Jm1973

3 hours ago, BrendanC said:

As mentioned, it might be worth trying the ASCOM drivers. I really did not expect them to work with my EOS 1000D but they did, first time, and every time since, and now I'm a happy bunny with Sharpcap's polar align feature which is awesome. 

I'll try to get the ASCOM driver to work with my camera tonight. That's the best method really, as I can use the ASCOM option in Astro Tortilla as well, instead of the 'File Open Dialogue' method.

50 minutes ago, Synchronicity said:

Why not ask on the forums there? The developer often responds in person.

https://forums.sharpcap.co.uk/

Michael

Great idea!

10 hours ago, rnobleeddy said:

I haven't used it, but perhaps https://github.com/vtorkalo/ASCOM.DSLR is worth a look?

I hadn't seen that github. It looks like they have very recently made some updates to the Nikon side of things. Thanks!

4 hours ago, StevieDvd said:

I presume you mean with the Nikon attached you will take & save an image at each appropiate stage asked and use the virtual camera to open it.  Whether the polar alignment routine has the option to open the image is another matter.

Prior to Sharpcap having the polar routine and before Polemaster one of the forum members created a polar alignment program which uses saved images and would prompt you in a slightly more manual way.

See PhotoPolarAlign if I recall correctly you can download and use test images to get the hang of it.

 

 

 

 

Hi. Firstly thanks for the reply.

You are quite correct, I am talking about manually taking a photo with my DSLR attached to the telescope (using digicamcontrol), and using the 'virtual camera' functionality in SharpCap to process the images within the Polar Alignment tool (assuming the virtual camera is integrated into the polar alignment module).

However, PhotoPolarAlign sounds like it may be a viable alternative. I will take a look at that and see how well it works. Thanks for the tip!

If anyone else uses SharpCap, I would still be interested in hearing whether the polar alignment module makes use of the virtual camera module.

I'm thinking of buying sharpcap, mainly for the polar alignment tool. However I have a nikon d3300 which is unsupported by sharpcap.

Does sharpcap's 'virtual camera' feature work with its polar alignment tool? If so then I could take images and use them for polar alignment.

I suppose the other possibility is to use as ascom, but last I checked there was no ascom driver for the d3300, although there had been talk of one.

Does anyone know the answers to these questions? Many thanks.

6 hours ago, Pompey Monkey said:

What camera are you using?

60 (or 45) 60 second subs won't get you a lot of nebulosity at all with a DSLR.

If you have poor data to start with, then you are already facing an uphill battle.

I'm using a d3300. 

I was able to get a reasonable image of Andromeda with 30 second subs, so I thought 1 minute would be ok for something like wixard nebula. You may well be right though. I've managed to get rid of the vignetting, but by the time I have brought out any nebulosity, the stars are so bloated that the image is ruined. Obviously It doesn't help that they aren't in good focus to start with, but I even if the stars were in focus.. I wonder would I be able to do anything with this.

This is the best I have been able to get. 

I would like to know whether it is my data that is bad, or my processing.. or both!

9 hours ago, Jamgood said:

How are you taking your flats?

The way I do it, which is not the only way or possibly the best, is with a ipad/tablet placed over the scope with just a plain white jpg stretched to full screen. If using a DSLR, switch to AV Mode and shoot away.

Nearly every time I've had a stacking issue it has been due to bad flats.

Also, look at focusing. You're out of focus in that stack. Zoom in the the stars look like bubbles. Do you have a Bahtinov mask?

Do you stretch a tshirt or anything over the telescope, or do you just put the tablet straight over the end?

Yeah they are out of focus. I'd been playing around with the settings on Astro tortilla and not having much luck, then I suddenly got it working so started shooting. It was only halfway through that I realised I hadn't got round to focussing properly. 

I haven't got a bahtinov mask yet, but my mum has bought me one for Christmas (I'm 47). I usually focus by finding a bright star and then zooming in fully using live view. When in focus the star will generally have diffraction spikes. Kind of like a poor man's bahtinov man I guess.

Well I just calibrated again but without the flats this time and the results look far more normal.

So I think I need to look at my process for taking flats.

I don't know about better... I would say different. Instead of a reddish ring I now have this:

I am still unable to get rid of the gradient, or even understand what's going on. 

