rubecula

I've been using my current calibration frames for the last 12 months and was thinking perhaps I should refresh them. For that time I have been imaging at -20C with exposures of 600sec. Many of you seem to use much longer subs and as the mount seems to track well I was wondering if I should change to say 900s, 1200s or even 1800s. Also whether I should move to a lower temperature. What's really detering me from going to longer subs is the frustration of when a sub has been running for 500+ secs and a bit of cloud comes over and SGP abandons the image thus loosing nearly 10 minutes of clear sky. I guess loosing nearly 1800s would be 3 times as frustrating. Maybe this is a question for those living above 51 degrees lat, would you, or do you, use longer subs? Thanks

I'm convinced, finally succumbed and bought a copy. Good luck with the Helmet Danny. I tried to get some more data the other day but the seeing was dreadful so had to delete 8 subs as they would probebly have made things worse.

I know there are much, much better images of Thor's Helmet, but I'm quite chuffed with this one. It's so low down in the murk that between the observatory cill and neighbours roofs I only get 1.5hrs a night on it. This is a HOO image from 14 x 600sec Ha and 19 x 600 sec OIII, a total of 6.5 hrs. I took the two sets of subs through APP steps 1 to 6 and then moved them unstretched to PS for further processing. I'm coming round to APP even though it seems a bit pricey for "just" stacking. I've got two weeks left of the trial period to go!

+1 for Thor's Helmet. I imaged that for the first time last night and was surprised how much OIII there is. It's very low down so from my position with houses and trees I don't get much time on it. Here's a completely unprocessed sub from last night:

"was the first image just a direct stack in APP using RGB combine ?" Correct Lee. This is a HOO image so I've put the OIII data into both the green and blue channels. After the RGB combine I tried several ways using the controls on the right (don't really understand what they are supposed to do) and the HSL selective colour but to no avail. I'll try taking the individual stacks into PS and see what I can do.

I've had a play with APP to see if I should purchase. So far I'm not convinced. The first image is my best effort so far with APP. I know it needs cropping and there's a row of cold (?) pixels that I thought outlier rejejection would remove. Otherwise it looks rather dull and star colours are way off. The second image is exactly the same data developed with DSS and PS. I've more experience with DSS and PS but am surprised I can't do better with APP. The lack of documentation doesn't help. I suppose I could move the APP image to PS or Lightroom and improve it but have any of you got better results from APP alone? Thanks

Brilliant, thanks Adam

Thanks Adam, I'm not sure what you mean by normalise. Other than DSS and PS the only other software used on the image was Gradient Exterminator that was run on the stretched images. I'll try calibrating a single sub to see what happens. I was also going to download a trial copy of APP to see how it compares to DSS/PS. Is there any particular file structure required for APP?

Very perceptive CloudMagnet. I did use flats, but here is a highly stretched raw sub with nothing else done to it and there's no sign of the dark areas. So it's a processing artifact. Now to find out how it got there. Thanks

I was inspired to have a go at the Wizard thanks to this wonderful image by MartinB: https://stargazerslounge.com/topic/299571-the-wizard-nebula-ngc-7380-in-bicolour/ My effort is an HOO image made from 15 x 600 sec for both Ha and OIII using an Atik 383L on an 8" Celestron Edge HD. I used DSS and then Steve Canestra's method for developing the image in PS. I've been fiddling with it on and off for days and now think this is the best I can do. I suppose that getting more data and better focussing might enable me to do better. I've been struggling with getting good narrowband focusing with a Celestron motor focuser and SGP. Anyway, here it is: But what's foxed me is the dark areas around some (but not all) of the brighter stars. It shows better in this stretched stack of the OIII data: Any idea what could be causing this? Thanks

Before I saw this image I would have said I don't like starless images. But in this instance I completely disagree with myself. It'a an absolutely majestic image. The detail is amazing, I can't believe it's only a 5.5hr exposure. Brilliant, love it!

Mmmmm ....nice. I like the detail and the overall composition. Amazing detail from 5 different filters at 1 hour per filter.

