105 replies to this topic

[elstargazer12]

Hello all,

 

I wanted to share some results with a series of eyepiece evaluations I've been doing.  

 

Back story is that after many years of being curious about binoviewer setups and reading people who say it's like they're seeing the Moon for the first time again, I got a good deal on a used Denk II with powerswitch.  That was a month ago and at the time, the only ep I had a pair was were Meade 26mm Series 4000 Super Plössls.  Certainly not a bad eyepiece, but I was hoping to upgrade both in FOV (to close to the ~27mm field diameter possible in 1.25 eps) and in quality.  So after a gratuitous amount of web surfing, especially Denis's and SomebodyElseEntirely's detailed reports here on CN (Thanks!), I decided I'd try a group of microscope eyepieces.  

 

And there's another reason I'm drawn to microscope eyepieces- I'm a geologist and have spent my share of days staring through microscopes for hours on end.  At my former lab we had a top of the line Zeiss Axioscope unit with W-PL 10x/23 eyepieces and currently we have a Leica unit with HC PLAN s 10x/22s.  

 

Ever since the first days I used that Zeiss microscope extensively (around 2012), I immediately had the thought "I wish the view through my telescopes looked like this!"  Everything was unbelievably sharp and contrasty, all the way to the edge of field.  And because microscope eyepieces are designed for comfortable binocular usage, it was SO effortless to look through them.  In fact, I did and still do look forward to any microscopy work I need to do at my job.  It's such a beautiful experience that's at the same time much more comfortable than most of my astronomical eyepieces.  

 

Speaking of those, my commonly used eyepieces are: APM UFF 30mm, Panoptic 19mm, Nagler T6 13 and 9mm, Radians and Delites at the highest powers. I do pay attention to the edge of field, which explains to a large extent these choices.  The question is: Can I find a pair of microscope eyepieces with 25mm focal length (i.e., 10x in microscope lingo) that have close to 27mm field diameter, decent edge sharpness, and preserve the extremely pleasing on-axis sharpness, contrast, and overall viewing comfort that I have come to love about my microscopes at work?

 

Stay tuned... I'm going to post in segments and hope to do these test over the course of the coming weeks.  

 

 

 

 

 

 

 

[Mark Strollo]

Sounds like a fun (and potentially expensive) search project.

A member of our club is exclusively using a binoviewer.  He was initially very happy with 24mm Panos.  After an extensive search, he ended up with some sort of a wide angle Nikon NAV set.

I use 19 Panos in my binoviewer, but only for solar.

Will be watching this thread to hear your results.

[elstargazer12]

Here are the eyepieces I've been testing:

 

Astronomical eyepieces:

- 26mm Meade Super Plössl- old standby and I think a suitable reference for a "good" mid-tier Plössl

- 24mm Questar Brandon- a reference for high resolution and contrast among astronomical eyepieces

- Baader Mark IV Zoom at 24mm- Just something I had on hand- another good astronomical "reference" with lots of reviews online to gauge relative performance

The known quantities (among microscope eyepieces for astro)

- Leica HC PLAN s 10x/25 M 507808 (A couple of very positive notes about astronomical use on Cloudynights.  Latest and greatest from Leica)

- Zeiss PL 10x/18 444132 (Supposed to be source of TMB 25mm aspheric lenses)

- Zeiss S-PL 10x/20 444039 (A couple of user reports are glowing- supposed to be the best of all microscope eyepieces in terms of contrast and sharpness but has a narrow FOV)

 

Note that the second number in these microscope ep names is the "field number" or the field diameter in mm.  So the close to 27mm the better!

 

And finally, we have the black horses (no written report about astro use at all on CN or elsewhere I can find):

- Leica HC PLAN s 10x/22

- Leica 10x/23B (stereo microscope eyepieces)

- Olympus SWHK 10x/26.5 

- Nikon CFUWN 10x/25

- Mitutoyo WF 10x/24 

 

The last three were at most $50 apiece.  It's incredible how cheap these things are used!  I guess there just isn't a big market for them since most institutions purchase microscopes as a set and in fact it's often difficult to do official business purchases off ebay (I know from experience!).  The Mitutoyos, Olympuses, and Nikons for example are something like $300-400 new.   I couldn't find anything written about the Olympus, Nikon, or Mitutoyo models regarding astronomy use, so I was hoping to be pleasantly surprised!  I've come across all of these makes of microscopes over the years to look at rock samples and I know they are all make top-notch stuff.  Mitutoyo especially is known for making kind of specialty items like extra wide field objectives and eyepieces, so maybe they'll have something a little different from the rest here as well.  

I've posted images of most of these below.

