Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_lunar_landings.thumb.jpg.b50378d0845690d8a03305a49923eb40.jpg

Deflavio

Members
  • Content Count

    26
  • Joined

  • Last visited

Community Reputation

34 Excellent

About Deflavio

  • Rank
    Nebula

Profile Information

  • Location
    Hampton, London, UK
  1. I have the 130ps AZ Gti bundle. I’m doing mostly EAA and I’m very happy with it. One thing I’m not entirely happy is the focuser of the 130ps but if you go for the 130pds you will have everything sorted... Flavio
  2. Ok, so the 15mm is ok in terms of vignette at reduction 0.68 but it may be limited as soon as I go up in reductions. For reference I put here the field stop of few plossl so people can compare with their own sensors. From the TV website we have: 15 mm = 12.6 20 mm = 17.1 25 mm = 21.2 32 mm = 27 40 mm = 27 I guess, the 15mm is out with reductions higher than 0.5 with a 6mm sensor. Also there is no obvious benefit in 40 vs 32mm... I had the 40 for an old Mak, now I just realised on both 130ps and 72ed its exit pupil is really off and I’m getting the secondary in the view on the reflector. Does the exit pupil value also affect the EP projection somehow or just the field stop? I should probably move then to the SW 25mm...although now I’m tempted to get a TV 25mm, eheh. About the blurring on the 15mm, well, that’s probably me. I was more interest to show the coma and with a windy day yesterday focus was moving a bit. About focusing, the 130ps has a very simple focuser not dual speed. I do have a baader T2/1.25 elliptical focuser that may help a bit. No coma corrector sorry. One question, in your calculations for the coma you say coma free circle is only 2.8mm but on my usual EAA sessions I don’t see obvious distortions with the 224 while now on 0.65 reduction they are very obvious from already 1/4 of the size the sensor and will be probably more with stars...is this just coma from the reflector? On the 40 mm, the image is all bad but I don’t think I see this increasing from the centre, no? Anyway, now that I know how to play with extensions, going back to the 72ED may actually avoid both coma and focuser issues. Let’s see if I can do something between today and tomorrow, after that I will be traveling for work for a couple of weeks...
  3. Ok, more testing this morning and I manage to get the proper EP working with quite strong reductions with different eyepiece. Interesting results but image quality is not there yet... Here a quick summary: @vlaiv as you mentioned by going with eyepieces with shorter focal lengths the extension are more manageable. However it seems I'm getting quite a bit of distortions (coma?) even at 0.68 reduction. I got similar distortion with a SW plossl 25mm but I'm not sure I good is this eyepiece. Optically my TV 15mm seems really good... Going back again to the long TV 40mm I can get EP by adding more spaces between the camara and the EP projection adapter. I have to admit the total extension is quite embarrassing and I'm pretty sure I may have some bending going on. Still, with the 40mm I think image quality seems more uniform although more fuzzy/blurrier. I tried but can't get a better focus...either because is very short or image quality is poor. Unfortunately I don't have a 32mm to test... I may try next the 40mm with less reduction and see if image quality improves.
  4. Well, at least with video astronomy, live stacking and NV we have so much choice and that’s the nice thing of this dynamic hobby ? I’m sure we can debate more how NV fits inside or outside the general umbrella of EAA. However, to be honest if people doing NV feel they are doing more of a “pseudo”-visual approach... (with no negative connotation intended) well at this stage, I don’t have a problem with it or better I don’t think I should decide on that but that’s just me. Where I think things get confused is with this new general definition of EEVA... the term visual is not fitting for me with live stacking and video astronomy techniques and opens the door for more confusion about visual observations vs the broad meaning of observation.... is it just me or is this a common impression?
  5. I think there is a terminology problem here. On one side peolple are considering observation = visual observation because that's looking directly at real photons or the other side other people thinks more along the way of observation = scientific observation, in the sense regardless of the tool (visual/NV/EEA,etc) the key point is to be able to observe something without worrying about perfect image/view either technically or artistically...just yesterday people on both CN and SGL confirmed a supernova in M100 looking back at some posted images. I'm biased here but for me this is a good and solid scientific observation that could have been done on any tool or visually... I think we can debate, agree or disagree on this all the time but I have the feeling we may never reach an agreement here because everyone is coming from different directions and experiences. Nothing wrong with that. Maybe we should try first to see if we can find a common ground where we all agree on something. Let me ask a couple of questions because I'm still fairly new here and I would like to understand the general feeling about EEVA: 1) Do you want to associate the term "visual" to EAA/live stacking observations? 