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WO ZS61 Optical Issues.

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26 replies to this topic

#1 Aaron_tragle

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Posted 23 August 2018 - 11:02 AM

I believe my ZS61 has some optical problems. The stars are extremely bloated even in relatively short exposures and have three weird things in the shape of a triangle. I have posted an example along with the post, it is a RAW 60 sub-exposure around the NGC 1499 area.

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#2 nicknacknock

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Posted 23 August 2018 - 12:17 PM

The spikes seem to be artifacts from the spacers / washers between the optical elements.

 

Also, there is some kind of tilt in your imaging system - too premature to blame the optical system as it could be how you connect the camera to scope, the focuser having some tilt, how any extensions used snap together etc...

 

Do you use a UV/IR Filter? If not, you will definitely have some bloatness in stars...


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#3 Aaron_tragle

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Posted 23 August 2018 - 12:23 PM

Everything is tightly threaded together. Focuser may be to blame. The cam is ha modded with a UVIR put back into the camera.



#4 timmbottoni

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Posted 23 August 2018 - 01:21 PM

Do you have the WO Flat 61 flattener?  

 

If not, curvature will be quickly seen on any image.

 

Check out some of the images in my Review thread from last year for comparison...

https://www.cloudyni...tions-welcome/ 

 

Timm



#5 Aaron_tragle

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Posted 23 August 2018 - 01:41 PM

Do you have the WO Flat 61 flattener?  

 

If not, curvature will be quickly seen on any image.

 

Check out some of the images in my Review thread from last year for comparison...

https://www.cloudyni...tions-welcome/ 

 

Timm

I do have the Flat61 and it works great



#6 Aaron_tragle

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Posted 23 August 2018 - 01:49 PM

Could this be pinched optics?



#7 entilza

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Posted 23 August 2018 - 01:57 PM

For any full analysis you need to give us a full raw-frame to examine.

#8 Aaron_tragle

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Posted 23 August 2018 - 02:01 PM

Can do. https://drive.google...iew?usp=sharing



#9 entilza

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Posted 23 August 2018 - 02:52 PM

It's really not so bad, not sure how much that would bother me as that was a fairly bright star. (Epsilon Perseus)

Are there any spacers around the edge of the cell that are in the path?

#10 Aaron_tragle

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Posted 23 August 2018 - 02:54 PM

It's really not so bad, not sure how much that would bother me as that was a fairly bright star. (Epsilon Perseus)

Are there any spacers around the edge of the cell that are in the path?

There are not, I think it may be the collimation screws for the lens cell getting in the light path.



#11 Lead_Weight

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Posted 23 August 2018 - 02:59 PM

I believe this scope is the same as the AT60ED which I have. I’ve also experienced bloated stars. I’m wondering if this has to do with it’s optical design and the fact that it’s a doublet.  Not entirely sure here, but here’s a link to a bunch of images taken with it that exhibit the same issues (some of mine included, but i see others showing the same issue). 


Edited by Lead_Weight, 23 August 2018 - 02:59 PM.


#12 Aaron_tragle

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Posted 23 August 2018 - 03:03 PM

I believe this scope is the same as the AT60ED which I have. I’ve also experienced bloated stars. I’m wondering if this has to do with it’s optical design and the fact that it’s a doublet.  Not entirely sure here, but here’s a link to a bunch of images taken with it that exhibit the same issues (some of mine included, but i see others showing the same issue). 

I am 90% sure they use the same lens elements and flattener. I have compared the scopes side by side before and they are shockingly similar. The only qualm I have with the Z61 is star shape, I think that may be my Achilles heel with this scope though.



#13 Aaron_tragle

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Posted 28 August 2018 - 07:08 PM

Just wanted to update this thread, I contacted William and he gave detailed instructions on how to remedy the spikes and bloated stars. We both believed it was pinched optics to blame, I loosened the lens screws a bit and the spikes are gone. Thank you to William for his amazing service.