I don't really understand how removing some slightly cloudy images has caused this to happen.

Is it possible my flats are causing problems?

19 minutes ago, alacant said:

Hi

Go through all the light frames and remove all those that have cloud or any other imperfection. Then stack again.

Any better?

HTH

I just went through my 60 lights and removed 15 that had slight amounts of cloud in them (over and above the others). Stacking now. WIll report back later.

Hi Everyone. 

I am quite new to image processing, but with the help of this forum I have managed to get a reasonable image of ANdromeda recently. So bouyed with this small success I decided to take a shot (no pun intended) at Wizard Nebula. Using AstorTortilla I managed to get it pretty much centred in my sights, and took 60 subs at 60 seconds each before the clouds arrived. I also took 25 darks, 25 bias and 30 flats. I registered and stacked them in APP. But when I stretched them there was a very prominent red ring present, that I have struggled to remove as it is a very similar colour to the nebulosity I am trying to bring out.

In fact in order to get the nebulosity to show at all, I have to stretch the image so much that the gradients are overpowering as are the stars. I have not had much luck clearing it up with either 'correct vignetting' or 'remove light pollution' in APP, and I've also not had much luck with removing the stars before stretching. 

Does anyone who is good at this sort of stuff fancy taking a look at my stacked fits image and see if anything can be done with it, or whether I should try stacking it differently? I don't want to spendanother evening messing about in PS, GIMP, APP etc. if it's a lost cause.  I know there is data there as I can see the nebulosity when thoroughly stretched, but I can't seem to get to it without ruining the image. This is after stacking, then stretching, in APP. I'm not sure what caused the purple banding.

. 

Here is a link to the FITS file: https://www.dropbox.com/s/4g46xszfuf4zlw2/Wizard_Nebula-RGB-session_1.fits?dl=0

Thanks in advance.

8 hours ago, chrisshillito said:

My guess would be that some, but not all, of these software apps are being run with admin rights.  The problem is that for each "run level" a separate instance of EQMOD will get launched by windows/ASCOM when the associated application "connects". The first instance will open the desired COM port but the second will not be able to as it is already open.  The solution, if this is the problem, is to ensure that all applications are installed/run with the same rights.

Chris.

 

Ah.. that makes sense. I am definitely running some stuff as admin. I will check to make sure everything else is too. Thanks!

edit: a quick update for anyone else with this issue: it worked! I launched Stellarium and AT with admin rights and both prgrams connected to my telescope.

Another thing I've realised is the epoch didn't match across mount and both pieces of software. I have fixed this now too.

Hi everyone!

I have a D3300, which doesn't play nicely with a lot of software, so I use digicamcontrol and have just started trying to use Astro Tortilla. With AT I have to use the 'file open dialogue' option, and manually take pics to use in order to refine my slew till it's spot on. This works well for the most part. However, most of the things I have read say to use somehting like Stellarium to slew to your target, then use AT to get a more accurate position.

My problem is if I launch AT first, it connects to EQMOD and picks up my telescope (so far so good) but then when I launch Stellarium it says no COM port found (or something like that). And similarly if I launch Stellarium first, that connects to my telescope OK, but then AT fails to connect.

What am I doing wrong? I can only seem to connect to one or the oher, but not both.

This has worked so far as I have been using pics from old sessions to feed into AT to get my position, but if I want to go somewhere I haven't got pics of I don't really know how I'd do that, apart from getting photos from elsewhere and feeding that into AT.

I had assumed assumed that both pieces of software would talk to each other, so that when I slewed to a position in Stellatrium, AT would know where I was aiming for, and thus when I then uploaded a photo of my actual position into AT it would be able to work out the difference and put me in the right place (possibly after multiple iterations).

Does anyone have any experience with these software packages who could possibly enlighten me?

Thanks for any help. Clear skies!

I've figured it out. 

Hi All! I have just instaled ASCOM and EQMOD, and I can now control my telescope in EQMOD.

I've just installed the latest version of Stellarium as iut now has native support for ASCOM, so no more StellariumScope required.

I'm trying to add my telescope, but under Telescope>Add there is no option for ASCOM. 

