25-26 mm 1.25" eyepiece for 8" SCT?

[Solanum]

I am moving my eyepieces from ones suitable for F5 newt to ones suitable for F10 SCT, my major gap at the moment is at 25-26mm (I have a TV 32 mm Plossl and a 20 mm Pentax XW, well the latter is in the post).

I've spent way too much on astronomy gear for the moment, but like to look ahead.... Any suggestions in the $200-$300 (new) price range?

Thanks!!

[mental4astro (Alexander)]

With 32 plossl and 20 XW, a 24/25mm eyepiece is pretty much redundant. The 32 plossl will give you the largest true field view possible with a 1.25" eyepiece (& that is the EP's AFOV will be limited to 52° at that focal length). A 24mm EP will give you the same TFOV as the 32mm, but with an AFOV of 68°. The 20mm XW will give you pretty much the same performance as a 24mm. Remember, you can't get a wider AFOV than 68° in a 1.25" EP at 24mm. The barrel size is the limiting factor. Only way to go widr is by using 2" eyepieces.

If you've spent too much, stick with what you have now. You won't achieve anything more. You can save your $$$ for a 2" adapter and diagonal for your SCT there's a hell of a lot more eyepiece choices then open to you,

Mental.

[Solanum]

Thanks for those thoughts, gives me something to ponder!

I guess I was thinking about the magnification more than the field of view, with my old scope I found I used 50x, 80x and 100x most often, with 150x and 200x only rarely used when seeing was good and with a discrete object. Having that 50, 80, 100 range allowed me to get the most suitable magnification, though now I think about it, you are right, the field of view would have come into the decision as to which eyepiece to use as well as the magnification.

I think in the longer run, I'd still like something at around 80x, but I wasn't going to rush out and buy anything anyway.

So, obviously the SCT is new to me and maybe I won't use it in the same way as I did my newt?

Also, I've been confused about 2" backs for the SCT as it is only high magnification or low AFoV 2" eyepieces that won't have vignetting right?

Do people really find 2" eyepieces in SCTs of this size useful?

[Camelopardalis (Dunk)]

SCTs are not really wide field scopes...but I use a 2" diagonal with my C8 and enjoy doing so. Despite those only believing in "technical details" suggesting otherwise, the baffle tube doesn't immediately cut-off light at the limits and I use a 40mm 70-degree eyepiece without obvious vignetting...I just enjoy the view and don't stress over any marginal dimming of stars near the edge, after all the scope has tracking

In addition to the longer focal length eyepieces, there are a number of eyepieces in shorter focal lengths that have 2" barrels...these are the ones with the mega wide (100 degree) aFOV.

One thing to note however is that my C8 is of the Edge HD variety...I'd suggest try-before-you-buy for that wide FOV as I found the combination of the regular C8 aberrations and my eyesight displeasing.

[Renato1 (Renato)]

A 20mm eyepiece gives a 2mm exit pupil in your telescope, and a 32m eyepiece gives a 3.2mm exit pupil. There isn't really anything useful for eyepieces delivering a 2.5 or 2.6mm exit pupil to do.

My C8 came with a 26mm eyepiece, and I used it till I got a 20mm eyepiece and then hardly ever used it again in that telescope.

Regards,
Renato

[ariefm71 (Arief)]

The baffle tube diameter of a c8 is 38mm. I can achieve 1.8° TFOV with a little bit of vignetting in my non-edge C8 using a 28mm UWAN and a 0.63 reducer/corrector. A 26mm Nagler T5 has 35mm field stop diameter will give 1.7° TFOV with no vignetting.