My first cooled camera image!

[Spad]

I took this last night in my back garden. I am more than happy with my first attempt, and I am utterly blown away at how much better a dedicated camera is over a DSLR!

30 X 300 sec lights, 10 x dark and bias. Not done flats yet!🤣

Question....

With it being a cooled camera, can I shoot bias and dark calibration images during the day, or does the air temp in the scope have to match when I actually shoot?

Thanks for any advice.

Edited August 12 by Spad

[vlaiv]

24 minutes ago, Spad said:

With it being a cooled camera, can I shoot bias and dark calibration images during the day, or does the air temp in the scope have to match when I actially shoot?

Yes, you can shoot them during the day, just make sure you can reach set point temperature. Cooled cameras have deltaT that they can reach (how much below ambient temperature) and it is colder during the night so it can go lower.

Most people don't try to hit the lowest temperature and usually have two sets of darks - summer and winter darks, with winter darks often being about 10C lower than summer (say summer darks are -10C and winter are -20C).

You can even take the camera of the scope and do the darks in air conditioned room if you can't hit your set point temperature during the day. I usually just cap it and set it "face down" on desk and then take darks. Some people add aluminum foil (plastic can sometimes leak IR part of spectrum and aluminum foil prevents that - but so does wooden desk if you place camera face down).

[Spad]

3 minutes ago, vlaiv said:

Yes, you can shoot them during the day, just make sure you can reach set point temperature. Cooled cameras have deltaT that they can reach (how much below ambient temperature) and it is colder during the night so it can go lower.

Most people don't try to hit the lowest temperature and usually have two sets of darks - summer and winter darks, with winter darks often being about 10C lower than summer (say summer darks are -10C and winter are -20C).

You can even take the camera of the scope and do the darks in air conditioned room if you can't hit your set point temperature during the day. I usually just cap it and set it "face down" on desk and then take darks. Some people add aluminum foil (plastic can sometimes leak IR part of spectrum and aluminum foil prevents that - but so does wooden desk if you place camera face down).

What are delraT and set point temperature? If you don't mibd ne asking?

[LandyJon]

You don't really need bias frames with astro cameras, darks, flats and maybe dark-flats are all you need.

You also don't need to cool that low, the difference between  -5 and  -10 is very little, anything below that is negligible.

There's a good video all about camera sensors, if you can get through it you'll understand a lot more about how they work and and what makes enough difference to be worth doing.

 

[Spad]

18 minutes ago, LandyJon said:

You don't really need bias frames with astro cameras, darks, flats and maybe dark-flats are all you need.

You also don't need to cool that low, the difference between  -5 and  -10 is very little, anything below that is negligible.

There's a good video all about camera sensors, if you can get through it you'll understand a lot more about how they work and and what makes enough difference to be worth doing.

 

I know bias images are not beeded on DSLR, is it a similar thing with a dedicated camera?

Edited August 12 by Spad

[vlaiv]

9 minutes ago, Spad said:

What are delraT and set point temperature? If you don't mibd ne asking?

Set point temperature just means that you can select temperature at which you want your camera to be cooled (point at which you set temperature) and cooling controller will keep it at that point.

There are cameras (usually denoted as "air cooled" - because they cool just by circulating air without peltier cooling element) that can't do that - they just keep the fan on and cool close to ambient.

deltaT is just name for difference in temperature. Peltier cooling element can make temperature difference on its two sides, but just how much difference depends on properties of that element. Now we take hot side and cool it to close to ambient (much like air cooled cameras with fan) and cold side then gets really cold as peltier element always tries to keep the difference roughly the same. That difference (together with rest of cooling system) is what determines deltaT.

Depending on camera design this deltaT can be different, but it's max is usually in 30C-40C range. and is published for each model.

Now popular ASI533 has max deltaT of 35C

Which means that it can hit -10C (just about) if ambient temperature is 25C, because difference between these two is 35C.

It is risky to try to always hit that max deltaT as you don't control ambient temperature. Say you decide to go for -10C with 35C deltaT camera and ambient temperature is 24C at the start of the evening. Now, it is rare, but can happen that warm wind starts blowing and ambient temperature goes to 26C. You can no longer maintain -10C temperature of camera and it will produce some subs at -9C instead.

This is then problem for calibration as you won't have all the subs on the same temperature. For this reason it is best to save some room for any possible changes in ambient temperature.

[vlaiv]

Just now, Spad said:

I know bias images are not beeded on DSLR, is it a similar thing with a dedicated camera?

Bias signal is "included" in darks, so if you use darks - you will remove bias signal. Bias, on its own, is needed if you want to do fancy things like dark scaling or similar where you want to remove just bias signal from the rest so you can process the rest (dark signal, light - whatever) in particular way.

For regular, simplest calibration you need:

darks (to match the lights) and flat darks (to match flats).

[Spad]

2 minutes ago, vlaiv said:

Set point temperature just means that you can select temperature at which you want your camera to be cooled (point at which you set temperature) and cooling controller will keep it at that point.

There are cameras (usually denoted as "air cooled" - because they cool just by circulating air without peltier cooling element) that can't do that - they just keep the fan on and cool close to ambient.

deltaT is just name for difference in temperature. Peltier cooling element can make temperature difference on its two sides, but just how much difference depends on properties of that element. Now we take hot side and cool it to close to ambient (much like air cooled cameras with fan) and cold side then gets really cold as peltier element always tries to keep the difference roughly the same. That difference (together with rest of cooling system) is what determines deltaT.

Depending on camera design this deltaT can be different, but it's max is usually in 30C-40C range. and is published for each model.

Now popular ASI533 has max deltaT of 35C

Which means that it can hit -10C (just about) if ambient temperature is 25C, because difference between these two is 35C.

