Upgrade at 24mm for SCT

[stormioV]

I'm looking for an upgrade eyepiece for my LX90 ACF 8inch at 24mm to get maximum fov for 1.25 fitting. I do not wear glasses. Currently i have BST Starguider and Meade 4000 SP 32mm. I don't really get on with the Meade Plossl, I struggle with eye placement with this eyepiece. Optically it is great. 

I am willing to spend up to £200 new for this. I am thinking about either

ES68 24mm

Stella Lyra(APM, Altair, Celestron) UF 24mm ,

Baader Hyperion 24mm

 

I do use a 2 inch diagonal with 1.25 adaptor so it is an easy switch.  My only 2inch is ES 68 34mm which I find stunning. 

Would I be better looking at 20mm 2 inch such as Stella LYRA 80/Founder optics or stick with my original 1.25 upgrade idea.

Thanks.

 

 

 

 

[mikeDnight]

The Altair 24mm Ultra flat is superb, as are any of the UF  brands.

 

 

[Mr Spock]

24mm UFF - various brands available but the StellaLyra is the least expensive https://www.firstlightoptics.com/stellalyra-eyepieces/stellalyra-24mm-ultra-flat-field-125-eyepiece.html

[paulastro]

I'd go for the ES24/68.  It's Argon filled so sealed and so it can't  mist up iside or let in debris.  It's quality of construction is excellent, it feels and is very well made. Optical performance is right up there, and I prefer it to the 24mm Panoptic, it's certainly better for comfort of use and eye placement for me.  Fine to the edge at least to f4.7.

I also have the 24mm Hyperion which is also a very nice eyepiece down to f6.  Less good at faster focal ratios. Though not as good as the ES, but I've kept it as a spare as its worth more to me than the used price I'd get if I sold it.

[Don Pensack]

3 hours ago, stormioV said:

I'm looking for an upgrade eyepiece for my LX90 ACF 8inch at 24mm to get maximum fov for 1.25 fitting. I do not wear glasses. Currently i have BST Starguider and Meade 4000 SP 32mm. I don't really get on with the Meade Plossl, I struggle with eye placement with this eyepiece. Optically it is great. 

I am willing to spend up to £200 new for this. I am thinking about either

ES68 24mm

Stella Lyra(APM, Altair, Celestron) UF 24mm ,

Baader Hyperion 24mm

 

I do use a 2 inch diagonal with 1.25 adaptor so it is an easy switch.  My only 2inch is ES 68 34mm which I find stunning. 

Would I be better looking at 20mm 2 inch such as Stella LYRA 80/Founder optics or stick with my original 1.25 upgrade idea.

Thanks.

 

 

 

 

It sounds like you struggle with the Meade 32mm because of its long eye relief.

You probably need an eyepiece you can get closer to without experiencing blackouts.

That makes the two in the price range most likely to satisfy the 24mm UFF (27.6mm field stop) with eyecup flipped up, and the 24mm ES 68° (27.2mm field stop).

Edited April 13 by Don Pensack

[stormioV]

Thank you for your help so far. It seems this version of uff is best priced in UK @£109

https://www.altairastro.com/altair-24mm-ultraflat-eyepiece---precision-barrel-stainless-steel-237-p.asp

With field stop of uff being 27.66 mm compared to 27.2mm, of ES does this mean UFF will have a slightly larger /very similar fov?  I thought UFF was 65 and ES68?

 

[Louis D]

36 minutes ago, stormioV said:

With field stop of uff being 27.66 mm compared to 27.2mm, of ES does this mean UFF will have a slightly larger /very similar fov?  I thought UFF was 65 and ES68?

Yes, very similar.  Distortion characteristics account for the difference in apparent field of view.  The ES-68 will tend to stretch things toward the edge more than the UFF.  Thus, the moon will remain more round shaped and less egg shaped in the UFF.

In my comparison image below, note how little distortion the APM UFF 24mm has center to edge.  The rulers maintain roughly the same height edge to edge, and the individual millimeter markings maintain similar spacing center to edge.  You may need to select and enlarge the image to see this level of detail.

Now notice how much the Tele Vue Panoptic 27mm distorts the rulers' height center to edge.  This is how the the TV Panoptic 24mm would appear.  Since the ES-68 24mm is a design copy of the Panoptics, I would expect it to have similar center to edge distortion.  The Panoptic 24mm would be just as sharp center to edge as the 27mm version if you demand perfection.  The ES-68 line tends to lag a bit behind the Panoptics they copied in edge correction.  It could be the designer chose to use less expensive glass types that don't preserve edge correction as well.

Edited April 14 by Louis D

[Don Pensack]

2 hours ago, stormioV said:

Thank you for your help so far. It seems this version of uff is best priced in UK @£109

https://www.altairastro.com/altair-24mm-ultraflat-eyepiece---precision-barrel-stainless-steel-237-p.asp

With field stop of uff being 27.66 mm compared to 27.2mm, of ES does this mean UFF will have a slightly larger /very similar fov?  I thought UFF was 65 and ES68?

 

It means the Altair Astro 24 will have a larger True Field on the sky, but a slightly smaller apparent field.  This is because distortion characteristics are different among the choices.

The difference in apparent field is small, and the extra true field is a nice bonus.

