A Cooke, Troughton & Simms

[75RR]

Try this: http://www.science-info.net/docs/CTSmod ... e1940s.pdf

MichaelG.

Nice find.

What happened to page 100?
.

[MichaelG.]

What happened to page 100?
.

I guess they could only scan what they had
... There are quite a few pages missing

MichaelG.

[MichaelG.]

Here’s another treat for CTS fans :
https://ia800703.us.archive.org/23/item ... rrerey.pdf

MichaelG.

[apochronaut]

Cant see anything1

about apo on my Cooke things ! How would I know ?

The good news is that they are RMS threaded, so I am able to use 2 cheap achros off ebay (more to come) to experiment with on the massive beast (it has a beautiful focus action and stage mechanism) and put the Cookes to one side while awaiting better experience/knowledge of phase stuff

Am i reading that you are going to set up your scope using other objectives and save your CTS objectives?..... or is there something wrong with them? They no doubt need cleaning.

Keep in mind, their parfocal length. CTS, Cooke-Baker and Baker objectives all had short parfocal lengths. 33 to 35mm, so in choosing any replacements, they should be short parfocal ones.

Later Baker and and then renamed as Vickers, which began as the same Baker designs, were 45mm and may be too long, as may be any other more modern D.I.N. objective.

[Mraster2]

Am i reading that you are going to set up your scope using other objectives and save your CTS objectives?

Yes, I will be experimenting with other objectives on the mechanical body of the CTS.
The Cooke objs are now set aside for safekeeping.
It is good that you alert me the 33 - 45 mm types, thank you.
I already have 4x and 20x 185conjugate cheap obs. which appear to be in the 33mm region. - shoulder to slide surface. I will get a cheap10x later.

[75RR]

It would be a shame if, through my incompetence, I did some irreversible stuff to this venerable old curiosity ! :)

I would suggest that you do that microscope a favour and put a dust cover on it and place it on a shelf, at least until you no longer need 'L Plates'.

[Mraster2]

Oh dear.

[Mraster2]

Served its purpose, no longer needed

[BramHuntingNematodes]

yeah not sure what you would do to damage the stand besides drop it, which is just as likely to happen on the way to the shelf as anywhere. Certainly nothing like lab techs of yore seemed to like to do all drilling holes in things, swapping pieces, losing parts, cranking focus knobs so hard they break in two etc. Lord knows how much cigarette ash was dropped any given B&L stand

[BramHuntingNematodes]

Don't like, drop a hot dog down the eyetube

[Mraster2]

Yep, I think my foot is in greater danger from it than it is from me !

[apochronaut]

Here is a beautiful CTS Universal. Love the , probably Mahogany , armrests.

[Mraster2]

Here is a beautiful CTS Universal. Love the , probably Mahogany , armrests.

Very nice, and its state of polish ! It looks like it has had a better state of captivity than the one I inherited,
but to be fair I think, in its early years, mine would have been much treasured, it is just that in its recent 2 maybe 3? decades the ability was a little lacking, , , anyhows :

probably to the despair in certain quarters of the Iberian Peninsular, I dont have a shroud for mine (shroud ?! quiet in the back row) but I do have an original (I expect) box complete with lock and key (key = a bit rusty but it still works, glides even, so a tribute to its craftsperson all those years ago )

If there is any interest I could do pics of the box (without polishing, as this would no doubt further enrage antiquarians and chronologists of patina ) , , , ?

[MichaelG.]

... but I do have an original (I expect) box complete with lock and key (key = a bit rusty but it still works, glides even, so a tribute to its craftsperson all those years ago )

If there is any interest I could do pics of the box ...

Now that you are are ‘signed-up’ CTS enthusiast : You may enjoy browsing this photo archive
https://dlib.york.ac.uk/yodl/app/home/search?query=cts

MichaelG.

[Mraster2]

... but I do have an original (I expect) box complete with lock and key (key = a bit rusty but it still works, glides even, so a tribute to its craftsperson all those years ago )

If there is any interest I could do pics of the box ...

Now that you are are ‘signed-up’ CTS enthusiast : You may enjoy browsing this photo archive
https://dlib.york.ac.uk/yodl/app/home/search?query=cts

MichaelG.

Gosh. what a lot of broth !

[herbivore-mode]On
Thanks.

[Leitzcycler]

Here is a beautiful CTS Universal. Love the , probably Mahogany , armrests.

This is something... Really very elegant!
I would very much like to replace the plastic hand rests of my Orthoplan with wooden lacquered hands rests like this.

[apochronaut]

... but I do have an original (I expect) box complete with lock and key (key = a bit rusty but it still works, glides even, so a tribute to its craftsperson all those years ago )

If there is any interest I could do pics of the box ...

