41 replies to this topic

[azure1961p]

Masking of the ball effectively at the field stop and it's narrower FOV - and these oculars do exist - is there ANY contrast gain against say, a good Ortho or Plossl?  I know for some it's an eye relief issue but those things aside, does it ever meaningfully exhibit higher planetary contrast - imagine a driven telescope if that is at issue.

 

Pete

[Astrojensen]

According to credible sources, it really does. I've not tried one myself, though. I've made some Dollond eyepieces (a single, achromatic doublet with the flat side towards the focal plane) and they're shockingly sharp and bright, with stunning contrast, so I do believe those who say Ball eyepieces are super good. 

 

They require a long f/ratio, though, as do the Dollonds. 

 

 

Clear skies!

Thomas, Denmark

[azure1961p]

That's it, that's the one you did, the Dolland in which you said it had " world class contrast".  Thanks for chiming in. I'm going to see if Seibert does it.

 

Pete

[CrazyPanda]

According to credible sources, it really does. I've not tried one myself, though. I've made some Dollond eyepieces (a single, achromatic doublet with the flat side towards the focal plane) and they're shockingly sharp and bright, with stunning contrast, so I do believe those who say Ball eyepieces are super good. 

 

They require a long f/ratio, though, as do the Dollonds. 

 

 

Clear skies!

Thomas, Denmark

For me the hardest part is sourcing good achromatic doublets. A premium Plossl from a high-end maker is going to be better than Dollond made with a mediocre doublet.

That said, Tak TPLs seem to be symmetricals. I wonder if you could buy one TPL and turn it into two high-end Dollonds for binoviewing, which you typically do at long focal ratios.

[Astrojensen]

For me the hardest part is sourcing good achromatic doublets. A premium Plossl from a high-end maker is going to be better than Dollond made with a mediocre doublet.

 

Some of the best Dollonds I've made have been from cheap plastic Kellners (with glass optics). A 10mm Kellner becomes a 25mm Dollond, when you remove the field lens and reverse the eye lens. The resulting eyepiece has noticeably less glare, and much better sharpness and contrast than a 25mm Kellner. Noticeably smaller field, too, but excellent eye ergonomics. Very good eye relief and relaxed positioning. 

 

A 25mm Kellner becomes a 40mm Dollond. In my 63mm Zeiss, the contrast on deep-sky objects is ridiculously high. 

 

Given how good the performance is with non-optimized designs, I wonder how good it could be in an optimized one. 

 

 

Clear skies!

Thomas, Denmark

Edited by Astrojensen, 05 November 2024 - 01:28 PM.

[slavicek]

I have Harry Seibert's ball eyepieces AKA "planispheres". Last year I briefly compared them to Tak ABBE, TOE and TPLs on manual mount. I cannot find any difference in the views (= that's how good they are). However you have to observe within 10 deg of eyepiece center. This year's planetary season I am going to use tracking mount so that should give me more reliable comparison.

Narrow FOV = good for planets/doubles only.

If you are "minimalist" then that's the way to go!

[saemark30]

Some of the best Dollonds I've made have been from cheap plastic Kellners (with glass optics). A 10mm Kellner becomes a 25mm Dollond, when you remove the field lens and reverse the eye lens. The resulting eyepiece has noticeably less glare, and much better sharpness and contrast than a 25mm Kellner. Noticeably smaller field, too, but excellent eye ergonomics. Very good eye relief and relaxed positioning. 

 

A 25mm Kellner becomes a 40mm Dollond. In my 63mm Zeiss, the contrast on deep-sky objects is ridiculously high. 

 

Given how good the performance is with non-optimized designs, I wonder how good it could be in an optimized one. 

 

 

Clear skies!

Thomas, Denmark

I did the same thing with the cheap Synta supplied eyepieces.

Mars looked very constrasty with a Dollond doublet.

