The Lazy Astronomer

32 minutes ago, Jonny_H said:

Thanks alacant,

I am thinking that the issue could be down to my flats being 'too White/bright'.  When I initially read up on them prior to my first session I think I missunderstood/misinterpreted the process 😳

Assuming this could be the main/sole cause?

The histogram peak for flats should be about half way between the white and black points. If you think they're not good, you can go back and reshoot them if you haven't disturbed the imaging train (or changed focus position).

52 minutes ago, Jonny_H said:

Its actually the other way around. The first photo is the stacked image from APP (not quite sure why the calibration frames didn't remove the vignetting - i'm still feeling my way around the processing side of things).

I think what alacant was getting at is that it doesn't seem like the flats have been applied in the stacked image.

The fact that there is clear vignetting shows either the flats were not used during the stacking process or they are not correcting the image properly.

Currently using a very small, light scope (seriously over-mounted) on an EQ6R Pro, so am just about able to move the whole lot in one go.

Routine is: caps on, unplug power and data cables from mount and camera, move whole setup straight from the garden into the dining room (which is quite poorly insulated, so tends to be a fair bit colder than the rest of the house), then do a second trip for the cables and laptop.

Glad you got it sorted. NINA is a fantastic piece of software once you get all configured.

With the skies clear and me currently lacking in narrowband filters to do deep sky work, I thought I'd have a go at one of those over-saturated colour images of the moon. So, in went the planetary camera and out came this:

Two panel mosaic taken with ZWO 290MM + RGB filters @ approx. 500mm focal length, best 25% of 3000 frames for each panel in all colour channels. Stacked in AS!3, stitched together with MS ICE, then processed with Startools and GIMP, red channel used as luminance. 

Quite pleased with it for a first attempt, what do people think?

7 hours ago, Jonny_H said:

Random question re: cooling.  Can you have 'too much' cooling depending on the ambient temperature? E.g. if it is 9 degrees can you still set the cooling temp on the camera to -10, -15 and so on? Apologies in advance if that is a daft question!

Check out the specs for your camera, ZWO usually state their cameras can be cooled to 30 - 40C below ambient temp, once you set the target, it should hold that temperature indefinitely (provided adequete power and as long as the set point isn't outside of its maximum cooling capacity in relation to the ambient temperature).

Also, don't worry too much about cooling massively - the noise reductions are quite insignificant. Check out this talk from Dr Robin Glover for some very helpful info on CMOS imaging:

From Wikipedia:

Flexible Image Transport System is an open standard defining a digital file format useful for storage, transmission and processing of data: formatted as multi-dimensional arrays, or tables. FITS is the most commonly used digital file format in astronomy

As mentioned above, all the astro stacking programs will handle FITS files. I think all astro-specific post-processing software will also handle them, so you can output your stack as FITS as well.  The newer versions of GIMP can open FITS, Photoshop requires an extra piece of software. Plenty of freely available FITS viewers on the web - I use the one that comes with ZWO's ASI Studio for viewing to weed out bad subs before stacking. 

Hi and welcome. The requirements for visual and photography are quite wildly different.

For visual use, you'd ideally want a large aperture - dobs are usually recommended as you get the largest aperture for your money. But for starting with photography the preferred option is a small refracter (say 60 - 80mm). An EQ type mount is also needed for long exposures, and these are not exactly beginner friendly (not to say they are difficult to use, but they do need a careful set up to get the best out of them).

If you already have a DSLR, then you could buy a camera tracking mount and try out a bit of widefield astrophotography. This would give you an opportunity to decide if astrophotography is something you want to get into before committing to a telescope and mount.

If, on the other hand, you've got enough disposable income (perhaps not right now if you're just about to move house!), by all means go ahead and get yourself a scope more suited to visual use and then maybe 6 - 12 months down the line buy some more kit better suited to photography.

Are you able to take an image normally (i.e. in the imaging tab and not via the plate solver)?

Do you have the auto stretch on? 

