2 inch vs 1.25 inch EPs

Setting up an observatory, I have been comparing a lot of telescopes and EPs. A question arises. For a 1200-1800 FL telescope, I find that I am using all 2 inch EPs--the new 2/1.25 inch Ethos (13mm), an old 9 mm Nagler with a 2/1.25 inch base, a 22 Nagler, 35 mm and 41 mm Panoptics. The combination works wonderfully. So except for the very shortest of FLs, who needs 1.25 inch EPs? Am I missing something here?

Robert

Robert
That would depend on if you want to get to higher powers. Your 9mm in the 1800mm scope is 200x. If you want to or need to go higher, then you will have to move into the 1.25" eyepieces. Personally I do go higher when contditions allow.
Buck

Robert Howe said:

Setting up an observatory, I have been comparing a lot of telescopes and EPs. A question arises. For a 1200-1800 FL telescope, I find that I am using all 2 inch EPs--the new 2/1.25 inch Ethos (13mm), an old 9 mm Nagler with a 2/1.25 inch base, a 22 Nagler, 35 mm and 41 mm Panoptics. The combination works wonderfully. So except for the very shortest of FLs, who needs 1.25 inch EPs? Am I missing something here?

Robert

I think the others have pretty much covered the issue. Even at 1800mm a 9mm eyepiece is only 200x, at 1200mm it is a paltry 133x.

I have 3 scopes 12.5 inches or larger that have focal lengths between 1200-1900mm, if the seeing is decent 200x is definitely just getting started. With your 16 inch Starmaster I would think you would want to be prepared for 500x or more on the good nights. Besides the planets, 200x is notenough on a good night for globulars and double stars either.

As a planetary eyepiece, I am not so sure about the old 9mm Nagler. Not long ago I had a chance to compare one to a rather inexpensive 9mm Widefield eyepiece on Jupiter in a 12.5 inch F/4.06+Paracorr. I was quite surprised but both the Nagler's owner and I saw noticeably more detail in the inexpensive eyepiece.

Somewhere along the line, one needs to have the capability to use 1.25 inch eyepieces even if it is just to take advantage of the good eyepieces available in that format.

Of course one can always just put an adapter on a 1.25 inch eyepiece and leave it there...

Jon

Rob: Well I'm not sure what the issue is. Judging from your equipment you know full well that to get to a decent magnification in your fast refractor you need 1.25" format for the range 10mm and under, and for your larger aperture you'll use longer fls and hence two inch.

Some of us BTW have standardized on Pentax and therefore two inch territory starts at 30mm. One need not make excuses for being addicted to Pentax.

Among people with smaller investments, 1.25" eyepieces are a good way to break into the hobby, and on the humble but popular c8, "the coffee can scope with an aperture punch", one gets perhaps 1.07 degrees fully illuminated fov, one might want to stick with 1.25 inch format eyepieces (but I've enjoyed two inch wide fields).

There are a few small Newts out there--I have one--that have 1.25 focusers.

Since 1.25 inch covers everything from the 24 Pan to Edmund RKEs to Chinese plossls to the TMB super monos sold by Teton telescopes, there is something to be said for the tremendous range and variety available in this format.

In my C14 planetary viewing is typically at 14mm to 10mm, and I don't need an Ethos for that thanks; I do fine with the XW14 and the XW10, and Mark Rieck's 10mm TMB super mono, which I've had for months, and finally got to use for about five minutes the other night (pretty nice Mark).

What I CAN sympathize with is the HASSLE of switching eyepieces with adapters and without adapters etc. I solved this problem by just buying an adapter for every 1.25" eyepiece, the eyepiece lives in the adapter and so EVERYTHING is treated "as if" it was a 2".

regards
Greg N

Robert,
Nope. With my larger reflectors, my EP kit is one pure 2", three 2"/1.25" that get the 2" treatment, and a 7mm Nagler, which gets the adapter all to itself, so it becomes like a 2" eyepiece too. Just seems like less fooling around that way.
Ron

Robert,
I own a 15" Obsession and find myself using the 2 inch eyepieces a lot as well. But I find myself using the 10.5mm pentax XL quite a bit in my scope. Although the skies in Wilbraham aren't as steady as we'd like, I do have a 7mm and 5mm pentax for the more steady nights. I have had my scope up to about 685X with a 2.5 Nagler, but this was at WSP and it was an EXCEPTIONAL night. I've found never to need anything shorter then 5mm up here in MA. But having them is key. When the skies do steady I'm glad their in my case.

Jay

Robert Howe said:

Setting up an observatory, I have been comparing a lot of telescopes and EPs. A question arises. For a 1200-1800 FL telescope, I find that I am using all 2 inch EPs--the new 2/1.25 inch Ethos (13mm),

Uhm -- that's a 1.25" eyepiece. If a skirt is all you need to call an eyepiece a 2" eyepiece, then you can simply buy dedicated 2"-1.25" adapters and call everything a 2" eyepiece...