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Can anyone send me a raw sub taken with an Orion ED80?

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#1 janame

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Posted 09 July 2020 - 03:00 AM

I've been trying to figure out why I have non concentric red and blue halos around stars with my Orion ED80 for some time now. Eventually I concluded there must me something wrong with my copy of the telescope, so I bought a new one directly from Orion. To my surprise, it's *exactly* the same.

Now I'm starting to wonder if this is just how the ed80 is. Can anybody send me a raw sub taken with their ed80 so I can compare?

#2 sharkmelley

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Posted 09 July 2020 - 03:21 AM

You might be better off posting an example of what you are seeing.  People can then give advice on whether or not it is normal.

 

What kind of camera are you using?  Are you using a filter?

 

Mark


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#3 Stelios

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Posted 09 July 2020 - 03:23 AM

I had a Celestron ED80, which should be essentially the same scope (F/7.5 ED doublet).

 

Here's a link to an unprocessed .CR2 image taken more than 7 years ago with a Canon T3i DSLR. (I have more recent images, but taken with a mono camera).

 

I don't know for a fact that the Orion ED80 and the Celestron ED80 are identical, though they definitely *look* very similar and have similar specs. 

 

I also want to know if you're using a filter. 

 


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#4 Huangdi

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Posted 09 July 2020 - 05:04 AM

It's a doublet. That's the end of the story. If you want nice stars, buy a triplet..
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#5 Tapio

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Posted 09 July 2020 - 05:18 AM

Don't know. It's a pretty good doublet and slowish so it shouldn't show too much CA.

But let's see if we can see some evidence in the form of images.


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#6 sn2006gy

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Posted 09 July 2020 - 07:44 AM

It's a doublet. That's the end of the story. If you want nice stars, buy a triplet..

I have an Orion ED80 with their focal .8x reducer and I get nice stars.

 

Here are some processed images

 

crescent nebula
 
elephant Ha Oii
 
ring nebula take 2
 
My bloated stars are mostly me messing with L-Enhance and too long exposure so i'm practicing with that right now.  
 
Most people are rather impressed with my FOV, Flattness and quality i'm getting off this amazing scope.

Edited by sn2006gy, 09 July 2020 - 08:07 AM.

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#7 sn2006gy

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Posted 09 July 2020 - 07:45 AM

non debayered single 300s sub just screenshotted from PI... it will look a bit funky so my processed images are probably better to look at. I only mask my stars, i don't ever shrink/binarize/reduce or cheat them of their glory smile.gif

 

single Sub 300s
 
We don't have a "Real" apo because its not a TRIPLET but i find the no true scottsman argument to be a complete waste of time.
 
I'm a double sinner, i shoot OSC

Edited by sn2006gy, 09 July 2020 - 07:56 AM.

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#8 sn2006gy

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Posted 09 July 2020 - 08:10 AM

I *am* getting a bit of halos around stars with the terrible Saharan dust we have... making imaging/tracking very fun and focusing even more fun.. is that what you're running into? most of my stars are fine for me... some will "blow out" on my l-enhance - just ran a different much shorter but more subs run last night i'm about to process to see if that helps with dust/star blow out


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#9 sn2006gy

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Posted 09 July 2020 - 08:17 AM

Here are a couple of raw subs in fits for the above image - https://1drv.ms/u/s!..._Hn88A?e=TQy6oD


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#10 Stelios

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Posted 09 July 2020 - 01:29 PM

It's a doublet. That's the end of the story. If you want nice stars, buy a triplet..

Not my experience. The difference in star quality is small, and has nothing to do with concentric circles of different colors.


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#11 janame

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Posted 09 July 2020 - 02:48 PM

You might be better off posting an example of what you are seeing.  People can then give advice on whether or not it is normal.

 

Here's an example:

m13-180s-100-50-newscope.jpg

 

This is a crop of a single sub to make the image small enough to attach here.  M13 is centered in the frame and the star in the upper right corner shows what's going on.  Big blue halo on one side, small red halo on the other, and they're not concentric.

 

Another example with more stars:

m16-180s-100-50-newscope.jpg

 

Again, a crop from center.

 

Processed in PI with: Debayer, ABE, ArcsinhStretch.  You can even see one side of the star is red and the opposite side blue with just the debayer.

 

I'm using: ASI2600MC (I've also used a stock Canon T2i, same issue), Orion Field Flattener for Short Refractors (have tried removing, same issue), Orion ED80.  There's nothing else in the optical train, no filters.

 

-M13 was pretty much straight up last night, so it's not atmospheric dispersion.  M16 was lower, about 35 degrees.

 

With the old scope:

-I thought sensor tilt might be the culprit, so I tried loosing two of the three screws holding the focuser and intentionally putting some small angle on it, expecting the problem to get either worse or better, but it was the same.

-The "axis" of the halos rotates if I rotate the camera.

-I tried cleaning the objective (it was *really* dusty), no effect. 

-I removed and replaced the lens cell from the OTA (but did not take the lens cell apart), no effect. 

 

Edit: I forgot to add, with the old scope I was autofocusing with NINA and getting nice V-curves, so I don't think focus is the issue.  Last night, with the new scope, I just used a bahtinov mask and focused manually because I didn't want to move my EAF until I tested the scope.

