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Pinched Optics ? Founder Optics triplet

Collimation DSLR Equipment Imaging Optics Refractor
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#1 the_astro_guyy

the_astro_guyy

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Posted 14 May 2024 - 04:30 AM

I did post this earlier but no response from anyone hence posting again 

 

 

Dear community members,

 

My fot86 triplet 560mm focal length 86mm aperture when paired with Canon EOS 1500D dslr shows distorted stars in image.

Founder optics 1x field flattener is used.

I have checked with guiding still stars does not look completely round.

Pixinsight solves alot of star shape issues but my inner self is not satisfied because the software is correcting it.

There were few instances where star shapes looked normal so not sure what is happening . Jupiter looks normal , bright huge stars like Sirius Rigel look out of shape and tiny stars look square or rectangle .

Attaching images below hope to get some guidance on the issue .

 

 

Attached image is of Vega star 

Attached Thumbnails

  • IMG_4340.jpg


#2 Aibrahim

Aibrahim

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Posted 14 May 2024 - 06:36 AM

It does look like pinched optics indeed.
Here's some causes of pinched optics:
1. Lens retaining ring is too tight- user adjustable.
2. Collimation screws too tight- not user adjustable in most cases.
3. Tube rings too tight- user adjustable. Just loosen the tension a bit but be careful the rings don't open and let go of your scope when mounted.
4. Lens cell housing shrink due to cold temperature- not user adjustable and telescope needs to be returned. Bad design as in the espirit lineup .
Hope that helps. Unless you were seeking different information
  • Megawatt, RichA and the_astro_guyy like this

#3 the_astro_guyy

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Posted 14 May 2024 - 06:45 AM

It does look like pinched optics indeed.
Here's some causes of pinched optics:
1. Lens retaining ring is too tight- user adjustable.
2. Collimation screws too tight- not user adjustable in most cases.
3. Tube rings too tight- user adjustable. Just loosen the tension a bit but be careful the rings don't open and let go of your scope when mounted.
4. Lens cell housing shrink due to cold temperature- not user adjustable and telescope needs to be returned. Bad design as in the espirit lineup .
Hope that helps. Unless you were seeking different information

Thanks for the response , 

 

i mailed founder optics they said to use threaded adapters for tilt but you are right pinched optics not user adjustable in case of collimation or lens cell housing.. i kept scope under Sun will check again when sky is clear to see if heating up expands the contracted housing or not. 

 

Tube rings also i will check thanks :)




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