Author Topic: Shots from Pemberton Lake (Read 401 times)

jambroseus · « **on:** March 01, 2012, 08:29:55 AM »

Hello club,

Here is a set pf shots taken at Pemberton Lake last month. I think it is a good
alternative to Coyle while we wait for Coyle to come back. Looking East and
South are best and the launch area has a gravel surface to set up on. There are
no interfering street lights in the area.

http://johnambrose.brinkster.net/newShots87.asp

Shots were taken using my Canon 550D DSLR and Orion 10" astrograph on a CGEM mount,
guided with StarShoot camera through 50 mm finder.

John

Jason C · « **Reply #1 on:** March 01, 2012, 05:48:52 PM »

not bad John, have you tried exposing for 5 minutes or greater yet with the guiding?

El Paso Eric · « **Reply #2 on:** March 02, 2012, 10:45:37 AM »

Looks good, John.

It's interesting that you can shoot several targets in a single night. It takes me 5-10 nights for a single target.

BillA. · « **Reply #3 on:** March 02, 2012, 10:51:53 AM »

Very nice!
I love the Thors Helmet photo!
Bill

jambroseus · « **Reply #4 on:** March 02, 2012, 01:49:55 PM »

Thanks guys,

Jason, I have successfully shot up to 3-min subs. But have experimented with exp vs ISO, and am finding that shooting higher ISO with shorter exposure is doing the job nicely, but will continuing experimenting. A lot depends on the processing.

Eric, I am able to shoot multiple objects in a night because I do higher ISO and shorter exposures. <g> And I am using a fast scope at f/3.9.

John

PS - Jason, you need to try Pemberton Lake. It is half the distance to Coyle and skies south and east are comparable. BTW, congrats on your new camera! Best of luck with it.

David (djrLX90) · « **Reply #5 on:** March 02, 2012, 04:54:19 PM »

John, please do not take this a a criticism but rather something to learn from. You really need to put a lot of time into a single target to increase the signal to noise ratio to a point where the data can be pulled out with out damaging it.Eric's point rungs true to me also
I typicaly spend at least 6 hours for a single channel to produce data that can be successfully processed. By successfully I mean that the color is natural, the luminance has a low noise content to support color data. With a OSC like a DSLR this means lots and lots of exposures that are each just below the sky fog limit. The brighter the skies the more data is needed...roughly speaking as you will hit the point of diminishing returns. Data can only be stretched so far before it breaks down. Lassoing the target, inverting the selection and lowering the black point to hide the noise simply looks unnatural. Please to try exposing a few hours on a single target and see the difference. I believe you will be pleasantly suprsed at how much easier it s to process.

Les (t_total123) · « **Reply #6 on:** March 03, 2012, 08:39:02 AM »

Agree with Dave on this one

jambroseus · « **Reply #7 on:** March 03, 2012, 08:42:30 AM »

I am continuing to experiment with various aspects David and Les, appreciate the input.

John

Astrovirus · « **Reply #8 on:** April 29, 2012, 12:14:28 AM »

That has been my greatist improvement last year, upping the overall exposure time on a single object from 60-90 min to 3-6 hours. Indeed it opened up the world for me.

Never the less, the shots are still nice, especially Thor's helmet. The other 2 seem to need some more exposure in order not process them them as hard. (Which me also just be my very old on loan laptop, as my astro Acer decided to die on me, well the NVidea 8600M video card actually, all the data is save however. Never let your kids on the laptop wit lemonade around, duh. New one (core i7, 8GB RAM, 2048MB Nvidea videocard, 640GB HD) is on the way.

Regards Tim