Mix 'n' match problems

[GaryB]

My setups are generally made from a whole bunch of mismatched parts scraped together as funds allow and I'm wondering how much this could be affecting optical performance. Specifically eyepiece to objectives.

First off, my eyepieces are both Zeiss but one is Kpl 10x 18, the other is a Cpl 10x 18. They are different lengths, the Cpl has a smaller lens so when looking through them, the Kpl exit pupil is about 30% wider, though I have totally acclimatized to it and don't even notice much of the time. Finding a single ocular of either type is outrageously expensive so I learned to live with it.

The real problem is CA with certain objectives. I have a Nikon M 20 .40 and the CA is quite bad, even worse with my Beck (CBS) 40 phase. I did read that the Zeiss eyepieces compensate to the extreme, almost overcompensating. Could this be having an adverse effect on the CBS and Nikon if they're not designed for high level compensation?

My Wild, Lomo, Zeiss, B&L, Leitz and Leica objectives all work ok with just minimal CA. Are there any cheap alternatives to the Zeiss eyepieces that might work better with a wider variety of objectives if this is seen as the problem?

[zzffnn]

I read from Nikon S' manual that Huygens eyepiece should be used with low power achromats, which the Nikon M20 0.40 is (I have one of those too). Nikon labels those as HW eyepieces (high eyepoint wide field Huygens).

High power achromats, fluorites and apochromats should be used with K compensating eyepieces. Nikon labels them as HK or HKW.

I know nothing about Beck CBS. Phase objectives may be more sensitive to eyepiece mismatch though.

Member "Phil M" has experiences mixing and matching eyepiece/objectives. It may be hard to find a good universal eyepiece, though an old B&L Huygens may work well for some low power achromats. Matching high power, phase, apo or fluorite objectives may have to be done on case by case basis.

Sometimes eyepieces can be bought cheaply from eBay, at $10-15 shipped for each eyepiece, if you are very patient.

I heard some LOMOs are very close to Zeiss compensation, Leitz is not far off (a few members mismatched Leitz / Zeiss eyepieces/objectives and still got good results). Wild is supposed to be related to Leitz, isn't it? I heard B&L had collaboration with Zeiss and Leica got some designs from B&L. So maybe they may not be too far off.

[GaryB]

Yeah, the Zeiss and lomo are very close. The Wild is almost exact with zero color fringing with COL. I tried the lomo eyepieces but as you say, they seem to be compensating about the same amount. Similarly with my Periplan. It's just a couple of lenses causing problems so I'll keep an eye out for some Huygens eyepieces.

Thanks.

[ChrisR]

Did anyone make a projective Huygens-type eyepiece?

[Ichthyophthirius]

Did anyone make a projective Huygens-type eyepiece?

Hi Chris,

Yes, Leitz did. They were Huygens-type projection eyepieces for microscope projectors like the Prado: https://auction.catawiki.com/kavels/170 ... -for-prado

They generate an image "at infinity" (that is "far away" as opposed to projectives like the Olympus NFK, that generates an image at 125 mm camera length). The Leitz projection eyepieces can be used for afocal.

The most common one is the "Proj.-Ok. H4x" for 170 mm microscopes. "H" for Huygens as opposed to "P" for Periplan compensation which were also available. There were also version for 160 mm which look a bit different but I think they are compensating by default.

Regards, Ichty

[Pau]

Are there any cheap alternatives to the Zeiss eyepieces that might work better with a wider variety of objectives if this is seen as the problem?

There isn't such a universal eyepiece. Some are more compatible between brands depending of the compensation needed by the objective.

AFAIK Leitz and Olympus finite objectives have a similar level of color compensation needed. Although not perfectly matched Leitz Periplan work reasonably well with Zeiss objectives.

For non compensating eyepieces you can use other eyepieces superior to Huygens, like Nikon CF or some modern cheap chinese models.

Compensating eyepieces show an orangeish halo at the limit of the field, non compensating ones do show a very faint blueish halo or no halo at all if of the higher quality.