Lens mounting flanges - measurements and other info [Archive]

View Full Version : Lens mounting flanges - measurements and other info

Ron (Netherlands)

3-Aug-2020, 12:21

Fellow member pgk and I thought it a good idea to start a separate thread on mounting flanges, when we got some ideas about this topic on the ‘Filthy Flange - possibilities’ thread. Main reason is that apart from ourselves we guess that a lot of fellow members have a pile of mounting flanges that not fit precisely or don’t fit at all the lenses we have in our collection. Further it seems quite frustrating that in order to acquire a matching lens mount one has to have one made, which is quite costly, or – at least that is what I did several times – buy one flange or a pile on *bay - also quite costly - and many times afterwards discovering that it doesn’t fit.

So why this thread: eventually if there is a need, to be able to have an effective/practical – low cost - exchange of lens mounting flanges between fellow members. To do so we would like to agree on:
a. which measurements and additional info should be provided/needed;
b. how to take precise measurements of the flanges;
c. the thread/form to disclose your pile of spare flanges.

Ad. a. I guess at least the following information should be provided:
1. material (brass, aluminium, alloy);
2. outside diameter;
3. inside diameter;
4. thread (pitch v/s lead and coarse v/s fine) ;
5. number of screwholes;
6. number of visible threads.

I guess it would be too hard in many cases to determine the thread form, depth and angle.

Ad. b. Preferably the outside & inside diameter (and if needed the height) should be measured with calipers. Measurements taken with rulers are less accurate (it would therefore help to judge the measurements if info is provided on how measurements are taken).

Measurement of the thread seems less easy. Screw pitch thread gauges could be of help; there are gauges for Imperial, US and European thread pitches – which could be acquired at low cost. Not sure what the British used before they tried to get to a standard (i.e. I believe Whitworth). The Lens Vademacum has a short section on this topic:
“There are some pointers here:
(a) Old English lenses up to about 1880 came in fairly fine threaded flanges but many were in 1.5 or 2.0in flanges which were roughly standardized between Ross, Wray, Dallmeyer and Taylor, Taylor and Hobson lenses as well as some others. Thus there is a fair prospect of a match here.
(b) After 1880, the English makers tended to use 24TPI threads in a rather wide range of sizes so the problem is limited to finding the correct diameter but the thread is probably standard up to quite large sizes.
(c) Compur and Copal shutters use standard threads and flanges are available from the makers, though care would be needed with older shutters and some old sizes here. Some other lenses have used the same mounting threads but this is not very common.
(d) But there are many exceptions and here a new flange will have to be made with the trouble and expense this involves.
(e) There are a wide range of modern fittings used in miniature cameras, where some are easy to match but others are rapidly dropping into obscurity. The makers name on the lens may suggest the mount, but there are pitfalls as with the Canon lens for the Reflecta which fits no other camera satisfactorily.
It is stressed that the fit should be checked. Dealers can be optimistic as to whether threads match and have a tendency to screw lenses into flanges where the fit is surprisingly poor- half a turn and it jams suggests the wrong pitch rather than the right flange! What is needed is a smooth action and several turns till it screws up tight.”

Further pkg pointed me to the site of skgrimes on how to measure the thread pitch precisely: http://skgrimes.com/library/faq/how-to-measure-threads

Ad. c. Where to present our piles of spare flanges? I guess as long as we do not put up our flanges for sale or explicit exchange – it would be no problem to have them listed in this thread with all their specifications – having the possibility to have a discussion about them (like the many threads on lenses). However, when one wants them for a sale or exchange, the mounting flange should be listed in the correct “For Sale/For Trade” section.

If this provides a lot of info, we might take it further to a database on lenses / lensmount specifications.

More input from fellow members on these topics are welcome

https://kpmg0072.home.xs4all.nl/flanges/20200823_164702.jpg

Tin Can

3-Aug-2020, 12:25

Needs a formal database

I can't do that

pgk

4-Aug-2020, 01:33

That would be ideal and is potentially possible. But in the first instance this would be an information gathering excercise. Without information a database will go nowhere. So if anyone has lens/ring technical data please post and we'll eventually look into what can be done with it.

