More microscope eyepieces reworked!

[Highburymark]

Here are the W-PLs which arrived today.  Lenses mint. So sharp and clinical in a binoviewer. Three elements, according to a design posted on CN. For £75-80 each, they are an absolute steal. 

[Emperor!Takahashi!]

I'm curious whether the ~45° microscope eyepieces are sharp to the edges. I know that's not what's prioritized in microscope eyepieces, but I'd be grateful to hear from those who use them. The ~55° Nikons I use are sharp to ~65% of the field at f/5.5 and sharp to ~80% out at f/10.

[Highburymark]

56 minutes ago, Emperor!Takahashi! said:

I'm curious whether the ~45° microscope eyepieces are sharp to the edges. I know that's not what's prioritized in microscope eyepieces, but I'd be grateful to hear from those who use them. The ~55° Nikons I use are sharp to ~65% of the field at f/5.5 and sharp to ~80% out at f/10.

An interesting question. I always use them with a binoviewer, with between 1.5x and 8x magnification from GPCs, barlows and extenders. So they’re always operating at slow speeds and are  sharp to the edge. 
But I’ve just tried them native in an F/6 refractor on an artificial star to compare my four pairs: Zeiss W-PL 10x/23, Zeiss OPMI 10x/22, Leica HC Plan S 10x/22, and Leica HC Plan S 10x/25.
The Zeiss W-PL fared worst, with quite a lot of astigmatism at the edge, starting from 50% of the way out. The slightly narrower Zeiss OPMI got a little ragged in the final 10-15%. but these are 3- and 4-element eyepieces - mainly built for clarity and sharpness on axis in slow optical systems.
The two Leica pairs were very nice - the wider HC Plan S 10x/25 surprisingly so considering its wider field (25mm field stop, compared with 22mm for the other Leica). Neater than a typical plossl at the edge - both Plossls and abbé orthoscopics display edge astigmatism in my F/6 scope. But if they were compared with - say - a good widefield astronomy eyepiece on stars at the field edge, I’m sure the astro EP would be sharper.
I could see how the Leica compares with a Panoptic 24mm or Nagler 22mm at F6 later if I get the opportunity.

[Highburymark]

By the way, I think the wider Leica is about 56-57 degrees AFOV, so pretty wide for a microscope eyepiece. You can actually remove the field stop on some of the Zeiss EPs for wider views - again, that CN thread has details.

[Emperor!Takahashi!]

4 minutes ago, Highburymark said:

An interesting question. I always use them with a binoviewer, with between 1.5x and 8x magnification from GPCs, barlows and extenders. So they’re always operating at slow speeds and are  sharp to the edge. 
But I’ve just tried them native in an F/6 refractor on an artificial star to compare my four pairs: Zeiss W-PL 10x/23, Zeiss OPMI 10x/22, Leica HC Plan S 10x/22, and Leica HC Plan S 10x/25.
The Zeiss W-PL fared worst, with quite a lot of astigmatism at the edge, starting from 50% of the way out. The slightly narrower Zeiss OPMI got a little ragged in the final 10-15%. but these are 3- and 4-element eyepieces - mainly built for clarity and sharpness on axis in slow optical systems.
The two Leica pairs were very nice - the wider HC Plan S 10x/25 surprisingly so considering its wider field (25mm field stop, compared with 22mm for the other Leica). Neater than a typical plossl at the edge - both Plossls and abbé orthoscopics display edge astigmatism in my F/6 scope. But if they were compared with - say - a good widefield astronomy eyepiece on stars at the field edge, I’m sure the astro EP would be sharper.
I could see how the Leica compares with a Panoptic 24mm or Nagler 22mm at F6 later if I get the opportunity.

Extremely helpful! Many thanks 🙏 

[Emperor!Takahashi!]

