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Hotech 2" SCA self-centering field flattener to Canon 5D Mark III

Astrophotography Beginner DSLR Refractor
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#1 AlwaysANewb

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Posted 29 November 2021 - 07:38 PM

Hello Experts:

I am fairly new to Astrophotography.  I have a explore scientific 80mm refractor and a Canon 5D Mark iii DSLR.  To get sharp stars across the viewing plan, I choose to buy a Hotech 2'' Field Flattener (read a lot of discussion here and settled for it). The recommendation from the vendor is to have 55mm spacing between the focal plan or image sensor and the flattener. 

I had to buy a M48 to M42 t-adapter to get the flattener connected to the camera.  It is my understanding that the flange distance of the camera is 44mm. The T-ring(William Optics 48mm for Canon) is 10mm. So this give me 54mm.  Do I just need a 1mm spacer or more. 

 

Has anyone used this flattener and Canon 5D Mark iii DSLR?  How did you make it work. 

Also, In layman term can someone simplify the meaning of "self centering" for this flattener.

 

 

Thanks

AlwaysANewb


Edited by AlwaysANewb, 29 November 2021 - 08:35 PM.


#2 mehdymo

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Posted 29 November 2021 - 07:54 PM

You mean 1mm or more?

Just add a thin spacer. You can cut one out of any durable material such as the advertisement cards that you receive in you mails every day :) or simply by a few. There are some people here that sell them for a few bucks. 

 

Thanks,

Mo



#3 mehdymo

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Posted 29 November 2021 - 07:58 PM

Remember that sometimes these parts do not screw all the way and your final spacing can be different. I mean it is not always 44+10. The best way is to measure it by a caliper.



#4 michael8554

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Posted 30 November 2021 - 07:51 AM

"I had to buy a M48 to M42 t-adapter to get the flattener connected to the camera"

 

I thought the Hotech had M48 threads to connect directly to a M48 T adapter to give 55mm back focus?

 

The industry standard for EOS T Adapters is 11mm to give a 55mm combined flange distance.

 

If the WO one is only 10mm then it's non-standard.




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