Tin Can

4-Aug-2020, 03:47

I double space my sentences on purpose

Purpose being they are readable

The initial post is way too dense

I have many flanges, and have had a couple made

Some lenses can be mounted by ingenuity, even heavy long ones

Most flanges sell for so little, the effort is doomed, yet a good idea for those with time...

Ron (Netherlands)

4-Aug-2020, 05:33

Just to provide an example of what we are looking for:

Specifications mounting ring:
1. material: brass
2. OD (outside diameter): 2,420"
3. ID (inside diameter): 1.734"
4. TPI: 36
5. 3 screwholes
6. visible threads (groves): 6

In short you could specify this ring as: brass 1.734-36

matching lens: Perken, Son & Rayment Portable Symetrical 5x7 Optimus
Please note that the lens has a thread diameter of 1.745".

Another example is my TT&H 8 x 5 R.R. lens, which provides the following specs:
for the lens: 1.995-24
for the matching ring: 1.963-24

Here are some other samples of mounting rings, but these don't fit my lenses:
flange 1 1.360-34 brass, 3 screwholes
flange 2 1.445-40 brass, 3 screwholes (truncated thread - UTS/NC?)
flange 3 37,10mm-M1.0 black painted brass, 4 screwholes
flange 4 1.495-32 brass, 3 screwholes (truncated thread - UTS/NC?)
flange 5 1.600-32 brass, 3 screwholes
flange 6 1.630-36 brass, 3 screwholes
flange 7 1.665-36 bras, 3 screwholes
flanges 8 & 9 43,30mm-M1.0 aluminium, 4 screwholes (yes two identical mounting rings)
flange 10 1.703-36 brass, 3 screwholes
flange 11 1.960-26 brass, 5 screwholes
flange 12 2.186-24 black painted brass, 6 screwholes
flange 13 2.245-30 brass, 3 screwholes
flange 14 2.465-22 brass, 4 screwholes
flange 15 55,70mm-M0.75 black painted aluminium, 4 screwholes, inscription: C.P. Goerz - Berlin

Flanges for small lenses:
flange 16 1.300-28 brass, 3 screwholes
flange 17 32,00mm-M0.5 black painted brass, 4 screwholes
flange 18 30,60mm-M1.0 black painted brass, 3 screwholes
flange 19 & 20 24,50mm-M1.0 black painted brass, 3 screwholes
flange 21 0.846-48 chrome-plated brass, 3 screwholes

Ron (Netherlands)

5-Aug-2020, 02:49

About British standardisation on mounting flanges I had written down the following but lost the source:
A standard was agreed upon in 1890 and it seems that Dallmeyer was the driving force behind it. Before a standard came into use, 3 different groups of companies had agreed upon using the same threads:
1. Ross, Dallmeyer, Ray
2. Lancaster, Swift
3. Newton & Co, Reynolds & Co, Suter, TTH, The London Stereoscopic Co.

The 1890 RPS standard choose 55 dgr Whitworth and further made the following chart:
Thread pitch / TPI
1,00 / 24
1,25 / 24
1,50 / 24
1,75 / 24
2,00 / 24
3,00 / 24
3,50 / 12
4,00 / 12

Before the standard, mostly used was the 28 TPI until pitch 2,00

I'm not sure, but it seems that the lens industry (also) made use of BSF, British Standard Fine (as an alternative to British Standard Whitworth; BSW), which has a somewhat different use of thread density, i.e. 16, 18, 20, 22, 28 and 32 TPI. Found no info on how these relate to the different thread pitches.