 

The first thing I did with most of these is to take some photos through the eyepiece of a neighbor's chimney.  By assuming that the Meade's specified AFOV of 52˚ is correct (and comparing with to a TV Plössl using the "holding-eps-like-binoculars" method seems to confirm this is accurate to a degree or two, I computed the AFOV side of the other eyepieces by noting the size of the chimney compared to the field stop.  So it's possible that all these numbers are shifted by a degree or two due to inaccurate assumption of 52˚ for the Meade.  However, if they are shifted, they should be shifted uniformly.  

 

Not all the eyepieces are on this list- I didn't have a couple of them handy when I took these images.  But I hope to fill the gaps later!

 

Eyepiece                                 AFOV in deg

Zeiss S-PL 10x/20                      43
Nikon CFUWN 10x/25                57
Olympus SWHK 10x/26.5           60         
Brandon 24mm                           42
Mitutoyo 10x/24                          54
Meade SP 26mm                        52 (by assumption)
Leica HC PLAN s 10x/25            57
Baader zoom                              40

 

No big surprises except that the Baader is quite a bit narrower than the stated 50˚ at 24mm.  The "binocular" method qualitatively confirmed that it is indeed quite narrow.  The field stop numbers of all the microscope eyepieces correspond well to their AFOVs- so it seems like all these numbers are quite reliable, perhaps unlike some AFOV claims in astro eps.  This is not surprising, as people do actually use the field widths in microscope observations to estimate size, so there's more reason to make these accurate than AFOVs for amateur astronomy eyepieces. 

 

Lastly for now, here are some note about the optical design.  I did not take any of them apart aside from unscrewing major sections.  

 

These eyepieces have a positive field element before the field stop:

 

Zeiss S-PL

Olympus SWHK

Both Leicas

Baader Zoom

 

These do not- all optics are downstream of the field stop:

 

Meade Plössl

Brandon

Nikon CFUWN

Mitutoyo 10x/24

Zeiss 10x/18

 

Some tests so far suggests that moving the focusing mechanism on some of these microscope eps, which moves the field lens closer and farther to the rest of the optics group, changes the edge correction.  This is most apparent on the Leica 10x/25s.  More on this later!  I've done two nights of testing so far and will be posting these and future tests here in the coming weeks.  

 

One teaser is that, yes, the Zeiss S-PL seems to deserve its reputation on some CN posts of being the perfect eyepiece, aside from a narrow AFOV.  

 

That's it for now!

 

 

 

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[j.gardavsky]

Thank you El for having started this review!

 

The Zeiss E-Pl design has been iterated between the eye lens convex out, and concave out.

 

The Leica HC Plan S 10x has a meniscus field flattener in the insert tube. So it is not an intrafocal design.

The shorter focal version Leica HC Plan 12.5x has as well the meniscus, the Leica HC Plan 10x does not.

Besides, there is also the Leica L Plan version, and available for f=32mm.

 

The Zeiss S-Pl is a projective eyepiece.

Its projective counterpart is the Leica HC 12.5x/13 PHOTO.

 

The last Periplan versions with up to 7 lenses count to the top EPs designs, as shown in the Olympus tutorial, Figure 4, https://www.olympus-...natomy/oculars/

 

The older Leitz Periplans (red dot) may be of potential interest because of their CVD correction.

 

Looking forward to your tests,

JG

Edited by j.gardavsky, 09 June 2020 - 10:55 AM.

[Procyon]

Really loved using 25mm TV Plossls when I had binoviewers. Clear, sharp and snap to focus. I should have tested 19 mm Panoptics or 20mm TV Plossls but never had the chance. I did test about 10 different pairs though.

Would have definitely gotten 24mm Panoptics if I had Binoviewers with bigger aperture.

Edited by Procyon, 09 June 2020 - 11:01 AM.

[RichA]

Hello all,

 

I wanted to share some results with a series of eyepiece evaluations I've been doing.  

 

Back story is that after many years of being curious about binoviewer setups and reading people who say it's like they're seeing the Moon for the first time again, I got a good deal on a used Denk II with powerswitch.  That was a month ago and at the time, the only ep I had a pair was were Meade 26mm Series 4000 Super Plössls.  Certainly not a bad eyepiece, but I was hoping to upgrade both in FOV (to close to the ~27mm field diameter possible in 1.25 eps) and in quality.  So after a gratuitous amount of web surfing, especially Denis's and SomebodyElseEntirely's detailed reports here on CN (Thanks!), I decided I'd try a group of microscope eyepieces.  

 

And there's another reason I'm drawn to microscope eyepieces- I'm a geologist and have spent my share of days staring through microscopes for hours on end.  At my former lab we had a top of the line Zeiss Axioscope unit with W-PL 10x/23 eyepieces and currently we have a Leica unit with HC PLAN s 10x/22s.  

