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alphatripleplus

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About alphatripleplus

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  1. Don, As I mentioned on CN, I am very grateful to see you doing the Hyperstar vs Freestar comparisons, as this exercise has been a real eye opener for me. It's great that you enjoy the testing and are game to try and objectively test different people's suggestions with regard to the Freestar. I'm sure we are alll learning something useful from the exercise, and I'm hoping that in the future when others do camera comparisons, for example, they are just as objective as you are in this evaluation. Looking forward to seeing more results. Errol
  2. Hi Paul, Thanks very much for considering this idea! One complication that may arise is that if the image suffers from significant aberrations, e.g. due to aggressive focal reduction, then the star shapes in the outer parts of the field of view will exhibit some eccentricity (comet or egg shapes) and would probably skew the overall value of your metric of mean roundness across the field. Maybe just concentrating on stars in the central part of the FOV would get around this potential issue. Anyway, I think it's fantastic that you are open to looking into these sorts of suggestions. Makes me very excited to be a user of the software.
  3. Hi Paul, Thanks again for implementing the FWHM filter in v3.2. I have been using it for a while now and it is a big help with automating the process of rejecting low quality subs. One interesting observation I have made is that occasionally a sub in which the stars are definitely oval shaped will pass the filter and not be rejected, even if I tighten up my FWHM threshold. This tends to happen when I hit a bad part of my worm cycle. If I tighten the threshold even further to eliminate such subs, I end up rejecting a lot of perfectly good subs as well. I'm sure the filter is working as advertised, but I wonder if there is some way to refine the FWHM filter so that it additionally looks at the ratio of FWHM in the directions of an elliptical/oval shaped star's principal axes for perhaps the two or three brightest stars in the FOV, and then rejects a sub for stacking if the major/minor axis FWHM ratio is significantly above 1.0? For perfectly round stars, the major/minor axis FWHM ratio would be 1.0. I have no idea how hard it would be to implement something like this, but I suspect that the computational overhead could be managed if it was only applied to the 2 or 3 brightest stars. Just a thought for your consideration .
  4. Thanks, Brandon. This wide-field EAA stuff is fun, but I do like your narrow-field planetary nebulae EAA captures!
  5. Thanks very much, Peter and Jim. I'm beginning to appreciate the wide field of small refractors and telephoto lenses on the large emission nebulae. As soon as my tripod mount adapter (suggested by Dom) arrives, I will give the full IC1318 region near Sadr a shot with a 135mm telephoto. Should be fun.
  6. I took out my Orion ST80 for the first time last night with a 7nm Orion H-alpha filter and Lodestar X2 mono and Antares 0.5x reducer for views of some of the brighter emission nebulae. With the reducer and the X2 mono, the ST80 operates at exactly f/3.0 and yields a FOV of 1.5deg x 1.2deg. I think the views are sharper with the ST80 than with the Celestron Travelscope that I've also used, and I see a small degree of aberration in some of the corners of the field. Considering this is only an achromat, I'm happy with the views. I used the latest 3.2 version of Starlight Live, took darks but no guiding, and I stayed with fairly short exposures - 30sec and 45sec subs -with no total exposure over 9 minutes. Towards the end, with the Veil Nebula pics, I was getting tired and battling a couple of clouds and mislabeled these as ICs rather than NGCs in the caption. Also oriented the pics so that north is up. NGC281 (Pacman Nebula); 12 x45s: IC1396 (Elephant Trunk Nebula); 12 x 45: NGC7000 (North America Nebula); 12 x 30s: IC5070 (Pelican Nebula); 15 x 30s: IC1318 (Part of this huge complex surrounding Sadr in Cygnus); 12 x 30s: NGC6992 (Eastern Veil Nebula); 12 x 30s: NGC6960 (Western Veil Nebula); 8 x 30s - clouds rolled in:
  7. Hi Paul, I mentioned a very similar problem using restored darks in my post on H-alpha captures with the Lodestar X2 mono. These are the steps that I follow which have got me into trouble with restored darks - hopefully this might help. I won't be able to send you FITS data at the moment though, as I haven' t saved any. (Sorry): 1. Start application, set exposure to 15sec, for example, and switch to dark frame acquisition mode. 2. Take a sequence of dark frames (20 usually). 3. Save the master dark, but save and specify a specific file name. 4. Switch to image acquisition/start light exposures, stack images use mean stacking, linear processing, adjust white level, black level, contrast sliders and (usually) export image as .png after stopping exposure. 5. Change exposure to 30sec - not sure if I always do this step and start taking lights, or just move on to step 6 6. Restore a previously named and saved 30sec dark as the new master dark, usually saved in a previous session or earlier in the current session. 7. Repeat step 4 - image acquisition with 30sec subs, and the contrast level slider will not widen the histogram, which stays a narrow spike. The black level, white level and brightness sliders work. I nearly always use linear processing mode, and have the problems mentioned in step 7. The main difference I see between my process and yours is that I explicitly change the exposure length between taking darks and using them, and I always name my saved dark files. Hope this helps.
