Best AFOV With a 40mm 1.25" EP

[cloudsweeper]

Hi everyone - 

I'm looking for 40mm EP, 1.25", at the best possible AFOV.

I've noticed that suppliers make contradictory claims about these figures.  43 degrees seems about right, although I've spotted a Revelation at 45 degrees.

Does anyone know which model gives the best possible genuine figure please?  

Doug. 

[Stu]

It all comes down to the field stop size, but not many manufacturers publish these. I suspect that 43 degrees is probably more correct. I would focus on quality rather than worrying about a small difference like that.

[John]

Stu is correct - a 43 degree apparent field of view is the largest that can be squeezed out of the 1.25" barrel size, whatever the manufacturer claims.

 

 

 

[Stu]

How strange, I posted a little more info than appeared in my answer but it has disappeared? 2nd time that has happened today, must be gremlins!

I basically said that Televue quote a field stop of 27mm, and both TV and Vixen quote 43 degrees afov so I would go with these two trusted manufacturers info.

[Moonshane]

The best 1.25" 40mm eyepiece AFOV is provided by the 24mm Panoptic 

[Stu]

17 minutes ago, Moonshane said:

The best 1.25" 40mm eyepiece AFOV is provided by the 24mm Panoptic 

That's very true! Unless you are looking to reduce magnification in a mak for instance, you are better off with a 24mm Panoptic, or a Maxvision if budgets are tight

[Ruud]

A 32mm 52° Plössl or a 24mm 68° wide field will also maximize the true field of view in a 1.25" barrel

[cloudsweeper]

Thanks!  I'm sold on the 24mm Panoptic.  Better start saving!

Doug.

[Dave In Vermont]

Having read about the 24mm TV Panoptic all over the web, I can safely say it is the most highly regarded and popular eyepiece that TeleVue makes. And for very good reason - they are simply wonderful! If you buy only one TeleVue EP, I'd counsel the 24mm Panoptic.

Aldous Huxley summed it up on an unrelated subject, but it rings true with this EP: "To explain the ineffable is impossible." In other words, the reason this Panoptic is so good is for greater reasons that is more than the sum of it's parts. A gestalt. Simply put - you'll truly love this eyepiece.

Orion-USA briefly had the 40mm eyepiece pictured below. It's FOV is 43° - at the limit for these. This particular EP is long gone. They were truly excellent, but by the time the rave-reviews came pouring into the astro-press - they were long gone. I have one and consider myself very fortunate.

Have fun!

Dave

[Mak the Night]

I like my 40mm TV Plossl. I need an eyeguard extender with it as it has a long eye relief. 

 

I call it the 'ice cream cone' lol!

 

http://www.televue.com/engine/TV3b_page.asp?id=51&Tab=EP_EPL-40.0

[John]

I don't generally like using 40mm 1.25" eyepieces because, to me, the 43 degree AFoV is rather claustrophobic - too much barrel interior and not enough sky !. I'd rather use a 32mm with a 52 degree AFoV, a 24mm with 68 degrees or even an 18mm with 82 degrees. All will show as much sky as the 40mm 1.25" plossl can.

Despite the above, over the years a number of 40mm 1.25" eyepieces have passed through my hands including a number of the chinese 40mm plossls that Dave shows (I believe the Orion range in that colour scheme were called the "Highlight" plossls), a 40mm Tele Vue Plossl and a couple of Meade 40mm PL's too.

The one I liked the most was the Meade 3000 series 40mm plossl. It was Japanese made and despite being their "budget" alternative to the 4000 series at the time, seemed optically better than the 4000 40mm and one of the most immersive 40mm 1.25" eyepieces around. 

The widest field stop found in a 1.25" eyepiece is 49mm which the Celestron Ultima 35mm's manage to squeeze in by placing the field stop above the interior of the 1.25" barrel. These eyepieces are the same as the Orion Ultrascopic's and the Parks "Gold" series plossls. The price to be paid for this innovation was that the 35mm Ultima requires quite a bit more inwards focuser movement than most eyepieces which can cause problems with reaching focus in scopes with limited focuser travel.