5 minutes ago, Highburymark said:

An interesting question. I always use them with a binoviewer, with between 1.5x and 8x magnification from GPCs, barlows and extenders. So they’re always operating at slow speeds and are  sharp to the edge. 
But I’ve just tried them native in an F/6 refractor on an artificial star to compare my four pairs: Zeiss W-PL 10x/23, Zeiss OPMI 10x/22, Leica HC Plan S 10x/22, and Leica HC Plan S 10x/25.
The Zeiss W-PL fared worst, with quite a lot of astigmatism at the edge, starting from 50% of the way out. The slightly narrower Zeiss OPMI got a little ragged in the final 10-15%. but these are 3- and 4-element eyepieces - mainly built for clarity and sharpness on axis in slow optical systems.
The two Leica pairs were very nice - the wider HC Plan S 10x/25 surprisingly so considering its wider field (25mm field stop, compared with 22mm for the other Leica). Neater than a typical plossl at the edge - both Plossls and abbé orthoscopics display edge astigmatism in my F/6 scope. But if they were compared with - say - a good widefield astronomy eyepiece on stars at the field edge, I’m sure the astro EP would be sharper.
I could see how the Leica compares with a Panoptic 24mm or Nagler 22mm at F6 later if I get the opportunity.

A quandary is that there really don't seem to be any longer focal length (i.e., 25mm and longer) 1.25" astronomy eyepieces that are well corrected for faster scopes. See: https://www.cloudynights.com/topic/929461-well-corrected-35mm-28mm-125-eyepiece/

If the HC Plan S 10x/25 is better corrected than a Plossl and as sharp as the best orthos, that's a pretty big deal... I would really love to see the comparisons that you mentioned.

[Highburymark]

Having done a few tests, the Televues are better corrected right at the edge. So depending on what purpose you want to use a low power 1.25” eyepiece for, the Panoptic 24 is about as good as it gets, I would think. The Nagler 22 is lovely, but it’s 2”, and shows some field curvature in my F/6 scope. The Delites are excellent but only go to 18mm, and my recently acquired Ethos 6 - tried out here just for fun - is mind-blowingly sharp at the edge - wow. Thing is, I’ve never really worried about edge sharpness - I don’t do much DSO astronomy. I’m much more interested in what I can see in front of me. So the reason to buy the Leica is definitely not for edge correction, even though it performs very well in this respect to my eyes. These are £400-£500 a pair secondhand. You’re paying that for outstanding definition, transmission and contrast on axis, with a very reasonable AFOV. But I wouldn’t pay that sort of money just to use them in a fast scope. Just as I wouldn’t buy Ethos for a slow Maksutov or SCT. Put them in a apo, with a binoviewer, and push them up to 200x on the Moon or Sun, and they’ll blow you away. 

[Louis D]

4 hours ago, Emperor!Takahashi! said:

A quandary is that there really don't seem to be any longer focal length (i.e., 25mm and longer) 1.25" astronomy eyepieces that are well corrected for faster scopes.

The only one I can think of off the top of my head is the discontinued Pentax XL 28mm.  Good luck finding one.  I've only seen one come up used on CN Classifieds over the past 10 years.

[Emperor!Takahashi!]

15 minutes ago, Highburymark said:

Having done a few tests, the Televues are better corrected right at the edge. So depending on what purpose you want to use a low power 1.25” eyepiece for, the Panoptic 24 is about as good as it gets, I would think. The Nagler 22 is lovely, but it’s 2”, and shows some field curvature in my F/6 scope. The Delites are excellent but only go to 18mm, and my recently acquired Ethos 6 - tried out here just for fun - is mind-blowingly sharp at the edge - wow. Thing is, I’ve never really worried about edge sharpness - I don’t do much DSO astronomy. I’m much more interested in what I can see in front of me. So the reason to buy the Leica is definitely not for edge correction, even though it performs very well in this respect to my eyes. These are £400-£500 a pair secondhand. You’re paying that for outstanding definition, transmission and contrast on axis, with a very reasonable AFOV. But I wouldn’t pay that sort of money just to use them in a fast scope. Just as I wouldn’t buy Ethos for a slow Maksutov or SCT. Put them in a apo, with a binoviewer, and push them up to 200x on the Moon or Sun, and they’ll blow you away. 

Such a useful comparison. Huge thanks!

[Highburymark]

11 hours ago, Louis D said:

The only one I can think of off the top of my head is the discontinued Pentax XL 28mm.  Good luck finding one.  I've only seen one come up used on CN Classifieds over the past 10 years.