[stormioV]

Thank you.  24mm uff looks great on the ruler matrix . My 25mm Starguider not so good.

If I struggle with long eye relief with my 32mm plossl, would that be similar  case with 24 uff?

Edited April 14 by stormioV

[Louis D]

I've measured my two 32mm Plossls (a GSO Super and an Orion Sirius) as both having 15mm of usable eye relief.  They are right at the limit of usable with eyeglasses for me.

I've measured the APM UFF 24mm as having 17mm of usable eye relief which is comfortable to use with eyeglasses resting on the folded down eye cup.

I skipped the Meade 5000 SWA 24mm when it went on clearance sale a decade ago because of its tight usable eye relief.  The optically identical ES-68 24mm is even tighter due to slight eye lens recession.  Ernest in Russia has measured it as having 11mm of usable eye relief.

[Don Pensack]

21 hours ago, stormioV said:

Thank you.  24mm uff looks great on the ruler matrix . My 25mm Starguider not so good.

If I struggle with long eye relief with my 32mm plossl, would that be similar  case with 24 uff?

Possibly.  Though that depends on how recessed the eye lens on your 32mm Plössl is.

I' have see 32mm Plössls with very deepset lenses which reduce the effective eye relief significantly and are not usable with glasses.

The 24mm UFF has a tall eyecup and a deeply recessed eye lens.  Its 29mm of eye relief is reduced to about 7mm with the eyecup in the up position.

So it's likely you wouldn't have any issue with the large eye relief, especially with the eyecup flipped up.

[Louis D]

On 14/04/2024 at 11:56, stormioV said:

Thank you.  24mm uff looks great on the ruler matrix . My 25mm Starguider not so good.

If I struggle with long eye relief with my 32mm plossl, would that be similar  case with 24 uff?

My 25mm A-T Paradigm (Starguider) has 17mm of usable eye relief with the eyecup all the way down, so identical to the 24mm UFF with eye cup folded down.

I've not measured the eye cup up eye relief of either.

[LondonNeil]

The Hyperion is a lot less then £200, about £110-120 new.   The Morpheus is about £220, were you thinking of that?

[IB20]

On 14/04/2024 at 14:08, stormioV said:

Thank you for your help so far. It seems this version of uff is best priced in UK @£109

https://www.altairastro.com/altair-24mm-ultraflat-eyepiece---precision-barrel-stainless-steel-237-p.asp

With field stop of uff being 27.66 mm compared to 27.2mm, of ES does this mean UFF will have a slightly larger /very similar fov?  I thought UFF was 65 and ES68?

 

I’m looking at the same upgrade for my scopes and I’d narrowed it down to the ES68 24mm and the UFF.

That’s a cracking price for the UFF. Does anyone know if the housing/eyecups for the different clones make a difference to the specs or user comfort?

[Zermelo]

It may or may not be relevant to the decision that the Altair version (I have this one) has a steel body, and is heavier than some of the others.

[EDIT]  I just looked it up, 331g

Edited April 16 by Zermelo

[stormioV]

Thanks, I was trying to look for weight of Altair option.

It was hyperion for wider fov. Morpheus would be better optically.

[Louis D]

I weighed my APM UFF 24mm to be 346g.  Weird that it's heavier than the Altair version.

[Mr Spock]

2 hours ago, Louis D said:

Weird that it's heavier than the Altair version.

Maybe similar looking on the outside but using different alloys?

[Louis D]

APM claims it weighs 331g.  I'll have to get it and my gram scale out again to double-check.

[stormioV]

I think Altair is stainless steel nose piece.

I have all my Starguiders eye cups  twist/turn  3 -4 times for best comfort/experience for me and normally hardly ever adjust. They are probably just over half way up.

I will need to twist down 25mm to see what eye relief is like in that position.

Edited April 17 by stormioV

[Don Pensack]

I sold APM eyepieces for years.

On my gram scale the 24mm UFF was 331g without eyepiece caps.

[Don Pensack]

On 16/04/2024 at 10:01, Zermelo said:

It may or may not be relevant to the decision that the Altair version (I have this one) has a steel body, and is heavier than some of the others.

[EDIT]  I just looked it up, 331g

The Altair Astro version is heavier than 331g.  In an early thread about the green eyepieces, someone quoted the actual weight, but, alas, I can't remember what it was.

The APM, with aluminum lower barrel, is 331g.

[Wardr77]

I use the ES68 24mm with my LX90 12, works very nicely. Very pleased with the views it provides. Also transforms the views through my ST80 as well.

[stormioV]

I have just noticed these

https://www.firstlightoptics.com/ursa-major-eyepieces/ursa-major-fmc-flatfield-eyepiece-25mm.html

Would this be to similar to what I already have? 

I'm still thinking uff 24mm or es68 24mm would be better option.

Edited April 20 by stormioV

[Ricochet]

1 hour ago, stormioV said:

Would this be to similar to what I already have?

I would think so. What is the edge of the field like with the 25mm Starguider at F10? Do you see astigmatism or is it sharp? I know the eyepiece performs well by the time you get to F12.

1 hour ago, stormioV said:

I'm still thinking uff 24mm or es68 24mm would be better option.

Yes, but at F10 eyepiece aberrations will be small so the biggest upgrade will be in terms of coatings/transmission/reflection control. If you add a faster telescope at a later stage the differences will be more apparent.