I believe the same trick is used in some versions of the University Optics 32mm Konig eyepiece in the 1.25" fitting.

 

[Ruud]

How about the Explore Scientific 24mm 68°?

I opted for the €90 Maxvision SWA 24mm (rebranded Meade Series 5000 SWA 24mm) because it was far less expensive than the  €159 ES 68° or the €325 24 mm Panoptic. (prices are from my friendly neighbourhood dealer robtics.nl, who may still have the MV 24mm 68°)

Bill Paulini compared them. The difference in performance is much smaller than the difference in price. Actually, the MV is so good that I got four in the range from 20 to 34 mm.

[cloudsweeper]

Lots of good advice, lots to think about - thanks everyone!.

I know that a lower mag with a 40mm will only give a tiny extra bit of TFOV above what a 32mm gives.  I'm still tempted to try a cheaper one like the 40mm Celestron Omni so that I can compare differences in brightness and contrast (with and without a Baader Nd Filter).

Any views on the 40mm Omni?

Doug.

 

[Dave In Vermont]

There's a small outfit in Arizona that caters to people looking for esoteric eyepieces - Russell Optics & Machine. I've been reading some obscure reviews on these and they look fascinating. So I've pulled the ol' trigger on one of this guy's handmade 50mm Super Plossl EP's. These are his 2" ones:

http://russell-optics.com/two_inch.html

No word on the FOV of these. But I'll be finding out soon enough. Unfortunately, he doesn't ship international. Or to Alaska & Hawaii either.

If this incoming 50mm is good - I may have just started down a very slippery, and steep, slope. I love 'esoterica!'

Dave

 

[Ricochet]

Go with the 24mm ES68 as suggested by Ruud. There are still ex demo pieces available from Bresser http://www.bresser.de/en/Sale/Display-Items/Explore-Scientific-68-Ar-Eyepiece-24mm-1-25.html and at that price point I don't think a 32/40mm Plossl should even be a consideration.

[Riemann]

At the risk of hi-jacking this thread, can I pick up on the 24mm Panoptic?

I have also read only glowing things about this eye-piece and have wondered more generally what this and other TV eyepieces would offer over my X-cel LXs. 

What is that a 24mm Panoptic would offer over a 25mm X-Cel LX, apart from the wider field of view?   I am particularly interested whether it would offer a significant increase in contrast for DSOs, and if so would that manifest itself as more stand out against the background or more detail within?

And how would that compare to a TV Plossl, or to put it another way does the Panoptic offer anything above a TV Plossl other than field of view?

I have been tempted to splash out on a TV or two to see for myself but would appreciate some expert opinions before I part with my cash.

[John]

3 hours ago, cloudsweeper said:

Lots of good advice, lots to think about - thanks everyone!.

I know that a lower mag with a 40mm will only give a tiny extra bit of TFOV above what a 32mm gives.  I'm still tempted to try a cheaper one like the 40mm Celestron Omni so that I can compare differences in brightness and contrast (with and without a Baader Nd Filter).

Any views on the 40mm Omni?

Doug.

 

The Omini series are a decent chinese plossl very similar to the Skywatcher SP series, Revelation ploslls, etc, etc.

Whether there is actually any additional TFoV over a 32mm plossl will depend on how closely the actual field stop diameter matches the specified diameter. There are often variations in this I've found with the retailers blurb usually a touch optimistic !

As I said above, the AFoV frames the view you see so even if the TFoV is a tiny bit more, personally I find the aesthetics of the larger AFoV and the additional benefits of the darker background sky that the shorter focal length make the 32mm preferable, to my eyes. The 24mm / 68 degree format even more so.

Still, the 40mm plossls are cheap enough so you can try, compare and decide for yourself which you prefer !