Tin Can

5-Aug-2020, 03:23

Restoring Brit motorbikes, I never found a Whitworth Pitch Gauge, yet now common here (https://simplybearings.co.uk/shop/product_info.php?products_id=780045&currency=USD&gclid=CjwKCAjwsan5BRAOEiwALzomX8gp1plqa8m8anrly_XilvRq8Tw3pG2b-CgsW_pKgdf0byNftdRPYBoCHhQQAvD_BwE)

I have 3 sets of 8 sided Thread files I use for thread repair

Standardization is tough, I found no exact filter match for a modern 1951 Kodak 405 mm, but a miss match works

My last very large flange I had custom made was affordably made in Thailand to match a 900 mm Jena Tessar bought from there

Mine is not the one for sale, which is missing the flange

Your cause is righteous and difficult

Good luck

Jody_S

5-Aug-2020, 05:27

pgk

5-Aug-2020, 05:30

Restoring Brit motorbikes, I never found a Whitworth Pitch Gauge, yet now common here (https://simplybearings.co.uk/shop/product_info.php?products_id=780045¤cy=USD&gclid=CjwKCAjwsan5BRAOEiwALzomX8gp1plqa8m8anrly_XilvRq8Tw3pG2b-CgsW_pKgdf0byNftdRPYBoCHhQQAvD_BwE)

Its a long time since I had British motorbikes and worked on them but if I remember correctly they used UNC and UNF threads by the 50s and 60s. I think many threads 'approximated' Whitworth threads in terms of pitch angle because it works but even so there are lots of discrepancies. And that's before looking into tolerance and hand matching together with steam or water powered lathes, wear to tools and a myriad of other variables.

But all that said it would be very useful to have some starting points at least! The RPS 'standardisation' was a bit of a mixed bag I gather as tolerances and subtle differences in production meant that it wasn't as standardised as it was hoped it would be.

And the problem has been with us for a long time. Photographer Samuel Bourne of Simla, notes in an article that it is useful to have all lenses set up so that they use a common mount - by which I assume he means that his varied lenses (from various manufacturers including Dallmeyer and Grubb) were fitted with some form of adapter to standardise them and make them easier to use. Unfortunately he doesn't describe this further.

pgk

5-Aug-2020, 05:32

If only it was that easy. I tend to measure the lens thread as high up and near to the top as possible because lower down threads can be very worn indeed, especially softer brass ones. Even so I think that there has to be some 'judgement' in finalising measurements. But its not impossible.

Ron (Netherlands)

5-Aug-2020, 08:25

The difficulty if course is that if you take your fancy digital caliper and measure the outside diameter of a lens' thread and the inside diameter of its flange, you will get 2 completely different numbers. Perhaps a section on the math of triangles and thread pitch and angle would help take out some of the guesswork? Even a table or two would do it, such as you will find in machinists' handbooks.

Ie: for a 60 degree 1.25mm thread, subtract "x" from your lens thread measurement to get the thread peak in a flange, or subtract "y" from your flange inside measurement to get the nominal thread diameter of your lens. Decrease that number by a range to account for visibly worn threads, and compare to standard diameters used by different makers.

Yes I do have a big stack of mismatched flanges, and a pile of lenses missing their flange.

In theory this all would be best to strive for. However since - I guess - most of our vintage lenses and mounting rings are quire worn and considering differences in tolerance when they were produced, ruling out the risk of mismatches will be an illusion, and too many variables make it impractical - e.g. most of us won't have instruments measuring a difference between the 55 and 60 dgr angle or the thread pitch. Consider also that most of our vintage lenses & rings are not perfectly round.
However at some points we could strive to more detail, e.g. when I was looking more closely at the threads of my rings, there were two with clearly truncated threads.
Further, looking at the imperial measurements being measured in thousands of an inch, some tolerance between lens and mounting ring should help in successfully matching ring and lens. If you get as you say completely different figures, you won't have a match, however if the differences are in the thousands of that inch (see above example of the Perken lens: difference is 0,0011", providing a perfect match), a match might be possible.
For me it is definitely worth a try.

pgk

5-Aug-2020, 11:31

Further, looking at the imperial measurements being measured in thousands of an inch, some tolerance between lens and mounting ring should help in successfully matching ring and lens

Some makers seem to have worked in fractions of an inch, so a good start point for some early lenses might be matching up the thousandths to fractions, depending on their country of manufacture .....

