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maxchess

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About maxchess

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    Guildford, UK
  1. Thanks all, for some really helpful advice. I have only been imaging a year and just started exploring guiding. Before that I was doing up to 120 secs unguided and getting (for me) decent results. My best image was https://astrob.in/373575/0/ 160 x 60" unguided and I am interested in your comments on what is achievable with my HEQ5 Pro if I guide it. At present I am trying just to get sub 2 arcsec guiding but seem to be getting bad backlash related errors errors. Once achieved it sounds like I need to stick to my DLSR through the ES102.
  2. I am experimenting with guiding, and want to understand what I need to guide my ES102 with a ASI 1784 on an HEQ5-Pro. I have an Orion SSAG mono guide camera and its 50mm guide scope, fl= 162mm. I also have an ST80 fl=400mm. I am having a bit of trouble guiding with the ST80 using PHD2. I get large guiding errors. I am considering going back to the Orion 50mm. However when I calculate the FOV for the ES102 + ASi1784MC I see it is 0.6° x 0.4°, which is equivalent to DLSR on a 2100mm focal length scope! Therefore I wonder if the 50mm/162mm FL will cope. In the discussions on Focal Length for guiding I only find references to matching the FL of the main and guide scope, not the FOV, but surely its the FOV that affects the apparent angular motion and therefore the required guiding accuracy? Or have I missed something.?
  3. OK, sounds good. Moon washed out last nights images so waiting for Moon to disappear before experimenting further.
  4. This is the article that gives the example settings for long exposures. It is a different sensor, but the principal seems to be that for Highest Dynamic Range on long exposures you set gain to 0, offset 10. In the example they have unitary gain as (G: 139 O: 21). So I assume that G=0 maximizes well depth and offset 10 lifts the lower values. In my simplistic way of thinking I assume that with G=0, O=10 I can usefully increase exposures until the highlights reach saturation, at which point I am getting the best dynamic range, ie making optimum use of the ADC to record the widest range of values in the most detail. I notice from Astrobin that many ZWO camera users use large numbers of relatively short exposures 60-120 secs , rather than DLSR users who go for fewer much longer exposures. Still struggling with this camera, will process last nights Moon affected images later.
  5. To be safe I am trying some captures at Gain=10 , Offset=10 on M81, (20 x 120 secs) but with a full moon they are likely to be poor. M81 is about as far away as I can get from the Moon. However lights so far are showing minimal Amp Glow. Hopefully with Darks, Lights & Bias I can eliminate it.
  6. I have the uncooled version of this camera and the same problem. I tried Gain=200 and got what looked like a star shaped light leak in one corner just like yours. I also took flats & Bias frames, but they did not help much. I assumed it was a problem with my scope, but found its was AMPGLOW, see this ZWO article. I tried taking 90 second Darks at various levels of Gain and found it diminished until it was virtually invisible at Gain=10 . To see the effect take a Dark into your processing program and stretch it. ZWOs solution is to control via Darks and disable any dark optimization feature of your calibration program eg DSS. They say that this effect only occurs in "specialist" sensors and not in those used for DLSRs. I was staggered, sounds like a design fault to me. These guidelines appeared in another ZWO post: Unity Gain ==> Gain: 180 Offset: 25 Highest Dynamic Range ==> Gain: 0 Offset: 25 Lowest Read Noise ==> Gain: 270 Offset: 340 So my interpretation is to go for Gain: 0 Offset: 25 for DSOs on long exposure and disable dark optimization. Waiting for moonless/cloudless night to try this out. Any other experiences most welcome. Never had this problem with my trusty 450D.
  7. Ok, as i write i am finally guiding using the 90mm fl500mm frac on my C8 with the Orion SSAG camera. I am using the internal guider with Indi Ekos on a Rasperry Pi3+. This allows me to sit inside and track progress via VNC on a tablet or laptop, All seems fine and the camera can find stars with the gain turned up to 70 out of 100 on the SSAG. Seems to be keeping within the 2 arcseconds limit most of the time, but my Polar Alignment probably needs some work. I also think I am guiding at the limit of my EQ5-pro weight. Currently the total weight of the two scopes and the cameras etc is 10.2 kg. I think the max for imaging is 11 kg. I am only doing 200 sec exposures because its M2 and quite bright, but the surrounding stars look sharp.
  8. I followed that advice and now get the prisim fully iluminated, by day I can see distant trees clearly full frame in the oag guide camera and the main camera image seems unaffected. The problem is that at night the very few available stars are too dim to guide on. The Orion SSAG and the ZWO ASI 178MC do not seem sensative enough despite adjusting gain, applying darks and various transformations. I can guide ok with a 50mm guidescope but not with the oag. Everything I have read elsewhere confirms this view and while it might occasionally possible to use a cheaper camera , to get reliable OAG guiding at long focal length you need a very sensitive guide camera, like the lodestarx2. So I am going to plan B and mounting a 90mm fl500mm frac on my C8 and try to guide with that. Should be a lot more photons.