I figure I must be doing something wrong, as apparently there should be an option for ASCOM telescope.

Does anyone here use Stellarium and know how to add an ASCOM telescope please?

11 hours ago, Tommohawk said:

I would say  that's pretty good. I used DSS for ages but have now moved over to APP - it does seem more reliable.

You seem to  have lost some of the blues maybe? Also you have something of a trail that might have happened on one sub only - how many did you take, and do they all show the same trail? Maybe if you post some more details re your kit and settings folks here could make more constructive observations?

As you say  clear skies would help!

Hi. Thanks for the reply.

At the time of taking the subs used in that image my kit consisted of a skywatcher 200p on an eq5 synscan pro goto, with an unmodified d3300 attached directly to the focusser with a T ring. 

A number of the subs have some trailing, one in particular is quite bad. However I think they are not primarily due to tracking issues, as many of them do not have trails at all. I think they are due to me not having an intervalometer, or shutter release, at the time so I had to manually push the button on the camera for each exposure. I think that caused a slight trail on a lot of the images. I may be wrong though.

I took about 100 30-second subs, at iso800.

Since then I've bought a long usb repeater cable, and nikon data cable and downloaded digicamcontrol, so if that was the cause of the trailing it shouldn't happen next time.

Sadly the weather has been terrible the last few weeks, and even though tonight turned  out to be unexpectedly clear, I'd agreed to watch a film with my better half, and didn't even realise the clouds had vacated until it was bedtime. Hopefully the clear weather will continue tomorrow evening.

Clear skies.

Sorry for the bump, but did anything ever happen with this?

I've just bought an eqdirect cable and installed ASCOM and EQMOD and want to start using Stellarium to control my telescope.

Do I have to download old versions of Stellarium and stellarium-scope to get this to work, or are there other methods available?

As I've had no good weather lately to get the telescope out, I've gone back to some subs I took a while back. I had previously processed them entirely with GIMP. I was pleased with it as it was my first time stretching an image, but there was a lot of 'haloing' around the image and the core was very bright.

I downloaded the free trial of APP and had another go at it. I used the 'Correct Vignetting' tool (which didn't seem to do an awful lot), and the 'Remove Light Pollution' tool which seemed to work quite well. Then I stretched  with GIMP again. I think the result is a lot better. I am just waiting for clear skies now to get some other footage I can play with.

7 hours ago, ollypenrice said:

I didn't address gradients in my first demo, I was focusing only on the stretch process, but Wim is quite right that they do need a fix. A gradient is simply a gradual drift in brightness across the image. If this drift is strongest in one colour (as it usually is) this will appear as a 'colour gradient.'  Where they come from is anybody's guess. Even at one of the darkest sites in mainland Europe I still get them on 99% of the images I take. (I'd have said 'on all of them' but I recently shot some gradient free colour data!)

Flats won't remove gradients caused by skyglow. As far as the camera is concerned any light going onto the chip is real signal - as indeed it is, even if you don't want it. Flats only remove the effects of uneven illumination caused by the optics, so vignetting and dust bunnies. Gradient removal is done in software by well engineered algorithms. Here are some pointers:

Pixinsight's Dynamic Background Extraction. Stunningly effective. With the image still linear but with a temporary visualization of its stretched appearance on screen you place markers on what is genuinely background sky to tell the software that those places should be at the same brightness in every channel. It makes a map of the gradients it finds and you then subtract the map from the image. A nice by-product is that it also performs a fine colour calibration in the process. Don't use DBE to fix local artifacts like dust bunnies. It won't. Use a small number of markers to find the broad underlying gradient.

Russ Croman's Gradient Xterminator. A reasonably priced Ps plug-in which is pretty good. There are videos online about how to get the best out of it.

AstroArt has a gradient removal tool and is a top quality stacking and calibrating program, far better than DSS, for instance.

Astro Pixel Processor is highly recommended by several friends and clients. I'm certain its gradient tools work because I just processed a 32 panel mosaic from individual subs made in APP. They were admirably flat.

Core: just make a second stretch, almost as hard as the first, but concentrating on the core. Avoid getting that 'stellar' central part and put it as a layer under your present version and use a feathered eraser to remove the saturated bit on top.

