daemon

Apologies if I am starting a new thread for a question that may have been asked before, but here goes:-

I have an HEQ5 mount (in a remote location) that is relatively new, around a year since it was delivered. I have only had the opportunity to use it maybe 5 or 6 times for short sessions so it can be considered virtually brand new. When slewing it is certainly noisier than my EQ6R Pro (that I use at home) but then I would expect that. I have only used it for short imaging sessions (unguided so far) and so I have not been able to properly assess its tracking capabilities. So my main question is as follows:-

• Is there anything to be gained from performing the Rowan belt mod now or should I wait and use the mount as it is now until the tracking/guiding starts to deteriorate?

I hope to be able to use the mount a lot more soon and want to be able to guide for long sessions. Currently I only have an ED80 for the mount so it is not particularly challenged by weight. Thanks for reading.

Cheers,

Steve

Cheers Ivor! Yes, I also have Warren Keller's book and have found it an excellent guide. Much better than I had been expecting. Thanks for the tip on the GAME script. I will definitely check that out - anything that makes life easier is worth a look.

Cheers!

Steve 

In principle I don't think it's a bad idea. I have a set of NB filters and am eager to use them but would say there are two things from my POV to consider:-

1) Guiding - you probably want long exposures for the subs, to gather enough data and guiding is likely to be needed to allow this. 

2) Target Selection -  sadly this is the blocker for me. The only viable NB targets worth imaging that I am aware of in the Northern Hemisphere at this time of year lie in the East and mostly around Cygnus (Elephant's Trunk Nebula etc) and as I have trees to the East I can't effectively image that area for long.

So, if you can see decent targets from your location and you can run decent exposure lengths, then maybe it is a viable exercise. For me - unless anyone has another suggestion - I think I will be sticking to broadband galaxy targets until conditions and target locations permit.

Happy to be corrected though!

Good luck!

daemon Steve

Nice one Ivor! Some lovely detail evident in that crop there!

Better than my recent efforts on the Sunflower, but then I've only got the 150PDS 😉 

I've also been checking out that AnnotateImage script in PI and it does add a different perspective. I'll definitely be experimenting more with that.

Thanks for the interesting post!

Cheers,

Steve 

A very short session (30-40 mins) after struggling to find anything else worth imaging late last week (due to the Moon mainly).

In RGB only as I understand Luminance is not really needed with Globular clusters. I'll try again when conditions are better.

Good effort. Some nice detail in the cigar there.

I think the biggest thing for me would be - what nebulae are you thinking of imaging? I have a set of NB filters and I am eager to use them. Unfortunately I have few targets that are worth trying - unless someone wants to correct me. My view to the East is inhibited by trees so Cygnus (with some great NB nebula targets I think) is out of my reach.

I'm sticking to galaxies and clusters for the time being (when it is clear) but I am aching to get going on some NB imaging as soon as I have something decent in view.

Cheers Terry! Appreciate that. 

6 hours ago, MarkAR said:

Lovely image, got some nice detail that more time will enhance.

Thanks Mark! I guess I have to give the credit to Pixinsight and HDR Multiscale Transformation for dragging the detail out of relatively little data.

Just over 2 hours of LRGB on M63 - another short session, mostly due to the short spring/summer nights.

I really like this target and will definitely go after more data when the conditions permit.

This is the best I can do for now I think. ASI1600MM on S/W 150PDS.

Stacked in APP. Processed in PI and GIMP. Processing leaves a lot to be desired I suppose. Fun trying though.

Just over an hour on M92 - LRGB with ASI1600 on SW 150PDS.

The light nights and bright moon hardly make it worth imaging, but thought I'd give it a go anyway.

About 2.5 hours of LRGB from this week on M51. Tried for longer but the short nights do not help.

As usual, looks better on my monitors than on here! Still getting to grips with processing this.

