Olympus U-CA

[biofilmer86]

Before I consider getting one I would like to know if the magnification changer causes any image quality problems. Also, if the numerical aperture has to be increased for the objective being used. If I get a 60x objective I can "boost" it up to 120x by setting the U-CA to 2x?

[PeteM]

The numerical aperture is determined by the objective. Rule of thumb is that if you multiply the objective's N.A. x 1000 . . . that will be the maximum magnification you can get without getting "empty" magnification (just a larger blur). The 1000x rule assumes you're using the right condenser, oiling it to the slide if needed at high magnifications, and so on.

So, for a .65 N.A. 40x objective you could be fine using a magnification changer at 1.5x since the 600x magnification would be less than that .65 na x 1000. At 2x you're into empty magnification.

I don't know of any dry 60x objective that could handle a 2x boost. There are some 60x Plan Apos oil type objectives that might respond OK.

[biofilmer86]

Thanks for the small lesson on numerical aperture. Multiplying the N.A. number by 1000 makes perfect sense especially since the maximum limit of light microscopy is 1500x and the largest N.A. of any 100x oil objective I have seen so far is 1.45

https://www.spachoptics.com/NIKON-MRD01 ... ambda.htm

Something that is normally forgotten in microscopy is multiply the objective magnification by the eyepiece magnification for total / maximum magnification. Using the magnification changer on 2x is equivalent to using eyepieces with a value of 20x. Some microscope brands supply these eyepieces stating 2000x can be achieved which is true but useless since you exceed the 1500x limit.

[hkv]

I am using the U-CA on my microscopes. The quality is fairly OK with no or little signs of aberration. However, every lens you add in the pipeline is a potential weak link causing quality degradation. I rarely use the 2X setting except for video, but frequently use 1.25X. The main advantage of the U-CA is to achieve a better composition of images, especially when recording video as it is more difficult to crop without losing too much pixels (unless you shoot 8K video...). As already mentioned, all it does is to add empty magnification which normally should be avoided. I prefer to use a camera with sufficient resolution to resolve the full NA instead of adding tube lenses to increase magnification (if possible). If you use the Olympus PE photo eyepieces to connect your camera, it is preferable to go from PE2.5 to PE3.3 instead of engaging the 1.25 mag, in the U-CA. That gives approximately the same effect, but with one less lens in the pipe.