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mercedes_sl1970
19-03-2007, 05:25 PM
Hi there

I have a 2" 2x ED barlow which I've been using with my f7.5 80mm refractor, with a 2 inch diagonal. Was wondering if there is a difference in magnification when I put this before the diagonal? Unfortunately, I cannot seem to get focus when it is used "after" the diagonal.

There seems to be an increase but I'm not sure if I am just imagining it.

Thanks

Andrew

mill
19-03-2007, 05:44 PM
The longer the tube lenght of the barlow , the more magnification you get.
But, a 2x balow is not really made for that.
This means , as long as the picture looks good , just put it where you can get focus.
Just my opinion :)

Dennis
19-03-2007, 07:42 PM
Hi Andrew

Strange indeed - I experience the exact opposite!

WO 80mm + WO 2” diagonal + WO x2 Barlow + eyepiece = focus.
WO 80mm + WO x2 Barlow + WO 2” diagonal + eyepiece = no focus.

However, in my SCT and Vixen refractor, I have noticed that if the Barlow is placed BEFORE the diagonal, you do get an increase in barlow amplification.

Cheers

Dennis

mercedes_sl1970
19-03-2007, 09:41 PM
Thanks "Mill" and Dennis

Just did a bit more searching and it seems that a 2x barlow will get around 3x magnification when placed in front of the diagonal, which seems to align with what I was experiencing:
http://www.bpccs.com/lcas/Articles/barlow.htm

Thanks

Andrew