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GazK

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  1. Thanks, that's very reassuring. It's just annoying that I'm imaging for 2x the amount of data I get. Thanks for the link, I'll work through it.
  2. thanks, that's a good point. Going to point it at Leo next chance I get, see how that goes.
  3. Yes it is balanced in both axes. I checked after moving the camera onto the target.
  4. Thanks. I don't know what I was expecting really, I'm a n00b! I suppose I'm just surprised at a) the amount of field shift between subs and b) the ratio of sharp subs. I'll set the rig up in the next couple of days and post a pic. Basically a Benro video tripod, fully extended, stock SA pro on top of that, standard SA Dec bracket with counterweight, camera mount as close as possible to RA axis without fouling the reticle illuminator, canon 80d and 70-300 mounted on a rack and pinion bracket to allow balance (this could be a weak point for one-ff shifts, the 1/4" fixing doesn't have as much grab as I'd like, but the lens doesn't have a tripod collar). Example good and bad frames attached, also a very rough process of the final image (I wasn't aiming for an actual image, hence the trees!)
  5. Thanks, I get that. But right now I'm back at square one, trying to work out why I'm getting star trails in most of my images in 1 minute subs at half that focal length. See my last post.
  6. Thanks all for responding. I went out last night and pointed the DSLR with my 70-300 @ 200mm at Orion, purely to do a tracking test. The lens is mostly plastic, so pretty light; DSLR + lens is under 2kg. Polar alignment was pretty accurate I thought, rechecked after the load was added. Balance was also checked in both axes. Also there was no wind and I'm inside a walled garden. The following gif is a crop into one section of the resulting 2 hours worth of 60 second subs. E-W is roughly in the Y axis. Ignore the stars moving through the tree line and clouds in the later images. You can clearly see a periodic shift in azimuth, which I don't understand at all. It is the same behaviour I've seen on previous shifts. I don't think bad polar alignment could explain this could it? If not, then what is going on? I wouldn't mind if it was just shift between subs, but 2/3 of these subs were useless because of star trailing in the same axis. Surely a 2/3 rejection rate when the mount is within its load envelope isn't right?
  7. Thanks to everyone who responded - no I'm not using a field flattener. About to hit "buy" on one to remove both the halo and the blurry stars.
  8. Hi all, n00b here again with another starter question. Flush from managing to get a result with M42, I decided last night to try to capture the horsehead and flame. Yes, I know, don't run before you can etc etc. It was clear, I got carried away, what can I say. I pushed the sub time to 45s with my WO Z71 on the star adventurer and took 1.25 hours of data. I'm now sitting here mid-process, and while I do have a head and it is horse-shaped, its a lot fainter than I'd hoped for. The first thing that becomes very apparent looking at my subs is that, while about 50% have acceptably round stars, the other 50% show minor or significant trailing when zoomed in - so I had to reject 40 mins of data. Additionally, the star field is moving around somewhat between frames, and not linearly. My last imaging session (same rig, 30sec sub) had a much lower discard rate and none of the wandering. There was no wind on either night, and while I don't think the seeing was very good - lots of twinkly stars - I'm not sure that would account for it. Can anyone help me diagnose the problem?
  9. First image was stacked in DSS, then followed one of Nico Carver's videos for processing in photoshop, admittedly that video was for an untracked DSLR stack. Second image was using Siril for stacking and most processing, using a different video tutorial. I just assumed that the lack of colour was down to the limitation of 30 second subs, I had to work quite hard to get anything at all out of the lower portion. But I screwed up the flats and so used a different session's flats, that could be the problem. And yes I did use the Siril background removal tool. I do have some 15sec subs from that session, so I'll try adding that as suggested for the core, might allow me to push the faint neb further in the 30sec stack.
  10. Taking advice from others on the forum, I'm starting to use Siril. When I first hit "autostretch" on my image I get this weird circular halo. It doesn't matter too much on this image as I'll crop in, but on others e.g. starfields, it will. Optical train is WO Zenithstar 71 > 2" to 1.25" adapter > 1.25" T-adapter > Canon 80d What could be causing this?
  11. Taken on the feedback and processed in Siril, with just the lightest of touches at the end in PS. Feels a much more natural image to me, plus the background is a bit more under control. Could have gone brighter but then I lose the core. Comments welcome.
  12. Thanks! The 80D has the advantage of being ISO-invariant, which I assume must have helped hold the core down despite 30 second subs.
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