Re: [tec-scopes] TEC-140 FF (flange to focal plane distance)


Mar 7 8:29 PM

 


----------------------------

#27273 Mar 7 8:29 PM

Hello,

A few months ago I was lucky to be able to acquire TEC-140 #199 (with 27TVPH reducer). I also have a NJP Temma-2 mount and 2 DSLRS (Canon 70d and Sony A7S) as well as a QHY9 CCD. My main focus is photography, I have about 1 year experience with a smaller mount with DLSR's, lenses and auto-guiding. I am lucky to own a quite dark site in the province of Quebec.

I just purchased the TEC-140 Field Flattener and I am preparing to make it work with my cameras, starting with the Canon 70d. If I am correct I need to also purchase the AP 27RTCanon adapter. This has a total distance of 42.3 mm according to astro-physics website. If I add the Canon EOS Flange-focal-plane distance of 43.9 mm I end up with a total of 86.2 mm.  This is larger than the required 85 mm. I'd like to be as close as possible to the requirements given that I am planning to use a full-frame (35 mm x 24 mm) camera. (The Sony has a much shorter flange-focal-distance but including a Canon to Sony nex converter it totals to the same 44 mm).  

My question: Is 86.2 mm too large for perfect stars in the corners? Do I need to use a different T-ring or is there some other trick to get to the exact required distance of 85 mm?

Thank you for your response and any comments you might have,

Thank you,

Marco



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#27279 Mar 9 8:29 PM

Actually I think the correct camera adapter is the astro-physics 67RLEOS. It has a large inside diameter (1.875") specifically for 35mm canon EOS cameras (avoiding the restrictive 1.5" t thread interface of other adapters). I hope that will connect well with the TEC-140 field flattener and avoids vignetting.



The flange-focal plane distance would be 86 mm which is close to the requirement.



If someone can comment that would be great,



Thank you,



Marco





--------------- On Mon, 3/7/16, marcovanderkooij@... [tec-scopes] tec-scopes@yahoogroups.com> wrote:



Subject: [tec-scopes] TEC-140 FF (flange to focal plane distance)

To: tec-scopes@yahoogroups.com

Date: Monday, March 7, 2016, 11:29 PM



Hello,







A few months ago I was

lucky to be able to acquire TEC-140 #199 (with 27TVPH

reducer). I also have a NJP Temma-2 mount and 2 DSLRS (Canon

70d and Sony A7S) as well as a QHY9 CCD. My main focus is

photography, I have about 1 year experience with a smaller

mount with DLSR's, lenses and auto-guiding. I am lucky

to own a quite dark site in the province of Quebec.





I just

purchased the TEC-140 Field Flattener and I am preparing to

make it work with my cameras, starting with the Canon 70d.

If I am correct I need to also purchase the AP 27RTCanon

adapter. This has a total distance of 42.3 mm according to

astro-physics website. If I add the Canon EOS

Flange-focal-plane distance of 43.9 mm I end up with a total

of 86.2 mm.. This is larger than the required 85 mm.

I'd like to be as close as possible to the requirements

given that I am planning to use a full-frame (35 mm x 24 mm)

camera. (The Sony has a much shorter flange-focal-distance

but including a Canon to Sony nex converter it totals to the

same 44 mm)..





My question: Is 86.2 mm too large for perfect

stars in the corners? Do I need to use a different T-ring or

is there some other trick to get to the exact required

distance of 85 mm?





Thank you for your response and any comments

you might have,





Thank you,





Marco



----------------------------

#27284 Mar 10 7:43 AM

Marco, that is correct part, and going +1mm from original 85mm will not change performance. Yuri   

From: "Marco Vanderkooij marcovanderkooij@... [tec-scopes]" tec-scopes@yahoogroups.com>

Sent: Wednesday, March 09, 2016 9:35 PM

To: tec-scopes@yahoogroups.com

Subject: Re: [tec-scopes] TEC-140 FF (flange to focal plane distance) 

 Actually I think the correct camera adapter is the astro-physics 67RLEOS. It has a large inside diameter (1.875") specifically for 35mm canon EOS cameras (avoiding the restrictive 1.5" t thread interface of other adapters). I hope that will connect well with the TEC-140 field flattener and avoids vignetting.



The flange-focal plane distance would be 86 mm which is close to the requirement.



If someone can comment that would be great,



Thank you,



Marco



---------------

On Mon, 3/7/16, marcovanderkooij@... [tec-scopes] tec-scopes@yahoogroups.com> wrote:



Subject: [tec-scopes] TEC-140 FF (flange to focal plane distance)

To: tec-scopes@yahoogroups.com

Date: Monday, March 7, 2016, 11:29 PM



Hello,







A few months ago I was

lucky to be able to acquire TEC-140 #199 (with 27TVPH

reducer). I also have a NJP Temma-2 mount and 2 DSLRS (Canon

70d and Sony A7S) as well as a QHY9 CCD. My main focus is

photography, I have about 1 year experience with a smaller

mount with DLSR's, lenses and auto-guiding. I am lucky

to own a quite dark site in the province of Quebec.





I just

purchased the TEC-140 Field Flattener and I am preparing to

make it work with my cameras, starting with the Canon 70d.

If I am correct I need to also purchase the AP 27RTCanon

adapter. This has a total distance of 42.3 mm according to

astro-physics website. If I add the Canon EOS

Flange-focal-plane distance of 43.9 mm I end up with a total

of 86.2 mm.  This is larger than the required 85 mm.

I'd like to be as close as possible to the requirements

given that I am planning to use a full-frame (35 mm x 24 mm)

camera. (The Sony has a much shorter flange-focal-distance

but including a Canon to Sony nex converter it totals to the

same 44 mm). 





My question: Is 86.2 mm too large for perfect

stars in the corners? Do I need to use a different T-ring or

is there some other trick to get to the exact required

distance of 85 mm?





Thank you for your response and any comments

you might have,





Thank you,





Marco



 







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