The Pentax XL28mm was limited to 55 degrees AFOV, and reportedly had a bit of field curvature and astigmatism, though I haven’t used one. I wonder if the old pseudo-Masuyamas were better corrected for fast scopes than four element Plossls? I had the 30mm Ultimas for a while but didn’t test their performance below F/7.    
I’ve read that the TeleVue Plossls are said to be corrected down to F/4. They are not. Much as I love them, they also display the astigmatism typical of the design, though less than some cheaper Plossls I’ve tried. But like the microscope EPs, they make wonderful binoviewer pairs, particularly for solar.

[Louis D]

1 hour ago, Highburymark said:

The Pentax XL28mm was limited to 55 degrees AFOV,

Obviously.  You're not going to get any larger of an AFOV at 28mm in a 1.25" barrel unless you move all the lenses well above the 1.25" barrel.  In that case, you'll need lots of in focus and will start to notice edge of field vignetting or outright outer field fuzziness.

[Highburymark]

2 hours ago, Louis D said:

Obviously.  You're not going to get any larger of an AFOV at 28mm in a 1.25" barrel unless you move all the lenses well above the 1.25" barrel.  In that case, you'll need lots of in focus and will start to notice edge of field vignetting or outright outer field fuzziness.

I don’t think there’s an answer to the question then really. Nothing 1.25” below 24mm/68 degrees that’s well corrected in fast scopes.    
 

[Highburymark]

Reading a couple of other past threads, looks like the 35mm pseudo-Masuyama is the best bet. Don P thought it performed well enough at F/5. 

[Emperor!Takahashi!]

1 minute ago, Highburymark said:

Reading a couple of other past threads, looks like the 35mm pseudo-Masuyama is the best bet. Don P thought it performed well enough at F/5. 

I have a pair of the 30mm Ultimas on the way 🙂 An issue with the 35mm is that it requires lots of backfocus, just like @Louis D stated above. And they also vignette. I owned a pair and loved the views but didn't love how I had to refocus so much when using them.

I'm confused by online reports on the 30mm. There are people who state they're well corrected in their fast scope, and there are others who say the opposite. So, I'll try it and see how it goes!

[John]

The Celestron Ultima 30mm was quite well corrected in scopes such as F/7 and F/8 but suffered a bit at the edges in scopes faster than that.

When I had F/10 scopes it, and the 35mm, were probably my favourite low power eyepieces. A touch better even than the TV 32mm plossl.

 

Edited July 18 by John

[Louis D]

Was the whole point of this well corrected in fast scopes 1.25" eyepieces between 24mm and 32mm simply for the purpose of increasing the exit pupil in fast scopes that can't take 2" eyepieces, or was there some other use case I missed?

I have an upcoming posting showing it is possible to use 2" eyepieces to some effect in 1.25" focusers if a 2" diagonal is used that has had its nose piece adapted to 1.25", and there is plenty of back-focus/in-focus on the OTA.

[Emperor!Takahashi!]

On 18/07/2024 at 19:18, Louis D said:

Was the whole point of this well corrected in fast scopes 1.25" eyepieces between 24mm and 32mm simply for the purpose of increasing the exit pupil in fast scopes that can't take 2" eyepieces, or was there some other use case I missed?

That was related to another thread that I started on another astronomy forum. I shared a link earlier. But it was a departure from the topic of this thread.

To get us back on topic, I'll share information on the Nikon CFIUW 10x/25 microscope eyepieces that I mentioned earlier.

 

 

According to the limited information I've found online, these are Nikon's high-end "ultra-wide" (that's what the UW in the name means) microscope eyepieces. The AFOV is approximately 55°. I've used them in a few scopes now, so I can comment a little on their performance. I find the eye relief totally comfortable, and the construction of the eyepieces results in the "floating effect" that is most commonly associated with the Edmund 28mm RKE. Some observers (including me) love this, and some don't and prefer eyecups for a more "contained" view.

