DSS problems

[Ande]

Hi all. Tried my first imaging session earlier, and it did not go well. I set up for a crack at the Pleiades. I took fairly short exposures of 20x20 seconds, which I knew wasn’t going to be amazing, but I was more concerned with just having some images to feed into DSS, just so I could sample the mechanics of the process. I also took 20x20 dark frames, and 20 bias frames. No flats.

I followed a YouTube tutorial along, and got all of my images loaded in, but when it came to registering the images DSS could not find any more than 6 stars, no matter where I positioned the slider. I had a quick Google, and someone who had the same issue had suggested trying to stack only lights, in case the calibration frames were somehow interfering. So I tried that but still no difference. So I forged on, and DSS informed me that of the 60 pictures it was given it was only going to stack one. Not much merit in that.

So, I googled a bit more, and someone said that DSS was picky over star shapes if tracking was poor, and was also intolerant of poor focussing. But I did a pretty good polar alignment, and got good focus with a Bhatinov mask. Plus, the exposures were only 20 seconds, so no trouble for the Ioptron Skyguider. My stars looked pretty crisp. Any ideas on why DSS kicked everything out?

I was using a Canon 80D, unmodified, a Samyang 135mm lens, and an Ioptron Skyguider.  ISO 200 (this is supposed to be optimum for the 80D), f2.8 and 20 seconds exposures.

To be honest, I actually tried SIRIL first, as I thought that looked really good on YouTube. But as soon as I asked it to process the images it imploded and crashed instantly. So I’ve abandoned that particular idea.  I had heard that it was a bit unstable. 
 

Edit: Forgot to mention that light pollution is quite heavy, with some LED lampposts quite nearby. Although the images looked alright in spite of that.

Edited January 9, 2021 by Ande
Omission

[PeterCPC]

Could you post a light frame.

[shropshire lad]

I'm quite new to this as well but I think your iso is probably the reason, I have the canon 80 D and I use iso 800 and have had some suggest that I should go up to 1600. 

[alan potts]

I had this happen to me but can't recall what I did, ISO 200 is too slow really at 20secs, 800 or 1600 will give you more and you will get decent results. I started out with 60second subs, with decent alignment you should get away with that without guiding.

Alan

[happy-kat]

Please add one jpeg of one of your light frames so we can assess the image.

[Ande]

Thanks each. I’ll try and post a light frame if I can work out how to get one that displays. Apart from DSS, I don’t seem to have anything that wants to look at a RAW file. I think the Canon spits them out as .CR2 or something like that. I’m currently away from the camera and PC and am not sure about that, but it rings a bell. I did try to feed one into PS, but it rejected it.

Regarding the ISO being low, I do get that as it seems low to me too. I was just going by this article: http://dslr-astrophotography.com/iso-values-canon-cameras/ which suggests that the 80D performs best at ISO 200. I guess I was clutching at straws with such a small exposure as 20 seconds.

Edited January 10, 2021 by Ande

[Ande]

Couldn't work out how to turn it into .jpeg. I thought PS might allow me to save it as a jpeg but it doesn't.  Not sure how the stars suddenly turned blue either.  I must have pressed something somewhere.

 

 

Autosave002.tif

Edited January 10, 2021 by Ande

[Davey-T]

1 hour ago, Ande said:

Couldn't work out how to turn it into .jpeg. I thought PS might allow me to save it as a jpeg but it doesn't.  Not sure how the stars suddenly turned blue either.  I must have pressed something somewhere.

 

 

Autosave002.tif 213.26 MB · 3 downloads

If you import it into PS as 16 bit Tiff then under file / save for web and devices / save as PNG , you may have to reduce it in size also easily done in PS.

Dave

[Davey-T]

Had a look at it in PS, stars are out of focus so probably why DSS didn't like them, did you take any calibration frames as there's a lot of vignetting ?

Dave

Zoomed in

 

[Ande]

Hi Dave. Thanks for having a peep. I did take calibration frames, but DSS only allowed 1 light frame to enter the equation.  Not sure what to do about the focussing issue, as I did use a Bhatinov mask, and it looked good.  Mind you, I did have a bit of a game with the ball head after focussing. I’m now thinking that I could well have kicked it out of kilter during the struggle. Next time out I shall make sure that I re-check focus just before starting sequencing. 

[Davey-T]

5 hours ago, Ande said:

Apart from DSS, I don’t seem to have anything that wants to look at a RAW file. I think the Canon spits them out as .CR2 or something like that.

Have you got the Canon Utilities loaded, it will transfer CR2 files as Tiffs to PS.

