I just bought a 35mm Panoptic and 22mm Panoptic and can't wait to use them tonight. On the 22mm it has the 1 1/4" built in and I am wondering if I should sell it, buy a 27mm and switch to a true 2" barrel. Am I losing light collection, sharpness or FOV by using a 2" eyepiece? If not, why use a 2" anyway? My equipment - Celestron 8" GPS XLT at 10,000 feet in the Rockies!
Any difference between a 2" and 1 1/4" eyepiece?
Started by steveandtracy, 02/24/2006 07:29PM
Posted 02/24/2006 07:29PM
| Edited 02/24/2006 07:35PM
Opening Post
Posted 02/24/2006 08:02PM
#1
Steve Stainbrook said:
I just bought a 35mm Panoptic and 22mm Panoptic and can't wait to use them tonight. On the 22mm it has the 1 1/4" built in and I am wondering if I should sell it, buy a 27mm and switch to a true 2" barrel. Am I losing light collection, sharpness or FOV by using a 2" eyepiece? If not, why use a 2" anyway? My equipment - Celestron 8" GPS XLT at 10,000 feet in the Rockies!
The Meade series 4000 14mm and 8.8mm UWA eyepieces are also set up for either 1.25 or 2".
Personally, I prefer to use them as 2" ones because I have a 2" focuser and I feel the larger diameter barrel will give a better grip.
Posted 02/25/2006 02:44AM
#2
To elaborate on Jim's excellent answer, with the 68* FOV of the Panoptics, at all the focal lengths up to the 24mm the entire field of view can be accommodated by a 1.25" barrel, so that's what they have (with the skirt to fit a 2" focuser without adapter in the cases of the larger ones.) When you get to longer focal length, lower power eyepieces than the 24mm then the 68* apparent field yields a view too wide to be accommodated by the 1.25" barrel and they move to 2".
Notice the Naglers, with their 82* FOV, are 2"-only eyepieces in this range as the larger barrel is needed to accommodate their larger field of view. The Naglers have 2" barrels all the way down to the 17mm, because they need them to accommodate the FOV. Once you go down to the 12mm even the Naglers don't need the 2" barrel, so they don't have it.
IOW, your 35 has a "full" 2" barrel because it needs it. Your 22 doesn't have it because it doesn't need it and would gain nothing from it. Clear enough?
Notice the Naglers, with their 82* FOV, are 2"-only eyepieces in this range as the larger barrel is needed to accommodate their larger field of view. The Naglers have 2" barrels all the way down to the 17mm, because they need them to accommodate the FOV. Once you go down to the 12mm even the Naglers don't need the 2" barrel, so they don't have it.
IOW, your 35 has a "full" 2" barrel because it needs it. Your 22 doesn't have it because it doesn't need it and would gain nothing from it. Clear enough?
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