Clave plossls

[Chiefwiggum]

Hi guys anyone here had any experience with clave plossls or any other so called high end plossls, and how they compare with modern televues or taks
Are they really that much better or is it marginal
:thanx:

[Don Pensack]

They had excellent polish, but due to the older coatings, didn't transmit the percentage of modern eyepieces. Plus, the original Plossl design (which they may not have followed--some talk is that they followed the 1938 re-design by Konig) wasn't well-corrected in the outer field on today's short focal ratio scopes.
I had a set and loved them in my f/15 refractor, but I sold them and replaced them with TeleVue Plossls because the TeleVue's were better corrected in the outer part of the field.
As my tastes evolved, I actually ended up replacing the TeleVues with the 5-element Meade Series 4000 Japanese-made (by Kowa) "pseudo-Masuyama" design "Super Plossls" in the late '80s because they were equally well corrected in the outer field but did not suffer the vignetting common to the TeleVue Plossl design. They weren't really Plossls, of course.
Good Plossls have an incredibly small spot size on-axis, and are exceedingly sharp. It is the outer field, I feel, that distinguishes one from another. Looked at from that standpoint, unless you have a long focal ratio, you're better off with more modern offerings.
The Takahashi LE, which you mention, is also a 5-element "pseudo-Masuyama" design and not really a Plossl. It's a good eyepiece above f/5 to f/6.

[Chiefwiggum]

Thank you for your reply don, you seem to have lots of experience, what would be your top 5 eyepieces for dso's in an f5 or faster reflector regards chiefwiggum

[Don Pensack]

That depends, of course, on what the use is and whether the scope has tracking. If the scope has tracking and the purpose is primarily planetary observing, simple eyepieces like Plossls, orthoscopics, and the Takahashi LEs will do just fine.

If, on the other had, the scope does not have tracking, and you are watching the target drift across the field, the highest priority is a coma corrector since the image in a non-corrected newtonian of f/5 or faster is only free from coma in the central millimeter or two in the very center and has compromised images everywhere outside of that. Even Plossls are made sharper everywhere in the field by the use of a coma corrector.

After that, if star clusters and larger objects are being viewed, the a widefield design without astigmatism in the outer field becomes relatively important, and brands like TeleVue and Pentax come to the front, for consideration. Explore Scientific even has a few that meet this requirement, notably the new 92° series and 120° series.

Note that many well-corrected longer focal length eyepieces can be heavy--from 500 to 1300 grams. If the scope is large, this poses no consequential problem, but if the scope is small, say 8-12", then balance becomes a priority (and the ability to add and subtract counterweights), as well has having a strong focuser.

My own taste runs to 100°+ in DSO eyepieces, but that is because of the focal length in my primary scope. In my short focal length apo refractor, I can achieve nice wide fields with eyepieces of narrower field, and I'm enjoying immensely eyepieces like the TeleVue Delites and others of similar field.

[dannat]

i still use a set at Melb observatory, agree with Don -the are good in long f/l scopes, but narrow field, short er as you increase mag, they don't have any pixie dust which commands their high price on the used market - best left to collectors as an antique peice imo

[Chiefwiggum]

Thanks dannat
Any experience any of you guys with the baader orthos supposedly less glass better details?

[clive milne]

If you don't mind the narrow field of view (of a plossl)
also check out the old (out of print) Celestron Ultima range
which is basically their attempt at the Masuyama design.
It is one of the things that Celestron got right.... highly recommended.

[Chiefwiggum]

Are the ultimas better than the silvertops which were made in japan by vixen?

[ausastronomer]

Hi,

I have never compared them but I can guarantee you the 5 element modified plossls like the Celestron Ultima are excellent sharp eyepieces. These eyepieces were made in Japan and sold under several different names including Celestron Ultima, Orion Ultrascopic, Antares Elite and Parkes Gold Series. The Meade 5 element Japanese made modified plossls that Don referred to earlier are also very similar to these eyepieces. As Don mentioned the Clave Plossls were very sharp in slow scopes but had poor off axis performance in fast scopes. Their light throughput is also down a little compared to modern eyepieces like the 5 element modified plossls. In addition the Clave Plossls have a very warm colour tone. Probably the warmest I have seen in any eyepiece. On Jupiter that's a good thing, but on just about all other targets I don't really like it.

The above all having been said. I probably prefer decent orthos like the University Optics HD or the Baader over a good plossl. That's just personal preference and there is very little in it. There would be a lot of observers who would prefer plossls to orthos. However, a short focal length ortho will have slightly more eye relief than a plossl of the same focal length.

Cheers,
John B

[Chiefwiggum]

Thanks john,
I have read great things about the current baader classic orthos the 18mm looks good, has anyone tried the old kellner circle t's made in japan would they still stack up?
Regards chief

[ausastronomer]

On axis they will but EOF will be poor in scopes faster than F8, the FOV is narrow and eye relief is short in the shorter focal lengths.

Cheers
John B