Barlow question

[Hypernova]

I have tonight had a (brief) chance to try out the new focuser I fitted to my scope a week or two ago. My eyepiece on their own reach focus ok thanks to the seller including a 50mm extension tube with the focuser. I can't though unfortunately reach focus with my barlow in place, with or without the extension. It seems the focus point with the barlow is somewhere in between so I think I will need to buy a moonlite 1.5" extension if I am to use a barlow but I am not sure if that offers the right length.

I have though found out that I can focus eyepieces if the barlow lens element is screwed directly into the filter thread of an eyepiece. So the question I have to ask is what is the amount of extra mag I can get out of an eyepiece if I do this? I am thinking it is somewhere in the region of 1.5x, I am going on a barlow I saw that said by doing what I do it will offer 1.5x.

[kniclander]

I don't know the answer but I know a man who does... there was a thread on this by Andrew* (I think) who had done some calculations about the differing mags you get when you put the barlow in different places in the optical train...

[Hypernova]

I cannot seem to find the particular thread you are referring to, it must be buried somewhere in his post count.

Anyone have a link?

[Andrew*]

http://stargazerslounge.com/equipment-discussion/100507-magnification-factor-barlows-binoviewers.html

HTH

Andrew

[Hypernova]

Cheers thanks for the link to your thread, reading on of your posts further down you say that a 2x barlow element screwed directly into an eyepiece results in a bout 1.6x mag.