M83 first colour with ZWO1600

[Shiraz]

Hi

have been hoping for more data, but the weather...

So, best I can do for now is 126x60second lum + 59x60second colour for a total of about 3 hours. Tried to get as close as I could to the Hubble APOD as a colour reference, so it looks pretty red. The camera is low noise, so no calibration. Vignetting is an issue with the 1.25 filters, so I have cropped the image, awaiting a decent set of sky flats. Stars need work, but will do that when/if there is more data to work with.
http://www.astrobin.com/full/251726/0/?real=&mod=

Not a geat image, but probably enough to confirm that there is no major issue with the camera. Thanks for looking. Ray

[rmuhlack]

woohoo ! I'd say that is a great start :thumbsup: What gain setting did you use?

[Shiraz]

thanks Richard - 100

[glend]

Very Smooth Ray! I like it. I need to order some LRGB filters.

[rmuhlack]

So a read noise of about 1.8-1.9 ? From my calcs based on this (http://www.iceinspace.com.au/forum/showthread.php?t=117010) thread that would give a required sub time for your 250f4 of ~ 62-69secs, so an actual 60s sub sounds about right (on paper). Do you think you'll continue with these acquisition settings for future LRGB images ?

[Shiraz]

thanks very much Glen - fun eh?



thanks Richard. While I try to work out the best way to treat the data, will continue with these settings, but the real interesting stuff will come with gain of 200 and above where 20 second subs will be optimal. Hope to gradually work up to that, but the sky will need to clear. Also want to try some NB some day.

[RickS]

Looks promising, Ray!

[TR]

Very nice colour. Ray, what is the diagonal size of the chip?

Terry

[Shiraz]

thanks Rick - at least there are no obvious problems to date.


thanks Terry - it is 21.9mm
https://astronomy-imaging-camera.com/products/asi-cooled-cameras/asi1600mm-cool/

[Atmos]

It looks pretty good Ray, mostly just lacking data but another night or two would fix that.

[gregbradley]

Very impressive Ray. You must have copied some of Eric's data! Sorry, not funny.

Very sharp and detailed and I love the colour. I can see some star "fuzz" that I associate rightly or wrongly with small well cameras. So close to the formula here. Perhaps back off the gain a tad more to protect the stars more or you will have to use star masking almost from the start of your processing.

The core is nice and intact though. You probably also have some tilt as the centre stars are nice (except the brighter ones with some edge fluff) but they are off the further out you go.

Greg.

[RobF]

Whoa, that's a seriously good first "serious" image. Up there with the best M83s, not a quick first effort.

More please! :cheers:

[strongmanmike]

60s exposures huh...? and not that many either, Wowee :eyepop: and a fine image to boot :thumbsup:..Gee back in the day, we would admire someone who eyeball guided a 2hr exposure :lol: ...I only did it once :scared3: and after developing it, the negative showed it was out of focus :doh: :scared: and needless to say the guiding was rather dodgy :lol:...never again :rolleyes:

A new age of imaging....? :question:

Mike

[Placidus]

Superb! Beautiful colour. Ok, glorious colour. Background galaxies look great.

Lovely contrast in the dust lanes too.

[Peter Ward]

Like the colour. Resolution is good. Lovely highlight and shadow. Nothing to dislike really.

Nice one :thumbsup::thumbsup:

[Retrograde]

Looks great Ray. I suspect you're going to be very happy with the camera.

[bugeater]

Wow. Very nice.

[Paul Haese]

Nice work Ray. Detail is very nice and I like your star colour. Not 100% a fan of the galaxy colour, but it still looks good. Back ground has a quite a lot of noise left in it. It looks like colour noise but could also be noise in the luminance, so while it might be a lower noise camera I think with short subs and stretching some noise amelioration is going to be needed. That aside though, the sensitivity of the sensor is clearly obvious with 60 second subs compared to those that I do with the STXL of 20 minutes. My f ratio is quite slow but not that slow.

Resolution is very similar to mine. Watch out you'll be accused of pilfering an image too. It seems a 10" scope can trump a 20" too. :P:lol:

[rustigsmed]

great first light Ray. camera is looking the goods.
looking forward to seeing what happens when you crank the gain and shorten the subs (and apply some flats).
are you going to hold onto the 694 chip?

[trent_julie]

This is an impressive step forward. I would like to see a side-by-side KAF- 8300 vs ZWO 1600 image.

I would also love to see what I could do with this chip and a small refactor.