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#14 Lead_Weight

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Posted 28 August 2018 - 07:20 PM

Did it do anything for the bloated stars?

#15 Aaron_tragle

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Posted 28 August 2018 - 08:31 PM

It helped reduce them a tad.



#16 Salty_snack

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Posted 28 August 2018 - 11:55 PM

It really didn’t look bad before but I’m glad William got it ironed out for you.

#17 gferla

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Posted 07 January 2019 - 09:44 PM

Hi Aaron,

 

Could you please provide those instructions?  I'm experiencing the same issue with my Z61, and I think it's exacerbated by the very cold temps I shoot in in the winter.

 

Thanks!

 

Guillermo



#18 Taylor

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Posted 08 January 2019 - 12:59 PM

Here is my AT60ED shot. Zoom in on the brighter stars, it looks to have the same issues. https://www.cloudyni...-1546734581.jpg

#19 Aaron_tragle

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Posted 08 January 2019 - 08:43 PM

Hi Aaron,

 

Could you please provide those instructions?  I'm experiencing the same issue with my Z61, and I think it's exacerbated by the very cold temps I shoot in in the winter.

 

Thanks!

 

Guillermo

"Please remove the dew shield first, just loosen all three screws start from 1/8 turn counterclockwise .

Wait for 6 hours and see if it will fix the shape on star.

If not, try again with 1/8 turn and check.

See pictures attached

I think it will fix the problem.
Please let me know.

Thank you."


Edited by Aaron_tragle, 08 January 2019 - 08:44 PM.

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#20 gferla

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Posted 08 January 2019 - 09:00 PM

Thanks, Aaron!



#21 timmbottoni

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Posted 09 January 2019 - 03:41 PM

To remove the dew shield, hold the colored ring with one hand, and unscrew the white large dew shield part with the other hand (counter clockwise of course).  

 

All of the current WO scopes have dew shields that are assembled this way smile.gif

 

Everything on a WO scope is essentially "assembled" from parts that thread together or screw together somehow so essentially everything could be removed or adjusted by the user (although I wouldn't advise total disassembly of most parts).  It depends on how mechanically inclined (and brave) you are.  

 

A very small amount of loosening of the collimation screws in the lens cell, may be enough to make those spikes totally go away.  Take a pencil or some sort of marker and mark where the slot is positioned before you start if you like so that you know how much you loosened it.  1/8 turn is likely all that is needed for each.

 

And keep in mind that in some cases large temperature change can make a big difference to the thermal expansion rates of the different parts, i.e. glass vs aluminum expand and contract at very different amounts and rates.

 

If you live in Chicago, that can happen in a matter of hours. It was 52 deg F on Monday, today its a high of 20. bawling.gif



#22 Mike Conley

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Posted 11 January 2019 - 07:41 AM

I have the at60ed and could get the dew shield to break free from the colored ring. 



#23 Hypoxic

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Posted 07 May 2020 - 09:43 AM

"Please remove the dew shield first, just loosen all three screws start from 1/8 turn counterclockwise .

Wait for 6 hours and see if it will fix the shape on star.

If not, try again with 1/8 turn and check.

See pictures attached

I think it will fix the problem.
Please let me know.

Thank you."

Which screws were loosened? There are two screws at each adjustment point under the dew shield on the Z61.



#24 Aaron_tragle

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Posted 26 June 2020 - 06:13 PM

Which screws were loosened? There are two screws at each adjustment point under the dew shield on the Z61.

I can try to dig up the email with the mentioned pictures, but it is almost 2 years ago now and I have cleaned my email since.



#25 OldManSky

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Posted 26 June 2020 - 10:23 PM

I can try to dig up the email with the mentioned pictures, but it is almost 2 years ago now and I have cleaned my email since.

It's the front (towards the front of the scope, away from the focuser) screw of each pair.  Leave the rear ones alone.

You shouldn't need more than 1/4 of a turn 1/2 at the most, to completely relieve the issue.


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