Jannis

Michael, sorry for the late response. Yes this is with the most aggressive hysteresis setting, not the default 2 degrees. The problem is that the temperature keeps dropping for a while after peltier is turned off, causing it to wait for a while before turning on the peltier again. This again causes the temp to raise for a while after peltier is turned on. So even though the controller tries to keep it within +/- 1 degree, it swings with +/- 3-5 degrees at best. Allinthehead, I tried with the filter in place and didn't seem to get any reflection issues. However, I wasn't able to test much as even with a heater on the filter fogged up. I haven't quite given up yet though, and it does appear the best option is to leave the filter in place and have a bit more heating on the filter itself. A heater strip like that won't really work though as it would heat up the camera body and not the front filter, but I'll see if i can make something that will fit somehow.

I really love everything about how this image turned out, great job!

I run a rather high power TEC as i don't just cool down the sensor, it's around 60-70W at full power. For just the sensor you don't need more then a few watts, and so it might not be a problem for you. I recommend to leave the fan running at all time, yes.

Thanks for the info on the sensor heater power usage. It doesn't look possible to install this on my camera, but I'm sure it will come in handy in the future. May i ask why the 30 ohm resistor instead of stepping down the voltage? Michael, i have several of those and they are great for heating, but this type is not very good for peltier cooled sensors as it turns off the peltier completely for too long time and gives a lot of temperature swings even when set to the quickest mode. When i turn off the peltier, it only takes a few seconds before the heat from the hot side transfers and defrosts the camera. What i would need instead was a regulator that instead adjusted the volt/current gradually (not PWM), but i don't have this at hand.

I can't see any protective glass on this sensor, and so i don't think that will be a safe modification in my case, but how did you attach it, and how much power did you find out you needed?

Giving it another go now after yet another sensor cleaning. Running cooler at 5V now for a less aggressive and longer cool-down time, and with filter in place. Hopefully the trapped air, slower cooling, and heating around the front will be enough. Just hope i'm not getting any reflections... Edit: just checked, sensor is clean, but filter is fogging up. Still need to work more on this... It's just 2c outside, but the difference is still noticeable with only 5V on the cooler. Here are 10 sec darks with gain 100, before cooling, after 10 minutes, and after 30 minutes.

The heater helped stopping the buildup of ice in the front, and when i looked trough the telescope i could see the sensor. However, once i started capturing i noticed it wasn't going to work. I could only see fog, and water droplets, so i removed the camera to have a closer look. Unfortunately not a promising sight.. So not sure what to try next. Lower power on the peltier, higher power on heater, slower cooldown, simply attach the filter again and see if that works, - or accept it without cooling until i can afford a QHY163M... Haven't quite given up yet though, but any ideas and thoughts are welcome

Yes, the UV/IR filter is removed once attached to the wheel. I have an L filter in the wheel already, and I'm also worried about internal reflections if i leave two sets of filters in place. I put together a low power heating strap now, and placed it on the outside between the wheel and camera. I'm guessing this should mostly heat up the wheel and air in front of the camera, rather then the camera itself. Turned it on now, and we'll see how it looks in 30 min or so - if i can still see anything, or if things are all covered in ice or dew. Now if it all works, i just need to work a bit on my cables haha...

Thanks for the replies. Naturally the Polemaster was never designed for cooling, and i guess the main issue is that instead of cooling just the sensor i'm cooling the entire camera house. I can make a heater in a few minutes, but how will this work with an exposed sensor? Is the idea that the heating will keep the moisture away? Or did you mean to leave the 1.25" filter on and heat up just the filter?

As I'm on a tight budget for the moment, I'm using the Polemaster for imaging. I've noticed how much the sensor temp affects this sensor, and so I made a cooler for it. It cools well, however, there's always this slight issue with things that get cold fast... The ice appears to be only on the outside, and when scraping some ice of the filter, the sensor looks clean. However, this filter is only there temporary attached while i have it disconnected from my filter wheel. So my worry is that when i remove the filter, and attach the camera to my filter wheel, will the front of the sensor get as icy as the front of this filter? I'm using an EFW, but due to the 1.25" NP adapter there will not be an airtight seal. If an airtight seal would help significantly I could use a different adapter though. Any thoughts/ideas on how to keep the sensor frost free?

I tried to tighten up this backlash on mine as well, but eventually had to accept that the mounts gears are not precise enough to allow it. If i removed most of the backlash, the slight unevenness on the gear would make it jam at one point or another. I don't know exactly how large my backlash is, but around 2 sec sounds about right. I've learned that the best way is simply to off-balance the mount a bit and accept the backlash.

That's a really nice image you have there! You could try these 4 steps in Photoshop that i think improved it a bit. It's usually noisier in the red channel, and in the full res image you can see red spots here and there. 1) after duplicating the image as a new layer, reduce the noise. I tried these settings: 2) Filter -> Blur -> Gaussian Blur. I tried 3 pixel radius in this case. Just to smooth out the colors a bit, but not enough to loose too much of the smaller color details. 3) Image -> Adjustments -> Hue/Saturation. Increase saturation with +10 or so, just to compensate a bit for the faded colors due to the previous steps. 4) Set layer as "Color", and you will have the original sharpness, but with a more smooth color. Note i did not take the star colors and background into account here and it's often good to protect them a bit, as well as the previous steps can also be tweaked a bit, but give it a quick 30 sec reprocess with the galaxy color in mind and see what it does.

I have actually not had even one single clear night since the end of January, so I have yet to see how the real effect is. Thought, due to moonlight, target location in the sky, and filter being used, i guess it might take several nights to get a conclusive answer. At least i know what my exposure limits were before the light was put up, and i will update and post a comparison as soon as i get to have a clear night!

Thanks for the replies. I would complain about it keeping me up at night and so if i could, but the fact is that it does not direct any light towards the windows on my house, so the only thing i could complain about is that it lights up part of my property. Don't know if complaining about this would have any effect? A few years ago when they installed a madly bright white light bulb that really did lit up our bedroom at night, I did send in a complaint, and attempted to make calls when i didn't get any response. To this day i still never got any response, but luckily the bulb burned out and was replaced by a normal one again - until now. Moving the observatory is not really an option as it was built last year and consists of around ~3000KG concrete. I could install a shield on my side of the property, but it would only shield the observatory itself. Maybe that would be enough though?

Knowing i had a traditional old sodium lamp next to my observatory i wasn't much worried as both my Baader RGB filters, as well as the CLS and narrowband filters would take care of it. However this bulb burned out nearly a year ago and was never replaced - until yesterday... It seems they don't replace any sodium bulbs anymore, and instead replace them one by one with LED. Now I'm not against LED if it's used properly (directed correct, dimmed at night when there's no traffic etc), but this one happens to shine right on my observatory and is never dimmed even though it usually only passes 4-6 cars per hour at night... Being at a street crossing i guess they installed an extra strong lamp, and i doubt they will want to install any kind of shielding on it, so I'm wondering if my best bet is to install one myself? As in, put up a pole with a plate on it midway between my observatory and the light. Does anyone know if this will have any affect, or will the light shatter from the lamp do too much damage to image anywhere near that direction anyway? This is how it now looks... And i gave the CLS a test... Same exposure, same white balance. Without: With: