Quote:
Originally Posted by multiweb
So you can increase magnification by increasing the spacing? Cool. Sorry if it's a stupid question but what's the difference between a barlow and a powermate? I have a x2 GSO barlow. If I space it should I be able to get more magnification like x3 maybe?
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Hi Marc, I have attached a link to a primer on Barlows and Powermates.
http://www.bintel.com.au/Barlows.html
I think you will find that using extension spacers will increase the power that your barlow delivers.
For imaging purposes it would already deliver more than 2 x.
Your 2 x Barlow delivers 2 x at the top surface of the Barlow. Even without using a filter wheel there would be an added distance between the surface of your CCD chip and the top surface of your 2 x Barlow which would result in more magnification.
Marc, I have attached performance graphs for Televue Barlows and Powermates, these graphs clearly demonstrate the relationship that variations in the distance between the top surface of the Barlow or Powermate have on magnification.
Note that with the 4 x Powermate this effect is considerably less as the light leaving it is on more of a parallel path than with the other Powermates or Barlows.
Hope this helps to answer your questions.
Cheers
Trevor