Eyepiece upgrade for F10 SCT

[Guest 12green]

Hello, I have ES82 14mm and MV68 34mm as my favourite 2 eyepieces. Will ES68 24mm be much of an optical  improvement over my  Meade Super Plossl 26mms or my BST Starguiders 25mm. I think they will show similar FOV.

[RT65CB-SWL]

Hi @12green and welcome to SGL. 

If you go to the top of the page, click 'Resources' then 'Astronomy Tools' then 'FOV Calculator'.

Above is a screenshot I did for another SGL'er sometime ago.

[Davey-T]

Presumably thats 10" 2500fl which isn't very demanding on eyepieces, the Meade 26mm eyepiece generally supplied with the Meade scopes is excellent you can get something like an Eyeopener attachment to reach the full FOV which is limited by the baffle tube and squeeze the most out of it but probably not worth it in the grand scheme of things.

Dave

[michael.h.f.wilkinson]

I have a Celestron C8, and also have a MaxVision 24 mm 68 deg EP, which has the same optics as the ES24 68, and it works very nicely in a C8. It shows a far larger FOV than the 26 mm Plossl which has about 50 deg apparent FOV, and is well enough corrected to work well in scopes down to F/5. The BST has an apparent FOV of 60 degrees, so it is also noticeably smaller than the ES 24mm 68 deg. Although an F/10 scope is relatively forgiving on the EP, I do find that you still see some differences as you go to more expensive EPs. My Nagler 22 mm is definitely a bit sharper than the MaxVision, quite apart from the much bigger FOV. I use the MaxVision mainly as part of my travel set, or for outreach. It is a very nice EP that gives the maximum FOV for a 1.25" barrel.

[Louis D]

Another widest field option in a 1.25" barrel is the 24mm APM UFF.  It does quite well up to the last few degrees of field where it gets a bit indistinct.  The rest of the field is quite sharp.  I measured mine to have a 27.5mm effective field stop diameter, which probably accounts for the slight fuzziness at the edge since that is pushing what is possible in a 1.25" barrel.  By comparison, my 26mm Plossls have 22.3mm and 22.6mm field stop diameters.  I measured my 25mm AT Paradigm (BST Starguider) to have a 26.7mm field stop diameter, so it comes close to maxing out the available field of view in a 1.25" barrel.  The 24mm ES-68 at 27.2mm FS diameter has greater distortion to get to 68 degrees apparent field (AFOV), but not that much more true field (TFOV).  A 0.5mm difference in FS diameter isn't all that much.

If you already have 2" eyepieces and are comfortable with them, I would steer you toward the 22mm Omegon Redline (TS-Optics Expanse, Technosky Superwide HD, etc.).  They are better corrected than any of the above to the edge (just slightly behind the 22mm NT4), have excellent eye relief (once the eye cup is unscrewed) for eyeglass wearers, have a 28.4mm FS diameter (thus the 2" barrel), have a true 70 degree AFOV with very low distortion, and are lower priced than the APM or ES alternatives.