89 replies to this topic

[kgb]

Can you advise how to overcome the 500k limit so I can post a fits file?  The duo produces 50 meg files!

You can only upload 50mb gif, png, jpg, jpeg, tiff files into your gallery. You will need to create an album, use the upload feature and then link to the specified gallery when you post. If you want to link to a fits file, you will need to link to a file server like OneDrive, DropBox, etc...?

[Nemo51]

https://www.cloudyni...60edp-exemplar/

 

Truly awful jpeg. I’ll try to get a processed image posted later. Ic 405 under a full moon with 89 per cent humidity, 300 second sub, zwo duo, am5, optolong quad, and EAF. 
 

The large magnitude stars have “crosses” over them which, to me, look like faint Maltese crosses. 

Edited by Nemo51, 24 February 2024 - 03:35 PM.

[kgb]

I see what you are referring to. Looks like it might be a trefoil pattern, but the stars are too overexposed to see it clearly. This seems like it might be a common affliction, but given the sample size it is hard to arrive at a firm conclusion. At what temperature are you imaging? Pinched optics will cause a pattern like this. If that is the case, I wonder if Astronomics can provide instructions on how the user can adjust this out?

[Nemo51]

Zero C. 

[BlueMoon]

Offhand I'd say they look like ice diffraction spikes. 89% humidity with a 5 min sub would produce it easily.

[Nemo51]

Better-https://www.cloudyni...-60edp-crosses/

 

The ambient temperature was 45 F. 

[kgb]

Better-https://www.cloudyni...-60edp-crosses/

The ambient temperature was 45 F.

Is that the highest resolution you have available or is CN compressing the image ? I downloaded the image and it shows 167kb which doesn't enable me to see the stars clearly.

[Nemo51]

Is that the highest resolution you have available or is CN compressing the image ? I downloaded the image and it shows 167kb which doesn't enable me to see the stars clearly.

The file is 5.9 mb. I can’t explain the cn result. 

[Nemo51]

I found this under “large.”

 

https://www.cloudyni...-crosses/large/

[kgb]

That worked. The color correction looks great and at this resolution it is doesn't look like their is significant distortion in the corners or along the edge, but I see what you are talking about. Looks like the lens might be pinched. At Zero C the lens cell has contracted slightly and when this scope was assembled it was likely done so at a higher ambient temperature and with a little too much torque. Screwing off the dew shield will expose a series of screws at 90deg from each other which may relieve this issue if, singly, backed off and then finger tightened. I would speak to Astronomics before adjusting and to see what they recommend. I need to test mine out under the stars yet and hope to do so later in the week.

[Nemo51]

That worked. The color correction looks great and at this resolution it is doesn't look like their is significant distortion in the corners or along the edge, but I see what you are talking about. Looks like the lens might be pinched. At Zero C the lens cell has contracted slightly and when this scope was assembled it was likely done so at a higher ambient temperature and with a little too much torque. Screwing off the dew shield will expose a series of screws at 90deg from each other which may relieve this issue if, singly, backed off and then finger tightened. I would speak to Astronomics before adjusting and to see what they recommend. I need to test mine out under the stars yet and hope to do so later in the week.

Zero c was the camera temp. Ambient was 45 f    Just my luck. I have zero diy skills. Oh, well, I should not have sold the red cat….

Edited by Nemo51, 24 February 2024 - 10:17 PM.

[kgb]

Metals will expand and contract slightly with every change in temperature. Some metals more than others. I am not sure what the AT cells are made from. Steel? So, if these scopes were manufactured at 68deg F then that is a temperature delta of 23deg F. If the screws were overly tightened during assembly then that might be enough to cause, what would appear to be, a slight pinch in the optics.

[Helvetios]

If there are four screws securing the lenses, does it make sense that one would observe a trefoil pattern, with its 120 deg symmetry?

[kgb]

Zero c was the camera temp. Ambient was 45 f Just my luck. I have zero diy skills. Oh, well, I should not have sold the red cat….

You don't need skills to make an adjustment like this. You just need instructions. I've seen this problem with Redcats too. This is all too common in refractors manufactured in China. I guess they like to make things tight for their long journey. It's a 5 minute fix in most cases. The screws only need to be backed off ever so slightly.

[kgb]

If there are four screws securing the lenses, does it make sense that one would observe a trefoil pattern, with its 120 deg symmetry?

In the higher res image, it doesn't look like trefoil. There are four distinct dimples around the bright stars.

Edit: A classic trefoil pattern would render the shape of all stars as triangular when at focus. These appear to be more square which leads me to believe that the four screws centering the objective lens are a tad tight. There aren't any spacers visible so it's not occurring as a result of intrusion.

Any other theories?

Edited by kgb, 24 February 2024 - 10:53 PM.

[Nemo51]

My theory, err fact: I’m SOL.