 

Ever since the first days I used that Zeiss microscope extensively (around 2012), I immediately had the thought "I wish the view through my telescopes looked like this!" 

However, microscope eyepieces in-terms of field size and correction have mostly lagged telescope eyepieces, especially in the low-to mid end.  I  remember replacing a Leitz Periplan eyepiece on a microscope with a Celestron Plossl and being astounded by the jump in quality.  I doubt the microscope world has anything like Naglers to this day.

 

[elstargazer12]

However, microscope eyepieces in-terms of field size and correction have mostly lagged telescope eyepieces, especially in the low-to mid end.  I  remember replacing a Leitz Periplan eyepiece on a microscope with a Celestron Plossl and being astounded by the jump in quality.  I doubt the microscope world has anything like Naglers to this day.

Hi RichA,

 

Yes, I certainly have no illusions about edge correction at shorter focal ratios.  Microscope eyepieces are not designed to optimize this.  As you probably know well given your experience with microscopes, the eyepieces are a bit of an afterthought since the objectives are where the real engineering and costs go.  

 

I think there are a few reasons where are no Nagler-like eyepieces (or ultrawides in general) in microscopy:

 

- All higher end microscopes have binocular heads.  In my personal experience, the extra appeal of wide field AFOV is lessened when using two eyes.  I find myself enjoying my Naglers and Panoptics very much when stargazing and using Plössls and Orthos feel narrow.  But I don't ever find myself wishing for more FOV when looking at rock samples in a microscope.  A 50˚ AFOV feels expansive enough with two eyes.  I wonder if others have this impression, too. 

 

- Microscope eyepieces on the top-tier scopes are more or less standardized at 10x.  Changing power is completely covered by objectives.  I know there are 16x, 20x etc eyepieces out there, but they are much, much rarer than 10x eyepieces.  The max AFOV of a 10x eyepiece in the microscope is about 60˚, so there's no way to develop a 10x, 82˚ AFOV microscope eyepiece and a very small market for a, say 20x 82˚ AFOV eyepiece. 

 

- Distortion of all kinds, like lateral variations in magnification, are less tolerable in microscopy.  As I wrote earlier, people measure distances on microscopes down to a few % precision (I certainly do all the time).  So the some of the distortions associated with astronomical ultrawides would be a much bigger problem in a microscope eyepiece. 

 

- The f ratios of the light going into eyepieces on microscopes is much higher, f10 and potentially a lot higher.  So there's no pressure to develop Nagler-like eyepieces that have good edge correction at f4. 

 

Just some thoughts.

[elstargazer12]

Hi all,

Here are some notes about how I've been / will be taking notes.  

Overall, I want to evaluate these eyepieces for the following characteristics.  I list some thoughts I have about doing this.  Please provide any tips and feedback for what kinds of tests might work well!

- On-axis sharpness/resolution.  I'm treating this as mostly a spot size test.  I'm using double stars that are marginally resolvable as the primary tool for this.  Last night for example, I used Mu Bootis B/C (2.2") as a super close separation double but with little magnitude difference (observed at 48x in TV-85) and then Polaris at 24x as a large magnitude contrast double.  I'm using this to test the ability of the eyepiece to concentrate the light of the primary within a very small radius.  Planets and the Moon are not easy to see for the next few weeks, but I will observe them too for sharpness/resolution when they are back.  

 

- Contrast.  I'm mostly waiting for planets and Moon for this.  I tried using M57 last night to look at visibility of the nebula and background brightness, but did not reach consistent conclusions.  I plan to try on more marginal DSOs as well.  

 

- Transmission.  I'm counting stars in a given star field and trying to gauge the ease of holding certain stars in direct and averted vision.  

 

- Edge correction.  I'd like to use the method described elsewhere on CN about using double stars that are marginally split in the center of field and quantifying where they start being "unsplit".  So far I've just done qualitative observations, but even these are quite revealing. 

 

In terms of equipment, I'll be using:

 

1. TV-85 with and without 2x Ultima barlow.  This is an f7 refractor with spectacular optics that were cleaned and collimated by Televue a couple of years ago.  

 

2. A-P 130GTX at native focal length (f6.3) and with Denk II binoviewer (using just the right eye ) with powerswitch that results in f8.2, f11.0, and f15.0 focal ratios.  

[elstargazer12]

Some notes from Nights 1 and 2:

 

Eyepieces presents are:

 

- 26mm Meade Super Plössl
- 24mm Questar Brandon

- Leica HC PLAN s 10x/25 M

- Zeiss S-PL 10x/20 
- Olympus SWHK 10x/26.5
- Nikon CFUWN 10x/25
- Mitutoyo WF 10x/24

 

And as a reference with a different focal length, a Panoptic 19mm. 

