Zoom Baadder

[Rogering1]

Hi guys,

I've thinking about getting a Baader Zoom for the moon & also to barlow down for the planets and fill the gap below my 7mm SMC XW Pentax to achieve 5mm.

A lot of people say that the 24-20mm of the zoom is kinda limited due to AFVO stated as 50 but some people are saying more like 42, so looking at the moon my GSO 25mm plossl might have a greater FOV.

At the other end of magnification the 8mm can be barlowed to 4 or 5mm and give the same 68 AFOV as the Pentax, but the image more than likely will not be as good.

Like everyone I like the thought of a zoom especially for the moon, perhaps I should buy a less expensive zoom and buy a 5mm XW.

Your thoughts and experience are welcomed

[Spec-Chum]

The FOV is quite limited at low mags on a zoom, usually to around 40 or so degrees but the higher mags usually have quite a generous 60 or so degrees.

I use my Seben zoom all the time, granted it’s not the best optically but the convenience of merrily zooming in and out like a madman is really fun

Once I find something of interest that I want to look at in detail, I zoom in to a comfortable level take the Seben out take a note of the zoom level and insert the nearest fixed EP I have. When I can be bothered; usually the Seben is good enough for me . It’s very sharp in the centre but the quality tails off rather quickly off axis.

I’ve just purchased a 12.5mm plossl, and will be getting a 17-18mm one next month also, but I’ll always keep my zoom.

[John]

If you already have a Pentax XW you might find the performance of the Hyperion zoom just a little dissapointing. I found the zoom good but not quite as good as the fixed focal length Hyperions. The XW's are somewhat better than Hyperions in all respects - really top echelon eyepieces in fact.

Zooms use a sort of sliding barlow / smythe lens group to achieve their variable focal length so there are bound to be some compromises, however small. Even more so when you add another such lens (ie: a barlow) unless it's a really good one such as a Powermate. The field of view of the Baader zoom varies between 60 degrees at the 8mm focal length to around 40-ish at 24mm. The specs on some web sites sometimes claim more but I found this not to be the case when I tried one for a while.

I have a 5mm XW and it's a superb eyepiece - one of the best 5mm's around, bar none.