Ron (Netherlands)

5-Aug-2020, 13:38

Some makers seem to have worked in fractions of an inch, so a good start point for some early lenses might be matching up the thousandths to fractions, depending on their country of manufacture .....

Indeed, at least very good as a sort of double check - I did do so with several of the my rings and because of that changed my opinion about two of them (e.g. the Perken).
I'll have my list now posted in the "For Trade" section too - and if you don't mind, I'll lend your caveat....

Whir-Click

5-Aug-2020, 13:51

Ron (Netherlands)

5-Aug-2020, 14:53

This is a worthwhile endeavor. Given the uncertainties in measuring threads, it is helpful to have original dimensions as a reference wherever possible. To that end, I have attached flange thread information from Wollensak lens barrel and shutter engineering drawings.

Caveat: this table is not exhaustive for all Wollensak products. Dimensions are nearly all taken from post-war drawings, so they do not include some older flange sizes referenced in catalogs (such as the 4 11/16” flange for the 16” Vitax), nor flanges for legacy shutters such as the Optimo.

Engineering drawings for the Alphax #4 and #5 flanges are also attached. I will add others if I can find them.

Many thanks for your addition Whir-Click, and very interesting info!
Guess we can indeed extend our quest also to shutter mounting (although our title therefore would be a little restricted), why not (I must have some info on German shutters...I'll have a look). Other question is whether we really should include retaining rings which I consider to differ from mounting flanges considering their usage; well some shutters are of course mounted with a flange, others - the many German leaf shutters - are fastened with retaining rings at the back of a board. So I guess we here rather look for the rings with the screwholes, like in your drawings.

Whir-Click

5-Aug-2020, 17:03

I think it’s worth including shutter flanges since, in Wollensak’s case at least, there is considerable interchangeability between lens barrel and shutter flanges. For example, if you’re looking for a flange for a #6 lens barrel, it’s helpful to know that an Alphax#4 shutter flange has the same dimensions.

Other manufacturers may also have some degree of commonality between lens barrel and shutter flange dimensions.

Here is the Ilex shutter flange mounting information (as of 1951):
#00 Precise: 0.953x50
#00 Acme: 1.000x50
#0 : 1.173x40
#1: 1.327x40
#2: 1.606x40
#3: 1.913x40
#4: 2.500x30
#5: 3.232x30

Ron (Netherlands)

7-Aug-2020, 02:14

In my collection of spare mounting rings I found this one which has sort of tightening bots. Anybody knows what it was used for - perhaps an enlarger?
https://kpmg0072.home.xs4all.nl/flanges/retaining%20flange.jpg
the specs are: 40,10mm-M1.0 black painted brass, 4 screwholes.

Further I have supplemented the above mentioned list in #5 with rings for small lenses (also now in the For Trade section).

Next I'll provide a list of my older vintage lenses with their mounting flanges as a reference for anyone who is in search for a lens or mounting ring.

pgk

7-Aug-2020, 02:32

And FWIW I have an adapter flange for 1.712/28 to 1.912/36 - from ~1883ish and a pencil marking on the back cap which fits the larger male thread is marked Dallmeyer 1/4 plate. So although there was no standardisation of threads by this time, at least some manufacturers/dealers/photographers saw the need for common mounting systems for their lens sets.

peter brooks

7-Aug-2020, 10:07

One day there will be domestic version of the 3D laser scanner, as used to scan archeological sites, volcano craters etc. in remarkable detail. There are already some diy ideas on the internet. 'Male' and 'female' data files could then be produced and shared, and some clever software could analyse a pair and tell you if they fitted together. Oh well, one day...

Presuming that the measuring system used is often inches (for the UK and US in any case) what would be the starting point for making a thread? I made furniture years ago and while I delighted in quarters, eighths and sixteenths of an inch (so much more useful than boring old tenths), it wouldn't make much sense to design something that was (for instance) 223/32".