 

So, I concluded there must be something wrong with the glass in my copy of the scope (I'd read about wedge potentially causing an issue like this).  But since the new copy does the same exact thing... either this is the expected behavior of the scope, there's a common defect, or there's something else going on that hasn't been thought of yet.


Edited by janame, 09 July 2020 - 02:50 PM.


#12 janame

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Posted 09 July 2020 - 03:01 PM

I had a Celestron ED80, which should be essentially the same scope (F/7.5 ED doublet).

 

Here's a link to an unprocessed .CR2 image taken more than 7 years ago with a Canon T3i DSLR. (I have more recent images, but taken with a mono camera).

 

Thank you!  I do see a very, very slight amount of color in your image, blue on the top and red on the bottom.  But it's insignificant, and I'd definitely be happy with that.  In fact, it's so minor, I'm not sure I can see it in the JPG, but I do see it in PI.

 

M33-Stelios.jpg

 

To compare, here's the same field I took some months ago with a T2i, ISO1600, 180s, with the flattener:

M33-janame.jpg

 

So, either the Celestron ED80 is not the same as the Orion ED80, both of my Orion ED80s are defective, or there's something else going on.



#13 janame

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Posted 09 July 2020 - 03:17 PM

Here are a couple of raw subs in fits for the above image - https://1drv.ms/u/s!..._Hn88A?e=TQy6oD

Thank you!  Was this with the L-eNhance?  Looking at the transmission curve for that filter, it cuts around 470.  I do see the halo you mentioned and I'm surprised that would still happen with a filter that cuts so aggressively!  I'd been wondering if it was worth trying an Astronomik L3 which cuts at 420, but maybe not.



#14 Stelios

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Posted 09 July 2020 - 04:42 PM

I did something weird which improved your stars and sort of points your scope as the culprit.

 

You can try it.

 

I split the three channels using Channel Extraction (RGB). (This is in itself educational--the Green is much better focused than the rest). If you now blink the three channels, you'll see the stars are WAY off on the R and B compared to the G. 

 

Using the Green as the main channel, I now star-aligned the three frames. 

 

I now used Channel Combination to combine the aligned frames. This was still color-misaligned, but the alignment had shifted.

 

Using pixelmath I added (rescaling) the original and the combined-after-star-alignment images. This did not eliminate but certainly reduced the error. Similar experimentation should improve even further.

 

I do think that you have a rather poor example of an ED scope (whether that's within specs or not, I don't know). I think that the three colors focus quite differently, with their spreads overlapping. I *have* seen this, but to a far smaller extent than in your scope. 


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#15 sn2006gy

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Posted 09 July 2020 - 05:25 PM

Thank you!  Was this with the L-eNhance?  Looking at the transmission curve for that filter, it cuts around 470.  I do see the halo you mentioned and I'm surprised that would still happen with a filter that cuts so aggressively!  I'd been wondering if it was worth trying an Astronomik L3 which cuts at 420, but maybe not.

Yeah, now that you mention it,  this was screwing around with l-enhance waiting for nebula to get higher. I have other shots of Hercules cluster without the filter. Normally i'd use the l-pro or no filter on the globulars


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#16 janame

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Posted 09 July 2020 - 07:13 PM

[...]

 

Using pixelmath I added (rescaling) the original and the combined-after-star-alignment images. This did not eliminate but certainly reduced the error. Similar experimentation should improve even further.

 

I do think that you have a rather poor example of an ED scope (whether that's within specs or not, I don't know). I think that the three colors focus quite differently, with their spreads overlapping. I *have* seen this, but to a far smaller extent than in your scope. 

Thanks for taking the time to try this out!  I've done the split/align/recombine before and it helps, but it still looks pretty yucky, as you noticed.  What I haven't done is to add the original with the realigned image.  Can you tell me more about how you did that?  A pixel-by-pixel add doesn't seem like the right thing to do, so I think I'm missing something here.

 

The original ED80 I bought used a little over a year ago, so I doubt that there has just been a bad batch of these.  Perhaps they changed something in how they're manufactured?  I've contacted Orion to see what they have to say.  It would be great if they can exchange it for a scope that actually works but I'm not too hopeful about that.

 

Not to get too off-topic here, but this experience leaves me super frustrated.  Clearly I need a different telescope, but I don't know what I can trust at this point.  With a budget of around $1k, what refractor should I consider?  Not sure how to navigate FPL-51/FPL-53 and doublet/triplet.  Sure, I can read specs, but obviously that's not the whole story.  The Orion ED80 with FPL-53 is supposed to be good!

 

I've got an Orion Sirius (which I'm only lukewarm on with a guide RMS 1.5-2.5"), so I need to stick with something relatively light weight.  I don't want diffraction spikes, otherwise I might consider switching to a newt... not sure if the Sirius is up for an ES 6" mak-newt (15.5lbs and long), or an EdgeHD8 + Reducer (over budget anyhow).  RASA8 is definitely over budget, seems to have it's own quirks, and kinda sorta has diffraction spikes.