[kgb]

SOL? That's nonsense. I am sure a resolution will be found and I wouldn't sweat it too much. Which camera are you using? Sorry if I missed it.

[BlueMoon]

 

it is doesn't look like their is significant distortion in the corners or along the edge,

That is what I'd be looking for primarily, field distortion. A well executed Petzval, if it were out of alignment in most any way, would show more distortion across the field. Not seeing that.

 

 

I found this under “large.”

That image appears to show the brighter stars simply over-exposed. A common problem when imaging fainter background structures like molecular clouds or faint nebulae. Couple that with high humidity and seeing faint spiking from the brighter stars wouldn't be unusual in my experience.

 

Suggestion: try more 3 minute subs instead of 5 and see what the result is. I've found shooting 3 min or less helped in diminishing the star bloat on fainter background targets. I was also able to clear up some of the problem in stacking/processing as well more easily.

 

Question: what image format are you saving in? I shoot with a DSLR and I'm not familiar with your camera. Cheers.

Edited by BlueMoon, 25 February 2024 - 10:05 AM.

[Nemo51]

Zwo 2600 DUO.  Using this camera with an at 130edt, an Askar V, a quattro 150 and Quattro 200, I never seen this result. The histogram shows, if anything, underexposure. I’m SOL because I don’t have the skill or knowledge to fix it, and the weather will be Pure Dee …. For weeks now. 
 

[BlueMoon]

 

The histogram shows, if anything, underexposure.

Histograms read the average of the entire image for the most part. So, hot spots like bloated stars won't necessarily show up accurately on a histogram when the major portion of the image is dark.

 

 

I’m SOL because I don’t have the skill or knowledge to fix it ...

Well, no one is born with a digital camera in their hand so acquiring the knowledge is via experience. I've found AP is part science, part art and part luck. Keep at it and I think you'll find your results will improve over time. Cheers.

[kgb]

You have the skills to configure two fast Newtonian astrographs for imaging with an APS-C but cannot troubleshoot a small anomaly in a refractor? Selling yourself a little short maybe?

[KevH]

If this is like most other KUO manufactured scopes, there are going to be radial screws around the lens cell.  If those are a bit too tight, all that's needed is a screw driver and some very slight turns of the proper screws.  There are threads showing this process on similar scopes here on CN.  The other option would be to exchange/return the scope.  Astronomics is pretty good about making sure people are happy with their products.

[Nemo51]

Ok, folks, I appreciate the responses but please, this is about the product, not me. For those who care, I have no meaningful close vision after a cataract surgery that didn’t go well, and a neurological condition in my hands. 
 

yes, I have a glatter laser and tublug and find collimation zen like!

 

i speculate, based on the comments of apparently learned folks, here, it is a fabrication defect, resulting in pinched optics, not a design defect. Sadly, age has me in its grips and while I can see a laser spot, I cannot focus on a tiny screw head nor likely hold a tiny screw driver in place without scratching something. Fortunately, life was good to me and I can pay for someone to do it. 
 

Edited by Nemo51, 25 February 2024 - 11:14 AM.

[KevH]

Ok, folks, I appreciate the responses but please, this is about the product, not me. For those who care, I have no meaningful close vision after a cataract surgery that didn’t go well, and a neurological condition in my hands. 
 

yes, I have a glatter laser and tublug and find collimation zen like!

 

i speculate, based on the comments of apparently learned folks, here, it is a fabrication defect, resulting in pinched optics, not a design defect. Sadly, age has me in its grips and while I can see a laser spot, I cannot focus on a tiny screw head nor likely hold a tiny screw driver in place without scratching something. Fortunately, life was good to me and I can pay for someone to do it. 
 

Maybe I missed it in the thread and if so I apologize...  Have you reached out to Astronomics?  I would definitely contact them before paying someone to look at the scope.  My experience with them is they will make sure you are happy.  They may be able to make the small adjustments for you.  They may send you a replacement.  It's certainly worth reaching out to them if you haven't already.  Good luck!

[Helvetios]

This telescope has also received attention in the thread:

 

https://www.cloudyni...o-tech-at60edp/

 

I posted 3x3 inspection image there that shows the file flatness is very good over a full frame mirrorless sensor (36x24mm).

 

However, it does show distorted bright stars that have a 120 deg symmetry (reproduced here), not 90 deg.  Not sure what is going on, since there is nothing in the aperture that should cause this.  It is supposed to be clear for me tonight, so I will investigate further and also image the Rosette nebula with an ASI2600MC to assess the overall performance at this sensor scale for a deep-sky image.

 

It is supposed to be about 10 deg F warmer than when I first used the telescope.  If the problem is reduced, that would suggest temperature-induced pinch.  In any case, I will call Astronomics and report what I'm finding.  If they suggest loosening lens screws, I'm up for that.  I really like this scope and hope it's just overtightened screws, though I'm still not sure if this is what is going on in my case.

 

 

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