bst explorers

[rory]

just a quickie on bst explorers. if they have a 60 degree fov , is there a compromise elsewhere ?

are they well compatable with a good barlow ?

ta .

[Capricorn]

What do you mean by a compromise elsewhere?

60 degree is fair, bit more then a plossl (52) but less then many others. I have 70 degrees EP's as well.

80 degree EP's are not uncommon and there are a few 100 degree ones. Think that Alan at STL is selling 100 degree EP's as well that have a good reputation.

Just unsure what the compromise is.

[rory]

ahh, you can tell im a little inexperienced sorry. i thought 52 degree was standard as in plossl's. so are the bst explorers not a plossl design ? thanks.

[Capricorn]

No plossl's have 4 elements (lumps of glass) in them.

The actual plossl arrangement is 2 similar lens, each a doublet.

So you have a doublet, seperation of about 10-15mm and the second doublet. Simple and works well. They are symetrically arranged.

The BST's are a 6 element lens, cannot recall how the lens are arranged, but not as simple as a plossl. May be a triplet, single, single, single.

Pulling a plossl apart and putting back together is easy. Don't try the same on a BST, it is scary. Been there, done that on a similar eyepiece, still works.

52 degree tends to be considered "standard" as plossls are the most common and so using them as a "Standard" is simply a good point to work from. As in wider then a plossl. Like many things it has just turned out that way.

60 is nice, think that 68 degree is as wide as the eye can take without having to move you eye around to see everything.

[rory]

thanks capricorn, im looking to buy a couple and to use a barlow to double my options,these seem to have such possitive feedback.

thanks again.