AstroRookie

That's why I posted an image with manual focus by me, where the diffraction spikes served as reference and an autofocus by nina, which has indeed a "funky" focus curve; that's imho because the af routine tries to get round stars but then one can see that the image is not in focus looking at the diffraction spikes. On previous occasions when investigating this problem, nina was not even able to focus and even with a manual focus plate solving did not work, so in fact I'm making progress (the last remark is with a lot of irony)

@ollypenrice Don't know if I could orientate the camera as you showed, I think my guide scope and camera would somewhere be in the way - I'll check. I have considered upgrading the focuser, but if that is not the problem then this is yet another "useless" upgrade, and a "30 days money back guarantee" is taking into account my location not really helpful 😉 @michael8554 Diff flex: that's interesting, as I have to say up to now I've always been imaging near the zenith and this is the first time I have been imaging at +- 40° altitude south (rosette nebula) - I'll have a look on how the cables and guide scope behave at that position Thank you both! AstroRookie

Hi Clarkey, Maybe stupid question, but would that not be reflected in the graph of the guide software? AstroRookie

Hi Clarkey, no sweat, I don't feel patronized at all, thanks you're willing to look into the problem! About rotating the camera, no I didn't think of that - to be honest I was so disappointed yesterday evening, that the only thing I thought of was giving up this hobby ... As for "flex between the guide scope and the scope image", I'm sorry but I don't really understand (my native language isn't English) AstroRookie

Hi Clarkey, I tried 5 sec exposures and the stars are also not round; I'v been using a 60mm SVBONY guidescope without any issues so far; also the PHD2 graph looks fine to me. AstroRookie

Here's the answer of chatgpt to the following question: In astrophotography can a 4mm scratch in the 203mm primary mirror of a newtonian have an effect on all the stars in the picture taking with it? ChatGPT In astrophotography, the quality of the optical components, including the primary mirror in a Newtonian telescope, plays a crucial role in determining the final image quality. However, the impact of a defect, such as a 4mm scratch on a 203mm primary mirror, can vary depending on several factors including the nature of the scratch (depth, width), its location on the mirror, and the type of astrophotography you are engaging in. For visual observations, a 4mm scratch on a large mirror (203mm in diameter) is unlikely to be noticeable. The reason is that the overall surface area of the scratch is small compared to the total area of the mirror, and the light-gathering capability of the mirror remains largely unaffected. The diffraction effects caused by such a scratch are usually minimal, especially for visual astronomy. In astrophotography, however, the situation might be slightly different. Cameras used for astrophotography are more sensitive and can pick up finer details and imperfections that the human eye might miss. That said, the impact of a 4mm scratch on the overall image quality could still be considered minor for several reasons: Diffraction: The scratch might cause some diffraction effects, potentially leading to slight artifacts in images, especially around bright stars. However, these effects are often subtle and may not be noticeable unless you are looking for them specifically or are imaging objects with high dynamic range. Image Processing: Modern image processing techniques can mitigate many of the imperfections present in raw astrophotography data. Tools available in software used for astrophotography can help reduce or eliminate the visual impact of a scratch. Scope of Impact: The scratch's effect is more likely to be uniform across the field rather than causing a distinct or localized problem on all stars in an image. Depending on its location and the nature of the scratch, its impact might be dispersed or diffused throughout the image. Adaptive Optics and Stacking: For more advanced setups, the use of adaptive optics or image stacking techniques (where multiple exposures are combined to improve signal-to-noise ratio) can further reduce the visibility of any imperfections caused by a scratch. In conclusion, while a 4mm scratch on a 203mm primary mirror is not ideal and could theoretically introduce some level of diffraction or artifacts, its actual impact on astrophotography is likely to be minimal. The overall image quality would still be determined by a combination of factors including the optical design of the telescope, the quality of the camera, seeing conditions, and post-processing techniques.