At the center of their FOV, these are extremely sharp... so much so that after a brief comparison of these vs. the 100° XWA eyepieces I owned, I posted the latter for sale. The difference was obvious, not subtle. In comparison to the XWAs (which are highly regarded eyepieces), these Nikons displayed more pronounced star points and diffraction rings, higher contrast, and brighter/more intense colors. The view through the XWAs, while impressive due to their AFOV, looked slightly muddy (as though one is looking through a thin layer of water in the dirty dish sink) in comparison to what these little Nikons showed. That probably sounds too harsh, and I'll add that I loved the XWAs... until I compared them to these.

In an f/5.5 instrument, the center 60% of the FOV is sharp, and then there's gradually increasing astigmatism to the edges. But I don't find it obtrusive, and it's much, much cleaner than the currently produced Masuyama eyepieces that I've used. In an f/10 instrument, the center 90% of the FOV is sharp, and there is only slight astigmatism at the edges. At f/12, 100% of the FOV is sharp. You can easily unscrew the field stop on these eyepieces, but I've found it doesn't make much of a difference to the AFOV... maybe just adding ~3°. But what's nice is that unscrewing the field stop does not result in fuzzy edges when looking through the eyepiece. The edges are still crisply defined.

Now here's another thing I love about these... They're so easy to adapt to 1.25". Initially, I added aluminum tape to accomplish this.

 

 

And that works very well. I've used them up to 600x in my binoviewer, and the images merge perfectly. So, there's no need to make further modifications. But you can if you're inclined to 🙂 

 

 

The individual eyepieces have built-in diopters. One only needs to unscrew the barrel (at the center of the picture above), unscrew the diopter ring (on the left in the picture above), and the housed lens assembly (on the right in the picture above) fits perfectly into a thin 1.25" barrel.

 

 

The barrel in this picture was taken from an old prism diagonal, and it's longer than I'd like to use, so I ordered a few more simple 1.25" barrels from someone who sells such things. I'll rehouse my CFIUW pair once they arrive.

Finally, I'll note how tiny and light these are.

 

 

I have pairs of 25mm plossls and 24mm Brandons on the way, and a friend has agreed to lend me a pair of Leica HC Plan S 10x/25. So, stay tuned to see who emerges victorious from this clash of tiny titans.

Edited July 21 by Emperor!Takahashi!

[JeremyS]

On 17/07/2024 at 23:49, Louis D said:

The only one I can think of off the top of my head is the discontinued Pentax XL 28mm.  Good luck finding one.  I've only seen one come up used on CN Classifieds over the past 10 years.

I used to use my Pentax XL28 a lot in my Tak FS 102.

As I’ve reported on here over the years, I’ve been seeking a widest field 1.25-inch eyepiece. The winner is the Panoptic 24, unless the moon is involved as it becomes terribly distorted when approaching edge of fov. Tak LE 24 is very good, not quite as wide an fov, but is very small and light so I generally take as part of my slimmed down EP set for air travel.

[Louis D]

4 hours ago, JeremyS said:

I used to use my Pentax XL28 a lot in my Tak FS 102.

As I’ve reported on here over the years, I’ve been seeking a widest field 1.25-inch eyepiece. The winner is the Panoptic 24, unless the moon is involved as it becomes terribly distorted when approaching edge of fov. Tak LE 24 is very good, not quite as wide an fov, but is very small and light so I generally take as part of my slimmed down EP set for air travel.

Wow! I hadn't realized how the 24mm UFF dwarfs the 28mm Pentax XL.

[Highburymark]

5 hours ago, Emperor!Takahashi! said:

That was related to another thread that I started on another astronomy forum. I shared a link earlier. But it was a departure from the topic of this thread.

To get us back on topic, I'll share information on the Nikon CFIUW 10x/25 microscope eyepieces that I mentioned earlier.

 

 

According to the limited information I've found online, these are Nikon's high-end "ultra-wide" (that's what the UW in the name means) microscope eyepieces. The AFOV is approximately 55°. I've used them in a few scopes now, so I can comment a little on their performance. I find the eye relief totally comfortable, and the construction of the eyepieces results in the "floating effect" that is most commonly associated with the Edmund 28mm RKE. Some observers (including me) love this, and some don't and prefer eyecups for a more "contained" view.

