Lomo objective designations

[J_WISC]

AO 10XW.F. cat.146 is a slightly undercorrecting eyepiece yielding some ca beginning about 35-40° off axis to a lightly noticeable blue inside and yellow/red outside at the periphery. A tolerable eyepiece for that objective.

Good to know!

I have a pair of AO 10XW.F. cat. 146 eyepieces, so I'll have something to use when the 40x ВИ objective arrives! Which will discourage impulse buying. Sometimes I'm too enthusiastic once obsessed by something new, new for me.

Thank you for posting your test results.

[apochronaut]

If you plan on using the Lomo 40X .70 W.I. as a mix with a group of AO objectives in a 160mm tube, the # 146 eyepiece(s) may be your best averaged choice. However, it turns out those W10X-15.5MM eyepieces are quite common and were from the Japanese Swift manufacture. You can probably buy a set quite cheaply, if you keep your ebay eyes open. As an accident really, they just happen to nicely complement that older Lomo. It is a useful objective. The reason I have one is I bought one quite cheaply to use in a 3 objective water immersion nosepiece + 1 dry scanning objective on a series 4. A Lomo 30X .90 ( Fl. I think it is) and an F. Koristka 100X 1.2 were the others. As it turned out, a Baker 50X 1.0 water immersion showed up shortly after and the Lomo went into limbo. The Baker is a superior objective and is complementary to the AO system, since they had a working relationship until AO bought Reichert in 1962.

[zzffnn]

Thank you, Apochronaut for the test! I bought a pair of W10x 15.5mm. I have many short LOMO achromats that will benefit from them.

I dug into my old videos more carefully and found this darkfield recording (which reveals CA more than oblique and brightfield / phase), done with the LOMO 40x 0.75, afocal LOMO K10x/18: https://youtu.be/u5D3qsWQpyQ?si=06-bxcC7LIJPYcV6 there is quite some (yellow and blue) CA there in out of focus areas.

Do the F. Koristka 100X 1.2 and the Baker 50X 1.0 perform well with PZO DIC, much more so that LOMO? Those two objectives are not easy to find though.

[apochronaut]

That is good. The Swift eyepieces are very well made. There is a little stamp under the upper barrel lip : Japan. Does anyone reading this know who the manufacturer was?

I will try to fully test the Baker and F. Koristka on the PZO. Right now I am waiting for a replacement polarizer for the head.

I also have a Baker 100X 1.30 W.I. D.F. shearing objective, which I have to spend some time with in order to see what it's usefulness is.The engraving on the barrel is quite a mouthfull but all that is marked on it. That interesting 100X may only be of value as a measuring objective, although I think it must have a prism plate internally and possibly removeable. In BF it gives an excellent image but with an odd 3-D blur. Perhaps removal of the prism would render it as a plain 100X W.I. objective or perhaps it could be used with a Göerz condenser or Göerz condenser plus polarizer to advantage. I don't know what specifies it as a D.F. objective either, especially since it is marked as 1.30? Any transmitted light objective that I have ever seen that is marked for D.F. has a built in N.A. restricter and the reduced N.A. such as .85 marked on the barrel. Maybe Baker had some fancy really high N.A. D..F. condenser for the interference microscope.

I'm not sure it is headed onto the PZO because I have the PZO plan objective set with the integrated rotating prisms already, and they are used in one method for shearing but the rotational aspect of their prisms, 45mm parfocality plus the versatility of the entire Pluta system makes them fit the PZO platform like a glove. The Baker Interference Contrast system was out in the 50's and had incarnations based on the AO series 15 as well as the series 4 both using Baker objectives. The Wollaston prisms were individual and went in on an Akehurst slide.

I believe the short Baker objectives may have been superceded by 45mm parfocal Cooke-Baker versions. I have seen the 50X 1.0 Water objective as 45mm but I suspect that 100X died with the demise of the Baker Interference microscope.