parallaxerr

7 minutes ago, Nigel G said:

light frames are dark blue instead of the orange brown colour

Thanks Nige, this is my goal. The orange/brown makes processing so much harder! I'm really tempted by the 2" Baader Semi-Apo now, the Neodymium on which it's based gets good reviews for LP reduction and the fringe killer should help with CA, as I've observed with my 1.25" version.

1 minute ago, alacant said:

Hi. I find modern achros good for AP. You may want to get one of these which prevents invisible radiation being recorded by the sensor. HTH.

Thanks Alacant, posted as I was typing!

I've had a look back through the thread for posts about filters and came across two posts of interest.

@SteveNickolls, you mention using the semi-apo, have you tried it yet? I rate the 1.25" one I have highly for visual and am considereing the 2" for AP.

@Nigel G, you've had some success with an LP filter, can I ask which one you are using?

Thanks both.

3 minutes ago, Filroden said:

for bright objects like M33 this should not be a problem, it just adds processing complexity

I think you hit the nail on the head here Fil, I really need to get my head into Startools some more!

Update on last nights trial with the ST120:

I gathered about 150, 30s exposures of M33 along with 50 darks. Inspecting the light frames shows that the Baader MPCC works even better with the faster F5 ST than the F5.9 WO ZS66, I see no coma at all in the corners I had managed to get a reasonable focus but not perfect, so I've just ordered a mask.

The CA isn't as bad as I thought. Obviously the fainter the target the better I suppose? It was heavy on Pleiades as noted above but that was just a rush job with bad settings.

Being impatient as I am, I stacked the M33 frames up in DSS just to see what was there. No flats or darks flats yet, so there was some noticeable vignetting. I'll be doing them tonight and re-stacking.

The main issue is horrendous light pollution though, such a horrible orange noise to the image. The longer nights may mean I can get out earlier but I'm thinking there's not much point starting until gone midnight when the streetlamps go out and the neighbours go to bed! But, work and the nursery run dictate that I can't be doing that really.

Did I read somewhere recently that someone has had good results with an LP filter? I have a 1.25" Baader Semi-Apo which I found VERY effetive in the ST for visual. As I understand, it "overlays a slightly more aggressive version of the fringe killer coatings onto the neodymium substrate of the Moon & sky-glow filter" so I wonder if the 2" version may suit for AP?

1 hour ago, The Admiral said:

That's one advantage of imaging stars, they don't need such lengthy total exposures, and by keeping the sub exposure times short you run less risk of saturating them (though of course that will be more of a problem with DSLRs).

I learnt this last night! After imaging M33 I slewed to Pleiades as it's one of my favourite visual targets, however, I left the exposure set at 30s. Result = Big bloaty blue (with the achro) stars!

Hi everyone,

Good to see the thread's still going strong and getting far too technical for my brain! I've been out of it for a few weeks with illness and a back injury, boo.

Anyway, decided to get back to it tonight, I was planning to add to my M31 data only to find out it's now too high in the sky for my mount.

So...next target is M33. Also having toyed with the idea for a while I've decided to give the ST120 a shot, see if I can't capture a few more photons per sub! I couldn't use the St120 for M33, it wouldn't get it all in but no problem for the smaller targets. Really interested to see how the Baader MPCC works in a different scope - the ST120 is closer to the midpoint of the recommended focal ratio range so should be OK.

My ST already has a Moonlite fitted so the camera is hanging well, but I struggled with focusing a bit, the CA made it a little more tricky so may invest in a bahtinov mask.

Anyway, here it is in all it's glory. Results should be interesting although I'm not getting my hopes too high due to the moon glow and random left over fireworks!

41 minutes ago, SteveNickolls said:

Hi,

I'm curious to know what restriction your mount is causing you, is it because of potential collisions of the telescope and mount? Anyway good luck amassing frames of M31.

Cheers,
Steve

Yep, exactly that Steve. At about 62°, the camera contacts the base of the mount. I may be able to address this by fitting a long dovetail bar and sliding the whole lot forward as it's quite tail heavy at the moment anyway.

Well I chickened out and put the WO ZS66 to work tonight, I will definitely try the ST120 on smaller targets but want to get a good M31 first.

I got x106 30s subs on M31 tonight at ISO800, stacking now to see what comes out. Good news is I absolutely NAILED the alignment, M31 dead centre in all frames

If the ISO 800 data is cleaner then I'll keep adding to it every clear night I can. The only problem I have now is the Alt limitation of the mount which puts a stop to M31 imaging at around 10pm.

23 minutes ago, Filroden said:

It's always worth testing. Different scopes will give you different fields of view which might be better on some targets. Bear in mind that as focal length increases so does difficulty of tracking so you may need to watch your exposure times. 

Good shout Fil. There was me thinking"oh the focal ratios are about the same" but didn't think about focal length. Not gonna be much use on Andromeda me thinks...

Tonight's experiment. ST120 instead of WO ZS66. Nearly twice the aperture but plain old achromatic glass. Is it worth a shot?

Either way I'm going to drop the ISO to 800, see if I can reduce some of the noise I had at 1600 during my first attempt.

Here's my first attempt - M31

William Optics Zenithstar 66SD on a Celestron Nexstar SE Alt/Az mount. Nikon D3200 w/Baader MPCC.

Approx. 1hr of 30sec subs stacked in DSS with darks, flats & flat darks, processed in Star Tools (hardest part!). Poor conditions with hazy cloud hence the noise in the image.