So is a 1.712" female thread for a 1.75" (13/4") male thread? And a 1.912" for a 2"? Would the only difference be the pitch and angle of the thread? Knowing the pitch and angle would seem to be key to establishing a match. If the pitch can be accurately measured, and the thread depth also (with a very fine point depth gauge?) then the thread angle can be calculated.

I have a thread gauge and find it far easier to measure external (male) threads, in a similar fashion to the 'mesh two bolts together to see if they are the same thread' scenario. You can see light between, but obviously can't when measuring the internal thread of flanges. Would taking a 'cast' of a section with blutack (putty like stuff for sticking posters etc. to walls) or one of those cold curing modelling clays help?

Ron (Netherlands)

10-Aug-2020, 04:14

Presuming that the measuring system used is often inches (for the UK and US in any case) what would be the starting point for making a thread? I made furniture years ago and while I delighted in quarters, eighths and sixteenths of an inch (so much more useful than boring old tenths), it wouldn't make much sense to design something that was (for instance) 223/32".

Guess that is what fellowmember pgk meant when he wrote that "Some makers seem to have worked in fractions of an inch". However until now my experience deviates from that, and I think the optical designers were not hindered by the measurements of the barrel, but only preoccupied with the dimensions of their glasses....therefore the barrel construction had to follow the lens constructions and might have been therefore subordinate. Also the rings that match my (little collection of) vintage British made lenses, don't seem to have been calculated down to fractions of inches.

So is a 1.712" female thread for a 1.75" (13/4") male thread? And a 1.912" for a 2"? Would the only difference be the pitch and angle of the thread? Knowing the pitch and angle would seem to be key to establishing a match. If the pitch can be accurately measured, and the thread depth also (with a very fine point depth gauge?) then the thread angle can be calculated.

From my experience (see post #5 for some measurements) each type of barrel/lens seems to have a different 'gap' with its mounting flange, some only 0,0010 and other about 0,0030. At this stage however we cannot provide a definitive answer to this question, much more data would be needed to verify this aspect.

I have a thread gauge and find it far easier to measure external (male) threads, in a similar fashion to the 'mesh two bolts together to see if they are the same thread' scenario. You can see light between, but obviously can't when measuring the internal thread of flanges. Would taking a 'cast' of a section with blutack (putty like stuff for sticking posters etc. to walls) or one of those cold curing modelling clays help?

Could be of help, but I'm not so much into 'silly putty' :-) at least I wouldn't like to smear it into the thread flanges, but others might find it practical.

For a start we only want to ask the data from our fellow members on the basis of which you might rapidly find a possible match between lens and mounting ring, i.e. foremost internal diameter and thread (pitch) per inch. Next, when on the basis of those data two members think they may have a match, they can go ahead and ask for more data....much like a dating site :-)

...but we are of course still awaiting data from other members, there must be huge piles of flanges lying unused in their collections....

peter brooks

14-Aug-2020, 01:17

Here is the Ilex shutter flange mounting information (as of 1951):
#00 Precise: 0.953x50
#00 Acme: 1.000x50
#0 : 1.173x40
#1: 1.327x40
#2: 1.606x40
#3: 1.913x40
#4: 2.500x30
#5: 3.232x30

I'm in the UK, and am clueless about what threads were commonly used in the US... Does anyone know what thread standard (or angle) was used for Ilex shutters?

I have an Ilex #5 shutter without a flange / lock ring... :(

pgk

14-Aug-2020, 03:12

Ron (Netherlands)

14-Aug-2020, 08:34

I'm in the UK, and am clueless about what threads were commonly used in the US...

Here's some summarised information about US threads: https://www.sizes.com/tools/thread_american.htm
Main difference on older threads is that British use 55 dgr and USA/Can 60 dgr angles, which changed after WWII - both would use 60 dgr.

Does anyone know what thread standard (or angle) was used for Ilex shutters?
I have an Ilex #5 shutter without a flange / lock ring... :(
Don't have info about US shutters, but the post from Whir-Click mentions the #5.....
The US threads seemed to be mostly truncated at the top of the crest....

