Hyperstar issue

[smez]

I am using an edgehd 8 hyperstar and asi2600mc and my subs look like this. Any ideas?

[michael8554]

Posting a fuzzy, covered in reflections, camera copy of a computer screen, is not going to give us any useful information to work on.

Is this how you would process your images ?

At the very least use the PrntScrn button on the keyboard to grab a screen image to the Clipboard.

Even better Save the image and post that.

Michael

Edited May 7, 2023 by michael8554

[Elp]

As above, at the very least describe the issue you're seeing. If I had to guess I'm assuming something to do with what seems like an overexposed centre but without proper input it could be anything.

[smez]

This was a 10 sec exposure. I tried anywhere from gain 120 to 0, bin 1 and bin 2. It is like I see the optical tube and then a shadow of it below it and then black around the corners. I attached the original image and will take another tonight if it doesnt rain with just a screen shot

Edgehd

asi2600mc

hyperstar w / filter drawer 

and I am using a primalucelab esatto 2

[Elp]

Hyperstar does vignette quite a lot, do you know what version HS you've got? V3 has an imaging circle of 27mm and V4 is 28mm, your camera is 28.3mm so the vignette will be more pronounced. Any extended dew shield in the fov will also affect this. As long as your light frame histogram is not clipped in white or black they should be fine. The image will calibrate fine with correct flats and you may have to crop.

Edited May 7, 2023 by Elp

[ollypenrice]

It would certainly be best to post a stretched JPEG plus a link to to an unprocessed sub for those who can download it in a reasonable time.  What you've posted contains nothing of diagnostic value.

Olly

[smez]

Elp I have v4 and do not use a dew shield currently, I am going to try to rotate the camera to see if that helps with the banding as well.

[smez]

Thanks Olly as soon as I can get out again I will handle the image differently

[Elp]

As mentioned it will help if you post your existing image within this thread using the upload/insert button when you make a new post. If you can't convert and post a jpg image (no excuse for this as this is easy to do), at least upload the raw fits. People will be more likely to respond if it's a jpg image, and not a photo of your computer screen. They may also note issues which you aren't aware of before you go out again for a new session.

[smez]

Thanks for the help. I did find one image that was actually saved and converted to jpeg.

[smez]

I stretched it in pixinsight

[SamAndrew]

Probably collimation, judging by the chip not being evenly illuminated and the shapes of the stars. Could also be spacing as well, but can't get that sorted till the collimation is sorted.

Hyperstar is a challenging setup, good luck!

[ollypenrice]

9 minutes ago, SamAndrew said:

 

Hyperstar is a challenging setup, good luck!

Starizona say it is easy. They lie.

Olly

[The Lazy Astronomer]

Your solution is to buy a RASA. Don't worry though, I'll take the current useless scope off your hands 😁

 

*Obviously I'm joking!!

[smez]

Considered a RASA but chose the Edge for the different focal length possibilities

 

[Fegato]

If that's vignetting, it's strange how extremely off centre the sensor is to the light path, given the way the Hyperstar attaches. Sorry if obvious questions but did you reset the Hyperstar so it the adjustment screws were all at the same level (e.g. using small shims)? And is everything totally tightly attached? Beyond that, yes collimation is the first step

[Elp]

Collimation doesn't explain the vignette though, the stars aren't overly distorted at first view to suggest excessive tilt in one direction. You'd need to do an out of focus star test to determine the collimation. Regarding initial HS setting for the push pull screws Starizona recommend that there be no gap to start with. Regarding vignette have you tried without the filter drawer and are you using filters larger than your sensor size diagonal? I sometimes use a 294mc with mine and it does vignette at the edges because the sensor diagonal is larger than the recommended image illumination size, however my vignette is even in each corner.

 

[Fegato]

 

2 minutes ago, Elp said:

Collimation doesn't explain the vignette though, the stars aren't overly distorted at first view to suggest excessive tilt in one direction. You'd need to do an out of focus star test to determine the collimation. Regarding initial HS setting for the push pull screws Starizona recommend that there be no gap to start with. Regarding vignette have you tried without the filter drawer and are you using filters larger than your sensor size diagonal? I sometimes use a 294mc with mine and it does vignette at the edges because the sensor diagonal is larger than the recommended image illumination size, however my vignette is even in each corner.

 

Yes I had a small vignette with the ASI294MC Pro with mine too, but always pretty even as yours. Agree about the stars - if they're not too bad, then implies collimation should be close. And I forgot about the filter draw - but that would have to be wonky to produce that end result presumably?

re: the Starizona recommendation to start fully pushed in, that always seemed a bit silly to me, as you can then only move in one direction (albeit it does ensure you're totally flat I guess). I used John Hayes recommendations as here - https://www.cloudynights.com/articles/cat/articles/the-amazing-hyperstar-a-guide-to-optimize-perf-r3013

[Elp]

After much research I tried the shim method also with old bank card cut up (roughly an even 1mm all around), I wasted so many sessions trying to adjust, turns out my lens was faulty. The replacement as it was received with no adjustment gap with zero adjustment just worked. And I continue to use it like that and set up and break down every single session. Tbh I don't pay too much attention to the corner stars, at the end of the day I'm imaging a target centre of view, it's far easier to crop than drive yourself mad for perfection especially if setting up every time. I guess the larger the sensor the larger the problem.

Just out of interest, I was also advised when collimating only the centre star needs to be even (as the outer ones started to elongate from centre when defocused), this doesn't seem right to me and one would expect the whole field to be the same as the centre star. Maybe it's an f2 thing?

Edited May 8, 2023 by Elp

[smez]

When I received mine it was loose and I had read to tighten all the way down to start with, then I had to adjust tilt which helped with stars but the results of all my previews were the same. I do have some material I can use for shims and will try that tonight. Also want to make sure about back focus which I believe is 39.8 mm.  Not looking for perfection by any means that would make you mad for sure.