7 hours ago, The Admiral said:

Have a look at this Google Hangout where Ivo takes you through StarTools

Go to top of the class Ian, what a great video! Having the program writer explain what each of the filters/modules are actually doing really helps to understand what's going on. I watched the tutorial with Ivo whilst re-working my M31. It's obvious I have shed loads of noise which is hard to get rid of, more subs and clearer skies required.

It's easy to forget what it is you're processing and I have to remind myself I captured it in my back garden, so, for my first fully processed attempt, I'm very pleased with this. Final post of M31 with these (poor) subs! Thanks to everyone for the guidance

1 hour ago, The Admiral said:

but in order for wipe to work properly you need to crop the picture to get rid of the stacking artefacts which you can see around the edges

Hi Ian, neither of those images have been wiped, just auto developed. This lead me to think there was less info in the one with no calibration.

HOWEVER, light bulb moment! I had previously NOT been re-stratching after wiping, because with colour calibrated images from DSS ended up with mega amounts of noise which washed out the detail. BUT, having just re-stretched a non-colour calibrated image, the detail came back   Thanks!!!

Still very noisy but the colours look much better without having been adjusted, so I think I'm making progress. Just need to work out where to go from here...

I've been doing some trial & error testing with DSS and ST. Every "correct DSS settings for ST" thread I read suggests turning off RGB Background Calibration and Per Channel Background Calibration.

BUT, if I turn both of these calibration methods off, I seem to lose data in the developed image in ST. Pictures attached show the difference. Any ideas? I assume the orange glow to the non-corrected image is light pollution but as you can see there is less detail in M31, which further processing does not seem to be able to bring out.

28 minutes ago, happy-kat said:

But is it giving you the wow you had not thought possible with your mount :-)

Definitely. My first attempts have exceeded my expectations by far

Until I saw the images in this thread I assumed AP was out of reach until funds became available for better equipment, but, all it required was a small investment in a few adaptors and a flattener.

There is so much to learn with post processing that I think any further investment in gear right now would be wasted and add complexity and confusion!

Thanks everyone for the encouragement. I'm pleased with the progress and "starting" to understand ST a little, the colour tool is definitely the one  I need to work most at.

Also, I don't think my subs were that great in hindsight, lots of thin cloud cover so really looking forward to some clear, crisp air and dark skies

Progress

OK so I selected standard stacking instead of mosaic which knocked 100MB off the FITs file, which then opened instantly in ST. Also set RGB background calibration and got colour! However, I then read an ST instruction which says to set for no colour calibration so trying without that setting now.

Anyhoo, a bit rough and noisy but there's colour

56 minutes ago, The Admiral said:

You are not using drizzle are you? I gather that can give huge files. That might explain why you left it processing over night, or was that just convenience?

Nope, no drizzle. Overnight was just convenience, I'm re-stacking 1hrs worth at the moment with various settings. Takes about 15mins.

38 minutes ago, SteveNickolls said:

whereas mosaic could be a very large file indeed

That's what I've been using, trying standard now.

47 minutes ago, Filroden said:

It should just depend on the resolution of the camera

Hmm, 24MP so quite large.

38 minutes ago, alacant said:

You need 64bit and as much Ram as you can throw at it

Yup, 64bit and 12GB of triple channel RAM.

Looks like there's a few tweaks to be made, watch this space! Thanks everyone for your input

Jon

Just now, happy-kat said:

If you compare file sizes and see previous discussions the autosave tiff file is compressed

Yeah but you told me not to use TIFFs!? The TIFF I was using was about 180MB and that loaded fine within a minute or so.

Thanks for all the pointers everyone, getting somewhere at least. However, just hit the next problem, harrumph.....

The FITS file output from DSS is 379MB in size and star tools just will not load it up. Program hangs and if I click anything it goes into not responding mode. I think this is just a size issue, what size FITS files are you guys working with?

4 minutes ago, The Admiral said:

Are you saying that the little icon next to the raw file didn't show the four-colour array? That doesn't sound right. My camera doesn't do conventional Bayer raws, but I still get a colour icon, although not in an array. Background calibration is off, what I thought ST required.

Perhaps someone who uses a conventional Bayer camera could chip in here? Could it be something in the RAW settings?

Ian

My bad Ian, was looking at the column titled depth which reads gray 16bit. The coloured icon is there

OK made a bit of progress. Changed DSS output file to FITS, which ST now reads OK. Also noted DSS is classifying my RAWs as gray 16bit, thought that was the colour issue but apparently not. Turns out RGB background calibration was turned off, tried a stack of 3 frames and had colour so now restacking 190 good frames. Also changed light frames from average to Kappa-sigma clipping as per recommended. Will see what comes out the other side!

1 minute ago, happy-kat said:

Please you should only be using the autisaved fits file in startools. The autosave tiff file IS compressed.

ST won't open it for some reason, says it's incompatible?

18 minutes ago, Filroden said:

I don't know if it has an option to reject subs with scores less than a certain score

Yes there is Fil, I've just found it and I am re-stacking with frames under a score of 1000 ignored.

18 minutes ago, Filroden said:

I was also surprised by the lack of colour. With 30s subs you should not be saturating your stars. I wonder if you're missing a setting in either DSS or StarTools that is not debayering the subs correctly?

Definitely think I'm missing something. After developing and wiping in ST I've got a B&W image. Not sure if it's DSS or ST settings that I need to adjust, will have to play around a bit. ST does offer 3 options on loading a new image that mentions debayering so will look there.

Also, ST wont open the autosaved TIFFs from DSS, but WILL open a TIFF if I save it manually. However, in the latter case the file size is about half?