Ron (Netherlands)

14-Aug-2020, 08:42

My measurements suggest that you are applying very reasonable logic. However, in the early days of lens production, standards seem to have been a real rarity so my guess is that makers simply built a lens and used a fine thread on the final diameter. Certainly, one or two that I have measured look suspiciously like they were in 1/64". I also have several flanges from the same (model of) lens which vary not in thread pitch but in diameter and enough to mean that one flange will fit one lens but not the others but the other flanges fit all lenses. This may be a QC issue, but the fact that one flange is marked with the lens serial number makes me wonder if they were cut individually. I am starting to think that this might be a minefield. Perhaps the best approach would be to come up with a Fade Mecum style document which lists lens threads by maker - but its a massive job and needs substantial breaking down.

The only reason for me to start this thread was to see whether fellow members would like the idea to exchange their inventory of spare mounting flanges/rings in order to be able to try to get a match with a lens, for possible trade.
But I'm sure that trying to make a list for all known lensmakers seems not at all feasable (especially since spare rings usually don't have an indication about its maker), and IMHO doesn't serve a practical purpose......or am I missing something?

peter brooks

14-Aug-2020, 13:23

The only reason for me to start this thread was to see whether fellow members would like the idea to exchange their inventory of spare mounting flanges/rings in order to be able to try to get a match with a lens, for possible trade.
But I'm sure that trying to make a list for all known lensmakers seems not at all feasable (especially since spare rings usually don't have an indication about its maker), and IMHO doesn't serve a practical purpose......or am I missing something?

Ron, a laudable aim, and it has also sparked discussion about these things... very useful in itself, and surely the way that research develops? One thing leads to another...

As PKG suggests, a separate endeavour might be to record, categorise and thus start to recognise types of thread used. If nothing else it would be good to see if a pattern emerged, or if it was all just random chaos. It would make more sense to sample lens threads (rather than flange threads) as the maker is often known, and surely a manufacturer must have standardised on a thread within their own company - or hopefully at least within a production run of certain lenses. (Wikipedias History_of_standardization (https://en.wikipedia.org/wiki/Screw_thread#History_of_standardization) of threads). Measuring thread angle would be tricky, although external threads are probably easier.

It would be interesting to hear from someone who uses (or has used) manual (=not heavily automated) metal working lathes, and get a view on how a lens thread and matching flange thread might be cut, what decisions would have to be made, especially on the equipment of the time.

Greg

14-Aug-2020, 13:49

Side note about lens flanges and retaining rings: Good place to find them is on eBay. Every now and then someone puts up for auction a box of many of them. Years ago bid on and won a box of dozens of them for little more than the shipping costs. Forgot what the seller called them, but it wasn't "lens flanges" or "retaining rings" but something like a "collection of thin threaded rings".

tonyowen

15-Aug-2020, 00:52

The 1890 RPS standard choose 55 dgr Whitworth

A few years ago I contacted the RAS [Royal Astronomical Society] regarding Whitworth threads used in 'old' lenses. It seems that the Whitworth thread was used but slightly different from the standard thread. I can't remember, or find the relevant RAS archive, but it was to do with either the angle or depth of the thread form.

Regards
Tony

reddesert

15-Aug-2020, 21:11

It would be interesting to hear from someone who uses (or has used) manual (=not heavily automated) metal working lathes, and get a view on how a lens thread and matching flange thread might be cut, what decisions would have to be made, especially on the equipment of the time.

Threads are cut using a lathe whose tool is mounted on a leadscrew, with the leadscrew rotation geared to the spindle so that the tool moves along the piece as the piece rotates. Choosing the gear ratio controls the pitch of the thread. (Of course, this brings up a philosophical question: how were the threads on the first leadscrew formed? Probably by the chicken that laid the first egg, or by hand.) Practical screw cutting lathes have been around since the early 19thC, although I was a bit surprised to read that drawings of the idea go back at least as far as Leonardo: https://en.wikipedia.org/wiki/Screw-cutting_lathe

The subtleties in cutting a thread include getting the thread angle and depth right, and starting the cut in the same place as you make multiple cutting passes with the tool. Well-equipped machinists have sets of depth and thread gauges to measure the threads. Someone with a lot of machining experience (Bernice?) could explain more.