Now that you are are ‘signed-up’ CTS enthusiast : You may enjoy browsing this photo archive
https://dlib.york.ac.uk/yodl/app/home/search?query=cts

MichaelG.

I think the U of York, received the Vickers archives.

[MichaelG.]

I think the U of York, received the Vickers archives.

I know they did ... I have visited the Borthwick on a few occasions

MichaelG.

.
For those unable to visit ... here’s some of what you are missing:
https://borthcat.york.ac.uk/index.php/vi-vi

[Mraster2]

Thanks for all the helpful advice offered,
it has born fruit !
I have my first rotifers. Gosh they are small !

Today I learned how to video them with my Canon60D, using a 10x achromat on the CTS body.
I learned how to edit in VirtualDub*
and how to assemble into a movie, complete with some titles, in OpenShot*
** two nice, easy to use freewares in my Windows7

Just a humble little thing, no Oscars, dont interrupt your audience with the Queen to watch it !!!
https://vimeo.com/444387372
I cant see how to embed it as a picture, so go to the link, hosted on Vimeo
(I looked at Youtube but heck what a plalver google makes of it, I am surprised they didnt want my dna as well )

[apochronaut]

What a perfect and well timed interlude. Those rotifers. Uninvited, greedy and desirous. You have ushered them into a space devoid of intent were analysis takes precedence over appreciation, where define asks more of a lens than definition.
Great and obviously the CTS is doing fine. My congrats.

[MichaelG.]

Just a humble little thing, no Oscars, dont interrupt your audience with the Queen to watch it !!!
https://vimeo.com/444387372

Delightful

We were amused

MichaelG.

[MichaelG.]

Sorry for hijacking your thread, but this seems a good place to ask:

I have a Cooke M1451 [Apochromatic, with coverslip correction collar], as illustrated
.

721DC662-12D1-4C87-A2AD-98A12E298D2A.jpeg (139.31 KiB) Viewed 6542 times

.

... except that mine is clearly marked 42x not 40x

Can anyone explain the discrepancy, and perhaps date it ?

I suspect that 42 is a more accurate number, but that common practise led Cooke to mark them 40

MichaelG.

[apochronaut]

I have seen this type of discrepancy , particularly with Spencer optics. One explanation is that over the years of production, partially due to lens batch deviations and in particular those made from Fluorspar, some of the specs. changed slightly. This is reflected in the unique shimming that is found in many older objectives, particularly those that have a higher number of fluorite lenses; high N.A. achromats, fluorites and apochromats. Lenses are shimmed individually in order to perfect the final corrections. This makes it very difficult to make one good objective out of two bad ones with different defects.

Another possible explanation is that over time the conventions associated with establishing objective magnifications became more relaxed. For a certain length of time the convention was to put the focal length on the barrel and sometimes there is a decimal. Then the focal length and the magnification went on the barrel, then later the focal length was dropped as it became apparent that users related more to magnification. Old microscopy technique books, talk about installing such and such a focal length objective and one has to refer to a chart to cross reference the focal length for the eyepiece against the focal length for the objective and further against the tube length to arrive at a magnification.
Focal lengths for objectives varied somewhat due to the aforementioned glass batch irregularities so I doubt for instance that all those 40X objectives that have been made since 1960 are all exactly 40X. Nor have all the 1.8mm objectives been 100X. Way back I started a thread about this and objectives marked 1.8mm , I recall varied from 94X to 102 or something like that. My memory of the numbers may be off.

My favourite example of the former possibility is in the early Spencer catalogues. Sometime around 1900, Spencer started making apochromats but they had likely been using fluorspar for lenses way back to maybe the 1870s. One of the prime deposits of optical grade fluorspar is in Monroe county, with Rochester it's capital. Spencer was only a hop from there. Clearly both Bausch & Lomb and Spencer have used this resource. In the early catalogues ,Spencer listed a 2mm oil immersion apochromat. They also stamped the magnification. The earliest one I have seen is catalogued as an 80X. Several years later it became 82X,. then 85X and finally it plateaued at 90X, where it stayed for 35 years. All of them were also marked 2mm.

Interestingly another major deposit of optical fluorspar is in the U.K.....Cornwall or somewhere in that vicinity.

[MichaelG.]

I have seen this type of discrepancy , particularly with Spencer optics. One explanation is [...]

Interestingly another major deposit of optical fluorspar is in the U.K.....Cornwall or somewhere in that vicinity.

.

Thanks for the interesting notes ... if I can ever put a timeline on the Cooke 42x/40x history, I will post it here.

___ Edit: Advertisement in this 1955 journal shows 40x
https://jcs.biologists.org/content/joce ... matter.pdf

Meanwhile; going by this, from the British Geological Survey: https://www.bgs.ac.uk/downloads/start.cfm?id=1405
It looks like we are in short supply of optical grade, and busy making acid

MichaelG.