DSO photography under mag 4 skies (aka Use the force luke!)

[GordonCopestake]

Well had my first clear night here for a long while. Just to annoy me it coincided with a bout of "man-flu" that i seem to have picked up. Didn't stop me going out though, but i may regret it tomorrow!

Anyway, here are my results from "trusting the GOTO". Being under such light polluted skies at my home, i am a 95% visual observer. I have recently started dabling in imaging but have been having problems due to the LP. Anyway, after being given advice, i decided tonight to use the force and ignore what i could or couldn't see. All were taken with my ED100 with a focal length of 900mm and my Nikon D70 at prime focus with 30 second exposure times.

First up was M51, I've always had a soft spot for the whirlpool but have never seen it from my back garden. After focusing the DSLR on Jupiter and ensuring the mount was aligned i GOTO'd m51 and took a look through my finder (I'm glad no body was looking as looking through my straight finder at m51 near zenith made me look like i was playing twister with myself).

As expected i saw nothing at all. Nout, nada zip, zero not even a glimmer of the core. Forging on i set the DSLR to a 10 second delay to stop shudder and the result is below.

Well, i was a little disheartened to say the least, yet on i went.

M13 was next up, i was hoping for more as it's a brighter object. Again single frame 30 seconds with the DSLR.

Blimey, i can actually SEE something there! It even looks like m13. As i couldn't see anything on the view finder i only took one sub, but at the laptop i can see the smudge. Next time i'll try to capture a good few frames for registaxing to do it's magic: If i had taken a few more subs i might have actually gotten a useable photo

Next up was M57, again a favorite of mine as it's in the constellation Lyra. GOTO'd and hit the shutter. This time i actually saw something on the view finder. Will wonders never cease!? Took about 5 subs at 30 seconds each. Although i appear to have star trails, which shows how poorly my mount was polar aligned. Although i had hoped the tracking would have been a little better for just 30 second subs. Further investigation needed. Anyway i was happy to actually have something at all.

It even looks like m57..... Perhaps with the aid of a barlow and a decent polar alignment i could get a better image. When this man-flu has passed and i have a good clear night, I'll break out the guide scope setup that i haven't played with properly yet and try and get a good polar alignment. It gives me hope that I'm actually getting photons to hit my CCD though. It's more than i thought i would get at the beginning of the night.

[Grant]

Really great start Gordon and a great write up to, M57 is definitely there and the colour is showing through nicely.

Looking forward to your next outing!

[Jamie]

Got there eventually i see.

Nice one.

[CELESCOPE]

Nice start Gordon, glad you have got off the ground, now the bug will get you , yes the trailing should be better , good polar alignment doesnt really matter at those exposure times , but the tracking of course has to be good , as long as u are roughly pointing north.

i do have to say , if you want to start off with imaging the easier way , and can afford it , try one of the modded web cams , these do give very good results , , for instance a 30 second exposure that you done with the D70 , had you used a modded web cam , would have given you a splended image of m57 and also m27, using norm camera,s do take a lot more time and the mounts have to be pretty good, and of course longer exposure times required, nearly all my web cam images of DSOs are taken at 45 seconds using fast F Ratio of say f 3 or F1,95, any way just a suggestion ,

But a very well done on your first session .

Keep up the good work .

Rog

[Naz]

Gordon, your star trails are more likely to be camera shake! The D70 10 sec delay does not lock the mirror up until just before firing the shutter. I get the same effect with mine. You require a very sturdy mount / tripod for long exposures with the D70. I have found that short exposures are OK, the shutter has closed before the vibrations set in when using a cheap tripod or on my AZ3!

You might be better of with the remote control, but I have never used one, so don't know if the same thing happens.

naz

[MartinB]

Nice report Gordon - telling it like it is! Why the problem with polar alignment though? Do you have a built in alignment scope on your mount, if so it's a 2 min job.

[GordonCopestake]

No alignment scope im afraid, and to be honest i've never really bothered to polar align accuratly as most of my observing is visual. It's only now that im starting to take images that i need a good alignment. I can drift align though and then mark my tripod feet.

[Kaptain Klevtsov]

Have you tried Photoshop on these?

your M13

and

Just did the levels thing and there they were.

Captain Chaos

[Kaptain Klevtsov]

Gordon, your star trails are more likely to be camera shake! The D70 10 sec delay does not lock the mirror up until just before firing the shutter. I get the same effect with mine. You require a very sturdy mount / tripod for long exposures with the D70. I have found that short exposures are OK, the shutter has closed before the vibrations set in when using a cheap tripod or on my AZ3!

You might be better of with the remote control, but I have never used one, so don't know if the same thing happens.

naz

Also try a big piece of cardboard over the end of the 'scope 9not touching) as the shutter fires. Wait for the wobbles to die down, then move the card.

Do you have the remote blipper for "bulb" exposures? It's about 15 quid from Jessops and well worth it.

Captain Chaos

Captain Chaos

[GordonCopestake]

Owww M13 looks better in your version CC. Thanks.

I have heard of the hat trick but havn't got around to trying it yet. This was my first serious attempt at DSO photography, and whilst it was clear lastnight, my man-flu is making itself known and i didn't get out. I do have a IR remote shutter thingy for the D70, but the mirror flip will still occur. The hat trick is the way forward i think if it IS the shutter release that causing the wobbles.

Given the darkness of the M13 shot (30 seconds) i may try longer exposures. Although obviously i'll make sure my tracking is more acurate.

[Kaptain Klevtsov]

One thing I have worked out WRT digital deep sky images is never to discard any "blank" images. By adjusting the levels in Photoshop you can bring out loads of detail that is not there when you look at the preview screen. As I started off imaging with SLR lenses and teleconverters and very rough tracking I had to settle for images which were very stretched indeed as the f/ ratio was in the region of f/16 and the longest that I could go was a minute without the stars trailing too much. Now that I have the 1000mm focal length at f/5 and good tracking the imaging is a whole lot easier, though still challenging, and the galaxies are now possible. I originally got very pleased with snapping the bright stuff like M42 and quite overexcited with M31. Neither of these actually showed on the preview screen and only came out in Photoshop. Its quite a moment when you move the slider and something pops out at you.

Captain Chaos