george7378

Hey everyone,

I feel like I've got a good workflow down for processing my astro images, but there's one thing that's still bugging me - background (or gradient) removal.

The only tool I've found that offers to do it so far is IRIS, and while their 'remove gradient (polynomial)' works well for some photos, on others it seems to just add to the overall noise. For example, here's an M101 from last night with a visible background gradient from the top left:

If I could get rid of the gradient, I think this would be a really decent photo. So, if I run it through IRIS and their gradient remover, I get this:

It's done a decent job in the top left, but it seems to have inverted the gradient so that it's now starting from the bottom right. It also seems to always introduce fairly nasty banding artifacts which I think are worse than the original gradient.

While the gradient remover doesn't seem to be much help, I have found that the 'adaptive filter' makes a decent job of removing noise (even if it doesn't help with the background light much).

Anyway, does anyone have some tricks I can use for working with the IRIS gradient remover? There aren't many options to choose from, and I've tried all combinations but it always seems to do this 'inverting' effect rather than actually removing the gradient in a uniform way.

Failing that, what's a better gradient removal tool? I have GIMP and I tried doing a manual background mask with de-speckle, but the result really wasn't to my taste.

Cheers, appreciate the help. I feel that if I can get this sorted, I'll have a solid pic processing flow

Thanks for the replies. Yep - I'm actually just happy getting something I can share and play with right now! I am keen to try M33 again though, with a few more shots stacked together.

Regarding the stacking - I'm not 100% sure, no. I was using DeepSkyStacker with default settings, and I had 30 lights and 15 each of dark, bias and flat. The M31 photo above is just one of my lights from this session.

The final stacked photo preview in DSS looks pretty workable:

...but when I load Autosave.tif into GIMP, it looks terrible:

I tried adjusting curves, levels, exposure, darks, highlights, and all the usual things I fiddle with when photo editing, but I couldn't get anything that looks as good as just a single RAW frame! Also, maybe it's just me, but the stacked stars look blurrier and de-focussed compared to any one single light frame.

Thanks for looking, and for the kind replies! I've got a couple more quickies - M33 and M1 (same kit, same settings):

Hey everyone!

I thought I'd share my first ever DSO images. I'm pleased with them, since they are all single-shot files; I tried stacking with darks, flats, bias, etc... using DeepSkyStacker, but I actually preferred the single-shot edits to the end result. Both are taken with my Canon 1100D DSLR, and they are 3 minute shots at ISO 1600. My setup is also pretty simple - a Sky-Watcher 130PDS on an EQ-5 with just a simple motor on the RA axis.

Thanks for looking! I'm hoping to get some other, fainter objects in due course including M81/M82, M33, M1 and a cluster or two.

Oh yeah, good idea - will have a rummage and see what I can find. I actually like how the whole thing can rest on the spanner though. Might just end up drilling a hole in it and shaving a centimetre off the handle to make it fit nicely!

Hey again! A little update on this, as the drive came today and I've just finished fitting it to the mount.

It looks like a decent piece of kit, but it actually doesn't quite fit the SkyWatcher EQ5 out of the box without a bit of 'MacGyvering'. If you screw motor directly onto the mount, the gears won't actually mesh together. In order to get everything to line up, I had to put a metal spacer between the mount and the motor. One of the spanners that came with my telescope works OK. I also had to move the motor's gear out along the shaft to line it up with the one on the RA shaft.

Haven't tried it yet (no batteries!) but it feels solid and planted. I'll be on the lookout for a better spacer, as this one doesn't let me reattach the plastic case over the motor. Ideally I'd have a strip of metal with a hole in the middle, so that the long screw attaching the motor to the mount would pass through and distribute the force more evenly. The spanner is wedged on one side of the screw, so the screw is trying to pivot the motor over the top side of the spanner. We'll see what turns up 😆

Good to know, thanks for the help!

Hey everyone,

It's been a while and I'm thinking of getting a new setup, based around an EQ5 mount. I'm also hoping to motorise the RA axis, and of course the natural choice would be this motor.

I did however come across the Orion TrueTrack motor which is way cheaper, looks to be almost the same and claims to fit the Sky-Watcher EQ5 perfectly.

Can anyone confirm if the TrueTrack motor does fit the EQ5 out of the box? How is the quality?

Thanks for the help

It's probably the pictures of Mizar and Albireo I took this week:

http://stargazerslounge.com/observing-imaging-double-variable-stars/107522-mizar-albireo.html#post1467494

Hi everyone,

I ordered a sheet of solar film from First Light a couple of weeks ago, and it arrived within three or four days, which was brilliant. They also sent a receipt and a number of E-mails on the status of the shipping, so you are always well-informed with this great company. When it arrived, it was a very personalised package, with a confirmation receipt of the order, and a compliment slip. Also, the packaging their Baader solar film comes in is ideal for making filters with!

It was also cheaper than many of the other places I researched, so I am very grateful, and have just ordered two more sheets from them, and have received the same great service up to press.

George.