40 minutes ago, jimjam11 said:

Assuming this is at offset 50 which is typically about 800DN your median background is 6384. This means your background skyfog is approx 5600DN above bias. Optimal at gain 139 (taken from the CN thread) is approx 450DN above bias. You are therefore overexposed to the tune of 5000DN, a lot. If you look at the unstretched sub you can see tons of stars, these are over-exposed and you lose colour in them.

I ran the binarize PI process on your sub and converted all pixels > 0.95 (> 62000 DN) to white. These are all overexposed and will clip to white. You could easily use much shorter subs and as long as your total integration time is the same you will not get a noticeable drop in SNR. You will gain in terms of star clipping, lose less subs to clouds etc and probably see improved resolution. The downside is you end up with more subs which take longer to process!

As per the CN thread an optimally exposed sub will look terrible but this doesnt matter once stacked. This is one of my unstretched subs, 60s L , gain 0 @ F4.5. Raw frame is top left, binarized is bottom right:

 

Thanks for that feedback jimjam. It is very interesting and I had not considered such parameters.

Anyway, the main reason for the long subs that night was to test my auto-guiding and I would not normally shoot such long subs for LRGB.

I will certainly experiment with the gain settings you suggest now that I understand a little more.

Apologies if I have hijacked Adam's thread - but hopefully this information is useful for him also!

37 minutes ago, jimjam11 said:

I never use unity gain; 200 for narrowband, 0 for lum and 76 for rgb. 300s at unity gain is likely to be dramatically overexposed. I switch gain so I can use 60s subs for lrgb without massively over exposing. The tables linked (on cloudynights) are a brilliant resource.

Make sure your calibration frames match exactly.
 

If you have the newer Asi1600 it defaults to offset 50 for all gains. It can essentially be ignored unless you go fiddling!

Attached is a cooled (-20c) unstretched 300s luminance sub at 139 gain (ASI1600MM bought about a year ago).

It is of M101 and you can hardly see the galaxy, so I don't see it as massively over exposed. Or am I missing some point here?

I am still experimenting with this camera so will bow to superior knowledge, but none of my tests have yet involved adjusting the gain for any of the filters. I will experiment further on that though. 

L_Lum_2020-05-26_23-48-16_Bin1x1_300s__-20C.fit

Cheers Alacant! Fully agree on the processing comment, but I'll probably buy PI anyway. Gotta keep the Spanish economy ticking over! 😉

Brilliant analogy from John there! 

I have had the same camera for about a year and have only ever used Unity Gain (139) apart from one time when APT decided to flick it up to 200 without my knowledge!

For most targets I have shot so far I have found this to be fine, and to be honest my line of thinking has been that there were far too many other issues/parameters to worry about first before dwelling too much on gain. Just my thoughts though.

Cheers,

Steve

Thanks Steve! Appreciate that.

Yes, I am finding PI very frustrating. Not from a capability point of view though - it is clearly a cut above other apps in most areas -but from a usability perspective I have major issues with it (poor multi monitor support being just one!). However I will probably end up buying it in the end. Especially as I've already bought Warren Keller's book! Which I find is excellent by the way - better than I was expecting.

Clear skies!

daemon Steve 

A short session on M101 from last night. About 15 x 300s LRGB lights calibrated with Darks and Flats.

SW150PDS and ASI1600MM.

Really struggling with processing (as usual). This was mostly done in Astro Pixel Processor. May try again with my trial version of PixInsight.

Best thing about this session was finally getting guiding sorted out - enabling those 5 minute subs. The guiding graph looked better than the picture does! 🙂 

Comments welcome - sadly I notice that my images always look better on my monitors (even as JPEG's) and when I upload them here the result is usually terrible!

daemon 

Limited data and not great processing......but happy to get something in these lighter nights.

54 minutes ago, Adam1234 said:

Thanks for the advice Steve. Do you do much imaging in the New Forest? My Fiance and I had a drive around the New Forest yesterday looking for potential spots

Hey Adam, I have not ventured into the Forest for imaging. I live just outside the forest boundary and only image from my back garden. It's officially Bortle 5 but tends towards Bortle 4 I think. Deep in the Forest should be better but I can't complain. I can't really recommend any spots but will be glad to hear of any if you find some. 

