magnification rough guess

[sunshine185]

Using a wo binoviewer on a 200p, got 2 x 20mm ep's in, the 1.6 Barlow and a 2x Barlow. Considering a binoviewer increases magnification due to the position of the ep's, add the 3.6x I get with the barlows, what do you reckon my mag is? Jupiter looks absolutely incredible, so clear and the amount of detail is breathtaking.

[ronin]

Ignore where the binoviewers move the eyepieces to. The eyepieces have to focus on the image created by the optics in front of it. It is the size of this that is relevant and that I guess doesn't change.

Assuming that there is glass in the opticl path then the light path is less so the image is smaller, you may well be getting a smaller image size, not a geater one. Think about it light from a star will form an image at infinity, stick a lump od glass (lens) in the way and it comes down to a few inches.

Actually you won't :evil6: but stop thinking you have something for nothing.

Just work it out normally.

[sunshine185]

I am terrible at maths, so, 20mm with 2x Barlow would give me 10mm, then ads the 1.6 Barlow to this, so I am roughly at 6.5 -7mm, so I am in the region of 170-180x in the dob? You would think that all this glass, plus the loss of light by splitting one image into two, would, in theory, give a worse view than a decent 7-8mm ep, this isn't the case.it maybe that the seeing is so good the last couple of days, but the image I am getting wipes the floor with the view I got with a 7mm x-cel lx.