experimenting with eye pieces

A place to talk about Sky at Night Magazine's comprehensive reviews section

experimenting with eye pieces

Postby brian mac » Sun Apr 16, 2006 1:00 pm

Hi, as this is for group test, i thought i would see if anybody tries anythink like this!..messing about with mirrors, barlows and eyepieces. I found that if you put your barlow in first then your mirror,then your eyepiece, it increases power by another fifty percent, even using two barlows in various combinations works, double-double power is possibal, that is on my 120mm refractor, can't say if it works on other types of scope. But power is not as important as light gathering,that needs a bit more technical tinkering[:@]....[size=4]BRIAN[/size]
brian mac
 
Posts: 236
Joined: Mon Feb 13, 2012 6:25 pm

RE: experimenting with eye pieces

Postby sftonkin » Sun Apr 16, 2006 1:33 pm

Indeed. Putting the Barlow before the diagonal, or using an extension tube, is a common method of increasing the amplification factor.

The mathematics of why is on [url=http://www.astunit.com/tutorials/barlow.htm]this page[/url].

(This is also why the effective focal length of an SCT or MCT varies if it is focused, as is usual, by moving the primary mirror.)
sftonkin
 
Posts: 2826
Joined: Mon Feb 13, 2012 6:22 pm

RE: experimenting with eye pieces

Postby brian mac » Sun Apr 16, 2006 1:50 pm

Thanks Stephen for that info and the site on barlows, i don't fully understand these things but learning fast. Wish i was 18 again....[size=3]BRIAN[/size]
brian mac
 
Posts: 236
Joined: Mon Feb 13, 2012 6:25 pm

RE: experimenting with eye pieces

Postby jsc248 » Tue Apr 18, 2006 12:46 pm

Hi Brian and Stephen,
I have also tried using the barlows but have found that this decreases the surface brightness of the object you are observing. Plus if you have a hand driven scope like mine, then you need quick hands to keep the object in the eyepiece!
John.
To me astronomy is looking up and thinking "What the heck is going on up there!!"
jsc248
 
Posts: 3598
Joined: Wed Apr 27, 2011 7:23 pm
Location: Huyton,Merseyside


Return to First Light and Group Test

Who is online

Users browsing this forum: No registered users and 0 guests

cron