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alexbb

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Everything posted by alexbb

  1. alexbb
    Seems that the power source that I got does it job easily, as expected.
  2. alexbb
    This should do
  3. alexbb
    What a big lump of iron... what do you use to power it? I just got mine yesterday, I tried to power it from a Celestron small power tank (the LiFePo4 one) or a PC power source, but without enough luck. It was slewing OK until decelerating, then it drew too much power and the power tank cut the power and the PC source dropped the 12V voltage to ~9.xV. I couldn't check my main power supply as it was powering my old mount and I could not waste imaging time.
  4. alexbb
    As far as I know, the SW coma corrector is not that sensible to backfocus, the spot shape towards corners is not uniform at all wavelengths, I believe 1mm in/out won't matter. My solving for this was to put a ZWO OAG, another M48 ring on the thread (6. in the picture) and a 7.5mm extender between the SW CC and the EFW. If I remember correctly, I placed the sensor at about 56mm away from the CC and the result is this: https://www.astrobin.com/341636/ The image is from FLO.
  5. alexbb
    @FLO, how about selling also some of those?
  6. alexbb
    One more and perhaps the last solely with the 130PDS. I will add more data to this, but taken through another scope. This is 8h Oiii and 7h Ha.
  7. alexbb
    You can record longer wavelengths when seeing is worse
  8. alexbb
    Most of the times I found the guiding graph behaving better or worse, in line with their prediction. But I live in Romania, the weather can be more predictable here as there's no big puddle around where I live
  9. alexbb
    meteoblue predicts also seeing
  10. alexbb
    Meanwhile, I had some spare time today and I processed some partial data for M27. 8h of O3 and 4:40h of Ha. Need more data. Perhaps ~16h of O3, 10h of Ha and some RGB.
  11. alexbb
    I think I'll just skip those F/4 newtons. Unless it's 200mm+ one, I don't feel they justify the cost. An F/5 SW with a SW 0.9x reducing CC is already at F/4.5. I might just buy an 150mm one and if I don't like it, I will sell it for a small loss. I can realuminize the 130 mirror and try to image with a DSLR and an EQ5. At 1.5 arcsec/pixel with a Canon 550D I could just get away with the guided EQ5 without tossing too many subs.
  12. alexbb
    Check out also the generic one from FLO and the ZWO OAG. I believe they are thinner.
  13. alexbb
    I've one picture on my phone, I can add some more this evening if you want. I find quite easy to focus the OAG. Done once during daytime and then adjusted under the stars. Takes a minute to adjust and you don't have to focus perfectly.
  14. alexbb
    By the way, how does your guiding go usually with your AZ-EQ5 and the 130? With an OAG and > 685nm IR pass filter, I usually guide for a total error of 0.8"-1.3" RMS.
  15. alexbb
    With an OAG I have the advantage of having both cameras hanging down, towards the RA axis. This way I need only one counterweight which doesn't sit far away from the axis. If I were to upgrade to a 150 F/4, I would choose a carbon version, not really looking to spend all night refocusing Perhaps a TS UNTC OTA, the focuser appears better than ones on the PHOTON line. On the other hand, a 150mm mirror collects only 33% more photons than a 130mm mirror. Usually I just put my 130PDS on the mount a few hours before night fall for cooling down and when it's dark, I start imaging. If I were to spend extra time fiddling with colimation, would those 33% really be recorded? Also, a new 130PDS is 200 euros while a TS UNTC 150 F/4 with a GPU coma corrector are 1100 euros. Does it worth the extra money? I didn't even see that many images taken with these scopes.
  16. alexbb
    Thanks, guys! I can send it for a re-aluminization, but this will take a while. I'm not really happy wasting the clear nights so I'd take the fastest option. I found also mirrors >= 150mm, but no 130. I have to perform some more tests before concluding the mirror is not good enough anymore. If the mirror needs to be replaced, I might consider replacing the scope. At 750mm with the 0.9x reducing SW Coma Corrector, the 150PDS could be a better option for smaller targets and still within my AZ-EQ5 mount handling capabilities. Or a nicer carbon OTA.
  17. alexbb
    Does anyone know where I can find a replacement primary mirror for this scope? Is it the exact same mirror as for the lower cost 130/650 ones? I think I might overcleaned mine..
  18. alexbb
    Very nice details! You just beat me with your post.
  19. alexbb
    One more processed. I just installed yesterday PixInsight, but for now I seem to get better results with my old processing style. This is 7h of Lum and 48min each RGB. Light pollution - not max, but still red. One more M92 to be processed. Alex And one 100% resolution crop.
  20. alexbb
    Thanks! Actually, the image is cropped a bit and, however, I struggled a lot to remove the gradients and towards the corners they have waves patterns. What I heard is that there are 2 secondary mirror types. Ones for visual (which should be my case) and ones for imaging. I measured mine to be ~36mm wide, while the imaging one should be 47mm. It also appears that I have some astigmatism, but I find the weird gradients far more disturbing. I need to flatten the images a lot. If I were to go for IFN, I'd better do something else.
  21. alexbb
    That's Rayleigh's. For an 130mm mirror, Rayleigh's limit is ~1.06" while Dawe's is ~0.89".
  22. alexbb
    https://www.cloudynights.com/topic/1429-rayleigh-limit-dawes-limit/
  23. alexbb
    I've one finished image too while others are in progress. I will replace this weekend the secondary mirror with a larger one and, perhaps, cut a bit off from from one side of the focuser. Meanwhile, the finished image, in another thread and original. https://stargazerslounge.com/topic/311677-m13-lrgb-with-130pds/ Clear skies!
  24. alexbb
    I still have lots of time this season to acquire more data, but I processed what I have anyway. Lum - 120x30s and unity gain from last year, 77x180s and half unity (76g/15offset) this month. RGB - 7x180s each, this month. I don't seem to get along with this scope nowadays, there's horrible uneven gradient when I shoot with the IDAS-P2 filter, but none with the GB and just a bit with the R?!?! I didn't have any issue when I used the same filter with the Esprit 80 so I have really no clue. However, my best processing from last evening: And annotated: http://nova.astrometry.net/user_images/2033482#annotated
  25. alexbb
    You will reach focus with the OVL field flattener. The backfocus with that flattener appears to be 55mm - DSLR + T -> EOS adapter + flattener + scope produces a good image during the day, I can't yet confirm with stars, perhaps some day... I don't know about other flatteners.
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