 

- Sharpness resolution test: I looked at Mu Bootis B/C (2.2") at 48x (TV-85 with Ultima barlow) and Polaris (much larger separation but large magnitude contrast) at 24x (just TV-85).  Sky was very steady, I rated it 4.5/5.  Light pollution is in white zone (Cambridge, MA). Thanks to the pandemic, I anticipate all of these tests will be under this level of light pollution.

 

Also, I note that every time I changed eyepieces (which happened many many times), I cupped my eyes and closed them to relax them for 5 seconds to reset any eye strain.  

 

Mu bootis (at 48x, f14 light cone):

 

One important overall observation: For the most part, the differences among these eyepieces are small.  Even though the night was very steady, fluctuations in seeing and my eye strain are sufficient to make one higher ranked eyepiece perform as one of the lower ones.  It is usually with repeated observations I was able to see differences between Group 1 and 2, although ultimately the differences are consistent and repeatable.  

 

Group 1: 

Zeiss S-PL, Brandon, Olympus and Leica 10x/25 seem to make a peanut of the B/C pair under moments of good seeing.  The pair always looks elongated except at moments of high eye strain or poor seeing.  The Zeiss especially at times appears to result in a slightly more distinct darkness in between the components.  

 

Group 2: 

Mitutoyo and Nikon consistently allowed elongation to be seen.  But, maybe it's just a matter of luck, but I did not confidently see a peanut shape with distinct darkening/thinning in between the components with these.  The Group 1 and Group 2 differences are not at all dramatic.  If B/C weren't a double, I probably wouldn't be able to say that the single star images themselves are actually better or worse rendered in these eyepieces. 

 

Group 3: 

The Meade super Plössl was the only eyepiece to not consistently show an elongation.  This is also the only eyepiece where I can say that the star images themselves look a bit bigger than in the others.  There's a bit more of a fuzz around them.  But I want to emphasize, the image was still very satisfying by itself- just not clear as a double.  If I were just looking at a star field without other other eyepieces handy, I would not at all have the sense that there's a lack of performance. 

 

 

Polaris (at 24x, f7 from scope):

 

Group 1:

Zeiss S-PL is best.  The image of polaris A was neat and circular with very light irregularity.  It was distinguishably MORE CONSISTENT in showing the mag 9 B component flickering in and out and it was a bit easier to hold the B component in view.  The pure white rendition was also quite pleasing.  

 

Group 2: 

Brandon, Nikon, and Leica 10x/25 all performed similarly.  It's possible at moments of slightly better seeing/less eye strain to see the B components flicker in and out.  At good times it can be held in clear view for a few second.  

 

Group 3: 

In a surprise, the Olympus (Group 1 for mu Bootis) joins the Meade in Group 3.  I did see the B component in these eyepieces, but it was more difficult in the slightly higher number and intensity of rays coming out of the A component.  Why did the Olympus move down so much?  One difference is that there was no barlow for Polaris, so maybe the Olympus worked particularly well with the barlow.  More likely, I think it's a difference of magnitudes. I think for very bright stars, there is more energy from the star that is scattered as ray-like projections in the Olympus.  This is not as much of a problem with a dim star like mu Bootis B/C.  I think maybe there are some scratches on the lens?  I couldn't see these directly, but these are used eyepieces from a lab of some kind, so I don't doubt that.  

 

So overall result from these double star tests:

 

- The Zeiss S-PL is, by a tiny but consistent margin, distinguishably sharper than everything else. 

- The Brandon and Leica HC PLAN s 10x/25 are very similar in their resolution limit. 

- The Nikon is very very close to the Brandon and Leica, maybe even the same and it was just some variation in seeing and eye fatigue that resulted in these perceived differences despite my attempts to control for this. 

- The Meade is visibly a bit less sharp with more "ragged" looking stars that affects the ability to resolve marginal doubles. 

- The Olympus is a bit of an enigma- For the dim Mu Bootis, it performed very well, as well as the best.  But with Polaris, it showed more scatter from the A component in the form of ray-like protrusions.  This is a small effect, but enough to affect its ability to resolve the B component at times.  My bet is that very subtle scratches are the issue.  

 

Overall, all the eyepieces are satisfying and render aesthetically beautiful star fields.  If I weren't comparing then, I'd enjoy observing from any of them.  

 

Ok, enough for today.  I have some transmission and edge correction observations as well, but I'll type it up in a future installment. 

[elstargazer12]

Consolidating more notes from the first two nights of tests.  It looks cloudy for the next week or so around here, so I'll just have these observations to go on.  These are some notes on transmission and edge sharpness.

