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Jim Smith

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Everything posted by Jim Smith

  1. Thanks for the idea. My 130pds lives in the shed which, on a cloudy day, is no warmer than outside. So, I don't think that's the problem.
  2. Finally, the clouds parted for a few minutes. I managed to get one 30s, ISO400 shot of the Pleiades using my usual Z50 on the 130 pds on a SW AZ-EQ5. But as you can see, even with the latest modifications, the triangular stars persist! I am using a Baader MPCC mk III. I have a ring baffle fitted to the primary. I have shortened the draw tube. I have fitted a compression ring eyepiece holder. I collimated very carefully and focused with a Bahtinov mask. I think I will check out the primary clamps next! Uncropped...
  3. I know I'm changing too many variables at once here but in addition to shortening the focus draw tube I have replaced the standard eyepiece holder with the compression ring version and I have recollimated. I think the secondary was not as well aligned as I first thought. Still no sign of a gap in the clouds though...:-(
  4. Too late...the deed is done! Now awaiting a clear night to see if my star shapes will improve. Just a thought...won't you need a larger secondary if the distance between primary and secondary is shortened?
  5. Thank you. A little surgery coming up!
  6. Making progress with my 130pds. I'm using the Baader MPCC and I've fitted the mirror edge ring baffle. The focus tube protrudes about 20mm inside the main tube when I am at focus. The two images below were from last night. SW AZ-EQ5 mount, Nikon Z50 camera, 30 second exposures. Stacked in Affinity Photo, Astroflat Pro, Topaz DeNoise AI Can anyone suggest why I have triangular stars? Triangulum Galaxy 81x30s... Running Man and Orion Nebulae 72X30s...
  7. Last night I took some more exposures with my Z50 and they were all fine. They all had the same overall hue. There was a difference though. I was using my 5" Newtonian which is much faster at f/5 than the f/12 of my Cassegrain. I had to increase the exposure of the original batch of multicoloured images by about 3 or 4 EV in Lightroom to see much at all. I think the problem may have been caused by underexposure. I usually use Lightroom to review my images then stack in Deep Sky Stacker or Affinity photo. I will take a look at Siril as advised. Thanks, Jim
  8. When I said "the raw files were the same" I meant to say "the raw files were all different colours too"!
  9. I took some shots of the Horsehead Nebula with my Nikon Z50 on my 8" f/12 Cassegrain. 30 seconds. ISO 1600. The white balance was set to "Direct Sunlight". Below is a sample of some of the .tif files exported from LrC ready for stacking. As you can see, there are a variety of different colours. The raw files were the same. What might be causing this? Thanks, Jim
  10. Here is my first-light shot with my new 130pds. Nothing looked badly out of place through my Cheshire collimator. The primary screws needed a small adjustment. Nikon Z50 (aps-c), Baader MPCC. I think it's quite promising. I think I see some elongation of corner stars... more so at the top. Also there are some strange asymmetric fans of light radiating from the central star. From what I read, I think I need to... 1) Increase corrector to sensor spacing by a mm or two. 2) Find a way of eliminating some sensor tilt. Third locking screw? 3) Saw a lump off the end of the draw tube. (There is about 20-25mm of it inside the scope tube when in focus.) But before I do, I thought I would post this to see if other, more experienced owners might suggest an alternative strategy. Thanks, Jim
  11. I like your M33. It's a natural looking image, rather like what you might see through a biggish telescope. Did you use a coma corrector?
  12. I have had a TS Optics 80mm f/6 triplet refractor for a number of years. I have recently been trying it out for astrophotography but I'm not happy with the star shapes. Some of them are distinctly triangular. I've read that this may indicate pinched optics. Does anyone know of a service whereby I can send my telescope off to be tested and adjusted by experts who then return it in perfect working order? Thanks, Jim
  13. Yes. It works. I have used Affinity Photo's white balance adjustment layer. I leave the white balance control alone and set the tint control all the way into the red. Then, I duplicate the layer and the colours now look right. All I need now is a clear sky to try it out in anger! Thanks again. Jim
  14. I have now unticked it! PIPP can now read my tif files. Thank you! RGGB matrix seems to work best. Now I just need to work out why the images have a green cast.
  15. I have been experimenting with SharpCap and my Altair gpcam3 178c camera. I captured a .tif file but I am not sure if it contains any colour information. It is attached along with the settings file. If it does contain information how can I debayer it? If it doesn't, then how do I capture one that does? Thanks, Jim Capture_00001.tif Capture_00001.CameraSettings.txt
  16. Thanks for the report. I will look out for predicted clear skies in the early hours.
  17. Good conditions for trying to improve my lunar imaging last night. SW SkyMax 102 - Altair GPCAM3 178C roi 1520x1024 - 1/125s - best 200 of 5000 in AutoStakkert - tweaked in Affinity Photo
  18. Sigma 120-300mm f/2.8 DG OS HSM S @ 300mm and f/4.0 Nikon D5500 74x30s ISO1600 SW AZ-EQ5 Bortle 4 Affinity Photo, Astroflat Pro, Topaz Denoise
  19. That's an interesting idea. I might try that. EDIT: Just ordered a 105mm to 77mm step down ring from ebay.
  20. I've not done any formal testing but I understand that the sensor in my D5500 is "ISO invariant" so I have been using anything from ISO 200 to 1600 and increasing the exposure in post if necessary. try this... https://dslr-astrophotography.com/iso-dslr-astrophotography/
  21. I would be interested in any findings from your experiments. 🙂
  22. Thank you. Yes, it was f/4.0. I had previously done a comparison of f/2.8 and f/4.0 with this lens. Pictures below...everything the same except for focal ratio. I didn't like the asymmetric, blobby stars I get at f/2.8. f/4.0 has diffraction spikes but I don't mind those so much! I raised the exposure of the f/4.0 photo in post to make the comparison easier so it's a bit noisier. No filters...just the D5500 directly on the back of the lens. Clear Outside says I'm Bortle 4. Yes, it was cropped. Third image below shows full field of view captured.
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