  9. Alacant, I notice from another thread that you use a monochrome Datyson T7 with your OAG. Would that be any better than my Orion SSAG or ASI 178MC? its a lot cheaper than a Loadstar.
  10. The Celestron OAG I use has a helical focuser on the guide camera fitting, so achieving focus was not the issue. I focused during the day as you suggest and I could get focus when pointed a a bright star. I used Altair, but when the scope was pointing at my intended real target the potential guide stars were too feint. I could see them, but they were very dim and lost amongst noise of high gain. I tried lots of settings for gain and various transformations available in EKOS and I used darks. This lark is difficult enough already and using a poor camera just makes it harder. It all worked fine through a 50mm mini scope, just not the tiny prisim of an OAG at extended focal length.
  11. If you try using the QHY5L-II-C on an OAG you may have problems. I have been trying to get my OAG to work on a Celestron C8 + .63 reducer, using the Orion SSAG mono camera. I had guiding working fine through a 50mm mini scope on 90mm frac, but the OAG uses a prism and gives you a tiny fraction of the light coming through the scope. The result is that with the wrong camera the stars are very few and very feint and not good enough for guiding. Many of those who use OAGs successfully do so with a lodestar, which is mono and very sensitive (and expensive). You camera is also the colour version which reduces its sensitivity further. As a result of my experiences I am going to mount a 90mm scope on my C8 and see if that works, while I save up for a Lodestar. I would be very interested to hear if you get the OAG with a QHY5L-II-C to work. I might just be me.
  12. I used a combination of all the advice above and made progress. By adjusting the prism I got the guide scope fully illuminated and increasing the gain gave brighter images. However I am finding that with my two cameras I only get a few indistinct stars that my software won't guide on. I am using the INDY EKOS internal guider which worked well when I was guiding a 90mm scope with the Orion SSAG. I am coming to the conclusion, after my own experience and reading various forums that I need a better guide camera to guide using an OAG, something like a lodestar. (maybe I should try PHD2, but the stars are so indistinct, even using darks that I am not optimistic) My next step is to try guiding through the 90mm scope (f=500) mounted on top of the C8. I have read that I might get "Flexure" but I am using a Focal reducer with only a C8 so I hope it will not be a problem. The mounting uses what looks like very substantial rings from ADM. Now waiting for a clear night.
  13. OK tried to test the new set up in between the cloud with no spacers in the OAG having achieved daylight parfocal as described before. . After focusing tried to image M27 Dumbell Neb. The DLSR bit worked with only mild vignetting , but my guide cameras could not find any stars. Only had a short time to try swapping guide cameras and playing with settings. Wondering if Orion SSAG and the ZWO ASI 178MC just not sensitive enough.
  14. My image train is: C8 - F Reducer - OAG - Spacer -DSLR. and OAG - spacer - guide camera ZWO ASI 178MC Does anyone have this combination working without vignetting, if so what is the spacing? I used the 11mm spacer to the DLSR and 6mm to guide camera as recommended in the OAG manual. I can get both the DSLR and guide camera in focus, but after trying last night I found that both cameras have vignetting. On closer reading I noticed that the Celestron OAG instruction book does not include any mention of use with a FR. Odd really since I would guess that most imagers use one with an SCT. Checking round the forums I find that this is a common problem especially with larger Edge SCTs. However I have the basic 8" SCT. It is also clear that the OAG is quite fat and places the camera further away from the telescope back than my standard 2" nosepiece. So I have just done a daylight test with no spacers or nosepieces on either camera and they both focus and it looks like vignetting has disappeared on the DSLR and is much reduced on the guide camera with increased image brightness, So I will test it on the next cloudiness night. However I would still like to hear from anyone who has the C8/FR/OAG/DSLR combo working Max
  15. Hi, I am setting up the Celestron OAG (93648) but get severe vignetting on the guide camera. The scope is a standard Celestron 8" SCT with a 6.3 focal reducer. The main camera is a Canon 450D (APS). I have two camera I have tried as guide cameras. The Orion SSAG and the ZWO ASI 178MC which I already have. I am trying a daytime setup using a distant tree. I can get both the canon 450d and either guide camera both in focus, but the guide image shows severe vignetting, such that I get a moon shape half image, but I can still see the tree. Is this normal or should I expect a full image? I have not tried adjusting the prism depth as the manual cautions against it and I am worried about intruding into the main image space. Any ideas., or will it work like this. I would rather not buy yet another guide camera.
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