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alexbb

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alexbb last won the day on September 12 2018

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About alexbb

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  1. The significant difference comes from the low read noise and the recommended typical usage. With a CMOS sensor camera you'd probably want to take more shorter exposures. The mono Panasonic sensors found in the ASI1600/Atik Horizon/Qhy163 has a full well of ~20000 electrons which is converted by the ADU to a value represented on 12 bits (0-4095). Using a gain for the highest dynamic range, the ADU will indeed limit the resolution of read data. But for the highest dynamic range, the read noise is highest and this is not the best way to use such a camera. As I said in the beginning, with these CMOS sensors, for optimal results you should increase the gain - in order to benefit from the lower read noise. This also decreases the dynamic range. For an ASI1600, above a certain gain the dynamic range decreases enough so that the recorded data can be represented on a 12bit integer value so the ADC is no longer the limiting factor. What you need to do is to record as many exposures as you can. Be aware that compared to the typical usage of a camera with a CCD sensor with long exposures, a sub taken with a CMOS sensor will be much darker and a stack of subs as well. In order not to lose relevant data, make sure that the stack is represented on at least 32 bits. Some applications (ie. Registar) doesn't work with 32bit float fits files, but most of them do (PixInsight, APP, GIMP 2.10). If you want a comparison, is like having a cup filled with water (stack of long exposure CCD subs) or the same amount of water in a bucket (same amount of hours stack of short exposure CMOS subs) - the water will have different heights.
  2. Hello all, I'm in a quest for finding a used 120ED, but if I'm not lucky enough, I also consider buying a new one, sacrificing some other planned/unplanned astro acquisitions. My dilemma is about the flattener. I know the flatteners look alike for the 80, 100 and 120 ED scopes, but I don't know if there's a difference between the one for the 80ED and the one for the 120ED. Both scopes are F/7.5. Usually, universal flatteners work with a longer backfocus with a shorter FL scope and the backfocus distance decreases as the focal length increases. The reducers/flatteners dedicated to the 80 and 120 both work at a 55mm backfocus distance. Did anyone try an 120ED with the flattener dedicated for the 80ED? Or does anyone if their optical formula is different? I already have a flattener for the 80ED, but if I really need the flattener for the 120ED, I'd rather buy the scope and the flattener together from the beginning. Also, did anyone try the 120ED with another flattener? Thank you for your time! Clear skies! Alex
  3. I don't know the guiding image scale you're using since there's no correspondence to arcseconds, but, indeed the RA drift is even smaller than the Dec, which is a good sign. If you enter properly the focal length of the guiding scope and the guiding camera's pixel size, you can read the guiding accuracy in arcsec/px. Rule of thumb says the RMS value should be about half or less than the intended imaging resolution in order to make full use of the scope/camera combination.
  4. Mine's like this: Testing when I received it. Not even the Dec drift is linear, something has to be bent somewhere. RA should have been almost linear with a small PE. What a joke. And on the field, used, guided: Calibration Guiding Above the Dec was a bit jumpy too so perhaps seeing was poor. But below, another night, isn't so jumpy anymore. Or another night. All of them were shooting Orion so the Declination was about 0. You can easily see how bad the RA is compared to Dec. Please click on the images for the full resolution. These nights resulted in these images: With an Esprit 80: https://www.astrobin.com/398170/ and with a Canon 70-200: https://stargazerslounge.com/topic/333000-last-orion-for-the-season-wide-mosaic/ Not too heavy I'd say. For comparison, my stock EQ6-R, another kind of beast indeed, but please compare the RA and the Dec: I can dig on the other laptop for some logs from an old stock EQ5 with motor drives. RA guiding is sub-arcsecond. Perhaps being able to knock at their door made them think twice and they really improved your mount, David. Unfortunately for me, I'm more than a few hours car drive. I heard before that paying them a visit helps
  5. Hopefully, iapa's will be better. Mine certainly wasn't, apart from an easier balancing, which doesn't improve my teacking. After Dave admitted that my mount should perform better, he went silent again. I'm happy that your mount is up or exceeding your expectations, David, but I'm not the only one to receive a poor performing item.
  6. Oh, wow, he still manages to surprise me. I don't understand why he didn't include the photos and the logs in the same email.
  7. I went back and read the old replies in the thread and the conversation I had with Dave. I tried to settle with him a reasonable date for a fix, but he didn't wanted to reply to this anymore. He only mentioned that during the Christmas holidays nothing is shipped. I then accepted that he fouled me and decided that having a not so great mount is still better than no mount.
  8. I still don't get it, was it something like: do you want some pics and logs? But without the photos and logs actually, and then nothing?
  9. "Testing" to make sure you don't need to send the mount back. Hopefully threads like this will force them to improve if they care about their business.
  10. Quite late to the party, but put me on the list if it remains available.
  11. How are the logs? I only received a picture of the mount assembled. And what is the excuse for having the mount for so long?
  12. I believe they have a few employees and the business seemed to grow over the years. Some people received a better mount though. Maybe the turn around is now longer for a better quality control. If they reply, perhaps a good idea is to ask for guiding logs before sending the mount back to you. I received excuses instead of guiding logs and lies about the mount being ready a few times.
  13. They sent me back a mount performing as an EQ3 should perform, according to Dave. I get a guiding accuracy of 1.2-1.5" RMS usually and the tracking/periodic error is 60-70 arcseconds. I strongly believe Dave doesn't know as much as he claims. As for his attitude.. For asking him about the delays it seems that I [removed word] him off, he told me that I [removed word] him off. He also told me that he doesn't really care about customer service that much. He cares above all how his mounts perform. Didn't seem to care that much about mine. I don't dare to send him back the mount to improve it to his claims, I'm afraid I won't ever receive it back after so many lies. 500-600 euros well lost. In the end, I asked OVL if the can import RA worms for the AZ-EQ5, and it seems they can, but it takes about 4 months. I ordered 2 and I'm waiting for them now, hopefully at least one will be better than my current one. Sorry to hear about another bad experience with DarkFrame, but I hope you'll get a better mount than I did.
  14. Thank you, all! There are a few galaxies lurking around, indeed. Happy that you like them!
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