On the focusing front I find it easier to zoom in on a bright star in live view to focus.

Dave

Edited January 10, 2021 by Davey-T

[Ande]

Yes, I think I have that. I shall look into it.  Focussing wise I’ve actually been taking pictures, and then zooming in on the result to check focus.  Your method sounds better.

[Ande]

Just had a quick go of your zooming in on liveview method. I used my housemate as a guineau pig, despite her protestations 😂. You are right, I was able to get pin-sharp focus on her eyes. Much better than I have managed before. I’ll definitely use that method next time I get the opportunity.

[Davey-T]

If you use a bright star and nudge the focus back and forth it will flicker between red and blue, try to stop on the blue just before it turns red, the shorter the focal length the trickier it is but also less critical.

Dave

[wxsatuser]

13 hours ago, Ande said:

Thanks each. I’ll try and post a light frame if I can work out how to get one that displays. Apart from DSS, I don’t seem to have anything that wants to look at a RAW file. I think the Canon spits them out as .CR2 or something like that. I’m currently away from the camera and PC and am not sure about that, but it rings a bell. I did try to feed one into PS, but it rejected it.

Regarding the ISO being low, I do get that as it seems low to me too. I was just going by this article: http://dslr-astrophotography.com/iso-values-canon-cameras/ which suggests that the 80D performs best at ISO 200. I guess I was clutching at straws with such a small exposure as 20 seconds.

What version of PS do you have?

If it's not up to date Camera Raw will most likely not open the file.
To open 80D files you will need version 9.5 of Camera Raw as a minimum.

[Ande]

3 hours ago, wxsatuser said:

What version of PS do you have?

If it's not up to date Camera Raw will most likely not open the file.
To open 80D files you will need version 9.5 of Camera Raw as a minimum.

CS2. Is Camera Raw a plug-in?  I am completely new to any form of PS, and am currently swimming in a sea of total bewilderment 😂

[Ande]

8 hours ago, Davey-T said:

If you use a bright star and nudge the focus back and forth it will flicker between red and blue, try to stop on the blue just before it turns red, the shorter the focal length the trickier it is but also less critical.

Dave

I’ve just ordered a ZS61, so am hoping that the dual focus will make it a tad easier to find. Currently, I’m working with a Samyang 135mm prime lens and, getting dodgier by the day, 58-year old eyes 😳

[wxsatuser]

31 minutes ago, Ande said:

CS2. Is Camera Raw a plug-in?  I am completely new to any form of PS, and am currently swimming in a sea of total bewilderment 😂

Yes.

Photoshop on it's own afaik does not read RAW files.

Adobe Camera RAW is the bit that does the decoding.
There are other programs that can read them as well, Canon software for one.

Most RAW decoders rely on dcraw which I believe is now not updated apart from what libraw do with it.

[Ande]

Thanks Mike. I’ll have a bit of a play this evening, and see what I can make sense of.

[Chefgage]

Read through this thread but did not see it but when you are taking your images on your DSLR can you not set it to take raw (.cr2) and jpg's at the the same time. That's what I do as I sometimes just want one the the raw images as a jpg (saves having to convert it). Also to view the raw files before stacking them (so you can throw out the bad ones) use Adobe bridge. It's a free download and quite handy for viewing the raw files as it has a handy magnifying glass that can be positioned on the raw image. Then when you click on the other raw images the magnifying glass stays in position so you can compare star shapes between images.

[Ande]

Yes, that is definitely an option on the camera, and not a bad idea. I think I may already have Adobe Bridge on the laptop, as part of the CS2 package, although I could be wrong. I’ll check on that next time I fire it up. 
 

Much appreciated 🙂

[wxsatuser]

1 hour ago, Chefgage said:

Read through this thread but did not see it but when you are taking your images on your DSLR can you not set it to take raw (.cr2) and jpg's at the the same time. That's what I do as I sometimes just want one the the raw images as a jpg (saves having to convert it). Also to view the raw files before stacking them (so you can throw out the bad ones) use Adobe bridge. It's a free download and quite handy for viewing the raw files as it has a handy magnifying glass that can be positioned on the raw image. Then when you click on the other raw images the magnifying glass stays in position so you can compare star shapes between images.

You can easily do this with the Canon DPP, it comes free with the camera.

You can see the RAW unedited, one click as a jpg or all as jpgs.

[Ande]

I hadn’t even thought of looking at Canon’s own software. Something else for me to look into. I hope the clouds don’t part for the next 3 months, as I shall be way too busy 😂

 

Much appreciated 🙂