Focuser Temperature Compensation Using N.I.N.A.

Merci! Excellente vidéo et comme toujours très claire.

Very clear and informative. Good job!

I always thank you for useful advice AND providing such a good device.

Thanks Julian for this informative video

Thanks for this - I have been reluctant to try the temperature compensation but after watching this I should at least analyse the data for my setup and give it a try. It is always a tough decision to spend a rare clear night trying something new or stick with old trusted settings even if they are not perfect !

I have been using Astro Photography Tool’s Temperature (APT) Focus Compensation and have been able to keep my RedCat 71 with in the Bahtinov Grabbers’ critical focus range for over 4 hours this fall. APT’s temperature focus compensation runs in the background after being enabled but can be enable and disabled in APT’s scripts. It can also be configured to adjust focus during or between images. I have wanted to use NINA but did not want to give up temperature focus compensation. You have solved the problem. Thanks

Good video of an important topic for everyone with f/4 and faster! I implemented a quadratic temperature compensation (with elevation residuals) in Kstars/Ekos, and I was fretting having to do this again with N.I.N.A upon changing mounts. Glad to see at least a linear Temp Compensation is available already in N.I.N.A. I've been using my own home grown Ekos Temperature Compensation for 2 years, and I couldn't ever go back to the old ways (delta C triggered AF run, HFR AF trigger, or time based AF trigger). I always run an AF to start on a target, then let temperature compensation take over. I have run several hours and always been inside the CFZ @ f/2.2 (RASA 11). It's just awesome. Now repetitive AF runs (after the first on a target) seem very wasteful of imaging time. When you say relative, I'm assuming that if for any reason you manually adjust focus, the "setpoint" (base) of the integrator will reset to the latest location? Both completed AF runs, and manual setpoints should be honored (whichever was done most recently) as the starting point for the relative position. Also, is there a threshold for allowed changes (so that nuisance/small changes are built up before being applied)? Thanks.

I found the HFR AF trigger in NINA works well for OSC imaging. For monochrome, not so much simply because the HFR can shift quite dramatically with filter changes, particularly NB. The end result is an AF with every filter change, which isn't really a terrible result, but there is a trigger available for that instance without the complication of HFR changes. I limit my imaging to 10/filter so that I be reasonably certain of capturing a full 'suite' of filtered images per session; Temperature compensation may get around that but filter offsets combined with AF per filter changes to establish a "zero" reference each time seems to work very well. IMO - YMMV

Thanks for your approach about this topic which is key for a great imaging session, I have question for you, how to revert driver is something goes bad? Also how much time I can save using this technique comparing with I focus every 30 minutes? The key is save time, and looks the driver and Nina are ready for this. Thanks

Merci pour cet exposé, clair, précis... et pas trop long. Sans prétendre utiliser la technique de compensation pour l'instant, une question de curiosité : j'imagine que l'info de température est récupérée par NINA et qu'il faut donc 1/ un focuser avec sonde et 2/ un driver capable de remonter cette info. Correct ?

It looks like that in NINA the focusing temperature compensation only works with focusers that have a proprietary temperature probe (like the ZWO EAF). I am not using the EAF but another DIY ASCOM focuser (inspired from your very good OAG focuser project). Is there a possibility to plug a sort of independant 'ASCOM' temperature sensor that I could use for the compensation purpose? I am using NINA and happy with refocusing in function of HFR changes, though, so it is more a curiosity question... Or why not using both...

Fantastic, thanks a lot! Exactly what I was looking for (got a jumpy EAF external T probe, too)… Do I understand it right that you collect the current temperature from the sensor every second and store this in a list with 120 elements, continuously deleting the oldest value when adding a new value. And the temperature your driver returns is the average of these last 120 raw values. TEMPERATURE_WINDOW_IN_SECONDS = 120 is the size of your moving average window, right? Although in the code comments you write “60 seconds”…? 😀👍

Thank you Dark Sky Geek, a few nights ago I was out experimenting with NINA’s auto focus and the temperature was dropping quickly. I noticed that every auto focus run gave me a different result. So that is why I started looking at temperature compensation. Your video was very helpful to me. I have already bought an external temperature sensor for my robotic focuser (an Esatto 2” from Prima Luce Lab). A couple of questions if I may; considering that it is the tube that is contracting, why not place the temperature sensor on the tube? I plan to stick the sensor onto the tube with some adhesive backed foam, with some heat sink paste to provide good thermal contact to the tube. The foam will partly isolate the probe from the air temperature changes and should provide a less fluctuating result. Secondly, I have found that NINA’s auto focusing doesn’t work so well with nebulas. My work around plan was to write into the sequence a slew to a clear star group, do the AF, and then move back to the target nebula for imaging. Your approach of getting NINA to monitor the HFR of the images taken and compare the change in HFR to the last AF run would not be possible for me if I use a nearby star group for my autofocusing. So I don’t know where that leaves me - another problem to solve. Anyway thank you for the video, well done. Regards, John Bellingham

I got a notice last night in NINA for a EAF firmware Update to version 3.1.9. I installed it and now the DarkSkyGeek's Virtual Focuser ASCOM Driver is not working. If I select your driver NINA is showing temperature of -273.00 C, sometimes NINA will show focuser movement, but the EAF is not moving, and the beeper will run continuously. I have been using temperature compensated focus since you released the driver and have had nights where the focus was still in the Bahtinov critical range after 4 hours without doing an autofocus. During this time my focus steps have increased over 200 steps. My autofocus step size is 150 steps.

Star HFR is bad approach for refocusing, since it depends on wind, seeing, etc. Those factors change a lot during night. For example, you have 3 then 4. Focus on, waisted time. This 4 could be 3.3 in the next frame without refocusing