Instrumentation and Equipment

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For discussions on all aspects of equipment, from building new devices from scratch, to what ready made products are the best for your current setup. Attached the "Instrumentation and Equipment" observing section.

65 552 By Richard Berry 2 days 9 hours ago

Question about dark frame scaling -new CMOS cameras

American Association of Variable Star Observers (AAVSO)
RGN Sun, 06/06/2021 - 10:06

I would like to know if dark frame scaling is possibile with new CMOS cameras in the event of a camera that shows zero amp glow such as the QHY600 or QHY268. Since the electronics of these new cameras are also very stable I wonder whether one could even skip master frames and just subtract one single dark frame of corresponding exposure or one single scalable dark after subtracting a single bias. Of course gain, offset and temperature match the ones of the calibrating frames.



Beginner with no camera

American Association of Variable Star Observers (AAVSO)
Andrew Bennett Tue, 06/01/2021 - 16:52

Hello All: I'm a beginner and this is my first post to an AASVO forum. I have searched for answers to the following questions and have found some. It would be a great help if you were to supply even just Y/N answers to any. I'll abide by the first answer to any question, but if you answer otherwise then I'll go scratch my head for a while. Anyway, thanks for reading this far!


I have a Takahashi CN212 on a Losmandy GM8 mount. The CN212 is  212mm f/12 true Cassegrain  convertible to a  212mm f/4 Newtonian.


Linear response curve QHY 294M (Sony IMX492 sensor)

American Association of Variable Star Observers (AAVSO)
Remco Kemperman Sat, 05/15/2021 - 12:41

I have made a response curve for my QHY294M camera. So i thought other with a Sony IMX492 sensor might benefit from it too.

For this I took flats of different exposure time and plotted the median and the maximum pixel read out against exposure time. I averaged the ADU count of 3 frames per exposure time.

As you see, for thethe sensor has a linear response up to about 62.000 of 65.535 ADU. This is linearity up to 95%, which is really good in my opnion. To be save I will expose my targets stars no further than 60.000 ADU in photometry (92%).

What type of telescope (reflector) for photometry?

Bundesdeutsche Arbeitsgemeinschaft fur Veranderliche Sterne e.V.(Germany) (BAV)
MatthiasK Sat, 05/15/2021 - 10:20


I am doing photometry with a 90/500mm refractor and a Canon 450D. I consider to buy during the next 1-2 years a new telescope and camera. I do not want to go to big telescopes, maybe something like 8" maximum. But I wonder which type, Newton, SC,..., is best to use for photometry? I am not experienced with reflectors.



Photometry with QHY 6 Mono CCD

American Association of Variable Star Observers (AAVSO)
GeoLek Fri, 05/07/2021 - 19:38


I create a new post because I am interested in exoplanet/variable star photometry. I plan to use a QHY 6 cooled Mono CCD which is an excellent guiding camera and a very good entry level ccd for astrophotography. I want to ask if anyone has used this ccd camera for photometry and if yes,how good were your results? I do not expect precise/excellent results but I hope I will get some decent results until I manage to buy a very good Mono CCD camera.

Kepler 4040 Advice Sat, 04/24/2021 - 04:11

Hi Folks -

Anyone using the Kepler 4040 (or any of the other 4040 chip makers).

If you have any, advice would be appreciated.   I know It's very sensitive and I am going live next weekend. 

I can't seem to find the search terms to see where people are talking about it.   I searched "4040" and nothing is coming up.   "kepler" seems gives me all the databases ... sorry to ask something that I know has been asked before. 




New photometric filters - Bessell design

American Association of Variable Star Observers (AAVSO)
RGN Mon, 03/22/2021 - 18:52

I have learned that Custom Scientific is in the process of changing the design of their photometric filters. Instead of using the classic colored glass sandwich to match the Johnson-Cousins system with Bessell prescription they plan to use a single piece of fused silica with an interference coating on one side and an anti-reflection coating on the other side. As a result the shape of the transmission bands are different compared to the old filters. I attach a pdf showing the comparison.

QHY268M for photometry

American Association of Variable Star Observers (AAVSO)
ka5sma Fri, 03/19/2021 - 17:20

Have emailed QHY several times with questions and not gotten a response


anyone using the QHY268M for photometry?  what mode are you using..?

what gain and offset settings..

getting what looks like blooming....on some images...starlight from one bright star streaks to another star...etc..

any comments?