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Is Takahashi EM-2 usable for long time exposure?

Started by Jianhuachu, 02/12/2004 12:40PM
Posted 02/12/2004 12:40PM Opening Post
Hi, guys
I am just getting into film astrophotography. I own a Takahashi EM-2 mount which has only one axis drive. I wonder If this mount is usable for long time exposure.
I understand that in order to do star guiding, you need to adjust both axis from time to time. The declination axis on the EM2 is only adjustable manually. Will the manual adjustion introduce vibration that fails guiding?
Are there anyone having experience takine long time exposure with the Takahashi EM-2? Thank you for any suggestions


Jianhua Chu
Posted 02/12/2004 12:45PM #1
Hi,

It really depends on your optics. If its focal length is less than 200mm, perhaps you can guided it without touching the DEC axis for 30 to even 60 minutes. Of course this also depends on the accuracy of your polar alignment. The polarscope of EM2 has reasonable accuracy. I believe 30min of guiding for f<200mm is easy.

Wei-Hao

Wei-Hao Wang
http://www.aoc.nrao.edu/~whwang