Another Newbie M8

keni (Ken) · #1 08-10-2011, 10:13 PM

Well after much gathering of equipment, picking peoples' brains and chancy weather I was actually able to start on the LOOOOOONG road to AP heaven.
I'm nowhere near there yet but these pics give me hope.
Both of M8, unguided (still sorting that out).
1st is 10x30secs 1600ISO stacked with darks and bias frames in DSS and fiddled in Gimp.
2nd is only 3x30secs at 3200ISO stacked with darks and bias in DSS and PS Elements.

600D Canon...hooray for live view.
SW 8" F4 BD Newt.
EQ6 pro.
MPCC...work in progress.

All hints, suggestions gratefully received.
Cheers,
Ken.

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jjjnettie (Jeanette) · #2 08-10-2011, 11:43 PM

A great start there Ken!

bmitchell82 (Brendan) · #3 09-10-2011, 07:24 AM

not bad mate your doing well for some of your first images! though ill let you in on it, you have to be aiming at 1o minute photos at a minimum anythihng less is well just not good enough at the end of the day.

get your guiding on the roll. but make sure of a few things

1. get your polar alingment on the money (try polar align max small donation easy alignment!)
2. work on your alignment for reasons i have already posted but for your benifit the better/more time you spend with your alignment the better your guiding will be.

read this artical i wrote

http://brendanmitchell.net/?p=386

its not just enough to say yay i have attained calibration that means diddly unless you have attained near perfect calibration but thats a whole nother post. Next is to run your exposures out to a fair time anything less than 10 minutes is a waste of time for anything other than a test to say yay i can shoot a photo!

I have to say taking a 300 30 second photos is not worth anything apart from wasting your time I know this is controversial but its silly to think that 300 30 second photos can capture more than 1 10 minute photo. sure your noise is reduced but your signal isn't increased...........

Ill leave you with that small bit of info but if you want more details just ask

i will be happy to expand and one day i will do a comparison to prove my words.

Brendan

batema (Mark) · #4 09-10-2011, 07:42 AM

It is a great start and the focus looks spot on. Go longer exposures.

Peter.M · #5 09-10-2011, 12:20 PM

I am very new to this like you Ken and I think you are off too a great start. However I disagree with Brendan ( Purely in a constructive way) While I agree that 150 minutes total exposure will be better at 10 minute subs than 30 second subs I dont think that 1 10 minute exposure will be better than 300 30 second exposures. The signal to noise ratio, which is what we are concerned with in AP will be far greater in the stacked photo.

keni (Ken) · #6 09-10-2011, 09:01 PM

Quote:

Originally Posted by jjjnettie

A great start there Ken!

Thanks jjj and thanks for your help too.
Now to work on autoguiding...Oh joy of joys....

Cheers,
Ken.

keni (Ken) · #7 09-10-2011, 09:09 PM

Hi Brendan,
Thanks and yes autoguiding is the next step.
Then longer exposures and all the rest.
I have bought a TV guider from a fellow IIS member and will be trying that as soon as work allows.
Got the alignment almost perfect...and wasn't that fun.

It's a steep learning curve but's that part of the "fun".

Cheers,
Ken.

bmitchell82 (Brendan) · #8 09-10-2011, 09:12 PM

Peter you are right with signal to noise ratio, general rule of thumb is tertiary number of subs 3,6,9.

The issue though peter is that 30 seconds you wont capture enough signal and this is where the 1 10 min sub will smash 300 30 second subs six ways to china as the signal will be strong enough to push past the "noise". Is it going to be a show stopper? No. will it have far more image yes! whats the use of having a smooth picture of black and a couple of white spots.?

RickS (Rick) · #9 09-10-2011, 09:12 PM

Good to see you producing recognizable images, Ken! You'll sort out the other stuff in no time at all, I'm sure. Just take it one problem at a time.

Cheers,
Rick.

keni (Ken) · #10 09-10-2011, 09:19 PM

Quote:

Originally Posted by batema

It is a great start and the focus looks spot on. Go longer exposures.

Thanks batema,
Yes I was surprised by how well I got it focused.
The live view helped especially after trying hoplessly with my 20D.
The 600D is great.

Quote:

Originally Posted by Peter.M

I am very new to this like you Ken and I think you are off too a great start. However I disagree with Brendan ( Purely in a constructive way) While I agree that 150 minutes total exposure will be better at 10 minute subs than 30 second subs I dont think that 1 10 minute exposure will be better than 300 30 second exposures. The signal to noise ratio, which is what we are concerned with in AP will be far greater in the stacked photo.

