Re: 1.25" TV plossl vs other 2"

I'm not Mark, but I do have experience with two of the eyepieces you
mention, and I've participated in this topic thread before, so I
thought I'd throw in my own two cents' worth.

I own both the TV 32mm Plossl and the ST80 (which is 30mm, not 32mm,
by the way). I use them on a 14" f/4.7 TScope (Dobsonian-mounted
Newtonian reflector).

The TV 32mm Plossl is my workhorse eyepiece. I use it more than any
other in my collection (20mm, 11mm, 8mm TV Plossls; 5mm, 3mm TV
Radians; 30mm ST80). In particular, it's my eyepiece of choice for
star-hopping and initially locating objects. I only pop in the ST80
when I want a panoramic view of a large object such as the Perseus
Double Cluster. Why not use the ST80 all the time for star-hopping?
Because the extra-wide field shows up the coma inherent in a short
focal length Newtonian to a degree that I find annoying (I know it's
the reflector's parabolic mirror because I've used the ST80 in a
refractor and there's no coma at the edges of the field). The 32mm
Plossl narrows the field enough to eliminate the areas of greatest
distortion and I don't have a problem with the tiny amount of coma
that's left.

I know, I know--get a Paracorr. Yes, I've thought about it, but for
now my budget is going to other scope paraphernalia.

The TV 32mm is also parfocal with all of my other eyepieces, whereas
the ST80 30mm is not. I can find something with the TV 32mm Plossl
and then bang in one of the higher power eyepieces without refocusing,
but that doesn't work with the ST80.

So here's one situation where the narrower field is an advantage (less
obvious coma), and parfocality (an ease-of-use issue) factors into the
equation.

Note that if a wide field is your primary concern, the situation is
reversed. The ST80 shows more of the Double Cluster than the TV
Plossl, and at a slightly higher power, to boot (30mm vs. 32mm).

Bottom line: Both eyepieces have their place. Each has certain
advantages and disadvantages.

Clear skies,

-Paul W.

On Sun, 17 Jul 2005 08:06:32 GMT, "Zarkovic" <zarkovic@xxxxxxx> wrote:
>
>Hi Mark. I know this is sort of a hard q for you to answer, but do you think
>that TV plossal 32mm 1.25" EP would be better than all Siefert, Burgess
>eyepieces, Rini's and the ST80 32mm, all which are 2" for deep sky
>observation? I am sorry, I know it's a crappy q and you said you don't have
>any experinace with the others, but I am just wondring if you could shed any
>light at all, or anyone else for that matter.
>

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