[Kent10]

I have all of Harry Seibert's ball eyepieces and the one thing I notice whenever I use them is the extremely low scatter.

[j.gardavsky]

A revival of the Dollond eyepiece has been made by Hensoldt in the "Wetzlar backyard" of Zeiss West,

 

 

Tomorrow, and during the daylight, I will check my antique Dollond draw tubes telescop, should I find it in the group of my draw tubes telescopes, for the eyepiece.

 

Best,

JG

[luxo II]

Yup... some of the really early, simple eyepiece designs do have some merit if you don't mind the narrow FoV, on a long focal ratio scope and with a tracking mount.

[Sarkikos]

I have Harry Seibert's ball eyepieces AKA "planispheres". Last year I briefly compared them to Tak ABBE, TOE and TPLs on manual mount. I cannot find any difference in the views (= that's how good they are). However you have to observe within 10 deg of eyepiece center. This year's planetary season I am going to use tracking mount so that should give me more reliable comparison.

Narrow FOV = good for planets/doubles only.

If you are "minimalist" then that's the way to go!

If there is no difference in the views, I'd opt for the Abbes, TOEs or TPLs instead, because there is a difference in ergonomic comfort.

 

Mike

[Alex.C]

I did the same thing with the cheap Synta supplied eyepieces.
Mars looked very constrasty with a Dollond doublet.

Super fascinating. I'd love to try this out! I'm probably missing something, though - would this literally be as easy as taking out the field lens and turning around the eye lens? Did you need some kind of spacer to replace the thickness of the missing field lens?

[Astrojensen]

 

would this literally be as easy as taking out the field lens and turning around the eye lens?

 

Yes. 

 

 

Did you need some kind of spacer to replace the thickness of the missing field lens?

No. In the cheap Synta Kellners, they're held by individual retaining rings. 

 

 

Clear skies!

Thomas, Denmark

[Alex.C]

Thank you! Looks like I know what I'll be doing this weekend.

[Sean Cunneen]

About 10 years ago I was obsessed with ball lens eyepieces. Edmund had a bunch of precision ball lenses available in the back of their warehouse. They also had barrel lenses, which are easier to work with/mount into eyepiece barrels.  I made myself a set of 20mm fl-5mmfl. They are scary sharp, but SO HARD to observe with. The eye relief is non-existent and the FOV so small all you could ever see was the disk of a planet, the moons of Jupiter for example would be seagulls at high powers. 

[j.gardavsky]

About 10 years ago I was obsessed with ball lens eyepieces. Edmund had a bunch of precision ball lenses available in the back of their warehouse. They also had barrel lenses, which are easier to work with/mount into eyepiece barrels.  I made myself a set of 20mm fl-5mmfl. They are scary sharp, but SO HARD to observe with. The eye relief is non-existent and the FOV so small all you could ever see was the disk of a planet, the moons of Jupiter for example would be seagulls at high powers. 

Hi Sean,

 

here is one barrel lens in my collection,

 

 

This type of eyepiece would be Stanhope 1825(?), according to Ch. Lord.

The design type would be monolithic)* with the focus inside the glass.

 

Best,

JG

 

PS: )^*  "Monolithic" as a free choice of terminology, in analogy with monocentric.

[Sean Cunneen]

Yes! That one is very interesting!  In the Edmund catalog at the time, the barrel lenses were ball lenses with the sides turned into cylinders. (So you can have a long focal length fit into an eyepiece barrel). They were monocentric singlets. I kept wondering which was better and if my choice of construction was somehow pinching the ball(they can be really touchy and sensitive to cold temps. At one point I would keep them loose and rattling so if I had a "bad" face I could jiggle it like dice to get a different face to look through. You think of strange things in the dark sometimes....

[slavicek]

If there is no difference in the views, I'd opt for the Abbes, TOEs or TPLs instead, because there is a difference in ergonomic comfort.

