Finderscope focal lengths

[Stub Mandrel]

What's the focal length of a typical 9x50 finderscope?

[Charic]

Astrobin mentions 180.00mm for a 9x50 Sky-Watcher ?

[Mak the Night]

According to this the Orion 9x50 RACI is 200mm. I have no idea if this is correct but it seems close to what I would imagine.

http://www.astrobin.com/gear/1224/orion-finderscope-9x50/

[Stub Mandrel]

Thanks,

Reason I ask is because I have a cheap 50 x 300mm scope with a RACI prism that might suit as a finder, but it needs a suitable eyepiece and it only has a .985" barrel. I made a usable ~40mm eyepiece using old binocular objectives that worked really well, but the field of view was really restricted. as 300mm doesn't seem too far off, I will try making a new 1.25" focuser assembly and see if I can get a cheap 35mm eyepiece to fit. another use for it might be as a basic guidescope.

[bambuko]

It is likely to be about 300mm focal length (or thereabout).

No point going for any eyepiece above 32mm if using 1.25"

My RACI (Altair Astro 10x60) is 230mm and it originally came with 23mm eyepiece (making it x10)

Going to 32mm (x7) made some difference (i.e. it was worth it), but you would gain nothing by using 35mm or 40mm (unless you used 2" eyepieces).

Another problem you are going to have with "...cheap 50 x 300mm scope..." when using low magnification eyepieces, will be distortion at the edges when using low magnification eyepieces.

[Stub Mandrel]

Another problem you are going to have with "...cheap 50 x 300mm scope..." when using low magnification eyepieces, will be distortion at the edges when using low magnification eyepieces.

I will look out for a ~32mm ep

:-) As long as I can see the stars I'm not worried about the shape for a finder!

[Charic]

On occaisions when I don't use any finder scope, my 70° afov Panaview takes the lead?