At the center of their FOV, these are extremely sharp... so much so that after a brief comparison of these vs. the 100° XWA eyepieces I owned, I posted the latter for sale. The difference was obvious, not subtle. In comparison to the XWAs (which are highly regarded eyepieces), these Nikons displayed more pronounced star points and diffraction rings, higher contrast, and brighter/more intense colors. The view through the XWAs, while impressive due to their AFOV, looked slightly muddy (as though one is looking through a thin layer of water in the dirty dish sink) in comparison to what these little Nikons showed. That probably sounds too harsh, and I'll add that I loved the XWAs... until I compared them to these.

In an f/5.5 instrument, the center 60% of the FOV is sharp, and then there's gradually increasing astigmatism to the edges. But I don't find it obtrusive, and it's much, much cleaner than the currently produced Masuyama eyepieces that I've used. In an f/10 instrument, the center 90% of the FOV is sharp, and there is only slight astigmatism at the edges. At f/12, 100% of the FOV is sharp. You can easily unscrew the field stop on these eyepieces, but I've found it doesn't make much of a difference to the AFOV... maybe just adding ~3°. But what's nice is that unscrewing the field stop does not result in fuzzy edges when looking through the eyepiece. The edges are still crisply defined.

Now here's another thing I love about these... They're so easy to adapt to 1.25". Initially, I added aluminum tape to accomplish this.

 

 

And that works very well. I've used them up to 600x in my binoviewer, and the images merge perfectly. So, there's no need to make further modifications. But you can if you're inclined to 🙂 

 

 

The individual eyepieces have built-in diopters. One only needs to unscrew the barrel (at the center of the picture above), unscrew the diopter ring (on the left in the picture above), and the housed lens assembly (on the right in the picture above) fits perfectly into a thin 1.25" barrel.

 

 

The barrel in this picture was taken from an old prism diagonal, and it's longer than I'd like to use, so I ordered a few more simple 1.25" barrels from someone who sells such things. I'll rehouse my CFIUW pair once they arrive.

Finally, I'll note how tiny and light these are.

 

 

I have pairs of 25mm plossls and 24mm Brandons on the way, and a friend has agreed to lend me a pair of Leica HC Plan S 10x/25. So, stay tuned to see who emerges victorious from this clash of tiny titans.

Great stuff. And good job with the aluminium tape. 
Worth saying for anyone looking online to steer clear of eyepieces that come fitted with graticules unless they are easily removable. There’s a large variation in prices as now some sellers have cottoned on to the more vibrant market for used microscope EPs - one example, I recently saw two pairs of the same Zeiss OPMIs at $250 (in the US) and $800 (China) in similar condition.
 

[Don Pensack]

7 hours ago, JeremyS said:

I used to use my Pentax XL28 a lot in my Tak FS 102.

As I’ve reported on here over the years, I’ve been seeking a widest field 1.25-inch eyepiece. The winner is the Panoptic 24, unless the moon is involved as it becomes terribly distorted when approaching edge of fov. Tak LE 24 is very good, not quite as wide an fov, but is very small and light so I generally take as part of my slimmed down EP set for air travel.

Field stop figures:

24 Panoptic 27.0mm

24 ES68  27.2mm

24 UFF  27.6mm

24mm Hyperion 28.0mm

35mm Eudiascopic/Ultrascopic/Gold Series/Ultima from the early '90s  29.0mm

The Panoptic has the smallest true field of all the above.

[John]

2 hours ago, Don Pensack said:

24 ES68  27.2mm

24 UFF  27.6mm

24mm Hyperion 28.0mm

35mm Eudiascopic/Ultrascopic/Gold Series/Ultima from the early '90s  29.0mm

The Panoptic has the smallest true field of all the above.

But it's the cutest by far ☺️

Edited Sunday at 19:24 by John

[JeremyS]

6 hours ago, Louis D said:

Wow! I hadn't realized how the 24mm UFF dwarfs the 28mm Pentax XL.

It’s certainly not the most good looking eyepiece in my collection, either 😊

[globular]

11 minutes ago, JeremyS said:

It’s certainly not the most good looking eyepiece in my collection, either 😊

Good looking through them though. Two of them in a binoviewer are lovely.

[Louis D]

2 hours ago, JeremyS said:

It’s certainly not the most good looking eyepiece in my collection, either 😊

It's much better looking in all black: