Bill The opinions expressed herein are solely mine as an amateur astronomer hobbyist & consumer. Information herein was correlated from experience, discussions with others, & research from multiple sources freely available at time of posting. All reasonable care & skill was used, but no warranty is made as to accuracy, & liability cannot be accepted for errors/omissions. This is for information only and not intended nor implied to be a substitute for professional advice.
"Many a night I saw the Pleiads, rising thro' the mellow shade, Glitter like a swarm of fire-flies tangled in a silver braid." Tennyson: Locksley Hall
Clear skies, Scott my scopes: a few refractors (50-102mm), 2 Newts (4.5-12"), and an 8" SCT
Quote:If that doesn't work, ScopeStuff has a negative profile 2" to 1.25" adapter that might work.
10" F/4.7 Modified Skywatcher Reflector 38mm Orion Q70, 17mm Modded Ultima LX 10mm TeleVue Delos, 7mm Pentax XL
Quote:If you use a Paracorr, all your eyepieces will be parfocal--only the tunable top goes in and out.But, I understand the 17.3 is like the 31 Nagler and 21 Ethos in a Paracorr I--the tunable top simply doesn't move in far enough to find the optimum position for the eyepiece.It would if it were a 2" eyepiece--it's the massive amount of pull-back that occurs in the eyepiece because it's 1-1/4".It needs about 1/2" more in-travel on the tunable top than the Type 6 Naglers.Since the Type 6 Naglers use setting 4 on the original Paracorr, you have only 1/8" additional you can move the Paracorr in from there--3/8" shy of the full 1/2" you need to move in but far from bad. Being 3/8" away from the optimum setting is more than the Nagler 31 and Ethos 21.In the Paracorr II, the Type 6 Naglers use setting D on the Paracorr, and setting A is the farthest in position, another 0.3" in from the D setting, so still 0.2" shy of moving far enough in to get to the optimum position.The obvious answer is a 1.25" adapter that's thinner than the one in the Paracorr. Since it's already a very thin adapter, the following would be a good possibility as a solution:http://www.astrosystems.biz/eyepieceadapter.htmThough the large diameter eyepiece wouldn't insert in this adapter all the way to the sunken shoulder, it WOULD move in closer than the top of a normal 1.25" adapter.And since what you really need is 3/8" on the original Paracorr and a smaller amount on the Paracorr II, I'm sure this adapter would help to provide some extra amount of inward focuser travel.And, there's no reason this adapter wouldn't work in any 2" focuser to gain inward focuser travel if you don't use a Paracorr.NOTE: I do not know what the bottom of the fat barrel diameter is on the 17.3 Delos. It is larger than the 6mm and 10mm. If it does NOT insert into the deep-set adapter far enough for the 1.25" barrel on the eyepiece to insert into the 1.25" hole in the adapter, THEN THIS ADAPTER WILL NOT WORK. I would measure the outside diameter of the 17.3mm Delos just above the 1.25" barrel and compare it to the inside diameter of the deep-set adapter BEFORE I bought the adapter just to be sure it would work.If the eyepiece body inserts into the adapter even a millimeter, that would be enough to help out the problem of inward focuser travel.If you use a 1.25" focuser, though, the 17.3mm will focus nearly 1/2" further in than a lot of 1.25" eyepieces.
Quote:Quote:Since the Type 6 Naglers use setting 4 on the original Paracorr, you have only 1/8" additional you can move the Paracorr in from there--3/8" shy of the full 1/2" you need to move in but far from bad. Being 3/8" away from the optimum setting is more than the Nagler 31 and Ethos 21.There is a 0.63" delta of the focal plane position between T6N and the N31 while it is only 0.48" between the the T6N and the D17.3. Ergo using setting 5 on a Paracorr 1 will be closer to ideal for the D17.3 than it is for the N31. While not ideal, 5 still helps for the N31 and it should work a bit better for the D17.3 plus the latter isn't in need of as much help to begin with since the FOV is smaller.
Quote:Since the Type 6 Naglers use setting 4 on the original Paracorr, you have only 1/8" additional you can move the Paracorr in from there--3/8" shy of the full 1/2" you need to move in but far from bad. Being 3/8" away from the optimum setting is more than the Nagler 31 and Ethos 21.
I'd rather be driving my .
Quote:You are forgetting....
Jeff Morgan - Wile E. Coyote School of Telescope Making
Quote:While I don't use a Paracorr, I find this interesting because I am building a truss scope. In the next month or two it is going to be time to start cutting aluminum, and I certainly want to accommodate my shiny new 17.3 Delos.From what I gather, the infocus is quite similar (almost identical) to the 31 Nagler. Is this correct?
//Anders 8" EdgeHD Skywatcher Equinox 120 Pro 80mm f/6 TS triplet APO
Quote:Thus creating a need for the Paracorr Type 3 that will be announced at NEAF much to the chagrin of those who invested in the Type 2 over the last year.
Active instruments: 4.25" f/6 Newtonian on altazimuth Springfield mount with crutch tripod -- telescope for the handicapped. 12" f/6 Newtonian Telescope maker since 1958; always more to come? Well maybe just one more and it will be something very special Stellafane Awards: 1977 1st award for 4" f/6 refractor 1978 1st award for 4" f/4 Lurie Aplanat 1983 1st award for Newtonian smoking pipe For Sky and Telescope articles, please see Bio info.
Quote:I'll check their return policy. I've decided maybe I just don't want to mess with the thing, over this one issue.
Quote: I have cats and a refractor. I did notice it wasn't parfocal with my 24 Pan.
The night sky is the canvas....
My optics are the brush....
The Milky Way is the masterpiece
Turtles top to bottom....turtles all the way down
A Brief History of Time