Filter Upgrade For ZWO1600 Camera

[groberts]

I've had a ZWO ASI1600MM-Cool 2nd Gen since the end of 2016 + using the ZWO 7nm 31mm filter bundle (LRGB & HaOIIISII), which I use with a WO GT81 and Bortle 5/6 skies + frequent planes as I live near Gatwick (or at least there used to be) using mainly <= 5 min subs.  Although generally happy with the results I am now considering upgrading the filters either to Astrodon or Chroma. 

• Is this a good idea / worthwhile?
• For NB is 3nm the way to go + what, if any, are the implications for imaging e.g. exposures, integration times etc?

Graham    

Edited October 6, 2020 by groberts

[SyedT]

9 hours ago, groberts said:

I've had a ZWO ASI1600MM-Cool 2nd Gen since the end of 2016 + using the ZWO 7nm 31mm filter bundle (LRGB & HaOIIISII), which I use with a WO GT81 and Bortle 5/6 skies + frequent planes as I live near Gatwick (or at least there used to be) using mainly <= 5 min subs.  Although generally happy with the results I am now considering upgrading the filters either to Astrodon or Chroma. 

• Is this a good idea / worthwhile?
• For NB is 3nm the way to go + what, if any, are the implications for imaging e.g. exposures, integration times etc?

Graham    

I owned a set of Baader LRGB and NB filters. While they were great, they're no match for the Chroma set I replaced them with (managed to get them less than half price each as part of a package). I would go for it.

The main issue with 3 nm NB is that it takes long exposure times to lift the histogram off the left edge, so you need to either have a fairly sensitive camera (the 1600MM definitely ticks that box) and a mount capable of guiding these. On the plus side, I'm yet to see those horrible halos you get with some filters!

[SyedT]

You can have a look at one of my integrations here: 

I only did 300s subs due to inconsistent guiding because of wind/poor seeing etc. You can see there's a fair amount of background noise which means it doesn't look as "clean" as it should, despite a good overall integration time.

 

[groberts]

Thanks Syed that's helpful.

I'm a little concerned as I said 300s is my highest exposure due to (a) numerous aircraft and (b) I have no view of Polaris, so my PA is OK'ish (using PHD2 technique) but not sure about going to say +600s - one of the reasons I like the ZWO which being sensitive + low readout noise produces a good bang for your buck @ 300s.

Graham

[SyedT]

15 minutes ago, groberts said:

Thanks Syed that's helpful.

I'm a little concerned as I said 300s is my highest exposure due to (a) numerous aircraft and (b) I have no view of Polaris, so my PA is OK'ish (using PHD2 technique) but not sure about going to say +600s - one of the reasons I like the ZWO which being sensitive + low readout noise produces a good bang for your buck @ 300s.

Graham

I think you'd be OK with the 1600MM and 300 second exposures. I used to have a 1600MM; my main issue was the 12-bit ADC giving posterisation in some scenarios, which is why I switched to CCD (Atik 490EX). However, all that may well change as there are 16-bit CMOS sensors being released, although I'm waiting for an APS-C size mono 16-bit sensor which would match well with my scope.

For polar alignment, have you looked into getting an iOptron iPolar? It's an electronic polarscope which doesn't require a view of Polaris.

[groberts]

I was also thinking of getting a second ZWO1600MM but am intrigued by what you're now saying about the 16bit-CMOS sensors - could you please  direct me to any / alternatives to the ZWO - althougb that sounds like we're thinking of the same thing re. APS-C size?

No I haven't heard of the iOptron - will take a look; one day I hope to have a static observatory + view of Polaris but for now have to work with what I have = dream on!

Graha 

[Ken82]

Yes I’d get the chroma without hesitation. The lack of halos was worth it on its own for me vs baader and Idas. I cannot comment on the zwo filters but I do have a few friends who have complained of large halos. 
 

3nm or 5nm is A personal decision I do believe chroma endorse the 5nm on most occasions. But as long as your exposing long enough so that read noise is swamped your good to go. 
 

here is my comparison with chroma, baader and Idas filters. Baader 140pixel halo. Idas 160pixel halo. Chroma zero 

ken 

[groberts]

Thanks Ken, looks convincing.  For some reason I figured 3nm was better then 5nm but maybe not?

Graham 

[SyedT]

17 hours ago, groberts said:

I was also thinking of getting a second ZWO1600MM but am intrigued by what you're now saying about the 16bit-CMOS sensors - could you please  direct me to any / alternatives to the ZWO - althougb that sounds like we're thinking of the same thing re. APS-C size?

No I haven't heard of the iOptron - will take a look; one day I hope to have a static observatory + view of Polaris but for now have to work with what I have = dream on!

Graha 

The issue with these 16-bit APS-C sensors is that they're all colour e.g. https://www.firstlightoptics.com/zwo-cameras/zwo-asi-2600mc-pro-usb-30-cooled-colour-camera.html and https://www.modernastronomy.com/shop/cameras/cooled-ccd/qhy-cooled-ccd-cameras/qhy268c-photo/

Same sensor, different companies. I'm getting in touch with both companies to see whether there is a mono version of the above on the cards, which would be perfect. I did hear of the QHY268 getting a mono version, but there don't seem to have been any updates since: http://www.iceinspace.com.au/forum/showthread.php?t=184422

EDIT: Just saw this https://www.qhyccd.com/bbs/index.php?topic=8252.0

Re: the iPolar, I did test it out yesterday. It's a bit more fiddly than the PoleMaster, but I was aligned fairly quickly. Didn't get to do any imaging as clouds rolled in, however, so the true test is yet to come.

