Jump to content

sgl_imaging_challenge_2021_annual.thumb.jpg.3fc34f695a81b16210333189a3162ac7.jpg

angryowl

Members
  • Content Count

    366
  • Joined

  • Last visited

Everything posted by angryowl

  1. It’s been a while since I’ve posted on here, so here goes. I’m currently using a RASA 11” with the Baader F2 HighSpeed filters (which I believe to have a FWHM of 10nm) and while they’re fine, I am based in Bortle 8 skies and have found that they pass just too much of the light pollution as well. This means I need rather high integration times to reach an acceptable SNR and even then, with so much LP the integrated masters are usually low in contrast. In doing research for a new set of narrower filters, I’ve discovered that finding filters with a small enough FWHM and a high enough
  2. Thanks for the reply Mark I must admit I hadn’t thought of that but now that you mention it, it makes sense. I know I read somewhere that NB filters nowadays use several coatings sometimes more than ten per filter and the idea that one or multiple of these coatings are reacting differently to light emitted from this particular star is indeed interesting. Learn something new everyday...
  3. Hi all, Whilst capturing data over the last clear nights on my latest object, NGC 7822, I noticed a star with an odd profile in the OIII subs but put that down to cosmic rays or some other weird artefact. But after my usual preprocessing, I’m still seeing this strange star in all of the OIII subs and much clearer in the stacked image. The OIII data is a stack of 54 300s subs making for a total of 4.5 hours and similar integration times for Ha and SII. What’s strange is that this only shows up in the OIII data and not the other channels. As can be seen, Ha and SII look completely
  4. Thanks to all who took the time to reply. I have found a QHY5L-IIC which should be delivered any day now. This has a 1.25" body so should be perfect for my setup.
  5. Hi Nikolas, I appreciate you taking the time to reply, but unfortunately the price is a bit out of my range and what I'm willing to spend on this since it'll only be used for polar alignment using SharpCap.
  6. Yes, that's exactly it. A mate of mine found someone selling a QHY5L-IIC which is perfect and am currently communicating with the seller. If this materialises then I'm sorted.
  7. I see, I've attached an image to my original post of my 60mm modified guidescope to better illustrate where the guidecam imaging chip needs to be.
  8. Thanks for replying, but I updated the Ad with more information. I have seen that DMK21 and I also have a DMK41, but these can not be inserted into a 1.25" focuser enough to reach focus with my guidescope.
  9. Looking for a guide camera (CCD or CMOS) with a 1.25" barrel size that could slide into my guidescope focuser. To reach focus with my guidescope the guidecam imaging chip will need to be positioned inside the 1.25" focuser so the camera will need to be inserted almost all the way inside the focuser hence the need for a 1.25" body. Examples of compatible cameras are QHY5 series, Lodestar guide cameras, ZWO ASI 120 mini. This is my guider and roughly how much the camera needs to be inserted into the focuser to reach focus Any make and model considered. Thanks for look
  10. When I tried the OAG lent to me by @souls33k3r I did manage to get the spacing right and guiding gave me pinpoint stars in all exposures. So far the OAG is the only thing I tried that actually works and currently I’m in the process of building a DIY one. The reason I’m not going with a commercial one is that the guide camera body and USB cable get in the light path of the scope and cause weird diffraction spikes whereas with a DIY one, I’m hoping to avoid that. Chip moving inside the camera…wow that’s scary! Glad you got that one sorted as I can see it being hard to solve. Seeing as the i
  11. Oh yeah, that I will do given the opportunity. Perhaps when Ahmed gets his one finished he'll let me throw it on top for a quick test ?
  12. Managed to get out during a clear night last week and tried guiding with the refractor piggy backed on top of the RASA and also with the 60mm guider clamped onto the bottom dovetail of the OTA. I also cleaned up the residual adhesive on the tripod head and sanded the bottom plate of the Mesu down which resulted in a much larger contact area with the tripod head. The results are not really what I expected, but a lot better than before and guiding is more consistent. That being said, guiding with either the 60mm guider or the refractor still doesn’t produce round stars. The elongation is mu
  13. Hi Jakub Welcome to SGL, you’ll find the very helpful and experienced people here will provide invaluable assistance and guidance when dealing with issues such as yours. Don’t yet have a final word on this, but so far it seems like the PTFE pads were only part of the issue and although I can now guide most of the elongation out, it’s definitely still present in most guided subs. In response to your question, I’ve tried anything from 1 second exposures all the way to a minute in most directions in the sky and no elongation whosoever was present in these short exposures. I find th