Welcome! Excellent choice of planet - Jupiter's my favourite too ☺

6 hours ago, Mr Thingy said:

Can't decide on whether to get an Astronomik L3. Not sure on the extent to which it will improve things, plus it's another bit of glass in the optical pathway.

Decisions, decisions.

I looked back at my first image, a mono shot taken with my Luminance filter and the stars are very bloaty, so it's tempting to get an L3.

Does anyone have any experience of how much this filter improves things?

In my experience, the difference is significant. The L3 greatly reduced bloating in L and B channels.

I was out earlier with my planetary camera and took a couple of single 20 second subs of a random area near Polaris: one with the ZWO luminance filter and one with the L3 filter, pictures attached.

I had to stretch them a bit, because the difference wasn't really visible in the linear data, and to be honest the difference still doesn't look massive, but the halo is definitely larger with the ZWO filter (much more obvious if you download and flick between them) - if l was smarter, I'd have found a big bright blue star to do this with. 

No idea why the ZWO one has the whole pacman thing going on either...

I need to get me an Ha filter...

4(!!!) Clear nights in a row, and over the weekend (so no worries about being up late), but a big fat bright moon spoiling the fun 

Until someone more knowledgeable comes along with an actual answer, I'll provide my theory...

Looks like it could be a stacking artifact to me, caused by the fact that your individual subs do not have the same framing (you can see the stars are in different positions within in the frame in the stacked image and the single sub)

Can you please upload to the forum as a jpeg so people don't have to download a 110mb file? - will be easier for others to help then

Can't pretend l know what's happened, but I'm going to throw some questions at you anyway 😁

How many stars did DSS find when you registered the frames? And how many frames did it report it included in the final stack? Do you know the bayer pattern of your camera and did DSS have the right one? (I think RGGB is pretty typical)

My personal opinion is there is no such thing as up. Unless something looked "wrong" (and l think an upside down horsehead is a good example of that), I'd say lets not get too bogged down with orientation.

Been grabbing some time on these two over the past few weeks too. Telescope wholly unsuited for galaxies, but they position themselves nicely above my house in the late night/very early morning.

Possibly went a bit too far with the colour saturation, but was the first target I've tried processing with startools, and as soon as l saw a hint of blue and red in the arms of M81 I wanted more!! 😁

You're going to have some level of bloat in the blue channel with all doublets. It can be reduced quite significantly by using a filter which cuts the blue end of the spectrum at around 400 - 420nm - the Astronomik L3 filter works well in this regard. 

That's a very pleasing image. ☺ Not exactly a shortage of nebulosity in there either!

If you reprocess, see if you can get the OIII teal-ish colour in the core. Can't for the life of me bring it out in my image, but I'm assured it definitely should be there!!

15 minutes ago, Mr Thingy said:

Yes, I was wondering about that. I bought some basic ZWO ones but maybe need to throw more money at them.

I was just having a sneaky peak on FLO but then the wife came in... quick! Hide page.

I suppose there is another slightlyslightly more expensive option: buy a Takahashi!!! 😅

8 minutes ago, Mr Thingy said:

Astronomik ones seem to meet that criteria:

https://www.firstlightoptics.com/rgb-filters-filter-sets/astronomik-deep-sky-rgb-filters.html

 

I was going to suggest them but didn't want to seem like an Astronomik salesperson! 😁

Will probably replace my ZWO filters with those at some point too. 

7 minutes ago, Mr Thingy said:

Thanks a lot. I will have to check that out, though I will need to consider where in the image train I can add a filter. 

 The other alternative, although more expensive, is to look for a new set of RGB filters which cut at around the 400 - 420nm range in the blue channel. 

If you haven't cracked the mirrors or the corrector, you're probably ok. You may have knocked the collimation out, so as has been said, check that (much better to do it on a star)

I had the same problem a while back too - the stars in both blue and luminance channels were bloated compared to red and green. 

After a bit of research, l came to the conclusion the problem was unfocused UV passing through the filters.

Bought an Astronomik L3 filter and problem solved!