Modded 840K Widefield

[asimov (John)]

Hi.

Thought I'd see what all the fuss was about with this DSO caper

I LIKE IT !!

I'm not really setup for it ATM, the EQ5 falls flat on it's face with a F10 SCT with a toucam shoved in it, brings out the worst in it even with a .06 FR. Spent 3 hrs drift aligning the bugga & got 8 second exposures tops

This widefield stuff with the standard lens piggybacked it does ok though

This is 7 X 2 min exp. stacked; Heaps of noise & hot pixels to battle against using this webcam it seems I took 2 darks & stacked 'em otherwise the outcome would have been a lot worse!

Question: Would faster exposure times & more stacked be the answer to killing off some noise & hot pixels? Perhaps more darks stacked into a master dark?

I'm hooked & I'll be doing a lot more of this kind of thing, hopefully improving along the way

[gbeal]

Good start Asi. Darks are something you may have to do regardless. (As a comparison, I don't normally do them with the 20D). A "bank" of master darks is a good idea, as long as the exposure and temp are similar. Paerhaps try a decent standard or widish camera lens, Steven Mogg makes adaptors.

[Dennis]

That is a very nice and detailed image Asi - you have done a great job at wringing this much detail out of your set up - well done! Tread the DSO path warily my friend; it is very seductive but also such an unforgiving and cruel mistress once you are hooked.

Cheers

Dennis

[h0ughy (David)]

yep Dennis is correct, there is no return after starting on the path! Nice start and I agree you have wrung just about all you could from that setup

[[1ponders] (Paul)]

Great shootin' Asi

Yes faster exposure will give you less noise, but you won't pick up as much detail/light. Noise is basically heat generated, ambient heat and the heat generated by the amp in the webcam, plus a few other electrical and light sources.

The answer is, stack lots, and subtract darks.

Here's a bit of a guide for you re stacking. To improve signal to noise by stacking you get this result. The first number is the number of frames stacked and the second number is the signal to noise improvement.

2, 1.4
4, 2
9, 3
25, 5
100, 10
1000, 32

See a patternt The signal improvement is the square root of the number of frames stacked. The same applies to your Darks, though to be honest I usually don't worry about more than 5-9 darks.

If you are just starting down the slippery road of long exposure webcam imaging, I can strongly recommend the "Introduction to Webcam Astrophotography" by Robert Reeves. Excellent starters book.

[RB (Andrew)]

That's so cool Asi....
You've captured good colour and detail.

Originally Posted by asimov

I LIKE IT !!

hahaha your hooked mate DSO imaging is like a black hole, it sucks you in and there's NO escape.

[Striker (Tony)]

wahoo..we caught another one.....no returning now Asi......your an astrophotographer now.

Like Paul said...stack more exposures will improve noise to signal ratio....try doing this even before you start getting into dark frame subtraction...unless you already know the process and if so then you can learn flats and bias frames...lol

Well done Asi.

[Starkler (Geoff)]

Asi i was interested to see your comments re the eq5.
What exactly is letting you down with this mount? I ask because I have an eq5 sitting idle and well, its not big enough to carry a scope I'd want to use visually, so Im curious as to its limits photographically.

[spearo (Frank)]

Well done, great effort!
Strangely, i share the feelings expressed by Tony/Striker....Wooohooo we have another astrophotographer here !
welcome to the club!
frank

[sheeny (Al)]

Good one Asi!

Can you post more details? Gain, brightness, etc.

Thanks,

Al.

[asimov (John)]

Hi guys & thanks for the welcome to the exclusive DSO photographic club

Can't afford to go any further at this stage so a better setup is not on the list at present. Thanks to Dave Pretorius for swapping cams with me temporarily (his has the mod & mine hasn't)

Geoff, my comments re the EQ5...I'm sure it's my inability to drift align properly thats the hold up I've been thinking & reading articles on the procedure & I think the penny has dropped now It also has got some wild PE going on I think. You can see the stars zig zagging across the preview screen as they drift across. (I assume this is PE I'm seeing anyway).

Tonight I'll try to get a better alignment happening & try to get the exposure times up a bit longer.

Piggybacking the toucam on the 9.25 it seems to be pretty tolerant of my alignment, but when it comes to shooting through the scope itself its a totally new ball game.

Heres 2 more pics (Beginner pics obviously )

The lagoon & orion. This is the minimum image scale I can achieve even with a 0.6 focal reducer using this webcam.

Check out the hot pixels on orion Is this the camera doing this?

Al, I read somewhere to use 100% gamma 50% gain 50% brightness but I'm not sure those are the best settings yet. I'll be doing a few experiments in this area.

Lagoon: My first attempt the other night. At that stage my alignment allowed me 3 sec. exposures tops! 20 stacked. 1 Dark subtracted.

Orion: 2nd attempt early this morning. 19X8 sec. exposures 4 darks stacked & subtracted.

Paul, thanks for the explanation frames versus signal to noise

OK! That big bright yellow thing in the sky is about to set!! ACTION STATIONS! ALL HANDS ON DECK !!

[Lester]

Hi Asi,

very good start. Interesting seeing the hot pixels in line, shows the tracking is cirtainly not quite there yet. Yep the hot pixels are comming from the CCD, and from my understanding must vary slightly under different temperature. That is why different dark frames are required for different temps.

Be interesting to see how the wide field goes to capture meteors.

[Lester]

That Lagoon is actually the Trifid. How come you have less hot pixels, or hardly any in the Trifid compared to Orion? Was your processing different?

[asimov (John)]

Ok, get you wallet out Lester! Bets are on gents! I'm saying its the lagoon!

[Lester]

Okay, I'll start with one wheel barrow of Pig manure, to get the betting started.

[asimov (John)]

I had to knock off your lovely LAGOON pic Bill Christie for practical demonstration purposes only, hope you don't mind! Excellent pic BTW

Now then Mr. pig manure boy....Is this plain enuff for ya or would you like to play double or nothing ?

Oh ye of little faith

[Lester]

MMMM! I think I have just been diddled 1 wheel barroow full of ......... Well I hope you grow some good strawberries out of it.

[asimov (John)]

Uuuummmm no, you diddled youself out of it! Damn, I should of played dumb & got a ute full of piggy poop!!

[sheeny (Al)]

You absolute shark, Asi! You knew someone would bite as the Trifid!
Lester, I thought it was the trifid at first glance too... flip that pic up quickly at a star party and you'll trap a few I'm sure!

Al.

[asimov (John)]

Al.

Yep! That pics my trump card lol. Game of poker Lester?? I've never played it before, I SWEAR!