Cutting threads properly seems to be a popular topic among home machinists - there are a lot of youtube videos on the subject to show how it's done.

goamules

16-Aug-2020, 07:11

There is a guy on a facebook brass lenses group that is making flanges. They seem to be working for those that bought them. I talked to him about making a flange for a rare lens of mine, but without having to send the lens. My idea is to use Cerrosafe, a low melting point metal that is used for casting and measuring things accurately. I'm going to make a cerrosafe dummy flange, send it to him, and have him replicate it in brass or alum.

pgk

17-Aug-2020, 02:35

Here is a shot illustrating the problem of measuring threads. The lens is an ~1860 Petzval which arrived minus flange. The gauge shown is a 22tpi Whitworth aligned with the flange thread on the lens which shows wear. I am reasonably confident about tpi and that the thread is Whitworth because examination shows wear on the camera side of the lens which is where I conjecture it would be most subjected to higher forces upon mounting rather than removal. The brass is probably fairly soft so the thread has rounded off as well as worn on one side. Despite this there are sufficient points of coincidence between the worn thread and the gauge to suggest they are the same thread. Or at least that's my take. Can anyone with more experience of thread measurement comment please?
206915

Tin Can

18-Aug-2020, 05:01

That will work if the glass can be removed, to protect it from Cerrosafe heat

Some lighter lenses may even be able to use a Cerrosafe flange

There is a guy on a facebook brass lenses group that is making flanges. They seem to be working for those that bought them. I talked to him about making a flange for a rare lens of mine, but without having to send the lens. My idea is to use Cerrosafe, a low melting point metal that is used for casting and measuring things accurately. I'm going to make a cerrosafe dummy flange, send it to him, and have him replicate it in brass or alum.

Ron (Netherlands)

19-Aug-2020, 05:03

With a gauge I measured my stash of German lenses/shutters. Some of the lenses/shutters have Imperial measures like some of the Compound and Compur shutters with an Ica Dresden label. I have a list of most of the Compur shutters with sizes of the lens tubes, but no list with the different Compound shutters [edit see table below] although they seem alike the later Compurs (they go up from no. 0 to no. 5).

One could have had the same shutter (e.g. the Compur no 2) with quite some different sizes of lens tube. Further Zeiss had the seizes of their barrel lenses indicated with a combination of letters and numbers, e.g. A VI 2 means a lens with a focusing device (A-Fassung) in barrel VI with a dept of 2 (I don't have a list to decipher the Roman and Arabic numerals)

You'll find detailed info on thread sizes below the picture on the flickr-site:

https://live.staticflickr.com/65535/50244318642_1b6cc5f552_c.jpg (https://flic.kr/p/2jxVgrU)
Vintage German lenses (https://flic.kr/p/2jxVgrU) by Ron (Netherlands) (https://www.flickr.com/photos/zorki_2007/), on Flickr

...just found this listing of the Compound shutter in a French Zeiss catalogue:
At one point my measurements deviate from this list: my no. 0 Compound has an iris opening of 22mm.

https://kpmg0072.home.xs4all.nl/flanges/Compound%20shutter.jpeg

Ron (Netherlands)

20-Aug-2020, 01:14

With regard to my post #32, from my lens/shutter combo's I could derive the following thread sizes:

Compound 0 M0.7
Compound 1 40 tpi
Compound 2 M0.9
Compound 3 M0.9
Compur 0 36 tpi
Compur 1 M0.6
Compur 1a M0.9
Compur 2 M0.9

Of course there should be Compound 1 and Compur 0 shutters with continental sizes, but mine - both stamped ICA Dresden - have a imperial thread size. Further the Compur 1 is an odd sized Compur since it is not mentioned in the list in post #32: mine doesn't have a tube size of 30mm but of 32mm.