  8. Very much appreciated, Paul. I'm really looking forward to trying it out
  9. Funny you should mention that , Peter, as I do have an old 58mm f/1.8 SLR camera lens that I have been able to mount the H-alpha filter behind. That would give a considerably larger FOV. The old reason I haven't used it yet is that I have to securely mount it to my scope or mount. I'm working on it, but it may be a while before I'm ready to shoot. Will definitely give it a try though.
  10. Hi Paul, That sounds like it would work really well - much appreciated.
  11. When using Starlight Live to stack with my Lodestar X2, I've noticed that on the Stacking Tab Starlight Live reports FWHM under status for each sub, along with #matched stars and other info. I wonder if there is a way for the user to specify a maximum FWHM in pixels for a sub to be included in the stack, so that a sub with trailing due to wind or poor tracking would be automatically rejected by the stacking algorithm? I know that a user can undo the last sub if one notices a poor sub. However, sometimes I'm not very attentive, and I'll miss a poor sub. Would be great if the software could automatically do the rejection by checking for a maximum FWHM. Perhaps this is already built in, but I'm not aware of it. Thanks for any insights.
  12. Thanks, Dom. I think you should be able to do the Wizard as it is circumpolar at mid-northern latitudes. On the other hand, I haven't had a chance to see any of the southern summer gems like M17, M8, M20 as I have no view to the south, and time is running out for those this season.
  13. Good point, Alex. I think you are right about CA inherent in the reducer. I noticed the benefit in reduced aberrations using H-alpha with the lowly 70mm achromat, but hadn't thought much about the reducer as an achromat too.
  14. I will also add that I was surprised to find that using just the 0.5x Antares reducer on a C8 in H-alpha @ f/4.2 seems to show noticeably less aberration in the outer FOV than the identical set-up without the H-alpha filter. I guess that at 656nm, for some reason, the aberrations are not as noticeable as when the whole visible spectrum contributes to the image. On the C8 without the H-alpha filter, I find that using a combination of the Antares 0.5x and a Meade f/6.3 (Japan) works better than just the 0.5x reducer when trying to get to around f/4 or below.
  15. Last night I took a quick look with the same set-up (Orion 7nm H-alpha filter, Lodestar X2 mono, 70mm finderscope/0.5x reducer) at NGC7822, a large emission nebula complex in Cepheus. With the scope @f3.4 and a 1.5 degree x 1.2 degree FOV I thought I might be able to get both the fainter northern (top) part of NGC7822 as well as the brighter southern part in the same field - but not quite as shown in the first frame. NGC7822 16x 45s In the second frame, I included just the southern emission region, Cederblad 214, which is illuminated by a young bright star cluster (Berkeley 59). Lots of dark nebulae are visible in front of the main emission nebula. A higher resolution, deeper view would also show more detail in the so-called pillars of creation star formation regions in this complex. A couple of these are barely shown near some of the cluster stars in the second picture - they appear as squiggles. A higher resolution and deeper view might make an interesting challenge for any pillars of creation fans. Cederblad214 10x45s