Edited October 7, 2020 by SyedT

[SyedT]

Just got a response from ZWO:

2600MM won't come this year but there is such plan next year
 

[groberts]

Interesting - I wonder what the spec will be + when = is it worth waiting rather than another 1600MM-Cool? 

Presumably a mono version of the colour version https://astronomy-imaging-camera.com/product/asi2600mc-pro-color ?

🤨

Edited October 8, 2020 by groberts

[groberts]

OK I'm sold on moving to Chroma 31mm filters but have one further small but practical question for anybody that has already made a similar change this. The filters will be going into a ZWO x8 EFW to replace the original bundled ZWO filters:

• I understand the Chroma filters are thicker than ZWO ones so - will the screws used to fix the ZWO filters be long enough to accomodate the Chroma filters and if not, where could I get suitable / longer replacement ones? 

Graham

[nfotis]

I think that the screws are M2x4mm or so, easy to find replacements if needed.

 

N.F.

 

[nfotis]

On 06/10/2020 at 21:34, groberts said:

I was also thinking of getting a second ZWO1600MM but am intrigued by what you're now saying about the 16bit-CMOS sensors - could you please  direct me to any / alternatives to the ZWO - althougb that sounds like we're thinking of the same thing re. APS-C size?

You may be interested in the ZWO and QHY 294mm models? These could be considered a big upgrade of the 1600mm, and you keep everything else the same (filter wheel etc)

Monochrome APS sensors like the 2600mm are expected to be quite pricey, and will necessitate larger filters and filter wheel etc.

N.F.

[groberts]

12 minutes ago, nfotis said:

You may be interested in the ZWO and QHY 294mm models? These could be considered a big upgrade of the 1600mm, and you keep everything else the same (filter wheel etc)

Monochrome APS sensors like the 2600mm are expected to be quite pricey, and will necessitate larger filters and filter wheel etc.

N.F.

I have an open mind but in what way are they an upgrade + they appear to be  only OSC versions, do they do mono?

Graham

 

Edited October 16, 2020 by groberts

[nfotis]

11 minutes ago, groberts said:

I have an open mind but in what way are they an upgrade + they appear to be  only OSC versions, do they do mono?

Graham

 

Yes, there are 294mm monochrome editions being delivered. The QHY model offers also an unbinned mode, where each subpixel is available separately, going from 14-bit 11 Mpixel to 12-bit 46 Mpixel.

Note that the sensor is the IMX492

 

https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=9 

 

https://astronomy-imaging-camera.com/product/asi294mm-pro

 

N.F.

 

Edited October 16, 2020 by nfotis

[groberts]

9 hours ago, nfotis said:

Yes, there are 294mm monochrome editions being delivered. The QHY model offers also an unbinned mode, where each subpixel is available separately, going from 14-bit 11 Mpixel to 12-bit 46 Mpixel.

Note that the sensor is the IMX492

 

https://www.qhyccd.com/index.php?m=content&c=index&a=show&catid=94&id=9 

 

https://astronomy-imaging-camera.com/product/asi294mm-pro

 

N.F.

 

Thanks I'll take a closer look 🤔

[groberts]

UPDATE - re. nfotis comments above regarding the 294 ZWO & QHY mono cameras.

Been looking at this all day + on CN it's clear that the ZWO294MM is very much the successor to the ASI1600MM-Cool, which I and many other people have.  This thread on CN is therefore well worth reading if, like me,  you're thinking of upgrading:

  https://www.cloudynights.com/topic/726990-zwo-asi-294-mm-pro-first-impressions-and-test-images/#entry10473357

Warning it's very long but probably points the way forwards for mid-range / price mono cameras for the near /mid-term so worth the time.

Graham

[nfotis]

Forgot to  mention this thread as well (quite intriguing reading).

It isn't the same as the 533 (it has visible amp glow), and you will need to calibrate similarly as the 1600. But it looks like it has fatter pixels (if you don't care about the QHY sub-pixel mode), much deeper wells, etc., while losing a bit of resolution.

The ideal would be to have a 533-like sensor in 4/3rds dimensions, but I suppose that Sony doesn't offer such an animal. Going to 2600 is a quite costly endeavour, because it involves larger filters and filter wheels, while the 294MM (or IMX492, if you prefer) should be a drop-in upgrade for 1600MM users.

N.F.

 

[Adam J]

On 06/10/2020 at 18:52, SyedT said:

The main issue with 3 nm NB is that it takes long exposure times to lift the histogram off the left edge, so you need to either have a fairly sensitive camera (the 1600MM definitely ticks that box) and a mount capable of guiding these. On the plus side, I'm yet to see those horrible halos you get with some filters!

It's talking longer because signal to noise has improved so I fail to see how it's a bad thing. 

[Starflyer]

I've been hanging onto CCD for years now, the 2600MM will be my next camera though.