Trying to capture and process the Triffid

[g__day]

The following is a 20 minute shot of the Triffid yesterday. I think I need a better flat frame and then gain more skill on colour processing. On a Canon 400D if I don't alter colour balance then the core is grey rather than red shades - must learn what is going on here.

Matt

[Alchemy]

you seem to have restored the colour, my first suspect would be the program you use to convert to a tif. try using the canon one that came with it.... i figure they made the camera they should know how to convert its raw file. maybee that will help

[spearo]

Clive may well be right,
Also just adjusting the saturation down a bit seems to restore a more natural balance to the colors to this image.
Captured lots of nebulosity there, well done

cheers
frank

[RB]

Can you post more of the details of your shot Matt, ISO? single shot or stacked subs, darks & flats, how did you combine the data?

For a 20 min shot your histogram looks a little starved, you should have more data in there than what is showing up on the histogram.
Also looks like some coma as well, outer stars seem to trail away from centre.

[g__day]

More details guys:

Its a single shot at ISO 800 of 1200 seconds duration captured on a Canon 400D in RAW mode, downloaded using the Canon EOS utility (triggered by DSLR Shutter) into Canon Zoombrowser.

Its then copied to PC and opened straight in Photoshop CS2, Where I played with levels, curves and Gaussian Blur on the Nebulae itself.

Yes there is coma introduced by the Lumicon OAG's focal reducer - it was alot worse but reseating this lens a bit more square in the tube reduced what was at first terrible coma. I suspect this focal reducer isn't quite perfectly seated.

There are no darks, flats or bias removed from this shot. So I handled vignetting by being very aggressive with levels - even at a individual colour channel level.

Then I finally play with colour balance because unless I shift everything very red - alot of the reds are a weird shade of gray - trouble is this shift everything red - I am not trying to lasso the gray and only shift that to red.

Will post some interim steps (cut down shots tonight to highlight what I mean).

Thanks guys,

Matt

[Dennis]

Hi Matthew

It looks like your data collection capability is ahead of your data processing capability. If that is the case, then I was in a similar situation until my big “aha moment” a couple of weeks ago when Jase reprocessed, or perhaps more accurately correctly processed, my M16 LRGB data.

Bearing in mind I am talking LRGB versus your 1 shot colour from the DSLR, I would still encourage you to swot up on LRGB processing as I’m certain you have really good data and your capability there appears not to require any significant improvement from what I can see.

I was very fortunate to have Jase’s M16 file which has helped me gain a quantum leap in understanding on the LRGB workflow. Prior to this, I was just thrashing around. I think an understanding of the following are vital to producing nice colour images:

Histogram reading and analysis for Lum and RGB subs.
Understanding how to inspect and set the Black and White points.
Stretching the data using Curves to better reveal the (subtle) tones in the data.
LRGB stacking related specifically to faint objects such as we encounter in astro photography.
Controlling colour noise.
Using Layers in PS to make various adjustments.

I’ve been swotting up on a few general PS books which have been helpful in understanding most of the above and I also recently acquired R. Scott Ireland’s book on Photoshop Astronomy and that is helping tune my developing knowledge specifically for astrophotography.

However, Jase’s example really helped to put all of the above into a specific context and by decoding and re-tracing his steps, I was able to improve on my previous effort, although the results are still short of Jase’s reprocess.

And, I’m having fun doing it, just as Jase advised!

Cheers

Dennis

[Alchemy]

did you use zoombrowser to do the converting to a tiff, i feel this is the critical step you need, then work on the tiff in photoshop..

[multiweb]

Hi Matt, any particular reason to do a single shot with such a long exposure time instead of stacking shorter subs?

[g__day]

Yep - DDS always seems to give me really botched colours - everything is green or grey. So I wanted to practice long shots :)

I will look at Canon ZoomBrowser to see if it can saw Canon RAW files .CR2 images as TIFFs.

Dennis - yep I reckon camera colour image settings then PS2 manipulations is the place to start next!