New ZWO mono camera on the way?

[SamAndrew]

1 hour ago, smr said:

It says minimum recommended filter size 30.34. So would 31mm filters be ok?

With regard to Mono imaging...

Just so I'm on the right track with how a Mono imaging session would go ... if any of it's wrong please let me know...

If I were to buy a Mono APS-C and a Filter Wheel, and I went for just LRGB Filters. I would need to buy

Camera
Electronic Filter Wheel, 5 or 7
LRGB Filters 

If I had a 4 hour imaging window for example.. I'd have everything ready to go and start off by just shooting an hour of L, the software then automatically switches the filter wheel around to the Blue Filter, I have to refocus by slewing to a bright star, put on bahitnov mask and focus, slew back to target and carry on imaging, then after another hour I repeat the same process with R and then G, at the end of the 4 hours I then take flats with the G filter in place for all filters. Imaging session complete.

This is really exactly what I'd like to know - how that is done ^ because at the moment it's very basic with my DSLR, just focus, slew to target, plate solve. Shoot, take flats at theend of the session. Just want to be sure what is different and what is involved with Mono imaging.

Really appreciate any help!

Depends on the F ratio of you telescope; faster scopes may need bigger filters, so I'd go up a size to cover yourself for future upgrades. Ideally a 7 position wheel for LRGB HA SII OIII. 

As already said, you'll want to add an autofocuser, as you don't want to be slewing back and forth and having to recenter the image between filter changes. You'll also need to shoot flats for each filter to correct for dust on the individual filters. 

[smr]

32 minutes ago, Starflyer said:

When I swapped from a DSLR to mono the first thing I learnt was that parfocal filters aren't and I absolutely needed to refocus on every filter change. This soon became a real chore and I added autofocus, it's one of the best additions you can make.

I started off with SGP refocusing on every filter change, and as this takes time I'd run all my blue subs, then green then red.  I found this was resulting in too many partially completed images, so I worked out the focus position offsets, initial focus is done with L and I can now run B - G - R - L subs and know the focus will be spot on for each filter.

Another advantage of autofocusing is staying in focus as the ambient temperature drops.  I autofocus every 1.5C temp change knowing I'll always have spot on focus.

Your example workflow assumes you'll have a four hour window of clear sky, the recent weather proves this isn't always the case.  You can of course shoot over multiple nights and I almost always do this, but with autofocus you can have subs to create a usable image after a relatively short period of time.

 

Thanks yes i would definitely add an autofocuser. I will buy the ZWO EAF when theyre in stock. 

I dont mind imaging over several nights. Infact this is my usual routine with my DSLR. I usually like to image a target as much as I can so I would typically spend several nights doing so.

So if we had 4 clear nights a month, I could image L one night, B the next, then R then G. Hopefully 4 clear nights a month before whichever DSO I'm imaging is unobstructed.

Do you have to work out focus position offsets with an autofocuser? Not sure what that means.

 

 

 

[smr]

1 minute ago, SamAndrew said:

Depends on the F ratio of you telescope; faster scopes may need bigger filters, so I'd go up a size to cover yourself for future upgrades. Ideally a 7 position wheel for LRGB HA SII OIII. 

As already said, you'll want to add an autofocuser, as you don't want to be slewing back and forth and having to recenter the image between filter changes. You'll also need to shoot flats for each filter to correct for dust on the individual filters. 

Thanks. If I was shooting one filter a night, say just L for one night, I'd take flats at the end of the night. 

But if for whatever reason I wanted to shoot G and B the second night, do I take flats after G and then again after B or can you take flats for both filters at the end of the night?

[DaveS]

If you're not breaking the imaging train down or rotating the camera then you only need do a set of flats perhaps every six months or so unless you see new dust bunnies appearing.

When I set up my autofocuser I took readings for each filter and entered the offsets into the sequencing software. It autofocuses on Luminance and appies the offset without my intervention. If your 'scope is truly achromatic, and your filters parfocal, then you may not need offsets at all.

[Deeko]

On 29/01/2021 at 21:52, DaveS said:

3nm filters are very useable under UK skies, and with the moon around can make the difference between imaging or not. A narrower bandwidth won't affect how much wanted signal you get, as the emission line is much narrower than the bandpass of the filter, but it will knock down the unwanted background signal, ie light pollution..

This is good to hear, having being back and forward over this and think I'll go for a set of the 3nm pro filters. The Ha and SII pro variants are available now but taking them (Antlia) longer to produce the OIII as coatings harder to make.

[Deeko]

OK, got my 268M this morning and drowning in adaptors  Can I just ask for a little clarity - out the box the camera has the M54-4mm plate on top as seen in photo, in total with that plate on its this the advertised 12.5mm back focus? If I remove that 4mm plate and replace with the one in my hand (M48-5mm) to connect to my ZWO FW, will the back focus then be 13.5mm to work with?

[Spongey]

1 minute ago, Deeko said:

OK, got my 268M this morning and drowning in adaptors  Can I just ask for a little clarity - out the box the camera has the M54-4mm plate on top as seen in photo, in total with that plate on its this the advertised 12.5mm back focus? If I remove that 4mm plate and replace with the one in my hand (M48-5mm) to connect to my ZWO FW, will the back focus then be 13.5mm to work with?

Backfocus of 12.5mm is without the M54 4mm adapter plate. With the M48 5mm adapter you have in your hand the backfocus will be 17.5mm.

