There's only two 1.25" mm Panoptics (19 & 24mm) although they both Barlow well. The 19mm goes for about £240 (around 290 USD) here now and the 24mm for about £300. I must say that I do get a lot of use out of my 19mm. It was the first TeleVue wide angle eyepiece I ever bought. I certainly don't regret it, but they're not cheap.

 

Hmmm...

Maybe TeleVue® is selling them based on weight? Now why wouldn't that surprise me.....?

Dave

 

Yeah, and they're getting too heavy for the market these days lol. Honestly, some of them seem to have gone up by 100% over here. Baader stuff and EP's are cheaper here than in the US as a whole, I think they are benefiting from the TV price increases. As are Vixen and Pentax. I know a few people who have bought Vixen, Baader and Pentax EP's recently when they would have bought TV's only a short time ago. I don't know what's going on with TV prices over here. Someone's 'extracting the urine', as we say.

I’ve been reading about magnifications and lunar observing. I can regularly (conditions permitting) get 300x, 281x and 260x on the Moon with the Bazooka (130mm Explorer). Over 200x can be achieved well on the Skymax (102mm) and StarMax (90mm) Mak’s.

The Moon’s a bit of an anomaly though, in that a lot of detail can be seen with quite low magnifications (even 8x binoculars), yet it responds to much higher magnifications better than planetary objects as a whole.

In his book ‘Observing the Moon’ Gerald North states that although magnifications are very personal, subjective choices he tends to spend a lot of time viewing with around a 1mm exit pupil.

About 5“ (127mm) seems to be the cut off point for me, and smaller apertures than that seem to often struggle slightly with resolution at exit pupils of about 0.75mm to 0.5mm. This is very much dependent on conditions for me though and I can occasionally even get sharp images at 0.43mm.

With the StarMax I tend to start lunar observations off with a 1.3mm exit pupil. I get 65.7x for about 1° TFOV with the 19mm Panoptic to get a nice overview of the Moon. Then work my way up with shorter focal length Plossls depending on which features I’m looking at. I can also Barlow some of the Plossls for more variation.

I’ve noticed I’ve been spending an inordinate amount of time at magnifications of between 80x and a 100x. Which not only roughly matches the aperture size of the StarMax (90mm) but also gives me around the 1mm exit pupil mark.

I think that for prolonged viewing sessions an approximate 1mm exit pupil may be more conducive of revealing lunar detail on scopes around 100mm and under.

Just a few loony thoughts.

 

The ST80 should manage that easily Ray. The Vixen should be superb at 100x. I can get a sharp 171x out of my ST80. 0.8mm is near enough 1mm. In fact the ST80 will give a sharper image than a 90mm Mak. The only problem is the CA and a lot of that can be negated with minus cyan filters. In fact, they can actually help contrast. The reason why I prefer the StarMax for the Moon is that it has a longer focal length (1250mm). I was mainly musing about reflectors above. The rules are a bit different for refractors.

 

On a night of excellent 'seeing,' the ST80 can be coaxed up to about 180X - using the old standard of 50X - 60X per inch rule. This is where a good Barlow will shine, and a poor Barlow will be given to a Cat to play football with.

Dave


Pre-Mod & Old SW ST80:

 

I tend to find 50x per inch is about right for highest planetary resolution and 60x per inch for highest lunar resolution. Well, except for Jupiter, which is an oddity in itself. Mars at opposition could probably be included with the 60x per inch as well.

I think Jupiter's combination of a very high albedo and being visually very contrasting contributes to problematical viewing. I find that reflectors below around 13cm/5" can struggle with some surface detail. From what I've seen, the 80mm ST80 shows about the same detail as a 102mm Maksutov.

I've often struggled to see the GRS with anything less than the 130mm Bazooka. Although a 102mm refractor would probably be as good as a 130mm reflector with resolution detail on Jupiter.

Weather's total pants here. Pity, as Petavius is near the terminator.



Oh well ... next time!

 

Revised grab'n'go kit for high powered viewing.



15mm, 13mm, 10mm, 8mm & 6mm Plossls (all Vixen NPL's except for the 13mm Celestron). These give me a range between 83.3x (1.08mm exit pupil) and 208.3x (0.43mm exit pupil) on the StarMax.

 

I'm not sure how the Olivon will work in an f/5 scope. Should be good with the Moon though. There will be a little EOFB and ghosting but the image should be ortho' sharp.

I still get subluxing with my right shoulder. I've learned how to click it back in lol.

 

Just been thinking ... it's a bad habit but I've tried to stop lol. Seriously though, the ST80 is f/5 with a f/l of 400mm. So usually you'd have to use some quality glass with a fast scope. But you might get away with a lot of EP's if you used a Barlow.

