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Here is a shot of a globular cluster which has a round 1 million stars in the field of view. Canon 300D, 5 minute exposure at 1600 ISO, manual dark frame subtraction, through my telescope....

Is there a thread somewhere on the forums to explain the setup you need to have the camera and telescope take these kinds of fantastic photos ?
(Please excuse the question, I'm very new to all this).

Hi Big V,
For those of us who know nothing about astro-photography, could you please explain to us what you mean by "Dark frame subtraction".

Happy to help... You will need a T Adapter, they make them for all the different model cameras. You place this where your lens would normally attach, then slide that into the back of the telescope and you are in business. Manual dark frame subtraction = taking an exposure for the same amount of time but not letting any light reach the ccd. Either put a cover over the telescope, or if you are using your lens, then place the lens cover on. When you get back to your computer, you will need to subtract the dark picture from your light picture, I do this in photoshop or my astronomy software, all depending on the mood I am in. This only needs to be done on long exposures as you will get noise from the chip when you start going a few minutes up to hours. Hope this helps..

Haha!, I understand now, we have a long exposure noice reduction setting on the D70 which basically does the same thing.

Phillipb, yes you have that feature but if you take one photo manually, then you can re-use it for the rest of the evening as long as the exposures are all the same length. This makes the whole procedure a little quicker...

Thanks Big V, what sort of telescope are you using ? If you don't mind me asking, a telescope is something that has been high on my wish list but never makes it to under the xmas tree

You could also use the merge to HDR feature in PSCS2 with multiple exposures of varying times

Awesome shot

since the exposure was 5 minutes how did you compensate for orbital and cosmic movement, do you have a stellar tracking telescope?

Outstanding Biggie, could you maybe post a photo of your telescope along with some details of it? There are a lot of people here interested in astro photog (me included )

cheers

Big V mate i think you need to clean your sensor it's looking a bit spotty.LOL
Nope nice shot i ahev never tried this and you have got it down pat.
Cheers
John

Hooly dooly. I like it. Im interested in seeing a picture of your set up if you can arange it!

Ooooh, V. Show us your big telescope!!
We should have a night meet at your place and everyone can check it out. I'd even cook for it (or make Pete!). Or, we could go to Woomera and everyone can see the big ones!

Just one word......Sensational!

Marvin wrote:Ooooh, V. Show us your big telescope!!
We should have a night meet at your place and everyone can check it out. I'd even cook for it (or make Pete!). Or, we could go to Woomera and everyone can see the big ones!

Marvin, following from the other thread, ( http://www.d70users.com/viewtopic.php?t=8307&start=15 )you really do have penis envy

Big V wrote:Here is a shot of a globular cluster which ahs a round 1 million stars in the field of view. Canon 300D, 5 minute exposure at 1600 ISO, manual dark frame subtraction, through my telescope....

Nice imageV I only counted 887,543 stars though, maybe you cropped some out?

As a comparison I have an image of the same globular cluster, Omega Centauri posted on my web page, however it was taken with an astronomical CCD, so is B&W, but it is only 50 seconds exposure.

http://members.ozemail.com.au/~loomberah/45cm.htm
There is also a pic of the telescope used to take the image.

Gordon

phillipb wrote:

Marvin wrote:Ooooh, V. Show us your big telescope!!
We should have a night meet at your place and everyone can check it out. I'd even cook for it (or make Pete!). Or, we could go to Woomera and everyone can see the big ones!

Marvin, following from the other thread, ( http://www.d70users.com/viewtopic.php?t=8307&start=15 )you really do have penis envy

Ah, 'tis true. But the big question is does anyone here have anything to be envious of???

(Can you tell I've had a couple of wines)??

quote="Marvin"]Ooooh, V. Show us your big telescope!!
...
Ah, 'tis true. But the big question is does anyone here have anything to be envious of???

(Can you tell I've had a couple of wines)??[/quote]

Marvin, you obviously didnt check my link, theres a huge instrument there

Gordon

Gordon. That is one BIG field telescope you have there. Also good to see my Planetary Society membership going to good use, (other than launching dodgy ballistic missiles from submarines.)

Big V. Nice image too. A good study of a celestial neighour. Your moon shot is good too.

phillipb wrote:Haha!, I understand now, we have a long exposure noice reduction setting on the D70 which basically does the same thing.

Only trouble is, the D70 will only allow 30 minute exposures. I'm pretty sure you can't do a mirror lock-up exposure, like you can with Canons and then use the manual noise reduction shot to fix it up. We're limited to max 30min exposure + 30min in-camera NR.

Love to hear if anyone's been able to improve on this method for longer exposures...

Hi Gordon, you and I have actually talked via email and I was with Frank Zoltawski in Woomera the night he did a follow up confirmation for you. My name is Tony Virgo. The last time we spoke was when one of the members of ASSA thought he had found a comet in the south and we were clouded out. Ended up being nothing. I am using a Meade LX90 8 inch and a Meade LX200 10 inch. I am currently working towards upgrading to a Meade LX200 12 inch. I also use the 20 inch at Stockport, although the seeing and guiding is limited with that scope at the moment. Your work is very impressive, are you still doing your NEA obs?

Gordon wrote:As a comparison I have an image of the same globular cluster, Omega Centauri posted on my web page, however it was taken with an astronomical CCD, so is B&W, but it is only 50 seconds exposure.

http://members.ozemail.com.au/~loomberah/45cm.htm
There is also a pic of the telescope used to take the image.

Gordon

I like the shots on your web site - particularly of Aurora Australis.

I also particularly like the photo of the telescope - it has a real home-made look to it, well made but with funny bits like the drums welded to the frame.

Gordon, I did see your large instrument. Very impressive!!!
Tony - get back to work!

Lee, are you at work or at home? I am at work but have 2 free lessons until after lunch, then a lazy afternoon of tennis...

Wendelit, yes the telescope has 2 motors, which allow it to track the stars as the earth rotates. You also need to be polar aligned, otherwise the stars will rotate in your picture and this is evident in as little as 30 seconds...

Big V wrote:... Your work is very impressive, are you still doing your NEA obs?

Hi Tony, thanks

yes still observing NEAs, although almost entirely at the Siding Spring Survey these days. After a 6 night run of observing, I generally want a break from it

Gordon

Good to hear that you are still involved.. Frank is using a 3m scope in Arizona with adaptive optics, one of the perks when working for the military I guess.

paulvdb1 wrote:I like the shots on your web site - particularly of Aurora Australis.

I also particularly like the photo of the telescope - it has a real home-made look to it, well made but with funny bits like the drums welded to the frame.

thanks Paul. Yes the telescope is all home made, although it contains no drums the drum-like parts are made of rolled Aluminium plate!

Gordon

Big V wrote:Lee, are you at work or at home? I am at work but have 2 free lessons until after lunch, then a lazy afternoon of tennis...

I was at work - on my 30 minutes non contact. Bloody secondary teachers..... (I know, we all have choices! )