AstroRookie

4 hours ago, Clarkey said:

Have you tried some short exposures and looked at the shape of the stars? If they are round it shows it is not an opitcal issue, but probably a guiding related problem. Are you using an OAG or guidescope?

 

Edit - probably unrelated, but your focus curve is very odd...

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:

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?

1 hour ago, Stefan73 said:

It sounds like you should have a 37.5mm spacer between the camera and the coma corrector and then the coma corrector goes fully into the focus tube clamp; like a nose piece on a camera.  Is that what you have?   Can you see if you're getting close to focus at either full extension or full retraction of the focuser?

 

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 ...

51 minutes ago, doublevodka said:

Think @Adreneline has hit the nail on the head there

https://www.firstlightoptics.com/coma-correctors/baader-mark-iii-mpcc-coma-corrector-photographic.html

"Requires 55mm back focus."

Near the bottom of the product page here it shows you how to do it - https://www.touptekastro.com/products/touptek-atr3cmos26000kpa-imx571-colorful-astronomy-camera-26mp-1-8-aps-c-tec-cooling-deepsky-astronomical-telescope-camera

Alternatively, if you are in a rush and don't have time to sort it before the next imaging session, you could simply remove the MPCC from the equation, you'd still have some coma, but not as much as is showing with the spacing issue currently.

Hope that helps 👍

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!

58 minutes ago, Adreneline said:

So frustrating for you.

Looks like you could have a spacing issue - maybe:

Hope you get to make use of the clear skies tonight.

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

27 minutes ago, david_taurus83 said:

Have you checked it with a multi meter to see if it is delivering 12v at the end of the individual cables powering all your gear? 12v is very susceptible to voltage drop the longer the length of cable used. That's why 13.8v is best to supply.

ok, will check it - thanks for the info

18 minutes ago, david_taurus83 said:

Yes but what are you using to power the Pegasus unit?

A 10A 220v to 12V power supply

36 minutes ago, david_taurus83 said:

With regards to the camera, you say you struggled to connect it at first but eventually you used the cameras power adapter and it connected fine. Do you mean a 12v power supply that came with the camera? If so, it sounds like there is an issue with your power supply that you use to power everything else. What are you using?

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

1 hour ago, bottletopburly said:

Have you installed the touptek drivers for your camera ? 

you need 55mm backfocus between camera sensor and cc shoulder to achieve focus

 

 

- 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:

1. 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 ...
2. 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

On 14/08/2023 at 00:39, Albir phil said:

Hi I will sort some pic out for you in a few days meanwhile can you post some pictures of your mount and pier maybe then I could draw some brackets for you to look at . It's difficult to draw  unless I can see how best to fit brackets 🤔

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 😉

2 hours ago, Albir phil said:

Hi I to have a permanent mount and use pole master I did get some misalignment,I rectified this by making a L bracket with 2 horizontal slot's which I attached to the mount base and to the pier the slot's let me align if I need to but since doing this almost 1year ago I have never had to realign. Hope this helps you it works for me 😃

Hi Phil,

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

AstroRookie

7 hours ago, StevieDvd said:

Is it the pier or the mount?

Once polar aligned place a strip of masking tape across the back of the mount where the alt axis is. Across the gap, so if this moves the tape will distort a little. Or you could just re-check your PA before you pack up.

You may have some movement during use that you don't notice.

 

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

9 hours ago, fifeskies said:

How recently did you install your pier.   

It can take a few months for a new foundation to settle fully, however I would expect any day to day change to be very small.

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

10 hours ago, michael8554 said:

What PA figure does PoleMaster report after you've aligned, and the next time when you start up ?

Michael

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