Imagining RedCat 61 SW Eq6 pro

[Bullmastiff]

Hi I’m really struggling with what exposure times i should be taking for deep sky with my RedCat 61 using the zwo 533mc pro colour camera. 
im looking for help on a ball park figure on taking lights, flat, darks bias 

 I also have an asiair plus any help would be really appreciated. Also what’s do I use to stack and process images 

[Stuart1971]

Maybe start with 2-3 mins for broadband and 4-5 mins for narrowband, now there are no rules about this, but the more data the better, you could go just 2 mins for all objects with all filters, and take many more subs…

As for the rest, Darks have to match the lights perfectly, same exposure time AND temperature…

Flats around 3 seconds and then take Dark flats at 3 seconds too, and no need for bias with these newer CMOS cameras, the bias is in the dark flats anyway….👍🏻

[Elp]

It depends on your light pollution saturation on the subs as it shouldn't be more than the target signal and definitely shouldn't cover it if possible, only you can determine that.

Total time is what matters overall. I usually image 30-120s, if it's breezy to the lower end. Narrowband I image up to 5 minutes but it depends on how good guiding is.

You don't need bias. Once you know how long your lights are you can do your darks during the day if you want making sure the scope and image train are dark (scope covered or camera removed with cover cap on and flat on a dark surface) and camera cooled down to the temperature you were imaging at. Flats have to be taken on the night (unless you're very lucky and don't shift absolutely anything on the setup, rotation, focus point, dust), it's easy with the asiair, go into autorun mode, add a panel, make them flats and set the exposure to auto, set the number of flats you wish to take and then run it. Once it's done, you can check how long they were and reset the autorun and make them darks now (dark flats, or dark frames for the flats), manually set the exposure time to the same as the taken flats, then cover the scope front and run again.

[Elp]

Are you using an LED tracer panel to illuminate for the flats?

Software you can used Deep Sky Stacker but I prefer Siril as you can do much more stuff with it and properly assess your calibration routine as I'd advise you learn to do it manually so you understand the process.

[Bullmastiff]

Hi all I really appreciate the help I’m getting here @Stuart1971you say darks have to match the lights so if I’m taking 2 minute exposure with lights I need to do the same with darks? Sorry to sound stupid.

Also what’s a good filter to use ?

I have been advised by FLO

L Enhance dual narrowband or

L-Extreme dual band narrowband?

[Bullmastiff]

3 hours ago, Elp said:

Are you using an LED tracer panel to illuminate for the flats?

Software you can used Deep Sky Stacker but I prefer Siril as you can do much more stuff with it and properly assess your calibration routine as I'd advise you learn to do it manually so you understand the process.

I’m using an A4 led panel for my flats as for software I have tried Deep sky stacker but not sure if it’s me or I’m totally stupid I do have siril but I think I need to learn more about how I actually image re light flats and darks 

my lights I set as autorun example 2 minutes for about 3 hours, then I take flats and darks maybe I’m doing something wrong when doing flats and darks I’m not sure ?

[Stuart1971]

1 hour ago, Bullmastiff said:

Hi all I really appreciate the help I’m getting here @Stuart1971you say darks have to match the lights so if I’m taking 2 minute exposure with lights I need to do the same with darks? Sorry to sound stupid.

Also what’s a good filter to use ?

I have been advised by FLO

L Enhance dual narrowband or

L-Extreme dual band narrowband?

Yes, if you take 2 min lights at, say -10 temp, then you need the same with darks about 40 of them should be fine…to create a master dark, you can do the darks in the daytime,  as you can set the temp on your camera, and build a library of them for different exposure times, and then you can use for the while season.

those are good filters if you want narrowband, well the L-Extreme is, don’t bother with the L-Enhance,  to do just normal RGB colour, then the Optolong L-Pro light pollution filter is very good and I use it with my OSC camera.

[Bullmastiff]

So let me just see if I understand this if I take 2 minutes lights, I need to take 2 minutes darks but around 30 to 40 exposures?