2) Do you want to associate the term "visual" to Video Astronomy observations? I personally would say no. How many people disagree on this? Do you prefer to keep the "visual" badge also for EAA? I'm asking this because I don't fully understand how/why the new name of this section. So we are are doing EAA/live stacking and we are calling this section of the forum Electronically Enhance Visual Astronomy? I think EAA can embrace both live stacking and video astronomy and I have no problem to admit that these observations are not "visual" in the "visual observation" sense but still genuine observations are. Reading back at the start of the post I got the impression that probably everything was done to make things more inclusive to NV, which I think is a really cool technique. Asking the same question about "visual" and NV: 3) Do you want to associate the term "visual" to Night Vision? I'm more likely to say, yes, but we can debate pro and cons. Nevertheless, given just the name "Night Vision" I would say, there is no doubt that NV can be considered way more visual than video or EAA, no? So if we split the concept of "visual" from "observation" I think we may have a way forward. My suggestion is to simply go more with a name like "Electronically Enhance Astronomy and Night Vision" . In this way, we are inclusive but also we keep the full identity of everyone and easy to find/search... Also, last comment, EAA and NV have now picked up almost everywhere on the web and beyond so going with a different name like EEVA for everything may be also damaging. This is my personal view and I hope to have not offended and challenged anyone...
  6. Thanks @vlaiv, that's really helpful. Now I understand the "proper" EP much better. I don't think I have enough extensions to reach that distances on the 72ED but yes I can try with a shorter eyepiece and maybe using my 130p instead. Since it has already a deep focus that would make a better use of the extensions. In the worst case... I'll get more ?
  7. Here the results of a quick test I did this afternoon... Setup: SW Evostar 72ED ASI224 MC Televue Plossl 40mm TS eyepiece projection for eyepiece 30-42mm as suggested by @vlaiv several M42 extenders and here some results... Left: Exposures=0.000168s gain=234(auto), Right: Exposures=0.000168s gain=0 Ok, I'm not entirely sure how I shall calculate the reduction but just looking at the scaling between the different tree branches, I think I'm getting something close to 0.294 ?. So if the scope is f5.8, does it mean I'm running at ...ahem... f1.7 !? ? Is this right or I'm missing something here? More details about the test: Eyepiece projection was in "prime focus" mode as discussed above in this discussion. Unfortunately, right image is taken with eyepiece/camera handheld because I can only get focus removing all 1.25'' adapters. More thinking is required here as focus is going very deep inside. If I "ignore" the blurriness (out of focus) and considering also that I was clearly off-axis when I took the picture, I think distortions are not too bad... The camera/sensor was as close as possible at the eyepiece as allowed by the EP adaptor and the sensor position. I think ~10/12mm but need to check. I tried to increase the distance just adding a T-mount UV-IR filter or other small spacers but I could not get focus anymore. I guess it went further inside the tube. Unfortunately, I didn't manage to get a bright image of the "proper EP" configuration. Working on it but it seems there is a minimal distance between eyepiece and camera below which I can't get any focus. I need to look more into the theory of EP projection and where/how the focus is moving... Anyway, regardless of the final reduction I'm getting, I think EP reduction is definitely something worth experimenting more...
  8. Does it mean, the shutter keeps clicking or can you raise the mirror and keep shutter open? I got unconfirmed rumours that some cameras may be able to "convert" them in a more traditional astrocamera "mode" by using a software shutter. I think the very expensive Nikon850 may do that, mine of course not. Not sure about Canon systems. Maybe mirrorless?