Olly

I might look at Xterminator, as I want to reach the limtis with Gimp and PS before exploring other software.. lest I get (even more) overwhelmed.

I will try your idea for fixing the core tonight. Thanks again!

3 hours ago, wimvb said:

I never use ABE, just because it’s difficult to control. For some reason, my flats correct dustbunnies well enough, but don’t remove all vignetting, and I have to clean up with DBE. It works good enough if you put samples in each corner and along each side (=8), plus from each corner along the diagonal, at most half way in towards the centre (+4). No samples closer to the centre needed. You also don’t have to avoid stars, because the are excluded from the samples. The sample plot shows which pixels will be included in the calculation of the background model. Black means excluded, white means included. Gray is a measure for weight. As long as stars don’t have haloes, they will be excluded.

@Jm1973: sorry for derailing this thread. Such is life on SGL, it makes this forum so alive and interesting. Welcome to the club. 😀

 

No problem. It's all very interesting, though a bit above my pay grade so to speak.

So I have got a little further with it now. I am bringing out more detail and more colour, but unfortunately I am also blowing out the core and background.

9 minutes ago, wimvb said:

Before you stack the sub frames, you need to calibrate them. For the setup you used to take this image, good flats are essential. This is what the gradient in your image looks like. The circular structure is vignetting. But there is also a colour gradient with a red band at the top. Most software can handle one source of an uneven background quite well, but a combined gradient can be a challenge to remove. Especially if you also have different gradients in the three colour channels, which makes it even more of a challenge to remove.

Here's what I managed to pull out of your data, before the remains of gradients started to pop up. Nothing too fancy. Arcsinh stretch (available in PS) lifted the colour in your image. after that, curves transformation as Olly already wrote about.

(click on the images to see a larger version)

Thanks for the reply. A lot of what you are saying with gradients kind of goes over my head a bit, but you are not the first person to tell me I should be using more flats.

I only used 10 in this image. The next time I get a clear night I will take more. 

You have managed to get my data looking pretty amazing, as far as I am concerned. I would be very happy if I could get to that stage.

I'll have a look at arcsinh stretch. Assuming it is on my rather old version of PS.

13 hours ago, wimvb said:

Light pollution is a likely candidate. If you get the histogram so far to the right with only 30 seconds exposures on an unmodded dslr, you probably have a fair amount of light pollution. If this is the case, consider investing in a light pollution filter. To compensate for the added noise, you will need long total integration times, ie lots and lots of data.

Hi. Thanks for the comments. LP filters seem to vary in price from a few quid up to over a hundred. 

How much would I need to spend to get something that would help. Are there any particular brands worth buying? I'm trying not to break the bank.

@ollypenrice

II've just spent an hour or so following along with your steps. I feel I have learnt a fair bit about where tools are in PS

I start with moving the black point up the same amount as you did:

Giving this:

I can't move the black point again as much as you did now, but I move it up to 7, being careful not to clip the histogram:

Giving this:

Next  I zoom in to make sure there are no stars etc where I sample, and I sample 4 points in the black. But the RGB values I get are very low. Nowhere near 22-23. Not sure what I did there.

I played about with changing values with colour balance, but I could only tweak them in relation to each other, not increase them overall.

I cannot slide the black point any further to the right without clipping the histogram, so I've had to leave the RGB values where they are. Ah well, onward and upward!

So I continued on to the curves. I have tried to emulate the curve you did, and I got something like this:

I noticed that my histogram is further to the left than yours at this point, not sure why that is. Setting the points on the curves is quite the fiddly task!

Finally I got something resembling your curve and ended up with this!

This is a lot better than I had previously, and I feel I have learnt  some useful stuff. Lots of practise is what's needed now!

I am confused about how the RGB values were so off though....

4 hours ago, Aramcheck said:

I had a quick play with the TIFF. Looks to me that you had movement of the mount on one image in the stack, resulting in the star trail.

Cheers
Ivor

Hi. You were correct. There was one particular RAW file which had very pronounced trailing, much more so than any other.

I have taken that one out, and also a number of other ones with a smaller amount of trailing. I am re-stacking now, and will see how it turns out.

Thank you for your insight, and you're great work with the image.