AO Spencer 146B?

[clengman]

Here's a quickie. What's the difference between AO Spencer WF eyepieces 146 and 146B? Anyone know?

EDIT: I managed to find both eyepieces in the AO Spencer "Cycloptic" catalog on PS Neeley's page. Looks like the 146 came with the cycloptics with Apo objectives. (And with the series 4 with achromat objectives.) The 146B came with the lower end achromat stereoscopic microscopes... That would suggest to me that there's some difference between them, but marketing language for both is, I think, identical...

[apochronaut]

Note in the catalogue that they are referenced for use , only with certain microscopes; series 23-28.
The series 23-28 microscopes, which were based on design parameters that go back into the pre-war years , had interchangeable objective lenses which could be mounted singly or in a 2x3 objective nosepiece. Achieving wide fields and tackling the problem of field curvature and chromatism along with a W.F. was possible in such microscopes but only by using very complicated and therefore expensive optical formulas for the objective lenses and or resorting to the previous practice of using very large eyepieces. This would make the microscope expensive and limit it's market, to only higher end research.
Those changeable objective microscopes were still popular in the 1950s, after about a 20 year run and versatile, with 7 objective magnifications and numerous body versions from a rail mount to articulating arm or boom stand. They were inexpensive and suited certain applications admirably but they needed to be upgraded, in order to provide better performance across a wider field. The 146-B, 147-B and 157-B eyepieces were adaptions of the fairly sophisticated for their time , 146,147 and 157 W.F. eyepieces, brought out for the series 2/4 and Cycloptic, and designed specifically to correct better for aberrations than the previous series of eyepieces, used with them.

[clengman]

The reason I'm asking is that I see a 146B listed on ebay for a lower price than the 146s that are currently available. Just wondered if itwould work as well as a 146 for eyepiece projection in my series 4. Sounds like I should stick to a 146.

[apochronaut]

I have a cat.# 437, if you want it. That is the matching photo framing eyepiece that was listed for the those series and the cycloptic. It is essentially the same as the # 1054 , I previously indicated worked very good in a series 4 photo tube . In fact, examples exist of # 437s being stickered over at the factory with a little 1054 tag. 1054 became the photo framing eyepiece for the series 10 and 437, the measuring eyepiece but I can't see any difference in them, just the reticle installed in each.
You can p.m. me if you are interested.