  14. That makes a lot of sense now, but didn't know any better two years ago when I built the tripod. Looked at the EQ8 and saw that the tripod they sell had PTFE pads and the mount is rated at 50kg, I thought adding 0.5mm thick pads on mine would be a safe bet. However, I'm thinking the EQ8 might have more contact area with those pads than my Mesu did which would make a difference.
  15. Hehehe, thanks mate. Don't want to get too excited as I said it could be only part of the issue, but further testing should confirm.
  16. Forgot to mention the subs above were taken with the mirror unlocked.
  17. Thanks for the suggestion.I mounted the guidescope as close to the mount as I could during one of my latest sessions and it drifted in the same direction and the same amount as the main OTA. Turns out this may have been caused by the PTFE pads between the tripod and mount, but further testing is needed to confirm this.
  18. Some more progress on this. Piggy backed the refractor on top of the RASA using a very solid adapter plate made of steel profiles welded together. I’m pretty sure the plate does not introduce any flexure in the mix. Started by guiding the RASA using the refractor and QHY camera. I also guided without sending corrections to the mount and just monitoring the guide star in PHD and this showed the star drifting in the exact same direction as it did in the main OTA. I wasn’t able to get a single sub to guide properly using the refractor as all subs showed substantial drift. I also ran the
  19. This is how I see the drift moving: Pointing South elevation 50 degrees E side of pier – both RASA and guider drift east similarly Pointing South elevation 52 degrees W side of pier – both RASA and guider drift west (although RASA drifts up in Declination a bit too) Pointing SE elevation 44 degrees W side of pier – RASA drifts mainly north and guider drifts NE Pointing West elevation 40 degrees W side of pier – RASA drifts north and guider drifts NW Not sure what to make of this as it could point to differential flexure or flexure in the OTA when guiding, but still doe
  20. It just occured to me that I've not added any images of my setup so here are a few. I've removed the motorised focuser seen on the back of the RASA a few months ago as I thought that may have been causing the elongated stars due to radial imbalance. Also the 3d printed parts on the guider are there as I wanted the flip mirror functionality, but a few months ago I took them off and replaced them with the metal parts that came with the guidescope as I thought I couldn't guide properly due to flexure in the PLA parts. This wasn't the case and I got exactly the s
  21. Sunday night was clear but just managed to find the time today to sort through the images and results. apologies in advance for the lengthy post. With @Davey-T's refractor mounted on the mount, I monitored both servo motors when slewing and foung the average current draw to be 0.2A for both Ra and Dec. The values varied a bit when seen on the ServoConfig screen, with the minimum being 0.1A and manimum 0.5A. With the RASA mounted the current draw was pretty much identical with an average of 0.2A for both axes and never exceeding 0.5A. After slewing around for a bit I touched the servos and
  22. Appreciate the reply Steve. Just though I’d check with you first as Celestron might have had some tests they wanted me to run. I can understand that there’s not enough information and other potential causes eliminated at the moment to be able to say the OTA is to blame here. That’s not coming off as being evasive and I suppose I’ll have to go through more tests to eliminate as many things as I can and hopefully I’ll be able to do this some night this week. Will post results once I get some clear skies.
  23. Thanks for the suggestion and I did consider this at one point but because the dual chip self-guide models available are physically large they would end up obstructing more of the light path than I’d like.
  24. @FLO – Any response from Celestron? Is this considered normal behaviour in the RASA? If not any suggestions for any tests I can perform or do they need more info? If this is normal and just regular SCT behaviour, then I suppose the only option is to go the OAG route and try to find the smallest camera I can and figure out a way to mount it all so that it doesn’t cut into the light path. With a bit of DIY this just might be doable.
  25. Was planning on having an imaging session last night as the forecast looked promising, but the conditions turned out to be very different so not had a chance to test anything else yet. In addition to the tests and checks suggested in the thread, been thinking of a few more: With the refractor mounted, check the current draw on both RA and DEC servo motors in the SiTech controller. If the mount is struggling with imbalance or the weight once the RASA is mounted, hopefully this’ll show up. The mount has a very distinct sound to it whilst tracking and I’ll also keep an ear close to t
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.