 

Mike

Yes. It's matter of personal taste. I've read different opinions on simple (planetary) eyepieces so I have decided to try them all myself. My mix also includes Bradons and ZAOs. I hope I will have some clear, stable skies this planetary season so I will be able to "split the hair" and see some differences between all those eyepieces. But it is splitting hair! Topic starter asked about ball eyepieces and I basically said that he will not be dissapointed with them.

[eblanken]

Hi All,

 

I'm following with curiosity and some interest (but I wear eyeglasses, so maybe not for me ?).

 

Best,

 

Ed

[Kent10]

The balls have very short eye relief and would not work with glasses.  I have to be careful my eyeball doesn't hit the glass on the shortest ones and sometimes I believe it does when I try to get in the full "wide" view.  When I ordered these from Harry, he warned me of the short eye relief.  I have used other short ER eyepieces before so I wasn't concerned and told him I understand.  He didn't want me to be disappointed. 

[eblanken]

Thanks (aka Kent10),

 

I was pretty sure of this already, but good of you to be clear for others to know for certain.

 

Best,

 

Ed

[azure1961p]

I spoke with Harry yesterday day of S.O.'s and he mentioned his 7.5mm ball was in stock but the price for the ball floored me $170.00-ish.  On the other hand, how many people make ball oculars at all?   They don't need coatings he mentions because the nature of reflections on the ball after all sends reflections virtually everywhere else but where it'll fog the image.  I'm wondering if these balls are from EDMUND.

[j.gardavsky]

A revival of the Dollond eyepiece has been made by Hensoldt in the "Wetzlar backyard" of Zeiss West,

 

Dollond eyepiece remake.jpg

 

Tomorrow, and during the daylight, I will check my antique Dollond draw tubes telescop, should I find it in the group of my draw tubes telescopes, for the eyepiece.

 

Best,

JG

Checked my Dollond and Dolland draw tubes telescopes, but their eyepieces are looking like intrafocal (1 - field stop - 1), not the Dollond doublet (field stop - 2).

 

Sorry,

JG

[NinePlanets]

Masking of the ball effectively at the field stop and it's narrower FOV - and these oculars do exist - is there ANY contrast gain against say, a good Ortho or Plossl?  I know for some it's an eye relief issue but those things aside, does it ever meaningfully exhibit higher planetary contrast - imagine a driven telescope if that is at issue.

 

Pete

Yes.

My limited experience with 2 ball lens eyepieces is thus: On one night of exceptional seeing at high altitude (10,000') a friend had his Mewlon DK and an AP Traveler set up, both pointed at Saturn. Another friend had his Zeiss Orthos and 2 ball lenses provided by a fellow in Florida (I believe). We were comparing the balls (of 6mm and 9mm EFL, if I recall)  to the views with the Zeiss and the TV Delos equivalents. The simple balls provided a sharpness and contrast that were stark in comparison. Very black blacks and sharp edges. However, only the very central part of the field was usable, which for viewing a planet was more than enough.

 

I regret we didn't think to look at a globular cluster, but the Saturn view alone was worth the price of admission.

 

EDIT: I must mention that the Zeiss were very nice, but my choice was to buy a 5mm TV Delite, all things considered. I still would like to get a ball lens at some point...

Edited by NinePlanets, 09 November 2024 - 11:26 AM.

[jeffmac]

The balls have very short eye relief and would not work with glasses.  I have to be careful my eyeball doesn't hit the glass on the shortest ones and sometimes I believe it does when I try to get in the full "wide" view.  When I ordered these from Harry, he warned me of the short eye relief.  I have used other short ER eyepieces before so I wasn't concerned and told him I understand.  He didn't want me to be disappointed. 

Is it possible at all just to back your eye off and see the planet ok? Or with a ball do you have to maintain a certain closeness to it to see anything? Many people don't like the Pentax XOs because of the short ER. I just back my eye off a little and concentrate on the planet itself and don't worry about not seeing the space around it.