When I view the Moon with the ST80 I use a 7mm ortho' or an 8mm TV Plossl. These would normally be fine on their own as they are high quality glass. Of course the 7mm only gives 57x and the 8mm less. So I use them in conjunction with a 3x Barlow, effectively tripling the focal length to 1200mm for f/15.

I wouldn't recommend Barlowing the Olivon/SW's though. They have a Smyth lens in the field position which definitely produces noticeable glaring/ghosting and light
scatter with the f/6.9 Bazooka. The Celestron X-Cel Barlow well in my experience.​

 

In my experience it's a pretty good quality apochromatic Barlow. If it was made in Japan (like the TV's) you'd pay twice as much for it at least. Synta have kept the unit cost of the X-Cel range very competitive. The X-Cel Barlows work very well on the ST80.

 

I think you'll be OK with the X-Cel Barlow and eyepieces if you keep the diagonal as upright as possible. For most DSO's you won't need more than 30x ~ 50x magnification anyway. I doubt a 25mm EP will be particularly useful on the ST80.

My plan with the ST80 is to use it primarily for DSO's, especially Messier Objects. The 19mm Panoptic will give 21x and be a good low power sweep/finder. I have the 9mm Expanse, which looks promising, and some 12, 13, 15 and 17mm Plossls which I'll use in conjunction with short Barlows to get around 30x ~ 50x.

 

The 18mm X-Cel will give you 60° AFOV as well. Plus it should give 44.4x with a Barlow. I doubt the Expanse will Barlow well but from my limited experience with the 9mm it does seem good for the ST80 as a low to medium power eyepiece. I've been looking at some Meade 4000 Plossls. None of them appear to feature the dreaded undercut and they are supposedly quite usable. Very nicely priced as well. The 26mm would make a nice bino pair. Weather's pants here! Hopefully in only a few weeks we'll be getting out and using this equipment. The Orion Nebula and quite a few Messier Objects should still be nicely visible well into March.

 

Hello Gentlemen (?) -

In that eyepieces are already one of interest to us, I just stumbled over a source for the much venerated Orthoscopic flavor. Ray - you most likely have heard about this company from way back time. Me, too!

As for you, Mak - you may have also. This as back in the Dark-Ages all of us scientific-inclined monsters' had so few choices for new toys to match our interests. This before the Public-School System in the Untied Snakes assigned a childrens' "Science Teacher" who so maligned our minds & soul at every opportunity, that even us 'science-kids' began to have a sense of 'HATE' for the science's too! This was one of my reasons for dropping-out of school at the age of 12. I'd say that was the single best thing I ever did.

So this rattled my cage: Edmund Scientific. A true "Blast From the Past!"

I always regretted not have enough money to afford to buy even one 'Orthoscopic Eyepiece' for my 3" F/15 Achromatic Refractor (this taking place in 1972 - '73) - and these were the same lenses in my Edmund 3" that Unitron (pardon my drool...) used in their refractors' too! I didn't know that until very recently: Carton Optical Industries from Japan. I only heard about this when Pat Putaendo asked me to do some research on them. Thank's Pat!

I may be getting my wish after all! Check it out:
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http://www.edmundoptics.com/microscopy/eyepieces/orthoscopic-eyepieces/2070/

Edmund Optics Eyepieces®
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Be sure to also read-up on their RKE - line of EP's. What you think these are for real? Maybe a special configuration of Kellner's?

Enjoy!

Dave & Raul

 

As you know, I'm a great fan of orthoscopics and I have a small collection. I can see why Plossls eventually became more popular though. Al Nagler had a lot to do with this when TeleVue 'reinvented' the Plossl in the late 70's.

I have 6mm Astro Hutech and 7mm Kokusai Kohki Fujiyama ortho's and I use them for high power lunar viewing at between 257x and 300x.

This is easy enough on a 13cm reflector on an EQ mount. The 6mm only has about a 42° AFOV though. I can deal with the short eye relief, smaller eye lens, 0.43mm exit pupil and the 8' 24" TFOV on a 130mm Newtonian with a manual EQ. However, on a 90mm Maksutov with an alt-az mount the wider TFOV of a Plossl makes life easier as the lunar topography flies past.

A 6mm eyepiece will give 208x on my StarMax. A Plossl will give a 14' 24" TFOV as opposed to an orthoscopic's 12' 02" TFOV. Notwithstanding the Plossl's larger field stop and AFOV. This can make a difference on a small Mak with a manual alt-az.

I'm pretty convinced that the Edmund Scientific, Astro Hutech and Kokusai Kohki Fujiyama orthoscopics all originate from the same Japanese workshop in downtown Tokyo.

I'm not sure about the RKE's.


https://en.wikipedia.org/wiki/Eyepiece

I think the Sky-Watcher giveaways are reversed Kellners.