Carole, thanks for your help once again. I'll have a look at APP, if it works well with re-sizing, registering and stacking then that might be the way for me to go. I've heard how good Registar is but it looks expensive for something that only performs a single function. More research, more money......... Thanks

Thanks Carole, I've already got 2x calibration images but all at 600sec so I suppose that defeats the point. I need to get some at 300sec. So do you resize the bin 2x images (in Photoshop?) and then use DSS to stack in groups and then move the stacked groups back into Photoshop to stretch, combine, etc.?

That's a new one on me also and has been added to my list of targets. Seeing what is possible in such a short timescale I must have a try at binning RGB data. So far I have done everything unbinned. Thanks for sharing Carole, Robin

I have a permenant set-up so the imaging train doesn't change. I have been using the same set of flats for the last 7 months and so far they seem ok. I take darks with the L filter but have flats for all 7 filters.

brilliant, puts my recent efforts to shame

I've never been that excited about NGC 7000 but your Hubble treatment really brings it to life, I'm going to have to give that a go whenever the skies clear,

It might be "luminance only" but that's a lovely image. Did you take darks, flats and bias frames for the 10s exposures or just the 300s?

As I don't have a dome rotator I can't leave things unattended but can confirm that Sequence Generator performs the flip without any intervention from me. In fact it seems to platesolve more rapidly than when first starting the imaging run.

Wow vlaiv! What a wonderful and comprehensive answer. You've given me so much to do and think about. Thank you so much

Yeah it is out of focus. The numbers in SGP looked ok so I thought I'd play with the image as I had nothing else to work on :-). The "grid" is definitely there particularly in the bottom third of the image and the horizontals stand out a bit more. If the grid is from the sensor, and I'm not sure either way, then I wouldn't have thought being out of focus would cause the grid and excessive noise. But what do I know?

About 2/3 weeks ago I got a set of Ha images of the Wizard - all were ok and they stacked and stretched with no issues. The other night during an unexpected clear spell I managed to get 24 x 600sec OIII images. A jpeg of the stacked and stretched images is below. Except for the top corners it shows an unacceptable amount of noise and there is a feint grid visible. Is this from the sensor? An extreme stretch of the Ha data didn't show the grid. I thought it might be condensation but on both occasions I was using a dew shield and the dew heaters were on. The only thing that changed is that there was a Windows update between sessions. The Atik 383L+ camera and the filter wheel wouldn't connect so I re-installed the driver and everything connected OK. I've experienced that before and had to re-install just the Atik driver after a Windows update. But in previous cases the resulting images have been fine. Anyway does anyone have any idea as to what is causing the noise and feint grid at the bottom in the OIII? Thanks,

I think I'm getting to grips with CCD and particularly narrowband imaging. Below are my last couple of efforts. The Cocoon Nebula is a HaLRGB image using Olly's recipe for adding the Ha, 15% to Luminance and 85% to the red channel. The Elephant Trunk is a an SHO image. In both case the processing has done nothing for the star colours. Is there a way of protecting star colour during development or is the best way to remove them, stretch the image, and then put them back again. If removing them is the best way I can see that there are a couple of apps to help with that (e.g. Straton and StarNet++) but how do you put them back? Thanks Thanks

Got out last night after nearly a fortnight's cloud cover. Set off to image the Wizard Nebula. I'll shorten what could be a long tale. The scope was out of focus - completely, nothing at all visible in either the imaging or guide cameras. After a lot of fiddling I re-calibrated the motor focuser after which it went to a random setting. I did a GoTo 21400 which was where the scope had previously been in focus - still out of focus. So I set it to go to 0. I expected it to count down from 21400 to 0 but instead it went upwards to 60,000 at which point the counter in SGP said 0. I don't know why but I thought if it thinks 60,000 is zero then instead of trying to go from 0 to 21400 I would try 60,000 to 38600 (60,000 - 21400) and lo and behold the scope was in focus. I've no idea what caused all this. Why it wasn't in focus as I had left it and why the focus setting was 38600 and not 21400. Anyone any ideas? Is this likely to happen again? Thanks