Clear skies!

Steve

Greetings Adam, from just the other side of the New Forest 😉

I was in exactly the same position as you about a year ago but never gave too much thought to OSC really. I simply consider my DSLR (Nikon D5300) to be my OSC camera - although it would be much nicer if it were cooled! 🙂

I took the plunge and went with the FLO package you have posted - ASI1600, 8 pos'n EFW and the LRGB and Narrowband filters - note that these filters are not mounted and will need careful loading into the EFW.

Here are my feelings on the points you raised:-

1) As you point out, you will probably end up going mono eventually anyway so I'm sure it will be more cost effective to just go this route now (that was my main rationale). Anyway, as I consider my DSLR my OSC camera I now have both options anyway!

2) The setup you have mentioned will be fine. I use my ASI1600 with an ED80 but mounted on an HEQ5 and also on a 150PDS Newt mounted on an EQ6RPro. The micro lens diffraction issue mentioned by scitmon is an issue. I noticed it most on bright stars, especially when imaging the Horsehead - Alnitak was quite badly affected. I have not let it put me off though and there are suggestions on here I think about how to get around it. I have attached a rather awful image which was an early attempt. It shows a rather exaggerated example of the diffraction issue around the star Alnitak.

3) Yes, you definitely need a recommended power supply to cool the camera. I would not take any shortcuts on this. Of course the camera really comes into its own when cooled. I also have a library of dark frames that I took at different temperatures and exposure lengths so it saves a lot of imaging time. I bought a water resistant power box off Amazon which has rubber seals and holds about 4 power adapters. This holds my power supply for my Sesto Sensor focuser, the mount, the ASI1600 and a USB power supply. It has been great and I have had no issues. I hang it from the accessory tray with a bungee cord so it does not even touch the ground! Of course I would never use it in soaking wet conditions, but then I would not be imaging.

4) As for tutorials - other than Steve Richard's book I find You Tube to be about the best resource.

All in all I have not looked back. Indeed, despite being told otherwise I have found the filters supplied to be almost par-focal. Maybe it is just my eyes but I have not seen a need yet to adjust focusing between filters. Maybe software measurement of the FWHM would tell me different but I have not got around to that yet.

You do of course need to take Flats for each filter. I find the APT Flats Aid excellent for this, especially with the EFW. You just set  a few parameters and APT takes care of all the ADU measurements for you and swaps the filters in and out as needed - brilliant!! Unfortunately I have had a few gripes connecting the EFW with APT, but I think the cables may be more to blame - still working on that issue.

Good luck and Clear Skies,

daemon Steve

A quick process in GIMP of just 40 minutes of data (10 mins each of LRGB) from last night. My colour balance probably isn't great. Calibrated with darks and flats.

Imaged during a very short break in the clouds and needed to be heavily cropped due to incessant satellite strikes!

ASI1600MM - SW150PDS - EQ6RPro - Tracking only, not guiding.

Clear skies,

daemon

My first attempt at processing M31 with my trial version of PixInsight.

This was just a few uncalibrated subs from last year - maybe 10 minutes of exposure so clearly not great data.

C&C welcome.

Nikon D5300 = SW ED80

daemon

19 minutes ago, MarkAR said:

Great effort, probably one of the hardest targets to get right in my opinion.

Cheers Mark! 👍🙂

Thanks for the feedback Wim, Ken and Ivor. All very valuable and I'll certainly take it on board with my next efforts to process this data.

Only having had the software for a week or so I was quite surprised by what it was able to achieve - despite the issues I have with the usability. I guess I'll get used to it. It is clear that I have only scratched the surface!

Another thing is that the image seemed to look much better on my monitor and phone before I posted it here. It certainly looks worse after I do the post - an issue I have had before. Hey ho!

Cheers,

daemon