www.photomacrography.net :: View topic - Stage micrometer slide image
www.photomacrography.net Forum Index
An online community dedicated to the practices of photomacrography, close-up and macro photography, and photomicrography.
Photomacrography Front Page Amateurmicrography Front Page
Old Forums/Galleries
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Stage micrometer slide image

 
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Macro
View previous topic :: View next topic  
Author Message
Photosbykev



Joined: 06 Mar 2015
Posts: 14
Location: Gloucester, UK

PostPosted: Tue Mar 27, 2018 10:09 am    Post subject: Stage micrometer slide image Reply with quote

Can someone just confirm my math is correct based on the image shown below please?



This link is to an image which has been resized by exactly 50%

regards
Kev
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 19240
Location: Richland, Washington State, USA

PostPosted: Tue Mar 27, 2018 10:37 am    Post subject: Reply with quote

That all looks correct.

--Rik
Back to top
View user's profile Send private message Visit poster's website
Photosbykev



Joined: 06 Mar 2015
Posts: 14
Location: Gloucester, UK

PostPosted: Tue Mar 27, 2018 10:54 am    Post subject: Reply with quote

rjlittlefield wrote:
That all looks correct.

--Rik


Thank you Rik, that microscope slide you suggested is a very useful little tool.

regards
Kev
Back to top
View user's profile Send private message Visit poster's website
ChrisR
Site Admin


Joined: 14 Mar 2009
Posts: 7826
Location: Near London, UK

PostPosted: Tue Mar 27, 2018 11:16 am    Post subject: Reply with quote

Yes, the LSA isn't precisely 200mm. I measured one a year or so ago.
Then forgot..
_________________
Chris R
Back to top
View user's profile Send private message
Photosbykev



Joined: 06 Mar 2015
Posts: 14
Location: Gloucester, UK

PostPosted: Tue Mar 27, 2018 11:59 am    Post subject: Reply with quote

ChrisR wrote:
Yes, the LSA isn't precisely 200mm. I measured one a year or so ago.
Then forgot..

rightly or wrongly, I mounted the LSA on a M42 tube extension and a M42 > M52 helical focuser and then used the focuser to focus on a star last night so it's at a true infinity.

regards
Kev
Back to top
View user's profile Send private message Visit poster's website
rjlittlefield
Site Admin


Joined: 01 Aug 2006
Posts: 19240
Location: Richland, Washington State, USA

PostPosted: Tue Mar 27, 2018 12:29 pm    Post subject: Reply with quote

Photosbykev wrote:
I mounted the LSA on a M42 tube extension and a M42 > M52 helical focuser and then used the focuser to focus on a star last night so it's at a true infinity.

That's the correct approach to nominally minimize aberrations.

If having exactly 10.0X magnification ever becomes important, you can slightly increase the extension behind the LSA to achieve that. With the roughly 3% increase needed to go from 9.67X to 10.0X, you would never notice a change in aberrations. This is the method that I used to match magnification and field size in my tube lens tests at http://www.photomacrography.net/forum/viewtopic.php?t=23898 .

--Rik
Back to top
View user's profile Send private message Visit poster's website
Photosbykev



Joined: 06 Mar 2015
Posts: 14
Location: Gloucester, UK

PostPosted: Tue Mar 27, 2018 12:47 pm    Post subject: Reply with quote

rjlittlefield wrote:
Photosbykev wrote:
I mounted the LSA on a M42 tube extension and a M42 > M52 helical focuser and then used the focuser to focus on a star last night so it's at a true infinity.

That's the correct approach to nominally minimize aberrations.

If having exactly 10.0X magnification ever becomes important, you can slightly increase the extension behind the LSA to achieve that. With the roughly 3% increase needed to go from 9.67X to 10.0X, you would never notice a change in aberrations. This is the method that I used to match magnification and field size in my tube lens tests at http://www.photomacrography.net/forum/viewtopic.php?t=23898 .

--Rik


I'm not overly worried by the exact magnification, 9.67x is just fine now I know what it is Smile I need to flock line the extension tube to minimise any internal reflections and I'm good to go Smile

regards
Kev
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic    www.photomacrography.net Forum Index -> Beginners Macro All times are GMT - 7 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group