Interesting that yours came with the M54 adapter already bolted on, mine was blank. Regardless, it's a simple case of unscrewing the M54 adapter and replacing with the M48.

[Deeko]

ah, thanks for clearing that up! The fact it came with M54 already bolted on threw me from the original calculations

[tooth_dr]

50 minutes ago, Spongey said:

Backfocus of 12.5mm is without the M54 4mm adapter plate. With the M48 5mm adapter you have in your hand the backfocus will be 17.5mm.

Interesting that yours came with the M54 adapter already bolted on, mine was blank. Regardless, it's a simple case of unscrewing the M54 adapter and replacing with the M48.

Mine blank too, also mine dont have numbers printed on them either.

[Deeko]

Just in case anyone finds the info useful I have now connected the 268M to the ZWO FW. to achieve this I used up 19.5mm of back focus = 12.5mm default BF + M54-5mm + 2mm T2-T2 adapter.

[teoria_del_big_bang]

2 minutes ago, Deeko said:

Just in case anyone finds the info useful I have now connected the 268M to the ZWO FW. to achieve this I used up 19.5mm of back focus = 12.5mm default BF + M54-5mm + 2mm T2-T2 adapter.

What size are the filters 36mm?

Steve

[Deeko]

Just now, teoria_del_big_bang said:

What size are the filters 36mm?

Steve

Yes, unmounted 36mm.

[teoria_del_big_bang]

Well inside the requirements then which are just over 31mm (guessed at actual distance to filter) but looks like you are good to go and just need some clear skies now 🙂 
So you best get some practice in before mine comes because there's bound to be cloud over all Yorkshire and into Lancashire then 🙂 

Steve

[Deeko]

2 minutes ago, teoria_del_big_bang said:

Well inside the requirements then which are just over 31mm (guessed at actual distance to filter) but looks like you are good to go and just need some clear skies now 🙂 
So you best get some practice in before mine comes because there's bound to be cloud over all Yorkshire and into Lancashire then 🙂 

Steve

Yes indeed  But first I need to find the rest of the spacers/adaptors to push out the rest of the back focus. I am swapping over to my OVL flattener with this camera as dont want to use the 0.79 reducer. If memory serves correct I ended up needing 65mm of back focus for that flattener to work well.

[teoria_del_big_bang]

Always a bit of a faff getting the BF just right on a new setup. I always tale a photo when happy and then mark where all the spacers go and their sizes, in case I have to go back to that setup after a strip-down.
Good luck I hope you get it near enough to give your new toy a tryout soon 🙂 

Steve

Edited February 11, 2021 by teoria_del_big_bang

[Deeko]

From what I have seen of a few others who have this camera, and coming from ZWO world where I just 'set and forget' gain/offset is a good starting place 56 gain 10 offset?

[Deeko]

Also, for the drivers etc. is it the stable version or the beta version (for Windows) I need from here: https://www.qhyccd.com/download.html

[Spongey]

8 minutes ago, Deeko said:

Also, for the drivers etc. is it the stable version or the beta version (for Windows) I need from here: https://www.qhyccd.com/download.html

You want the latest beta SDK located here, version 21.02.01.

What capture software will you be using?

[Deeko]

8 minutes ago, Spongey said:

You want the latest beta SDK located here, version 21.02.01.

What capture software will you be using?

Thanks for that! I will be using APT.

[Spongey]

14 minutes ago, Deeko said:

Thanks for that! I will be using APT.

No worries. I'd be interested to hear if you have any issues. I've been getting some QHY SDK crashes with Nina but it doesn't seem that anyone else is haha. Have done some debug work with the Nina devs and the issue is being reported back to QHY so will hopefully be resolved for me shortly.

I hope you don't have any of the issues I do!

[JamesF]

15 minutes ago, Spongey said:

No worries. I'd be interested to hear if you have any issues. I've been getting some QHY SDK crashes with Nina but it doesn't seem that anyone else is haha. Have done some debug work with the Nina devs and the issue is being reported back to QHY so will hopefully be resolved for me shortly.

I hope you don't have any of the issues I do!

On Linux I was getting crashes in the SDK with the previous release of the SDK (20.12.27), but a quick test suggests the same problem is not present with 21.02.01.

James

[JamesF]

Looks like there might be another SDK release on the way very soon, too:

https://github.com/indilib/indi-3rdparty/pull/319#issuecomment-777242217

James

[Deeko]

Installed the beta SDK and APT could see the camera via the ASCOM driver. The default out-the-box gain setting was something strange like 127 with 76 offset. I changed it to 56 gain 10 offset. Can anyone tell me what the readMode settings are for? Screenshot attached. I am not a fan of tinkering with extra settings to be fair. Also USB readout speed, is 0 fast or is it the slowest in this case? 

Edited February 11, 2021 by Deeko

[Davey-T]

Had first proper go with ZWO ASI2600MM  last night and chucked it all in Maxim which is still the simplest quickest way to calibrate and stack images and there is a problem with the temperature  stabilisation of the camera, set at minus 10 but there is so much variation of temp' that Maxim splits images into separate stacks depending on temperature so have to edit them to all the same.

Dave

 

[Davey-T]

Took 20 x 300sec's with SharpStar 150HNT F/2.8 ZWO ASI2600MM and Antlia 3nm Ha filter, had to scrap some because of clouds and ended with 12 subs.

Just stacked and stretched in PS.

Full frame

 

Centre cropped

Edited February 12, 2021 by Davey-T