  9. Well, I did some quick tests and my relatively small DSLR (Nikon 5600) was balancing ok but the dovetail was close to the limit... To be fair I haven't tried yet to do EEA using a DSRL but I just asked about that myself in another topic here below and it seems people are doing that. This may require a bit more thinking since you may need to use a different combination of software and, if I got it right, if you go for short expositions and continuous live imaging, the shutter will also keep going all the time. Not sure that is something I want for my sessions and how good is for the life of the camera. I'm thinking to try maybe something slightly different for a DSLR but to avoid to go off-topic I think it is better to keep the relevant discussion about DSLR on the page/topic above. Alternatively, if you are not interested in just EEA but in more classical imaging (i.e. with off-line post processing) with Alt AZ and DSLR you can have a look also at this great post. You can see many great images there and there so many possibilities...
  10. No, I’m using SharpCap. DSS is more for offline stacking and post processing... here all data is dark frame subtracted, stacked and histogram adjusted always live while observing. After a bit of stacking, when I’m happy with what I see, I save the image, stop stacking and move to the next target. As I said previously, this was the first time for me under a real dark sky and I’m very pleased with the result. I live in London, UK, light pollution is pretty bad but I can still do quite a lot of observations (when it is not cloudy!!!), many galaxies and other deep sky objects. It just takes longer to average a bit more data and also more fiddling around to find the right histogram settings, but that’s part of the fun.... Again, I would not worry about field rotation, if you stay with short exposures you are free from it.
  11. Well in theory if SharpCap can scan a folder for images to stack that should be not too bad... Over the weekend I was testing both digicamcontrol and APT. They both seems capable of controlling nicely my DSLR. One nice feature I found in digicamcontrol is the possibility to average in realtime multiple frame of the live view. No stacking just frame average... but that may be enough for quick focusing, goto and framing. If needed I can always shoot a test frame to refine focus or maybe even platesolving (not sure)..and when ready I can setup a batch to get 50/70 frames to stack. I haven't test the full thing yet so I'm not sure everything will work but it seems promising. I guess similar things can be done using Astrotoaster.
  12. Yeah, that's why I'm already planning to go somewhere dark nearby again for a weekend at the end of May... dark skies are really addicting!
  13. The stacking software is taking care of it by realigning each frame and rotating them if needed. You can see the effect of this on the borders of the first image, Omega Centauri. Over the full 4 minutes of the observation a bit of rotation is noticeable on the borders but with just 5/10 seconds expositions, or a bit more if you want, you can ignore any rotation issue within each frame. Field rotation is an issue for much longer expositions with alt az. Also, one thing I really like of EAA and in general short expositions is that they are more forgiving. Even if your tracking is not great, as long as you have not star trailing in your single frame, you can still stack without ruining your data and see the object... Well, at least until your target is still reasonably inside the field of view ?. You should definitely try. It is really fun and you can see so much more!
  14. @SIDO Well, I'm very happy with my 224, just really tempted by the field I could get with a DSLR I have sitting at home. My choice today will be to get either a 294 or 183mono but I like to explore with what I have and experiment around, that's also part of the fun for me. @Martin Meredith Uhm, yes an ASCOM driver for Canon is interesting and would make things simpler... but eh my camera is a Nikon ?. I was reading around and found on the SharpCap manual that, in theory, everyone could just use the "virtual cameras/ virtual folder monitor camera" option to scan a folder and still be able to use darks and flats and keep using the main live stacking functions. https://docs.sharpcap.co.uk/3.2/#Virtual Cameras ... Now, I can see few software like DigicamControl http://digicamcontrol.com and probably Astrophotography tool https://ideiki.com/astro/ (and I'm sure others) to set up scripts or batches for running and saving multiple shoots from DSLR and that should work. ... and if I save in Mono FITS I may even get to use Jocular! ....but now I see a problem why a DSRL may be not really ideal for fast EAA imaging... clack clack, clack clack, clack clack, clack clack, clack clack,... unless I can take 5-10 seconds exposures (or more) directly from the live-view mode the sound of the shutter, running all the time, will probably drive me crazy and it may be not that good also for the life of the camera.? Or maybe, is it feasible? Only few shots to goto/plate solving and then run ~50 shoots for stacking? I need to try and see...
  15. Very interesting topic! Any new update or more tests? I was thinking to combine a Televue ploss 32mm with an asi224 but not sure about the distance... (also we should probably move this topic out of the reports section and in discussions)
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.