Here you can find a list of different sizes of Compur shutters:

http://lostlabours.co.uk/photography/images/compur-1.jpg

peter brooks

22-Aug-2020, 10:46

Of course there should be Compound 1 and Compur 0 shutters with continental sizes, but mine - both stamped ICA Dresden - have a imperial thread size.

The VM seems to allude to this near the end of the section titled 'Threads, Lens mounting' -

In Europe, threads persisted as a different, partly metric series without so much standardization, except that the Deckel/Compur shutters forced a standard in some respect on their cells and flanges, but makers were slow to adopt them otherwise. The Leica used a metric diameter, 39mm but apparently a Whitworth form and pitch of 26 TPI perhaps due to tooling supplies. Many European firms were using machine tools made in the UK and used a mixture of metric diameters. and inch pitches as a result. Thus in remaking flanges, it is worth considering the use of Imperial Whitworth tools even when the actual diameters are metric.

Earlier in that section it is suggested that Ross were producing flanges for other manufacturers, and that their two sizes were so common as to almost be a standard (the sizes were investigated further by Mr Dallmeyer as part of the RPS standardisation process). The VM says -

The next meeting reported in 27/06/1890 p502, when Mr Dallmeyer announced that Mr Ross's 1.5in was actually 1.513in and his 2in was actually 1.98in. Thus they were not really 1.5 or 2in as claimed. Add in that other houses had no access to the originals, and relied on fitting their lenses to flanges purchased from Ross's and that these were not of hardened metal and wore while in use, and the cause of the general lack of interchangeability was obvious.

Ron (Netherlands)

23-Aug-2020, 03:06

The VM seems to allude to this near the end of the section titled 'Threads, Lens mounting' -

In Europe, threads persisted as a different, partly metric series without so much standardization, except that the Deckel/Compur shutters forced a standard in some respect on their cells and flanges, but makers were slow to adopt them otherwise. The Leica used a metric diameter, 39mm but apparently a Whitworth form and pitch of 26 TPI perhaps due to tooling supplies. Many European firms were using machine tools made in the UK and used a mixture of metric diameters. and inch pitches as a result. Thus in remaking flanges, it is worth considering the use of Imperial Whitworth tools even when the actual diameters are metric.

Earlier in that section it is suggested that Ross were producing flanges for other manufacturers, and that their two sizes were so common as to almost be a standard (the sizes were investigated further by Mr Dallmeyer as part of the RPS standardisation process). The VM says -

The next meeting reported in 27/06/1890 p502, when Mr Dallmeyer announced that Mr Ross's 1.5in was actually 1.513in and his 2in was actually 1.98in. Thus they were not really 1.5 or 2in as claimed. Add in that other houses had no access to the originals, and relied on fitting their lenses to flanges purchased from Ross's and that these were not of hardened metal and wore while in use, and the cause of the general lack of interchangeability was obvious.

Thanks Peter, for this additional info. Indeed tolerances weren't tight in the beginning and many times we will see German lenses/shutters with imperial threads.....
Further, fellow members who are not familiar with thread gauges, here is a sample - they cost only a few dollars and come in very handy when trying to find the thread pitch of your lenses/mounting rings:
https://3.imimg.com/data3/JH/PA/MY-4179049/faithfull-screw-pitch-gauge-55-metric-amer-nat-500x500.jpg
These in combination with your (digital) calipers will help you find almost all the pitches and sizes of your lenses and mounting flanges.

https://m.media-amazon.com/images/S/aplus-media/mg/9ed4f26f-4512-4bda-988d-a3a5adc1e8ff.jpg

Ron (Netherlands)

30-Aug-2020, 10:29

Retaining ring specifications for the many variations of the post WWII Ring set Compur shutters and the bigger Compound shutters (as from #3 with tube 7) can be found in the Compur Repair manuel:
https://www.suaudeau.eu/memo/rep/compur-repair/01-03.html