Thanks Peter,
Yes I've seen your pics too...very nice and good to see similar equipment.
It will be great to get comparisons as we progress.
As far as times go I'll wait until I try some longer exposures before commenting but I'll be experimenting.

Cheers,
Ken.

keni (Ken) · #11 09-10-2011, 09:56 PM

Quote:

Originally Posted by RickS

Good to see you producing recognizable images, Ken! You'll sort out the other stuff in no time at all, I'm sure. Just take it one problem at a time.

Cheers,
Rick.

Hi Rick,
Thanks now I just have to get my TV guider back from my mate so I can start on the autoguiding learning curve.
Cheers,
Ken.

A23649 (Nathan) · #12 14-10-2011, 10:01 AM

Brendan,
Reading through this post I believe the number of 30 second subs should be 20 rather than 300 which would bring the total imaging time up to 150 minutes, smashing the single 10 minute sub by half a month of Sundays.

Clear skies,
Nathan

bmitchell82 (Brendan) · #13 14-10-2011, 07:39 PM

Well my friend you keep going with your 30second images while ill keep on with my 10 to 20 minute images. When i get home ill dig up a 3 min to 10 min comparison so you can see that the only thing you are doing is reducing your noise and increasing the overall luminance of what is there you can't magically create data...

mill (Martin) · #14 14-10-2011, 08:20 PM

Nice start Ken

Don't listen too much to people who want you to make 10 or 20 minute exposures.
It all depends on the object and the light pollution you are working with.
I would not think about making a picture of Omega Centauri of 20 Minutes (unless you want a nice light bulb

).
Very dim objects can do with long exposures but when stars get saturated you can't get the color back in them.
Then you have M42 where you have to do multiple short exposures and some longer exposures, after that you be better of to get HA to get the dim surroundings.
So all in all it depends on what you are imaging,your mount,light pollution etc.
And since you just start out you better have fun first and some pictures you can show people instead of having the stress to to be perfect.

Just my 2 cents worth.

keni (Ken) · #15 14-10-2011, 09:46 PM

Hi Martin,
Thank you and yes I still have so much to learn and take in.
That's the good part though being a beginner I can only improve.
Or there maybe a mysterious "insurance" fire...

Joke..Joke Joke...for any assessors lurking out there.

Ken.

bmitchell82 (Brendan) · #16 14-10-2011, 11:54 PM

Well said Martin good advice for the beginner.

I just wanted to make sure that people don't think that taking loads and loads and loads of really short subs will somehow magically give you a photo that that looks like it has really long subs because it doesn't.

I would love for somebody to prove me wrong i have no issue with it but from experience really short exposures don't help with data

but are required for really bright objects.

I do layered images and M42 is perfect for it and im sure you have done alot in that area

. Then I have 15min sub exposure images for capturing dark nebulae. Though i am still learning and by no means of the swing know even 1/4 of everything.

After all whats the use of miss information in a beginners section

Brendan

adman (Adam) · #17 15-10-2011, 01:17 AM

Ken is shooting from inner Brisbane. Even on a new moonn night subs beyond 2 or three minutes are nearly washed out with sky glow. Getting out to peters (pmrid) place is much better - I often take 5 min subs there and end up thinking I could go longer.

Adam

bmitchell82 (Brendan) · #18 15-10-2011, 02:28 AM

once again

that is a location dependent issue

I used to live in the middle of perth. same thing the 10" would pick up enough light pollution that everything was shot after about 2 minute subs

but my new place me and my mate measured the skies here at 21.5 if i remember correctly which allows for 10 min colour shots not a issue.

bmitchell82 (Brendan) · #19 15-10-2011, 11:32 AM

Well here is a comparison of a 5 second 90 second and a 600 second image taken on the same night same scope same camera. This i hope shows that data doesn't magically appear

I have done a basic curves and levels on these images to bring out a fair bit of the details that are present.

adman (Adam) · #20 15-10-2011, 11:55 AM

Brendan, I don't think you'll get much argument that longer subs (up to a point) are better - but thats not really the point here. Ken is a beginner shooting unguided subs from a high light pollution area, so to say that

Quote:

you have to be aiming at 1o minute photos at a minimum anythihng less is well just not good enough at the end of the day.

is not very helpful at this point in his learning curve.

Adam