So last night, with the southern Milky Way well overhead, I finally decided to give my Nagler 26T5 a try in my 130mm F/5 reflector. The wide field is very nice, and the Milky Way fields sparkle, but I was surprised by what I found out was pincushion distortion. Sweeping through the Milky Way, it was like wooahhh shouldn't have drank that bottle of Wild Turkey 101! All you hear is how great TV eyepieces/Naglers are so I was taken aback, did not expect to see this. Stars near the edge fanned out, so not 'perfection' near the edge, but that was the coma from the F/5 system, and I assume coma is more evident in an ultra wide EP than an equivalent narrower field. Is my assumption correct?
The Nagler, and 82* EPs in general, is a brand new experience to me, so I am not at all familiar with its nuances. After doing a bit of reading, it appears that what I saw is infact a part and parcel of the Nagler, and other ultra wides. I guess the shock comes from the fact that on a regular basis I've only used LVWs, Delites, and plossls and never actually dabbled with uwa eyepieces.
Other scopes I'll try in are a 72mm F/6 refractor and a 8" F/6 dob, might clear up tonight hopefully. Trying in the 12" will have to wait as that's a much bigger setup and only worth the effort at my dark site, which atm I am too busy with work to head out to (home has too many trees and crud in the way).
For coma I have a paracorr 2 as my 12" is F/4.38, what is the correct setting for the 26 Nagler from your experiences? Televue's leaflet says the "F" position, would that be it? And does one focus the scope before adjusting the paracorr, or vice versa?
I used to live the simple life...
Edited by HellsKitchen, 15 April 2021 - 05:12 AM.