Hello, I'm using a Orion F3/9 Astrograph since 3 years and it has given decent recults, but now for months (only natural, taking into account the few number of clear nights we have over here in this windy [removed word]-hole by the North sea) since I switched to a dedicated astro-camera I have been struggling with the shapes of the stars in my picture (I switched back to my DSLR and I get the same problem, so I exclude the camera's). I considered every thing from bad collimation, over pinched optics, dirty primary mirror, bad guiding to camera tilting in the focuser. Took mesures for all of this: replaced the springs for the primary mirror with more sturdy ones cleaned the optics (to discover a tinny scratch of about 4mm long - but can this really have such dramatic effects?) installed a 3rd screw to hold the camera in the focuser tightened 2 screws of the focuser base plate that were not completely tight tried to have my polar alignment as good as possible (last night I had total RMS reported by PHD2 of 0.13 (0.49") - see screenshot tried to have my collimation as good as possible (looking in the corners of the attached pictures, my collimation looks ok) I am about to dump every thing in the ditch at the back of our garden ... so any suggestion really appreciated by, AstroRookie Atttached files: test_mf.jpg: 5 minute exposure after manual focus using the diffraction spikes as a reference test_nina_af.jpg: 5 minute exposure after nina's automatic focus procedure, that's by trying to get round stars is completely out of focus probleem.jpg: screenshot of the imaging tab in nina

So I got my collimation right. I took a picture of 5s in park position (no screenshot, you'll have to take my word), ran an auto-focus and all looked well. Then I started my sequence on the Rosette Nebula and got a warning after the focus routine (10s shots) and I interrupted it. The last picture taken during the focus routine shows very weird looking stars. To me it at first it looked like a guiding problem, but judging the graph my guiding looked pretty good. As in the upper left corner I don't see vignetting (normally I have vignetting in all 4 corners of the ilmage), could it be that my focuser (I'm using the Orion 8" astrograph stock focuser) flexed?

I think it might be a combination of tilt and collimation. Last summer I did an upgrade of my telescope, and had pinched optics. I loosened the screws a bit too much I guess and as I mainly photographed around the zenith at that time I didn't realize it that when the telescope is pointed a little (30°) above the horizon, the collimation is completely lost. Just tried to correct that by tightening a bit with the "business card" method. Next session I will try to inspect eventual tilt - thanks for the tip. But I think that at least the focus problem is solved. Unfortunately no clear nights according to clearoutside.com for the coming days to check it out.

Apparently I needed a 37,5mm space because that is what the MPCC requires when using a camere with T2 thread. I tried that and it looks better but far from good. Attached 2 screenshots of a capture with Nina, one with the image "fit-to-screen", the other 1:1. The stars look weird all over the image. Autofocus does no longer work (plate solving however went ok). I checked my collimation, and that looks ok Any idea what is causing this?

That is what I had this evening: a 37,5mm spacer between de camera and the coma corrector, then with this adapter it is screwed onto the focuser. But not even close to focus, not at full extension and not at full retraction, donuts stars ...

Still no go; if I use 37,5mm + 17,5mm from flange to the sensor, I cannot reach focus at all. Also after having read this thread I'm even more confused. Not using the coma corrector is not an option, as I cannot tighten the spacers in the focuser; did I purchase spacers with the wrong diameter ??? So too bad for this perfect nights - frustration is part of this hobby Back to my dslr for now ...

I've checked, and I think my error is that I did not take into account the 17mm sensor to flange distance; so I had 17+55 = 72mm. Corrected that, now it's a matter of waiting till it gets dark, because it will be ab excellent night: clearoutside's opinion Thanks for your help!

I'll check it out. Thanks!