 

 

[AstroMuni]

55 minutes ago, Bullmastiff said:

So let me just see if I understand this if I take 2 minutes lights, I need to take 2 minutes darks but around 30 to 40 exposures?

The exposure time for each dark frame needs to match exposure time for each light frame. You will need to stack around 20-40 such dark exposures to get a master dark. Does that make any more sense? 🙂

So if you are taking 30s exposures for lights, you would take darks with same 30s exposure setting. Total number of lights exposures could be many hundreds.

Edited October 4, 2023 by AstroMuni

[Elp]

I don't bother taking so many darks, 10-20 is fine for me, the more you take the better the average between pixels but its so minimal, the end calibrated result will need some sort of noise reduction done to the final image anyway. The total number isn't so much an issue if you're using a cooled camera as you can take them once per length, gain and temperature setting per batch at anytime, if you're using uncooled though that time at the end of the imaging session taking darks adds up.

[Bullmastiff]

5 hours ago, AstroMuni said:

The exposure time for each dark frame needs to match exposure time for each light frame. You will need to stack around 20-40 such dark exposures to get a master dark. Does that make any more sense? 🙂

So if you are taking 30s exposures for lights, you would take darks with same 30s exposure setting. Total number of lights exposures could be many hundreds.

So what your saying if my lights are 1 minute my darks should also be 1 minutes but only need between 20 to 40 darks correct?

[Bullmastiff]

4 hours ago, Elp said:

I don't bother taking so many darks, 10-20 is fine for me, the more you take the better the average between pixels but its so minimal, the end calibrated result will need some sort of noise reduction done to the final image anyway. The total number isn't so much an issue if you're using a cooled camera as you can take them once per length, gain and temperature setting per batch at anytime, if you're using uncooled though that time at the end of the imaging session taking darks adds up.

My camera is a zwo 533mc pro cooled camera 

[Stuart1971]

7 hours ago, Bullmastiff said:

So let me just see if I understand this if I take 2 minutes lights, I need to take 2 minutes darks but around 30 to 40 exposures?

 

 

Correct…

[Elp]

As you have a cooled camera you can make a whole library of darks at any time away from the scope with the camera and asiair. For example if you image at gain 100 (where the High Gain Conversion mode kicks in for the 533) and minus 10 degrees C, you can make a collection of darks at 30/60/120/180/300s and keep them stored on your computer to use for calibration. People mention to do this every year but I haven't done so for nearly three years, still use the same ones (per camera model, each camera needs their own set). I've even started making short seconds long darks to use for my dark flats to calibrate my flats with. So when at the scope at the end of the session I only need to take flats (but typically also take the dark flats to match the duration of the flats as they are used to calibrate the flat frames just in case I don't have any saved, just saves time whilst the camera is still cold and it's all still plugged in).

Edited October 4, 2023 by Elp

[AstroMuni]

15 hours ago, Bullmastiff said:

So what your saying if my lights are 1 minute my darks should also be 1 minutes but only need between 20 to 40 darks correct?

Correct. The 20-40 is just to average out the values. And as your camera is same as mine (the ASI533), I dont take any darks as there is no amp glow issues to deal with.

[Stuart1971]

33 minutes ago, AstroMuni said:

Correct. The 20-40 is just to average out the values. And as your camera is same as mine (the ASI533), I dont take any darks as there is no amp glow issues to deal with.

Darks are not just for amp glow, they are there to sort other things too, like hot pixels, walking noise to some extent, and dark noise, again to some extent, these issues can also be mostly sorted by dithering, but I find it much much easier just to use darks than dither…

[AstroMuni]

4 hours ago, Stuart1971 said:

Darks are not just for amp glow, they are there to sort other things too, like hot pixels, walking noise to some extent, and dark noise, again to some extent, these issues can also be mostly sorted by dithering, but I find it much much easier just to use darks than dither…

I should have mentioned all those too 😞 Those are quite low on the ASI533 and as you say easier to deal with hence I havent found the need to take darks (yet).