#42
Post
by PeteM » Wed Dec 01, 2021 10:59 pm
Phil, it seemed to me (and perhaps Stephen) that Nikon and its competitors aimed to use compuer-aided optical design, better lens coatings, and low dispersion glasses to make better objectives. Unlike most of their competition at the time, however, Nikon chose to put chromatic corrections in the objectives, rather than use correcting eyepieces. They introduced "chrome free" objectives (at various price and optical quality levels) that fulfilled this mission as best they practically could.
Their competitors (Olympus, Leica, Zeiss etc.) were still sharing finite chromatic corrections between the objectives and their dedicated ("C", "K," etc.) eyepieces. Overall optical results weren't all that different - we can get great images from all the major microscope makers from this era.
However, today, many of us trying to adapt digital cameras to finite microscopes from the film camera are serendipitously grateful Nikon took their "chrome free" path because we're not stuck with either an often-cumbersome afocal method or a very restricted set of suitable photo relay lenses that have the requisite (Olympus, Zeiss, Leica, etc.) corrections built in.
This forum is filled with cases of users struggling to get good images out of an otherwise excellent older finite microscope -- typically if they don't have a pricey full frame sensor camera with a no-vibration mode and the full frame (film camera) OEM photo relay setup originally designed for their microscope.
The Reichert Microstar IV thread as just one example where it proved difficult to get rid of chromatic aberrations.
Olympus users with a smaller sensor camera searching for that elusive 1.67x photo relay lens to use with their $1000 APS-C camera are another example. That correcting relay lens will typically cost as much as a complete BH2 scope.
Similarly, Chinese USB camera users with their 2x photo relay lenses and mediocre results - often in part because their microscope's objectives want a correcting rather than neutral relay lens.
With Nikon's "chrome free" scopes from the Labophot/Optiphot era (and now with effectively "chrome free" optics in many infinite scopes) one can get decent results matching up sensor sizes and fields of view with a wide variety of neutral relay lenses, C-mount adapters, Nikon's own readily and cheaply available 2x and 2.5x relay lenses, and even teleconverters.
As one practical example, Rob Berdan did a thorough review of cameras and found a "Rising Cam" camera with a 1" Sony sensor provided a fairly affordable (around $500) solution with excellent results. Ditto, in my experience, with $100-$200 used mirrorless cameras like the Sony Nex 5 or the Nikon J1. Most any good generic C-mount adapter (say .7x) can be used to easily adapt these cameras to a "chrome free" system. Other scopes, if they're expecting significant chromatic corrections in the relay lens, will suffer.
Last edited by
PeteM on Thu Dec 02, 2021 12:01 am, edited 1 time in total.