Leo Triplet

[SteveBz]

Hi Guys,eel

I see some of the images posted here and many of them are really fantastic.  I still have a long way to go, but here are the results of about 8 x 60 secs of stacked data with DSS. Really I was trying out my focusing with a Bahtinov made from an old paint lid, but what I feel is I really need to up my exposure times with guiding and noise filtering.

There is a fair amount of try it and see post processing, which also needs much more effort, none-the-less here it is:

 

Suggestions please.

Regards

Steve

[billyharris72]

Nice image - I've not tried the Leo Triplet myself and this makes me think I ought to give it a go. Thoughts for possible improvements:

1. There is a little bit of elongation in the stars. It's not bad (doesn't really affect the galaxies and doesn't bother me) but if they could be tightened up it would look more aesthetically appealing. Could be a guiding or polar alignment error? It might be possible to improve this in post processing, but I've not tried that.
2. More light frames would be good to get the signal to noise ratio up. An hour's worth of 1 minute subs would let you stretch the image more without getting artefacts.
3. The background seems to have quite a gradient to it. Did you shoot flat frames? One option would be gradient removal filter (AStroArt has one, I think there is a Photohop filter also). Can also do this manually by cutting out the stars and blurring to create a new "flat" later and then using "difference" in the layers menu.

Best of luck and hope this is some help.

Billy.

 

[Tommohawk]

Its a good start! Frankly if you're getting any clear sky you're doing better than me!

Stars top left look more elongated. This may be the result of poor collimation or it may mean you've cropped the top left and its just coma - that could be fixed with a coma corrector.

Focus looks about right - if you got a nice cross from your home made Bahtinov you should be OK. Are you guiding? If so do longer subs.

You might like to post more info re the kit used and ISO etc. For Canon ISO 800 or 1600 seems favourite - not sure about Nikon.

HTH

[SteveBz]

9 hours ago, billyharris72 said:

Can also do this manually by cutting out the stars and blurring to create a new "flat" later and then using "difference" in the layers menu.

Thanks generally for all your suggestions.  You're right about the gradient.  They told me I wouldn't get a gradient if I moved to 2 inch, so I did.  As you can see, with little effect except my filters fit. 

I haven't done flats and I should, but I'm never quite sure how it works.  I didn't know you could do it manually, so thanks for that.

Maybe I'll have a go this evening.

It's looking clear but a bit starless outside at the moment. 

Regards

Steve.

 

[tomato]

Nice image, I cannot frame all three galaxies on my current camera so it would be the Leo triplet (-1).

My first Bahtinov mask was cut from cardboard and worked just as well as a later purchased laser cut version.

[SteveBz]

1 minute ago, tomato said:

Nice image, I cannot frame all three galaxies on my current camera so it would be the Leo triplet (-1).

My first Bahtinov mask was cut from cardboard and worked just as well as a later purchased laser cut version.

Thanks for your comments.  I'm probably not going to change the paint lid Bahtinov, but I do have an Arduino which does exposure timing, goto and guiding, so I probably want to go straight to a software focuser with some sort of focus algorithm.

Then I can sit in the kitchen and it'll all be done for me by my hard-working little Arduino.

Regards

Steve.

[billyharris72]

I think flats are really important for gradient and vignetting. I do mine using a white monitor screen with a couple of sheets of paper taped over it, but lots of other options online. They can be fiddly but make a major difference.

The artificial "flat" isn't really a substitute  (or really a flat frame at all) but ideally something to do on top if there is a remaining gradient (e.g. from light pollution). You basically isolate the sky background in a layer and then subtract it from the image, then apply a bit of transparency to avoid it looking too artificial. Hit and miss, but can be very effective.

[DaveS]

I use the white T-shirt method with several layers to randomise any weave.

In the meantime, can you confirm the kit you are using? I'm thinking the C8 newt and Nikon D5000?

Unless you are in a really dark site some kind of LP filter could make a big difference, unless you're plagued by LED streetlights. As has been said, longer subs will help a lot, try different exposures and look at your histogram you can easily push the peak to halfway or more with advantage.

As has been noted. AstroArt 5 (And now 6) has several gradient removal tool which I make frequent use of, even with flats applied as I often have LP gradients across the image. AA5 will also handle your capture and guiding.

[SteveBz]

14 hours ago, DaveS said:

I use the white T-shirt method with several layers to randomise any weave.

In the meantime, can you confirm the kit you are using? I'm thinking the C8 newt and Nikon D5000?

Unless you are in a really dark site some kind of LP filter could make a big difference, unless you're plagued by LED streetlights. As has been said, longer subs will help a lot, try different exposures and look at your histogram you can easily push the peak to halfway or more with advantage.

As has been noted. AstroArt 5 (And now 6) has several gradient removal tool which I make frequent use of, even with flats applied as I often have LP gradients across the image. AA5 will also handle your capture and guiding.

Hi Dave,

Yes, the kit is a C8 Newtonian with a Nikon D5000 (2 inch nose).  It's well collimated (I think).  The subs were 60 secs, but not darks, biases or flats.  There was no guiding here, although I'm working on it.  The whole rig is powered by an Arduino that does anything I can get it to do, at the moment GOTO and bulb exposure control.  Arduino guiding and autofocus are on the way.

The day after these photos were taken, I practised guiding and got up to 90 secs with no drift, sadly at that point the program crashed, but I'm hoping for 2 minute subs or more.

I use the SkyWatcher light pollution filter, but next door is a bit of a security fiend and has security lights blazing much of the time.

I'm sitting here playing with GIMP trying to produce artificial flats.

Thanks for the suggestions.

Steve.