 

I just bought the ASI2600 so trying to keep my astro expenditure down for a while!  Need something to use it with, though.  Sigh.



#17 terry59

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Posted 10 July 2020 - 07:33 AM

I extracted the channels and found this pattern when I zoomed in. Can you make a single sub available?

Attached Thumbnails

  • Capture.JPG

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#18 terry59

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Posted 10 July 2020 - 07:37 AM

Here are the three channels from my Orion ED80 (now sold)

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#19 janame

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Posted 10 July 2020 - 02:38 PM

I extracted the channels and found this pattern when I zoomed in. Can you make a single sub available?

 

Sure, here's the raw sub: https://drive.google...iew?usp=sharing

The pattern you're seeing looks like JPG compression artifacts to me, and I don't see it in the raw sub.

 

Here are the three channels from my Orion ED80 (now sold)

Could you post the raw sub for this?  It's a little hard to see what's going on in the screenshot.  Thanks!



#20 terry59

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Posted 10 July 2020 - 03:07 PM

Sure, here's the raw sub: https://drive.google...iew?usp=sharing

The pattern you're seeing looks like JPG compression artifacts to me, and I don't see it in the raw sub.

 

Could you post the raw sub for this?  It's a little hard to see what's going on in the screenshot.  Thanks!

I'm convinced that the issue is with your processing. Your stars shouldn't look like they do in the extracted channels given how they look in the sub you shared. Here is a zoomed in .jpg image of mine taken with the ED80 and an Atik 314L+ mono camera....no artifacts like yours

 

The data is old and I don't have the raw subs any longer, just the final image....sorry

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Edited by terry59, 10 July 2020 - 03:17 PM.

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#21 Tor

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Posted 10 July 2020 - 07:59 PM

Hi,

 

I've been struggling with what i believe is the same issue, from my experience the arcsinh stretch really brings it out. With histogram stretch where i let the stars bloat a bit it is barely noticeable.

 

I have a Star71 with a ASI183MC Pro camera, I've tried with both a Astronomik L-1 and L-3 for uv/ir cut, with no difference.

 

The only workaround i've been able to find that look half way decent is displacing my red channel by half a pixel down and to the right, and the blue channel by half a pixel up and to the left.

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  • shift.jpg

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#22 Stelios

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Posted 10 July 2020 - 08:30 PM

Hi,

 

I've been struggling with what i believe is the same issue, from my experience the arcsinh stretch really brings it out. With histogram stretch where i let the stars bloat a bit it is barely noticeable.

 

I have a Star71 with a ASI183MC Pro camera, I've tried with both a Astronomik L-1 and L-3 for uv/ir cut, with no difference.

 

The only workaround i've been able to find that look half way decent is displacing my red channel by half a pixel down and to the right, and the blue channel by half a pixel up and to the left.

And a fine workaround it is! Did you do that in Pixinsight? I played with the Channel Match process but could not figure out how to control the shift direction--the arrows just changed the pixel numbers. 


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#23 sn2006gy

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Posted 10 July 2020 - 08:32 PM

Ran a different filter last night. No big stars to really worry about. Pretty happy with color - its NB all the way so i was surprised i got the stars cleaned up at all

 

panel 1 work progress

 

happy to share a raw if you still want to poke around. I hope my seeing is better tonight. Last night i couldn't stay below 0c on cooler and the dust was terrrrrible.


Edited by sn2006gy, 10 July 2020 - 08:33 PM.


#24 janame

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Posted 10 July 2020 - 11:05 PM

Hi,

 

I've been struggling with what i believe is the same issue, from my experience the arcsinh stretch really brings it out. With histogram stretch where i let the stars bloat a bit it is barely noticeable.

 

I have a Star71 with a ASI183MC Pro camera, I've tried with both a Astronomik L-1 and L-3 for uv/ir cut, with no difference.

 

The only workaround i've been able to find that look half way decent is displacing my red channel by half a pixel down and to the right, and the blue channel by half a pixel up and to the left.

Wow, yes, that looks very similar to what I'm seeing.  I'm really surprised though that a Star71 (FPL-53 quadruplet!) would have this problem.  Have you asked William Optics about it?

 

I agree arcsinh makes it more noticeable.  I've actually been using rnc-color-stretch (based on arcsinh) for a long time because I didn't have PI until recently, and I've tried repeatedly to do histogram stretch in GIMP and it *never* looks good.  Not because of the halo issue, but because I'm not doing it right, I guess.  I do need to get more comfortable with stretching in PI, though, because I'm starting to get frustrated with some of the limitations of rnc-color-stretch.

 

ChannelMatch definitely helps, although I like the automation of the split/align/recombine.

 

Here's my previous experience with ChannelMatch:

no_shift.jpg

shift.jpg



#25 janame

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Posted 10 July 2020 - 11:08 PM

And a fine workaround it is! Did you do that in Pixinsight? I played with the Channel Match process but could not figure out how to control the shift direction--the arrows just changed the pixel numbers. 

You can control the shift direction by putting in a negative value for offset.

 

Can you tell me about the pixelmath trick you mentioned previously?  I didn't quite follow what you were adding / rescaling.




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