Thank you for documenting your efforts to date.

Trent

[Shiraz]

thanks Colin - yep need more data, but the #$%@ clouds disagreed.


thanks Greg - naah nothing nicked from anywhere. I will have to do something about the diffraction patterns around the stars - the primary mirror has 6 clips holding it and they spray energy around. In addition, the secondary has a small ding (covered with black paint) that throws a diffraction highlight near one of the spider pattern.


thanks very much Rob - appreciated


Thanks Mike. Could be the start of a new approach - still a place for CCDs, but CMOS is getting there and has amazing low noise.


Thanks very much M&T - I was not too sure about the colour and appreciate the feedback


thanks for the positive comments Peter - appreciated.


Yep, happy so far Pete. The only downside is that hundreds of 16mp subs can take a while to process.


Thanke very much Marty!


Thanks Paul. The smaller pixels help with scale and the short subs definitely give a resolution advantage. Noise is still an issue, but most of it is shot noise from the sky and no improvement in camera noise will affect that. Just need more than 3 hours (particularly on blue - I only got a handful of usable blue subs).

The theory says that all good scopes from about 120mm aperture on up should have similar resolution in "good" Australian seeing - I suspect that might be the case when you look at what Lee is getting from his 120mm. The big scopes get lots of photons though and that is a real bonus.


Thanks Russ. In two minds what to do with the 694. It is still a wonderful camera and am pretty sure that it has the edge in QE, so it will outperform the 1600 in some types of imaging. For now, will hang onto it until I am sure that the 1600 does things well enough that I can bear to part with the 694.


Thanks Trent. Apart from image scale, I think that an 8300 should produce similar results to the 1600, but it will require very much longer subs to do it.

I guess that the 1600 should do well with a smallish refractor, provided the refractor is well corrected and has a flat field. It would probably be a killer chip on the FSQ106 or TV101 and the skywatcher APOs also look suitable

[topheart]

Hi Ray,
The new camera seems to be a winner!
All the best with it.
Cheers,
Tim

[lazjen]

Quite a promising start.

It's a shame about the vignetting. Are you going to go to a larger filter size?

[Atmos]

I think QSI is likely to be about the only manufacturer at the moment that will allow the use foe 1.25" filters with this sensor (you can with the QSI683) due to the closeness of the sensor to the FW.

[Shiraz]

thanks for that Tim!
Thanks Chris - see below



The vignetting may be manageable - I have just moved the filters back nearer the chip - the camera has a very short nosepiece that screws directly into the filter wheel, which gained about 11mm - should almost overcome the vignetting - but I can no longer change cameras in less than a minute. Will post a flat asap.

[codemonkey]

Great shot overall, Ray.

There does seem to be some pattern noise in the image -- the background looks a bit streaky. Did you dither? I wonder if dithering might have helped (assuming you didn't), or perhaps longer subs are in order?

[Shiraz]

thanks Lee. most of the luminance was taken without dither working (there have been some software issues), so the background has some "walking noise" due to differential flexure. Decided to leave it in, to show just how
low the dark noise really is - it is there, but it is not obtrusive and will be easily dealt with by dithering. Calibration might help as well.

[SimmoW]

Fantastic first light shot Ray! Only 60 secs? McDonalds era of imaging...

[clive milne]

It's pretty impressive Ray, but forgive me for saying this...
Your older images (with the 694) seem to have a bit more snap or realism, if you like..

The Antlia cluster image for example is liquid smooth in comparison.

I'd be interested to see you try an object with both cameras..

Also... could be an interesting match with the Keller reducer/corrector.
F3.8 would then become f2.85, and I suppose you would be looking at 15 second subs, which would open up the sky to big (driven) dobs.

That combination would be a heck of a supernova search machine.


best
~c

[Shiraz]

thanks Simon - yep, guess it is a bit like that.


thanks for the feedback Clive. The Antlia cluster image was smoother and cleaner because it had about 10x the exposure time. However, I take your point that the new camera is not yet an established identity - I still have my 694:thumbsup: I have the impression that the 694 has an edge in QE, so it will always be able to outdo the 1600 if long subs are used.

We are already at 15 second subs or shorter - with enough gain, the read noise drops to 1.2 electrons and really short subs are quite usable even at f4. It certainly does open some new doors, but I am having so much trouble finding even a little bit of clear sky (at a time that I am awake to baby sit the new system) that it will probably be up to someone else to test it out.

regards Ray