Eta Carina Keyhole@F10

wasyoungonce (Brendan) · #1 17-02-2010, 12:04 PM

Finally getting my C8 a workout.

Eta Carnia Keyhole nebula:
C8 @F10;
Canon 450D (non mod)
10 x 5 min ISO800;
10 x 5 min ISO400;
20 x 5 min darks, ISO800 & ISO400;
No flats;
G11, tracked with WO 70ED & QHY5.
Stacked in DSS, curves/levels & sharpened in CS2.

Well, it's not the worlds best, but it's my 1st real attempt with the C8. I really need to take a step back & buy & learn on a 6.3FL reducer before attempting F10 shots. A FL reducer will help with star elongation & I need flats to remove sensor motes. Tracking is OK but the focus is slightly soft.

Also the 450D is over sampling the stars.."a lot"...at around .57" per pixel. Not much I can do about that....but I really need to mod this camera filter

I have a GSO SCT focuser fitted & my guess this adds some extra FL to the image scale.

The attached pic shows star artifacts from compressing the image to a smaller size & lower resolution.

Well...if nothing else it's a start with the C8.

DavidU (Dave) · #2 17-02-2010, 12:19 PM

Yep, I like that. Natural looking.Get that cam modded.

wasyoungonce (Brendan) · #3 17-02-2010, 12:28 PM

Quote:

Originally Posted by DavidU

Yep, I like that. Natural looking.Get that cam modded.

I wish...I wish ...I wish ...I had a larger pixel camera...lets say 9 microns per pixel.

Maybe one day.

jjjnettie (Jeanette) · #4 17-02-2010, 12:44 PM

You've done well at that FL.
Like David said, very natural looking.

TrevorW · #5 17-02-2010, 12:48 PM

Good image as you've done you own critique I won't say a thing

telecasterguru (Frank) · #6 17-02-2010, 01:13 PM

Looks pretty good to me.

Frank

CoolhandJo (Paul) · #7 17-02-2010, 04:57 PM

Excellent Prime Focus shot! Great detail!

wasyoungonce (Brendan) · #8 17-02-2010, 05:11 PM

Quote:

Originally Posted by CoolhandJo

Excellent Prime Focus shot! Great detail!

I'm pretty excited by the C8...it's look'in up...so to speak.

But for prime astrophotography @ F10 it's a learning curve that resembles a mountain.

wasyoungonce (Brendan) · #9 17-02-2010, 05:11 PM

Quote:

Originally Posted by TrevorW

Good image as you've done you own critique I won't say a thing

All critique most welcome.

strongmanmike (Michael) · #10 17-02-2010, 05:13 PM

Yeh, I recon it's pretty good too.

The stars look a bit blobby so work on that, DDP filter can help here.

The nebulosity is lovely and the colours quite acceptable.

A nice shot of a....rarely imaged target

Mike

wasyoungonce (Brendan) · #11 17-02-2010, 05:17 PM

Quote:

Originally Posted by strongmanmike

YThe stars look a bit blobby so work on that, DDP filter can help here.

A nice shot of a....rarely imaged target

Mike

Ha...well it was nice and bright...a good starter target for F10

. I needed to try something simple...to get some results at least

.

I thought the stars were bloated because of the camera sensor (pixel size) oversampling?

strongmanmike (Michael) · #12 17-02-2010, 05:20 PM

Quote:

Originally Posted by wasyoungonce

Ha...well it was nice and bright...a good starter target for F10

. I needed to try something simple...to get some results at least

.

I thought the stars were bloated because of the camera sensor (pixel size) oversampling?

Try applying a ddp filter, this should reduce the stars but may dim the nebula at the same time so then adjust levels until you get the nebulosity back but don't quite resaturate the stars. Now apply a log stretch and see what you get. I use Astroart4 and the DDP filter is excellent

Mike

wasyoungonce (Brendan) · #13 17-02-2010, 05:24 PM

Quote:

Originally Posted by strongmanmike

Try applying a ddp filter, this should reduce the stars but may dim the nebula at the same time so then adjust levels until you get the nebulosity back but don't quite resaturate the stars. Now apply a log stretch and see what you get. I use Astroart4 and the DDP filter is excellent

Mike

Thanks mike...1st dumb question...what's a DPP filter. Please try not to laugh too much.

strongmanmike (Michael) · #14 17-02-2010, 05:30 PM

Quote:

Originally Posted by wasyoungonce

Thanks mike...1st dumb question...what's a DPP filter. Please try not to laugh too much.

....

:ro fl:

:r ofl:

sorry

DDP stands for Digital Development Processing it re distributes the brightness levels in your image to display all the tones:

http://www.noao.edu/outreach/aop/glossary/ddp.html

Does the software you have allow this? If not, I recomend Astroart4 as a great investment.... of very little money.

Mike

wasyoungonce (Brendan) · #15 17-02-2010, 05:31 PM

Quote:

Originally Posted by strongmanmike

....

:ro fl:

:r ofl:

sorry

Mike

Shhh not so loud you'll wake the baby...

Thanks Mike

AlexN · #16 17-02-2010, 05:33 PM

G'day mate..

Despite what you said in your first post, You have nothing to worry about here mate! Given that you're imaging at F/10 with tiny pixels, that image is utterly superb... Its come up beautifully!

A DDP filter is a filter used to brighten an image without changing the look of the high range (Bright) areas of the image, this includes stars... DDP filtering an image like this would help keep the stellar profiles as small as possible. Using a deconvolution filter would also help out a lot on this image considering how heavily oversampled it is... It would sharpen the detail, reduce the sizes of stars and help mask any elongation due to curvature or slight tracking problems

Both DDP and Deconvolution are filters that are most common in astroimaging software.. I think Photoshop has a DDP filter, but not deconvolution...

For a first attempt at imaging with a 2000mm FL, you've done an outstanding job and should be very proud of the image..

Alex.

bloodhound31 · #17 17-02-2010, 05:39 PM

It's a beaut in my book. Not over processed and very natural.

Well done.

Baz.

wasyoungonce (Brendan) · #18 17-02-2010, 05:40 PM

Quote:

Originally Posted by AlexN

G'day mate.. Alex.

Thanks gents..yes the star bloat is an issue I didn't like.

Probably the cure is a shorter FL and maybe a larger pixel camera. My guess the camera won't happen for a while so I'll try a 6.3 reducer.

I'll look around for DPP enhancement plug-ins for CS3. Problem is you get used to a suite for processing and I'm a bit reluctant to change without good reason.

That said if the reason is good enough...no problems. though I suspect the source of the bloat is the FL & pixel size.

multiweb (Marc) · #19 17-02-2010, 05:47 PM

Quote:

Originally Posted by wasyoungonce

...though I suspect the source of the bloat is the FL & pixel size.

It's a great shot Brendan. Your rig's fine. If the star size bothers you do a slight deconvolution then as Mike suggested selective DDP. It's all in the processing. You're 99% there. If you spent some more time on it, it'll be a corker in the end.

AlexN · #20 17-02-2010, 06:10 PM

I agree with Marc there - The star sizes can definitely be controlled with the correct processing steps... the nebulosity in your image looks pretty damn sweet, its just a matter of controlling the stars which shouldn't be too hard and you're onto a real winner! If you can I would persevere with imaging at F/10... The scale is really nice (in my, crazy, "I love narrow fields of view" opinion)