127 Mak and WO Binoviewer mag question

[ken spencer]

Using the Binoviewer with its 20mm lenses and x1.6 Barlow I appear to be getting magnifications higher than usual. I'm not complaining as the views are spectacular. I assumed with a FL of 1500 mm on my mak that would givem me a magnification of 75x plus Barlow would give me 112x mag but it seems much higher. Any thoughts would be appreciated.

Thanks

ken

[Macavity]

I suspect it is something to do with this...

Telescope Reviews: How to Calculate the Focal Length of an SCT

[ken spencer]

So could be my WO dielectic diagonal which gives me a greater FL? Or the focusing using Binoviewers or both. Interesting thanks for the link.

[kniclander]

it's more likely to be the fact that if you're putting the barlow on the binoviewer the distance between the barlow and the eyepiece is greater than if you just stuck it on the end of the e/p and that increases the mag. With some barlows you can unscrew the lens from the barrel and reduce this effect. if you put the barlow on the diagonal, it will increase the mag even more.

[ken spencer]

Thanks for the comments

[ken spencer]

So I've read a lot on this topic in other areas. Could someone give me an idea what mag I have with the 20mm on my WO Binoviewer using dielectic diagonal and the x1.6 barlow. I think according to other threads I could be getting as much as x5 with the x1.6 barlow taking into account the telescopes configuration. Thanks again

[pvaz]

It varies a lot depending on the barlow and the distance you add. I can't precise a value.

Tele Vue Optics Article Page

As you can see on this chart the higher the mag on the barlow the higher it increases as you add distance.

I use this effectively with my Ethos and big barlow.

Ethos 10mm + big barlow = 5mm EP = 240x

Ethos 10mm + 2" 50mm extension tube + big barlow = 4mm EP = 300x

Works great for planets. However the eye lens stays at like 35cm from the OTA.