It is risky to try to always hit that max deltaT as you don't control ambient temperature. Say you decide to go for -10C with 35C deltaT camera and ambient temperature is 24C at the start of the evening. Now, it is rare, but can happen that warm wind starts blowing and ambient temperature goes to 26C. You can no longer maintain -10C temperature of camera and it will produce some subs at -9C instead.

This is then problem for calibration as you won't have all the subs on the same temperature. For this reason it is best to save some room for any possible changes in ambient temperature.

Ahhhhh, I get it now!! Thank you so much!! 😀

[Spad]

8 minutes ago, vlaiv said:

Bias signal is "included" in darks, so if you use darks - you will remove bias signal. Bias, on its own, is needed if you want to do fancy things like dark scaling or similar where you want to remove just bias signal from the rest so you can process the rest (dark signal, light - whatever) in particular way.

For regular, simplest calibration you need:

darks (to match the lights) and flat darks (to match flats).

I use Siril, i believe I put the flat darks in the bias folder?

[vlaiv]

4 minutes ago, Spad said:

I use Siril, i believe I put the flat darks in the bias folder?

Don't know really. Haven't used Siril for calibration. I do my calibration manually in ImageJ, but I suspect that either someone will come along that will know how Siril does the calibration - or you can look it up in manual / help files?

[Spad]

Will do 😀

[LandyJon]

There you go, vlaiv is more knowledgeable than I and has explained better than I could, his list at the end a little vague though ...

Lights - the data

Darks - remove the sensor read noise

Flats - remove any light anomalies or dust specs etc.

Flat darks or dark flats (which ever is correct) that remove the sensor read noise from the flat frames

As he explained  -10 is about as low as you need to go, with a cooled camera you can generally reach that indoors, or at least somewhere away from central heating and as I said going lower has minimal benefit.

I don't know siril so hopefully someone can chime in on that side.

[TiffsAndAstro]

1 hour ago, Spad said:

I took this last night in my back garden. I am more than happy with my first attempt, and I am utterly blown away at how much better a dedicated camera is over a DSLR!

30 X 300 sec lights, 10 x dark and bias. Not done flats yet!🤣

Question....

With it being a cooled camera, can I shoot bias and dark calibration images during the day, or does the air temp in the scope have to match when I actually shoot?

Thanks for any advice.

This looks really really good. Lots of detail but deserves flats.

I'm a beginner and set my 533 to -5c as the difference between -5 and -10 seems negligible. At least at my skill level.

I use flats darks and biases mainly because I can use the processing scripts in siril quicker.

Edited August 12 by TiffsAndAstro

[TiffsAndAstro]

1 hour ago, Spad said:

I took this last night in my back garden. I am more than happy with my first attempt, and I am utterly blown away at how much better a dedicated camera is over a DSLR!

30 X 300 sec lights, 10 x dark and bias. Not done flats yet!🤣

Question....

With it being a cooled camera, can I shoot bias and dark calibration images during the day, or does the air temp in the scope have to match when I actually shoot?

Thanks for any advice.

Mind if I ask what gear you used as your 150 minutes  stomps my best 6.3 hours result on this? Also your bortle?

Edited August 12 by TiffsAndAstro

[Spad]

16 minutes ago, TiffsAndAstro said:

Mind if I ask what gear you used as your 150 minutes  stomps my best 6.3 hours result on this? Also your bortle?

Yeah sure....

SW EQ6R Pro
SVBony 503 102ED with 0.8 Red/FF
SVBony 60mm Guide Scope
ZWO ASIAir Pro - all plate solving, guiding and image capture.
ZWO AIR183MC-Pro
ZWO ASI120MC-S Guide Camera
SVBony Dual Narrow Band (HA & OIII)

Stacked and Stretched in Siril with StarNet, Post Processed in Photoshop, and TopazAI DeNoise.

Also my profession was Photography. So I have a very good working knowledge of Photoshop!

PS..... No i am not sponsored by SVBony.... I am Yorkshireman that is proud of my bargain hunting skills, and tight fistedness! 🤣
 

Edited August 12 by Spad

[TiffsAndAstro]

4 minutes ago, Spad said:

Yeah sure....

SW EQ6R Pro
SVBony 503 102ED with 0.8 Red/FF
SVBony 60mm Guide Scope
ZWO ASIAir Pro - all plate solving, guiding and image capture.
ZWO AIR183MC-Pro
ZWO ASI120MC-S Guide Camera
SVBony Dual Narrow Band (HA & OIII)

Stacked and Stretched in Siril with StarNet, Post Processed in Photoshop, and TopazAI DeNoise.

PS..... No i am not sponsored by SVBony.... I am Yorkshireman that is proud of my bargain hunting skills, and tight fistedness! 🤣
 

Cool Ty. My 533 is svbony very happy with it so far. 

I did  mine in broadband, but will hopefully have svbony DNb filter in a week or two. Will be interesting to compare.

Ps - I use similar software but graxpert instead of topaz. Graxpert does gradients and denoising. Astro sharp might be worth a look, I'm playing with a new feature within it called astro clean.

 

Edited August 12 by TiffsAndAstro

[Spad]

I find SVBony more than does the job for me! I was accused on the "American" 🤣 site of singing their praises to get free stuff..... Everything I have I paid for!

[TiffsAndAstro]

Just now, Spad said:

I find SVBony more than does the job for me! I was accused on the "American" 🤣 site of singing their praises to get free stuff..... Everything I have I paid for!

I'm a fan of svbony so far. I'm hoping they bring out a £500 strain wave drive mount

[Spad]

1 minute ago, TiffsAndAstro said:

I'm a fan of svbony so far. I'm hoping they bring out a £500 strain wave drive mount

I think that would make me wet me knickers!