 

Eyepieces present:

 

- 26mm Meade Super Plössl
- 24mm Questar Brandon
- Leica HC PLAN s 10x/25 M
- Zeiss S-PL 10x/20
- Olympus SWHK 10x/26.5
- Nikon CFUWN 10x/25
- Mitutoyo WF 10x/24

 

Transmission tests: 

 

I just took a star field with a moderate number of stars, in this case near Izar in Bootes and repeatedly swapped the eyepieces to see if I can see the same dimmest stars and how hard it was to see them.  Like the previous tests, I cupped my eyes and opened them in darkness to rest them between each eyepiece observation.  Telescope is a TV-85 operating at f7. 

 

There was an asterism of 4 stars to the NE of Izar, plus a fifth star that was just baaarely visible in some of the eyepieces in between the asterism and Izar.  I did not manage to find the magnitudes of any of these, but this is just a relative test.  

 

Group 1: 

Zeiss S-PL is best, again.  All 4 stars in the asterism can be held routinely with direct vision and there was hint of the fifth star most of the time.  Difference between the S-PL and the eyepieces in the next group is very subtle, mostly in the form of qualitative "easiness" to hold all 4 stars in the asterism in direct vision.  But the difference was consistent

 

Group 2:

 

Leica 10x/25, Meade SP, Olympus, and Nikon.  These four eyepieces were neck and neck.  I would say that all four asterism stars could be consistently held in direct vision, but just a little bit harder than in the Zeiss.  During moments of better seeing and lower eye fatigue (I suspect the latter is more important), there was hint of the fifth star.  

 

Group 3:

 

Mitutoyo and Brandon.  A bit harder to hold all four stars in the asterism in direct vision- two of them flicker in and out, while all could be seen consistently in averted vision.  No hint of the fifth star at all.  

 

 

Edge correction

 

This is a big one for me as I've always been pretty picky about edge correction.  

 

I pointed the TV-85 at the Ring Nebula and looked for stars around it.  Just by luck, several brighter stars in Lyra are roughly at the edge of the field with the scope in this direction.  No barlows or extenders- just the TV-85 at f7.  Sooner or later I'd like to do what Bill Paolini did with the 25mm eyepieces and use a double star to quantitatively measure edge correction.  But it turns out that the differences among the eyepieces are fairly clear, so here are some qualitative notes.  

 

Group 1:

The Zeiss S-PL has perfect edge correction.  I hate to say "perfect", but there's really no other word for it.  Stars looked identical- in their perfect roundness, the same pure white color, and in brightness- at the very edge of the field and at the center. 

 

Group 1.5:

As a comparison, I also put in a Panoptic 19mm.  It's a different focal length and so can't be compared critically, but I thought it would be a good point of comparison.  The edge stars look pretty round, but the shape of the edge stars are no longer perfectly round and there are clear threads of stray light emanating from them.  Still, while looking at the center of field, it's certainly not enough to be distracting.  These imperfections are only noticeable when pointing my eye towards the edge.  

 

Group 2:

 

Meade, Leica, Mitutoyo, and Nikon.  For these three, there is clear degradation of stars at the edge of field, but, for me, not distracting if I'm looking at the center.  The Leica clearly shows some astigmatism while the Meade, Mitutoyo, and Nikon show more bloated, asymmetric edge stars, but not so clearly astigmatic (more symmetrical through the point of best focus).  For all four, imperfection become noticeable about 70% of the way from the center of field to the edge.  The Mitutoyo is actually a tiny bit worse off than the other three, but I still put them in the same group.  

 

Group 3:

Brandon and Olympus.  Both show clear astigmatism off-axis starting at 50-70% of the way out.  They are enough to be distracting, even when looking towards the middle of field.  However, keep in mind that the Olympus has a MUCH larger AFOV, so in terms of absolute off-axis degrees, it's a much better corrected eyepiece than the Brandon.  This ranking is based on star images at the "edge of field" however, and so the Olympus ends up here.  

 

Summary so far:

 

- The Zeiss is the best eyepiece or tied with the best in every category.  Only downside is that it's FOV is quite narrow at 43˚.  

- The Leica and Nikon are pretty good all-rounders with the Leica having a small advantage in edge correction and sharpness

- The Mitutoyo is maybe a tiny step below the Nikon in sharpness, but otherwise also a very nice all-rounder.  

- The Olympus and Brandon are similar is that they excel at high resolution imaging, but have poorer edge correction and (for the Brandon) transmission.  But then again, the Olympus has the largest AFOV, so if you're good at ignoring less-than-perfect stars in your peripheral vision, it's area of good star rendition is a lot wider than the Brandon.  

- The Meade is not as sharp/high-resolution as the microscope eyepieces or the Brandon- it shows stars that are just a little bit "hairier".  However, it's still a very pleasant eyepiece with good edge correction and the benefits of modern coatings and so beat the Brandon in transmission.  

 

That's it for now!  Look forward to any comments.  Any surprises here for anyone?

[25585]

Is the Zeiss Jena or Oberkochen? I have a pair of 25mm ZJ for bino viewing & an OPMI B T* from BG Optic converted/adapted to 1.25". All very sharp, clear & contrasty   

[elstargazer12]

Hi,

These are oberkochen. I’m adding another Zeiss, a PL 10x/18 with expanded field stop to the mix in the next time once I get a clear night again.

How do you find the edge correction with your Zeiss eyepieces in your scopes?

Roger

[25585]

Not noticed anything bad with the Zeiss. I also use TAL 25mm  https://www.ebay.co....redirect=mobile

[j.gardavsky]

This is a very nice and helpful shootout of the eyepieces.

 

The use of the photo eyepieces, like the Zeiss S-Pl, for visual, depends to some extent on one's eyesight.

Some people like them, others like them less, in the microscopy at very high magnifications, they are definitely not used for visual.

 

More differences between the eyepieces, as tested above, will be seen at higher magnifications,

JG

[elstargazer12]

So does anyone find any of these observations surprising so far?  I was expecting the difference between the Brandon and Meade to be a bit more subtle, but it's actually quite noticeable, both in terms of the Brandon being much better on-axis and much worse off-axis.  Has this been others' experience with Brandons, even in an f7 system?  I had thought Brandons would be OK as long as we're not in the f5 and lower range. 

 

JG: what problems do people have with the S-PLs at high magnifications?

 

By the way, are there Leica or other brand equivalents for the S-PLs?

 

Happy Friday.

[Jeff Morgan]

I have used Brandons at f/6 and f/7.

 

At f/6 they are being pushed kind of hard. I was ok with them at f/7, but I was using them for small targets, placed center of field.

 

I have never tracked down an object and intentionally put it on the field edge for critical observation. 

[j.gardavsky]

So does anyone find any of these observations surprising so far?  I was expecting the difference between the Brandon and Meade to be a bit more subtle, but it's actually quite noticeable, both in terms of the Brandon being much better on-axis and much worse off-axis.  Has this been others' experience with Brandons, even in an f7 system?  I had thought Brandons would be OK as long as we're not in the f5 and lower range. 

 

JG: what problems do people have with the S-PLs at high magnifications?

 

By the way, are there Leica or other brand equivalents for the S-PLs?

 

Happy Friday.

Hi El,

the projective eyepieces are designed for imaging from some specified distance in the micriscope on the photography film or camera chip.

The visual eyepiece is not an imaging device, it is actually a sort of magnifying glass to observe the virtual image in the image plane of the telescope/microscope with a human eye adapted to viewing objects in infinity.

My guess is, that some people can use the both eyepiece types without any problems for visual, others have problem to adapt their vision to a view through an eyepiece which has been designed for another purpose.

 

I have never used the Zeiss S-Pl eyepiece.
I can test the Leica Photo on my refractor, just waiting for the next opportunity, it's already on my desk, not to go forgotten.

 

Best,

JG

[faackanders2]

24mm 68AFOV 1.25" TV Panoptics.

[elstargazer12]

Hi all,

 

I did some more testing this weekend!  First update is that there's a new eyepiece in the line-up!  It's a German-made Zeiss PL 10x/18 aspheric.  This is the same eyepiece that Denis talked about in a thread and said that it beat the Zeiss Abbe Ortho 25mm here:

 

https://www.cloudyni...tions-and-test/

 

Denis had said that the 10x/18 roundly beat the ZAO I.  I used the 10/18x with and without the field stop (i.e., with ~45˚ AFOV and with ~60˚ fuzzy-edged AFOV. 

 

So the line-up of eyepieces for these tests are:

 

- 26mm Meade Super Plössl
- 24mm Questar Brandon
- Leica HC PLAN s 10x/25 M
- Zeiss S-PL 10x/20

- Zeiss PL 10x/18
- Olympus SWHK 10x/26.5
- Nikon CFUWN 10x/25
- Mitutoyo WF 10x/24

 

Telescope was an A-P 130GTX with Denk II binoviewer and power switch yielding f/8.2, f/11.0, and f/15.0 with powers (for 25mm eyepiece) of 43x, 57x, 78x.  This is the setup I intend to use long term with these eyepieces, so I'm paying close attention, especially to edge correction as it changes with f/ratio.  I used all the eyepieces in the right barrel of the binoviewer.  

 

This time I tested three aspects of the eyepieces: Resolution (via double stars and M13), edge correction (via semi-quantitative double star method), transmission (M13 and M27), color rendition (Izar and Jupiter), and contrast (M27 and Jupiter)

 

Test 1: Izar for Resolution and color rendition

 

Izar is a 2.9" double with ~3 mag contrast and color difference.  Viewed at 78x.  

 

Group 1: Zeiss S-PL is the best all by itself again... this is getting boring isn't it?!  Quite consistently shows the B component as completely separate with a visible dark gap.  Shows the color contrast just a bit better than the Leica below.  

 

Group 2: Leica HC PLAN s 10x/25, Brandon, and Zeiss PL 10x/18.  These are in this group for different reasons.  I felt the Leica and Brandon were able to show the dark gap about as well as the S-PL.  The moments where they do not can easily be attributed to seeing or eye fatigue.  But the color contrast was more obvious in the S-PL than either the Leica or Brandon.  The PL 10x/18 showed very nice colors, perhaps a bit more obvious than the Leica/Brandon.  However, I felt it just showed the dark gap between the components a little bit less reliably. 

 

Group 3: Nikon and Olympus.  Both provided very satisfying views and at times showed the dark gap between the components.  I would say in this sense, they performed very similar to the Zeiss PL 10x/18.  However, the color contrast was less obvious, somewhat like the Leica/Brandon pair.  

 

Group 4: The Meade and the Mitutoyo consistently showed the star as a kind of "gourd shape" with bigger and smaller lobes connected in the middle.  However, the star images were not clean enough to really show the components as completely discrete.  

 

Test 2: Double Double in Lyra for resolution and quantitative edge correction

 

I mainly focused on the 2.6" pair, although both pairs were readily resolved by the best eyepieces.  Read on...

 

Group 1: Zeiss S-PL and Leica HC PLAN S 10x/25.  Finally another eyepiece joins the Zeiss in the top group! Both eyepieces very consistently showed a dark lane between both sets of doubles.  The star images were perfect little balls.  The separation still came and went at times, I believe mostly due to eye fatigue, but generally the separations were obvious and pleasing. 

 

Group 2: The Nikon did really well here.  I wrote it was "pretty much the same" as the Group 1 eyepieces.  

 

Group 3: Zeiss PL, Brandon, and Olympus were a tiny step behind the others, showing the split with a dark lane most of the time, with perhaps just a touch more difficulty than the best.  

 

Group 4: Meade and Mitutoyo again brought up the rear with clear elongation of the components and sometimes depicting a visible darkening.  But the stars just weren't quite TIGHT enough compared to the other eyepieces.  

 

Assessment of resolution tests so far: The first thing to conclude is that the Zeiss S-PL is amazing- it has been in the top bracket in every single resolution test so far with its tiny, tiny, color-neutral stars.  I've come to sub-consciously consider it the reference eyepiece- sometimes looking through a different eyepiece I would think "I wonder what it looks like in the Zeiss.  The performance of the other eyepieces relative to the S-PL varies a bit from object to object, but after looking over these notes, I'm starting to draw these conclusions:

 

- The Leica HC PLAN s 10x/25 is also really spectacular.  On dimmer doubles, it performs right up there with the S-PL.  However on the two brighter doubles tests (Izar, Polaris, and Algieba), there is just a little bit more scatter from the brighter star that hinders resolution a tiny bit.  The Brandon behaves very similarly in all these regards.  

 

- Olympus, and Nikon are very similar to the Leica and Brandon with perhaps just a tiny, tiny bit less consistency.  The Zeiss PL 10x/18 appears to belong in this group, too, but I need a little more time with it. 

 

- The Mitutoyo and Meade perform quite similarly, with slightly more scatter, but still quite pleasing star images.  If I had nothing to compare them to, I certainly wouldn't be complaining.  

 

 

 

 

 

 

 

 

 

[elstargazer12]

Test 2 Part 2: Double Double in Lyra for quantitative edge correction

 

I'm separating this out just to keep the post lengths shorter.  

 

For this test, I focused the 2.6" pair in the Double Double in the center of field and slowly moved it to the field stop and determined approximately where it is no longer resolved.  In the case of the Meade and Mitutoyo, where the resolution was not super obvious to begin with, I just determined where I thought the image broke down enough so that the elongated double star becomes more like a "blob".  

 

Here are the results (x% means the break down occurred approximately x% from the center to the edge):

 

Zeiss S-PL -    95%
Leica 10x/25 - 80%
Nikon -             80%
Olympus -        70% 
Zeiss PL 10x/18 - 80% (This is with the field stop detached, i.e., with ~60˚ fuzzy-edged AFOV)
Meade -           85%
Brandon -         70%

Mitutoyo -         80%

 

So what to conclude from this?

 

As expected, the Zeiss S-PL is essentially perfect.  However note that it has one of the narrowest AFOVs.  So if we multiple these numbers by the AFOV to find the total "sharp" AFOV, we get:

 

Zeiss S-PL -    41˚
Leica 10x/25 - 46˚
Nikon -             46˚
Olympus -        42˚
Zeiss PL 10x/18 - 48˚
Meade -           44˚
Brandon -         29˚
Mitutoyo -        43˚

 

From this, it seems like the Brandon has the smallest usable FOV.  Then the S-PL, Olympus, Meade, and Mitutoyo are in the middle of the pack.  The Leica, Nikon, and de-field-stopped Zeiss PL 10x/18 have the widest sharp fields. 

 

But perhaps more important than all this is the qualitative impression.  Like Jeff Morgan said, no one puts stuff at the edge of field to observe critically.  Edge correction is important to me because if it's too bad, it starts to detract from the object I'm observing, especially in a rich star field.  In this sense, I think these are the groups in order of most subject "enjoyment". 

 

Group 1: Leica, Zeiss PL 10x/18, and Nikon.  These have wide, 55-60˚ AFOVs with good sharpness at the edge of field.  Stars are clearly not round and perfect if I turn my eyeball to the edge of field, but it's not too bad, and I don't really notice the imperfect stars if I don't turn my eyeball.  

 

Group 2: Meade, Zeiss S-PL, Mitutoyo.  These are in here for different reasons again.  The Meade and Mitutoyo are quite similar- about 50-55˚ AFOVs with limited edge of field break down.  In fact, they are very similar in relative behavior to the Group 1 eyepieces, but they just start out with a slightly narrower field so they feel a bit less "immersive".  The Zeiss S-PL is not at all immersive with a 43˚C AFOV, but it's basically perfect to the edge and so is very enjoyable with a completely different "feel"

 

Group 2.5: Olympus.  I wasn't sure where else to put this.  It has the widest AFOV but also tied the Brandon with worst edge correction.  I think if one isn't too sensitive to peripheral vision, this eyepiece is great.  It certainly has the most immersion factor.  But for me, there's just a bit too much fuzziness in my peripheral vision.  

 

Group 3: The Brandon.  Ah the Brandon- starts narrow and gets pretty bad quickly.  To me, this is a dedicated double star and planetary eyepiece.  I can't really imagine using and enjoying this for deep sky and star fields. 

 

Thats all for now.  I have some notes and Jupiter, M13, and M27 that I'll type up in the next couple of days.  

 

Clear skies!

Roger

[elstargazer12]

Also, just about the comment about the TV Panoptic 24mm.  Yes, I've certainly thought about it. I own the Panoptic 19mm and have compared it in these tests.  However, I'm not really considering it because:

 

(1) These will be dedicated binoviewer eyepieces and I really want more comfortable eye relief.  All the microscope eyepieces here have about 20mm and are very comfortable to use.  

 

(2) I can buy one to several pairs of any of these other eyepieces for the price of one new 24 Pan (Ok, maybe not quite a pair of the Leica and Zeiss S-PL units, but close!).  

 

(3) According to folks on CN and Bill Paolini's tests, the 24 Pan is not really the top of the heap when it comes to on-axis resolution, contrast, and transmission.  I don't have one to compare to, but given the performance against reference eyepieces like the Brandon and Meade, I imagine that the 24 Pan would have a lot of trouble keeping up with the best eyepieces here.  

 

Anyone else tried a 24 Pan against some of the eyepieces here?  Or similar ones?

[j.gardavsky]

Roger,

 

thank you very much for the final rating, it is close to my expectation.

 

Best,

JG

[elstargazer12]

Hi all,

 

I'm going to try to write up some more observation today.  But first, here's a photo of the newest subject of my tests.  It's a Zeiss, PL 10x/18 eyepiece with an enlarged field stop of 24.5 mm (I bored it out on a lathe), it's made in Germany. 

 

Roger

Attached Thumbnails

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[Astrojensen]

You really should try a pair of these:

 

 

 

Clear skies!
Thomas, Denmark

[elstargazer12]

Hi Thomas,

 

Yes, I've read great things about the OPMI eyepieces, including your posts!

 

Can you describe the edge correction on these in a faster scope?  I find that Zeiss PL eyepiece has "good enough" edge correction at f/6 and above (I haven't tested below that), meaning I don't notice any imperfections unless I look for them.  The S-PL, on the other hand, has the very best edge correction I've ever seen, including compared to Naglers and Panoptics.  But then again, we're talking about a 43˚ AFOV.  

 

Roger