Help, the Triffid's got me!!!!

[cybereye (Mario)]

Evening all!

Finally I've managed to get a night where almost everything was as planned. I was able to guide the scope using PHD and my QHY5 no probs and I chose a target which was overhead. Unfortunately I'm not sure that the amount of lights making their way into my backyard really helped, nor did the arrival of the Moon (only one thank God!!!).

I managed to get 12, 2 minute subs at ISO 800 of the Triffid Nebula although I'm not that happy with the result. It looks a little washed out for mine but I guess with all the light around it was always going to be a problem. I've attached a quickly processed image for critique - both good and bad!!

Cheers,
Mario

[bloodhound31]

Guiding and tracking looks good, focus looks good.

For 12 x 2 minute subs, you should have a LOT more data though. Have another go at processing to see if you can drag out the light data in the image. Are you shooting RAW, FITS, TIFF or JPEG?

Baz.

[cybereye (Mario)]

Originally Posted by bloodhound31

Guiding and tracking looks good, focus looks good.

For 12 x 2 minute subs, you should have a LOT more data though. Have another go at processing to see if you can drag out the light data in the image. Are you shooting RAW, FITS, TIFF or JPEG?

Baz.

Baz,

Thanks for the feedback. I shoot RAWS and JPEG but do all my processing on the RAWS. I use DSS to stack them up and I've been playing with the background calibration as the results tend to look very "white". Anyway I went back to the RAWS and reprocessed and came up with the following.

I think I need to revisit M20 when the Moon isn't around as there was a fair amount of glow in the sky last night.

Cheers,
Mario

[cybereye (Mario)]

Here's another rework of just the portion containing M20. This is proving to be very frustrating!!!!

Now Mario, take a deep breath......

[RobF (Rob)]

Great going Mario. Don't be put off, just getting your tracking going well for 2min subs puts you in range of all sorts of objects. The astroimaging mountain is big however, and you're still in the foothills (but with plenty of experts here to help you up). Getting these basic foundations working reliably is so important for your sanity later on.

As you've already figured out, if you repeat this exercise on a moonless night (or even better dark sky site) your data will be a lot easy to push.

Some other things you'll come up against soon:
- need for flat frames if you're stacking frames with significant sky background (you've got signficant vignetting coming through there)
- possibly consider a light pollution filter if you'll be regularly shooting from the 'burbs
- processing (I'm starting to think no-one ever gets to the top of THAT mountain after seeing Martin Pugh post re-works recently...)

I think you've done great for a DSO shot from the 'burbs in strong moonlight!
Stop being so hard on yourself.

[bmitchell82 (Brendan)]

Like rob said Mario, you have to get your foundations right before anything else but 2 minutes won't get you a whole lot on these types of nebula. As a guide line i have found, If you can see it visually 5 min will capture a fair bit of it. If you cant 10 min is needed to capture the target.

The magic number i have found for DSLR's is ISO 400-800 10 minutes. This is the golden hour so to speak where the noise isn't un bearable but you capture the photons and push the data. Also dark skies will change you once you get your scope and camera under them!

Further more Flats are really important... like you wouldn't believe, because not only does it get rid of pesky dust motes and vignetting it helps control nasty gradients which then allows you to hammer the Curves and Levels and really push your data out.

At the end of the day capturing the data isn't overly hard its the processing that will foil your best attempts. As seen with the recent spate of repro's coming from Martin, some of those photos are unreal but the old processes they where just good.

The only thing that i could give you as something to help improve your images more at the moment is collimation! Its amazing how a accurately aligned newt will preform, the difference in details is phenomenal!!!

Keep up the work mate you will get there.!

Brendan

[cybereye (Mario)]

Thanks guys for the feedback.

I guess I was all fired up last night having finally got the auto-guider, etc. working and was expecting a bit more from my shot....ie perfection. I'll take all the feedback on board and will take some 5 & 10 minute subs when there's no moon about. What size light pollution filter goes in front of a DSLR? It won't be a 1.25" as I'm connecting the DSLR directly to Newt.

In the meantime I'm going to try a few processing techniques that I've found in my journeys along the information super-highway. If anything good comes out of it I'll let you know!!!

Update: Here's an image I'm happier with....

Cheers,
Mario

[midnight (Darrin)]

Your tracking looks very good Mario. I haven't got there yet but keen to give it a try.

How are you finding the QHY5? I'm getting eager to move on to deeper space. I have a very basic Neximage camera just an experiment to learn more about guiding but it's very early days for me.

Looking forward to seeing your longer exposure shots cause I think you'll produce some really nice pics. I like this one

Cheers
Darrin...

[cybereye (Mario)]

Darrin,

I have nothing but praise for the QHY5. I've yet to point it at a spot in the sky and not have a star to track on. Fantastic!!!

Cheers,
Mario

[RobF (Rob)]

Originally Posted by cybereye

Thanks guys for the feedback.

What size light pollution filter goes in front of a DSLR? It won't be a 1.25" as I'm connecting the DSLR directly to Newt.

You'll need a 2" filter Mario

I use an MPCC and you can screw filters on to that. Many T-ring adaptors have a thread too. 3rd option is to buy a clip in filter that sits inside the DSLR itself, although I have no experience with those.