Centaurus A and Trifid

[bloodhound31]

Finally! A new moon and no clouds!!
http://www.asignobservatory.com/images/Galaxies/CentaurusA10Mar08.JPG
http://www.asignobservatory.com/images/Nebulae/Trifid10Mar08.JPG
Baz.

[Peter Ward]

Baz,

Colour balance not good, plus there is a good deal of noise (horizontal banding is obvious) from too short an exposure time....probably needs at least 5-10x more time.

Tracking...good...no..make that: very good. Stick with it.

[EzyStyles]

Nice try Baz, keep it up mate . Longer subs will sure minimise that noise in those images. The framing looks very familiar :whistle: :thumbsup:

[skwinty]

Tracking for 25 by 1 minute exposures is very good ?
Was the mount a large garden rock?;):P

Sorry if I sound facetious but I thought good tracking involved more than 1 minute. If it was a single exposure @ 25 minutes then that description would apply.

Maybe I am wrong , I know I'm not the sharpest tool in the shed.
Regards
Steve:whistle:

[skwinty]

Hi Baz
I looked at your pix again last night and would like to offer another viewpoint.
I refer a lot to HAIP by R.Berry and J.Burnell.
Last night I reviewed what I felt were the pertinent issues.
See attached PDF.
The other suggestion I have for reducing noise is to use a lower ISO setting.
Regards
Steve:)

[Bassnut]

Steve, re the PDF, another blunt tool :P :whistle:. No mention of read out noise, and darks double the image exposure time?, dunno about that, doesnt sound right.

Halve the ISO, double the exposure time,? same diff??

So Peter was a bit generous re guiding, does that require a hard bite-back?.

Cheers (you started it :thumbsup:)

[skwinty]

:(
Hi Fred
If my reply was construed as a hard bite back then you guys must be more sensitive than I am!
Did you read the pdf? Read out and other noise sources were mentioned.
With regards the info in that pdf as i said comes from HAIP, so if you dont think it sounds right then you really are taking issue with a very credible and well respected international authority on the subject.
You must also remember that disagreement and critique is a two way street.
Regards
Steve;):thumbsup::P:rofl::scared::s crewy::rolleyes::help::D:)

[Bassnut]

2 way?, of course, bring it on (whats with the random emote-city thing).

OK, "noise" included read out noise (not obvious)., my mistake.

Darks double the image exposure time?, dont care about the scourse, thats not accepted practice. I dont know the math, I havent tried this, and I bet most other "credible and well respected international authorities" would be supprised at this revalation.

[skwinty]

Ill ask the question again. Did you read the pdf?
Readout and other noise dominant.
This was the second heading. Not too difficult to miss. Last time I looked the attachment showed no views.
What does "dont care about the scourse" mean? Being a blunt tool I dont understand.
Also why the need to defend Peter? In my my opinion he is capable of rebutting any argument presented.Also my comments are not a personal attack, merely a surprised observation. I find that many on this forum are quick to dismiss other peoples point of view without attempting to justify their own position. As i have said previously, my expectations from this forum are robust debate, not innuendoes and pearl casting before the swine.
I have an opinion like every one else and I expect that if some disagrees with my opinion that they at least read it.
Regards
Steve
PS the random emoticons refer to my confusion with regards to your message.

[Bassnut]

Whoa, Ok, its in the title, thats embarissing LOL.

You mentioned sharp tools, so did the PDF in the last line, just a poke, take it easy. Not defending Peter, just the response, actually, I guess yr point is savage but relavent, patronising shouldnt be tolerated. Sheesh I respect yr opinion, sorry for missing the PDF noise title, good point, I humbly appologise, but the dark exposure question stands, makes me doubt the authors expertise altogether (my opinion, not an expert). Robust debate, sure, I made a mistake, so hang me.

[skwinty]

To be fair here Fred, the pdf is me paraphrasing a whole chapter.
The objective in R.Berry's opinion is to get the noise to a minimum and to produce the best image you can without introducing more noise as happens when you apply all the different calibration procedures.
I will review the chapters again and elucidate on the dark frame issue.(If you are interested , if not dont read the post)
I also am not an expert but I have been studying this book for a while now and it is only through discussion and review do i make any headway.
Regards
Steve;)

[bloodhound31]

Whooooaaaa!!

I just posted a couple of images!! LOL! Wow, I didn't expect to check the replies to find an all-out war raging...sheesh.., you blokes...:whistle:

Anyway, thanks for your comments and critisisms. I get a great deal out of both.

I read the PDF and tried to understand it. Some people have told me that taking lots of shorter images will increase the signal and decrease the noise. Others have told me to take longer exposures to achieve the same thing. I'm confused now. I saw Eric's image of the Trifid and I noticed that he did 7 frames at 7 minutes, as a pose to my 25 frames at 1 minute.

His is MUCH better!

I think I will have to start going for longer exposures and lower my ISO.

The problems I have left, are the red creeping in, due to the unmodded filter in the 400D, the noise due to heat in an uncooled camera and the TERRIBLE vignetting I get now that I am using a focal reducer.

[bloodhound31]

By the way Eric, thanks mate for the pointers on the frame mate. I really like this one and give you the credit.

Baz.

[theodog]

Maybe a silly question but do you do dark frames?

[bloodhound31]

Yes mate, I do, and allso offsets. Havent moved on to flat lights though yet.

Baz.

[skwinty]

Hi Barry
like I said in the pdf, longer integrations are better, but there are issues that will limit the exposure time , like tracking accuracy. Allways go for as long as possible and shoot with low ISO.
Tomorrow I will post another pdf with 10 tips for dslr astrophotography by R.Berry etal.
Regards
Steve:thumbsup: