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.