BST Starguiders 3.2 too much?

[Colossal Plossl]

Hi All

I have been upgrading my ep collection and currently have a BST 8,12 and Vixen NPL 30mm

I just purchased a BST 3.2mm because I'm struggling to find the BST 5mm.

Do you think this is too much for this scope?  (Haven't received it yet by the way)

3.2mm would give 203x in this scopes FL of 650mm.

It's a big jump from the next ep down of 8mm (81x)

Or does it depend on good seeing conditions?

Steve

Edit: when I say 'too much' I mean for planetary observing.

Edited September 10, 2020 by Colossal Plossl

[Geoff Barnes]

7 hours ago, Colossal Plossl said:

Do you think this is too much for this scope?  (Haven't received it yet by the way)

3.2mm would give 203x in this scopes FL of 650mm.

Hi Steve,

I think 200x magnification is a really good power for planetary observing when seeing conditions are good. I regularly use a Morpheus 6.5mm giving 230x in my 12 inch Dob on the planets and get wonderful results unless the seeing is bad. I have heard that the 3.2mm BST is not the best in the range but I think you will be pleased with it on good nights. 😁

[AstroMuni]

11 hours ago, Colossal Plossl said:

3.2mm would give 203x in this scopes FL of 650mm.

Its the exit pupil that will be the limiting factor besides the maximum useful magnification (MUF) for a scope your size. With a 3.2mm your exit pupil will be 3.2/5 (F ratio) = 0.64mm. And at 50x 5 you are getting pretty close to your MUF with 203x.

I have a similar scope and using a 4mm I can see great views of the moon, but with the planets the crispness is lost (but that may just be because of my age and hence smaller pupil)

HTH.

[Louis D]

I generally back off on power with Jupiter to around a 1.5mm to 2mm exit pupil due to its low contrast features.  At smaller exit pupils, they just sort of mush together most nights.  Saturn's rings and moons, on the other hand, can take much more power due to their higher contrast.  The moon is another good target for using tiny exit pupils.

It's up to you and your wallet.  The BSTs aren't that expensive, and you're not eating out as much as you used to, so treat yourself to a 3.2mm for fun's sake.

[Colossal Plossl]

Thanks for the input guys