Replacement objectives for a McArthur field microscope

[Scoper]

Hi,

Any suggestions as to where to find replacement objectives for a McArthur field microscope?

They would look something like these…

https://microscope-antiques.com/kirkaccessenl.html

Thanks

[MichaelG.]

I think the parent page to the one you linked might have all the available clues

https://microscope-antiques.com/mcarthurs.html

and I wish you ‘Happy Hunting’

MichaelG.

[Scarodactyl]

They look like standard rms objectives though maybe short barrel. Having a 'prior' objective mixed in is a good sign too.

[zzffnn]

McArthur microscopes are not easy to find and are being sold at collectible antique prices, aren’t they?

I would love to have one for their features (as a user), but don’t really want to pay collector prices.

I believe I can still buy TWX-1 from China for $400 or so.

[apochronaut]

I believe the idea of the McArthur was that the correct objectives threaded into the sliding rail, being parfocal, would automatically be in coarse focus, requiring only a tweak of fine focus. Since various manufacturers of the instrument made slightly different versions, with differing mechanical proportions, the objectives would not be consistent down through the years. The Watson version used Watson objectives and the CTS version , CTS objectives etc.
Or have I got that wrong?

[MichaelG.]

Not wrong so far as I am aware …
the ‘parent page’ that I linked doesn’t say it explicitly, but

MichaelG.

[Scoper]

Thank you for the responses.

I would agree that the objectives are unique from what I have seen.

Did other types of scopes use this type of objective?

Are there any sites that specialize in McArthur type scopes?

Thanks

[MichaelG.]

Here is the patent, in the names of McArthur and CTS : https://worldwide.espacenet.com/patent/ ... DGB863102A

… Downloadable via the ‘three vertical dots’ menu at upper-right of the page.

MichaelG.

[Scoper]

Thanks for the posts… the patent is quite interesting.

Other than EBay, any others to watch for the very short objectives… the pickings are slim so far.

I have also considered modifying an objective from a toy microscope to get the form factor needed.

Thanks

[apochronaut]

It is highly unusual for those short Cooke/Vickers objectives to be separated from a microscope. I might have seen one instance of that in 25 years.
There were a number of fairly short parfocal lengths used over the years. 32 , 33 and 34mm. The Nikon system persisted long enough even for short plan objectives to be out there. Olympus are about 3mm longer. There were examples of short objectives made for special models by other makers.
Prior to the big revolution in microscope design created by W.W. II , companies produced certain specialized models for metallurgy or field medicine that used short objectives.
The metallurgical objectives are very short button objectives and like the short McArthur objectives , only about a cm. or less in height. Essentially, they put the optical section of a pretty standard objective in a very short barrel and then added the extra length that the barrel would have comprised to the tube length, so despite the objectives looking like little buttons, they require about a 190mm tube.
Those made for certain field/field medicine/folding microscopes were very short. One version I know for sure existed, because I have a set of them, were the objectives for the Spencer #60 folding microscope. The 95X oil immersion objective in that set, is about 25mm in length.
Is your intent still to modify a toy microscope as a field microscope?