, or The SkyX to control my QHY camera gain or offset like you seem to be trying to do. I have never had it work consistently, if at all, with any of those programs using the native or X2 drivers that are required for that type of control. The ASCOM drivers have always worked perfectly with all my cameras so that is what I use regardless of the imaging program controlling the session. You can set up the gain, offset, and operating modes with the ASCOM drivers any way you want it. You just can’t change it without rebooting the camera. For initial setup like this in most programs including Voyager you would select ASCOM Camera and not QHY imaging camera then follow the prompts to set up the ASCOM control. In Voyager that will disable the fields to enter gain/offset since it is now being controlled with ASCOM. I use a pair of QHY268M cams, a QHY410C cam, and a Player One Zeus Cam. I have found this to be true for all of them. Someone else may know of a workaround to do what you are trying to do. In my experience each company you contact related to this will blame the others software and nothing changes. :)
CS,
Jeff
Hey Jeff,
Thank you for pointing this out to me. Ill use the ASCOM driver instead :)
Clear skies
Roger
AstroStew · Oct 5, 2025, 09:57 AM
Mode 1 HGC, with Gain 56 and offset 25 with this camera all the time, and then adjust exposure length for different targets and or filters used. I use the native driver and always have done for many years, I use NINA, BUT I use the original driver that was the latest when I bought the camera back in 2020, so the driver I use is 5 years old as is the camera firmware, if it ain’t broke, then leave well alone is my moto
I’m just reading that QHY recommends the 2CM twin models. Has anyone compare Mode 5 to Mode 1 ?
“ High Gain Mode-2CMS (Mode#5) Based on the three basic modes above, 2CMS mode can greatly reduce readout noise by secondary sampling while keeping the same full well value and system gain. We prefer 2CMS modes than basic modes in astrophotography. By the way, the recommend gain values are the same as their basic modes.”
thank you
So here is an update,
I took Jeff’s advice, and my subs are very good now. They are clean and detailed.
I use the DSO setting, which I believe is Gain 56 and 74 Offset.
Works very nicely with 600s subs :)
Thanks for your assistance
CS