My First Prime Focus Attempt - M42

[kljucd1]

Hi,

Well I finally got enough of the equipment that I need to do some prime focus astrophotography.

Tonight there is patchy cloud in Sydney (closest thing to clear skies I have had) and I figured that my first attempt wasn't going to be that good anyway, so I may as well set up and test it all out.

My first target is M42. It is a single 28 second exposure at ISO400 on the Pentax *ist DS. Probably needs to be better focused, or better polar aligning (still need the reticle for that).

Anyway, here it is :D:

[madtuna]

congrats! brilliant first attempt...looking forward to more

[little col]

:thumbsup: nice image of the trapezium there well done :)

[kljucd1]

Hi,

Thanks. I guess that now I will have to go out and get myself a reticle so I can drift align properly.

Daniel...

[Tamtarn]

Hi Daniel

Good to see you are up and running with your first attempt at imaging well done.

Can I ask if your eq mount has motor drives ?.
Also a Hartman Mask can help will make it easier for you to focus.

David

[kljucd1]

Hi David,

Yep the mount has drives. Last night was really only a test as the clouds were around. Thanks for reminding me about the Hartmann Mask as I intended to get one, once I needed it.

Can I ask though, in the following image the stars are trailing, but not in a straight line. Can anyone explain why the trailing is curved and seems to jump into a different line anyway.

Any advice is much appreciated.

[Tamtarn]

Daniel, it could be coming from your mount as the gears don't always run smoothly so you can get variation in tracking.

Try shooting five images and then check the trailing, you may find you have four good ones and one with bad trailing.

Also check that after you have focused that you have locked up the bottom screw on the focuser ( focuser lock screw ).

Hope this helps.

David

[spearo]

Daniel,
Congrats on a first shot. You'll see the feverish obsession grow more and more as you go :] .

Some thoughts:
the trails could be shifting because of wind? or as David says the mount itself.
Good drift alignment will make a big difference I have no doubt
you may want to check the obvious (i've ruined many a shot having forgotten to check the basics) like any cables dragging/getting caught up, check the balancing (some say keep it a fraction heavier on the part that is rising (be that the weights or the scope depending on where you're shooting)
you can make your own Hartman mask :
http://www.iceinspace.com.au/index.php?id=63,187,0,0,1,0

looking at your first shot , you'll be there in no time
cheers
frank

[kljucd1]

Hi,

Thanks for the advice, I think I may need to get a little checklist together to remind myself of all of the things you need to go through when doing this stuff.

Yes a reticle is on the shopping list, so some time soon I should be able to sort that out.

Regards

Daniel...

[Omaroo]

Good stuff Daniel

Just a question - how do you fire your shutter? Do you do it remotely or just press the button?

[kljucd1]

Hi,

I use a remote switch, I wouldn't even bother without one; I shake waayyy tooo mucchhhh!!! :)

Daniel...

[Omaroo]

OK - because I get that star trail "kink" if I just press the button or use a cable remote.

I now use an IR remote that is set on a 5-second countdown - allowing the mount to absolutely stop shaking before firing the shutter - and there's no "tugging" on a cable..

[kljucd1]

Hi,

Umm, so when I said a remote switch I actually meant the cabled version. The camera has a 3 second delay setting for the remote, but this doesn't actually result in any delay at all.

Hmmm, might need to 'set' something up here.

So can the shutter opening cause these problems?

Thanks for the advice :)

Daniel...

[multiweb]

Got stacks of similar shots too :whistle:. I took the mount apart, degreased it, re-lubed it. That sorted out the wavy trailing. Once I had "straight" trailing I tried to balance the mount better. That took care of drift in RA. If you still get drift in DEC then better your Polar alignment, but it's more forgiving.

Worked for me (so far). Hope this helps.

[kljucd1]

Hi,

Cool, thanks Marc.

I actually plucked up the courage to follow iceman's guide on cleaning mirrors the other day :scared:. Pretty scary stuff but I think that maybe with a bit reading up I might be able to give your suggestion a go. It does seem that most people are doing this type of thing to their mount in order to get the most out of them.

Regards

Daniel...

[kljucd1]

Hi,

Well tonight I had another go at M42 :).

Tonight I still used the 8" Newtonian at prime focus, but, rather than 1 28 second exposure, I thought I would give stacking a proper go.

Focus was better tonight :) and I mixed up the exposures just to see what would happen.
Exposures were made up of:
ISO400 - 5 second x 5, 10 second x 5
ISO800 - 5 second x 5, 10 second x 5
ISO1600 - 5 second x 5

The final stack was made up of 22 images in registaxx and I also did Histogram processing here.

Well...at least it is an improvement :) and any advice on how to get better data or process better is much appreciated.

[NewToStars]

wow, what an improvement a few suggestions make from fellow ice members. that image looks awesome.

congrats on the improvement. looks tops.

jase

[kljucd1]

Hi,

Well it is certainly an improvement anyway. Lucky I have IIS to come to, I think I would be in trouble otherwise :lol:

Thanks

Daniel...

[multiweb]

well done.