Hello, I bought a second hand Touptek IMX571 (can't remember the real model name but for the problem here that is not relevant, I presume) in August 2023, got scammed (previous owner advertised the camera with pictures of an identical one that did not have the protective glass scratched, but that is an other story), had to send it via teleskop-express.de (big thumbs up for them) to the manufacturar and finally got it back in November. Real first light was just to find out that I could not get focus, so had to buy some extra adapaters. Second first light, I realized that adapters and camera were not held straight in the focuser, so bought an adapter which allows me to screw every thing tight in the focuser. All this during the last 3 months with hardly any clear nights ... So yesterday and with the upcoming beautiful 2 nights, I thought it's now or never ... and alas, it looks more like never ... So here's my setup: Telescope: Orion 8" astrograph Coma corrector: Baarder MPCC Mark III Camera: Touptek ATR3CMOS26000KPA (IMX571) I collimated the scope with the Farpoint collimation tools 20 light frames - 300s processed with darks, bias, flats - not really relevant the the problem, as the problem was obvious during the capturing of the lights ... capture software: Nina - autofocus Now my questions: how come that only the center is focused? how come that away from the center stars are out of focus elongated Is this a focus problem? Is this a collimation problem? Is this a coma problem? Or is this a combination of all the before mentioned problems? Any help really appreciated, as tonight and tomorrow night will perfect conditions over here! AstroRookie

ok, will check it - thanks for the info

A 10A 220v to 12V power supply

Yes, with the camera's power supply it connects ok. The switch I'm using is the pegasus pocket powerbox micro

- Driver: Nina comes with native support for this camera, so I don't think it's a driver issue. - As for the cc, I'll a extension - thanks for the info

I finally had the chance to test my secondhand purchased astrocamera, a Touptek ATR3CMOS26000KPA. I purchased it in august, but as I got scammed: the seller had 2 identical camera's - I found that out on his astrobin profile - one which had a scratch on the protection glass and an other which wasn't damaged; he advertised on https://www.te-les-koop.nl/ with pictures of the intact one and once I transferred the money he sent me the broken one ... To cut a long story short, I had to send it back to the manufacturer for repair. My setup (the relevant parts for my problems): Telescope: Orion8 astrograph Coma corrector: Baader MPCC Mark III PC: mele quiter 3 Mount: EQ6R pro Switch: PPB Micro switch - with next to the camera, 2 dew heaters, pc and mount connected Software: Nina All this worked fine with my dslr Canon 6D, but with the Touptek I experienced following problems: When I tried to connect the camera with nina, I got 2 messages one that said it correctly connected, immediately followed with an error message that nina was "not able to pull", the result was that the cooler part could not be enabled in nina. I immediately thought about a power problem, and turned off the dew heaters, but same result. Then I plugged the camera in the different usb ports. When plugged in to the usb on the back next to the power port it connected ok with the cooler options enabled. But as soon that I tried to start the cooling error message and the camera disconnected. I also tried to connect it to the adjustable power port set to 12V, but same problem. Then I used the camera's power adapter and it connected ok and I could start cooling ... No way to get focus; with the focus tube completely extended the bright stars just show me the spider vanes and the secondary mirror holder. So I suspect I need some extension between the coma corrector and the camera but I haven't got a clue which size - the camera's back focus is according to the spec's 17,5mm All comments and advice greatly appreciated! AstroRookie

Hi Phil, sorry for the late reply, I've been busy with too many other things. As for my "observatory", here's a post form when it was finished - don't worry, my cable management has improved in the meantime 😉

Hi Phil, I'm sorry but I can't visualize what you're describing, would you mind posting a picture, thanks! AstroRookie

That was also my next move, to check at the end of my session ... but I admit I'm mostly too tired to ... next time, I promise AstroRookie

Hi, it has been installed end 2021, so I would hope the foundation has settled by now. The ground is clay however and I know clay has the tendency to contract when dry and expand when wet, but I don't think this is causing it. AstroRookie

Hi Michael, I'll have to pay attention to that; but with the weather we're getting in our "windy sh.thole by the Northsea" it might take some time, but thanks for the hint. AstroRookie