First M106

[Uranium235]

Hiya,

For the first time last night i broke the 1hour barrier for imaging, I wasnt sure how long the battery lasts on a 1000d so I settled for 1h 20min on M106. It was virtually overhead, but the moon was being a bit of a thug (as usual) and I had to toss the first 4 subs because it wasnt properly astro dark when I started.

Hmmm I expected more for such a long time, but its done now - time to move to the next target! Will be out there again tonight cos were set for glorious weather all week heh even booked a day off work tomorrow so i can stay out all night tonight!

Got a great PHD graph too (for a change!)

20x4min Light, 20x4min Dark, 15 bias, 10 Flat

[sgazer]

that looks great Uranium235, I'm intrigued as to how you get such a nice mix of colours. I have the same set up as you and in fact tried M106 last night. However, my images are usually monochromatic with a redish brown tint. Is it all in the processing? What settings do you use for DSS (RAW settings)?

cheers

[Uranium235]

To get the colour into the finished result, the RAW settings are with both white balance boxes unchecked and black point set to zero.

When stacking I use RGB background calibration (not per channel), and I usually choose not to align the RGB channels in the final image.

When the final image is processed mine too are B&W - but first do your curves as normal - then flick over to the saturation tab. Setting that to about 30% is enough to bring the colour back, if its a bit too red just shift the red channel slightly in RGB/K Levels.

Its best to just test the settings on a zoomed-in selection first, just to save you the time of applying the adjustment to the whole picture. You will know its worked because all of a sudden you will see the orange, blue or white star colours.

Heres an example of M44 that I used that method on.

[sgazer]

that's great thanks, I'll give your tips a try. By chance I tried setting the black point to zero a couple of days ago (it was a recommended setting as I used some bias frames) and it did indeed seem to increased the amount of colours in the image, rather than just being a reddy brown.

ps, I never realised you could select an area of the final image to work on and zoom in!! Thanks for letting me know.

cheers

[Uranium235]

did you take enough darks? At first, I used to be a bit of a cheapskate and take 15x30sec dark for every 20 light frames (of any length). Its only now that I have the "set up and walk away" method of doing darks that the 1000d offers that im getting better results.

Basically, after all my light frames are done (eg: 30x3min) I take the OTA with the cam still attached into the basement and set it up to do the same amount in darks (same ISO, same sub length) while i go to bed. It switches itself off after a while so no need to worry about burning loads of leccy.

Get up in the morn, stack it.... jobs a good un

[sgazer]

ah yes, that's exactly what I do too, put in the the shed with the remote timer attached and set it going. The only issue I have is because the fridge is in there, on the really cold nights over winter, the shed was noticeably warmer than outdoors, so I was struggling to match the darks with the lights, particularly with the 300d I was using as the amp glow was much more obvious than the background dark noise and if it wasn't matched in temperature accurately, it was difficult to remove the amp glow.

However, with the 1000d (specifically no amp glow) and as it's a bit warmer outside now anyway, the method seems to work, I usually take about 9-16 darks, but could possibly do with more.

ps. the fridge is important as it's got my beer in it! (plus some frozen food for the kids, but I suppose that could go )

[Uranium235]

the fridge is important as it's got my beer in it!

Ohhh yes, very important indeed!

I had a wee idea in regard to darks.... on inspection, Ive noticed that nearly all of the darks look the same (well... dark!), maybe a few hot/cold pixels here & there but no ampglow.

So.... what stopping me from taking 10 good darks, and then just duplicating them to get 20? Its the same data, and just as dark as the others so I cant see why that wont work as a shortcut. It might be even possible to generate 20 from 5... though I wouldnt want to do the same from just 1.

[blinky]

You cannot duplicate the number of darks as the idea of taking multiple dark files is to average out the noise leaving only the recurrent hot pixels/amp glow etc.

Duplicating the darks would simply duplicate the noise and make no difference to the averaging.

Nice image BTW, Since your guiding is looking that good I would be tempted to up the subs to something like 6 or 8 or even 10minutes. As with Darks the idea of taking multiple subs is to average out the noise thereby re-inforcing the signal. The thing to remember with subs is that if not enough photons are hitting the sensor to register a signal then no matter how many subs you take, the signal wont be there.

Anyway, as I say it's a very nice image!

[Uranium235]

Thanks blinky! Ahhh, so there is no shortcut around darks then.... well it was worth a try

I would go for 6 minutes or so (10min would be madness), but LP starts to take over after about 5 min and my tracking isnt always that perfect. But I'll give it a go next time theres a clear sky and hope PHD can hold it together for that long (whenever that may be!).