blankdl Posted September 6, 2014 Share #1 Posted September 6, 2014 (edited) Advertisement (gone after registration) I have an Elcan 21mm f/4 immersion lens (S/N 251-0002) in excellent condition. Can anyone tell me anything about this lens as I can't seem to find it mentioned elsewhere? Edited September 14, 2014 by pop Conformance to forum rules Quote Link to post Share on other sites More sharing options...
Advertisement Posted September 6, 2014 Posted September 6, 2014 Hi blankdl, Take a look here Elcan 21mm f/4 immersion lens. I'm sure you'll find what you were looking for!
jip Posted September 14, 2014 Share #2 Posted September 14, 2014 Rating value is not allowed here on the forum. Elcan stands for Ernst Leitz Canada if I'm not mistaken. 1 Quote Link to post Share on other sites More sharing options...
Guest Posted September 14, 2014 Share #3 Posted September 14, 2014 I have an Elcan 21mm f/4 immersion lens (S/N 251-0002) in excellent condition. Can anyone tell me anything about this lens as I can't seem to find it mentioned elsewhere? ... Could you perhaps show some photos of this lens here? Quote Link to post Share on other sites More sharing options...
blankdl Posted September 16, 2014 Author Share #4 Posted September 16, 2014 Thanks to Elcan who provided me with a description of this lens, I've learned a great deal since my original post. The purpose of this lens is in underwater photography. Unlike other lenses, this one is designed to use a plano parallel porthole window of a submersible yet be compatible and fully corrected with any salinity (read refractive index) of ocean. It doesn't suffer from the reduction of angular field of view commonly associated with plano parallel windows. Although not mentioned in the Elcan brochure description, it seems to me it would work in any watertight housing with a flat optical glass window. It does all this by permitting a fluid of the appropriate refractive to be infused into the lens and serve as a lens element. I believe this lens to be quite unusual and very rare. The field of view in sea water is 76 degrees, back focal distance 8.3mm (for 7' iin water), spectral range 480-650 mu, weight 10 oz and has a Leica M-Bayonet mount. I've attached some photos and the Elcan description. Elcan was unable to tell me the date of manufactured nor how many were constructed. According to the serial number, this lens is the second one made. 5 Quote Link to post Share on other sites More sharing options...
blankdl Posted September 16, 2014 Author Share #5 Posted September 16, 2014 Will resize photos and post another day. sorry. Quote Link to post Share on other sites More sharing options...
jip Posted September 16, 2014 Share #6 Posted September 16, 2014 Interesting!!! Quote Link to post Share on other sites More sharing options...
blankdl Posted September 17, 2014 Author Share #7 Posted September 17, 2014 Advertisement (gone after registration) I think I've uploaded three photos of this lens as well as a pdf file from the manufacturer. Hope you can see them.Elcan 21mm immersion lens.pdf Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! 1 Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/233513-elcan-21mm-f4-immersion-lens/?do=findComment&comment=2671662'>More sharing options...
luigi bertolotti Posted September 17, 2014 Share #8 Posted September 17, 2014 (edited) Thanks !!! Very interesting item, and intriguing details... By sure, a product (or, more probably, a prototype) designed for some military related project / bid / study. I think it never appeared in the Forum, and I found only a quick reference to it into a list of Elcan lenses, wthout any detail. Apart its interest... With the infos you got from Elcan in official form it could be a star at some specialized auction... I suppose your lens has not, at the moment, any fluid inside the space reserved for it.... so, I'd be curios to see how it performs mounted on a std. Leica M... (can be ? seems to me there is a long protrusion over the bayonet mount) btw, it would be a nice view too, with that huge front element ... looks even bigger than the famous Elcan 90mm f1... Edited September 17, 2014 by luigi bertolotti Quote Link to post Share on other sites More sharing options...
MarkP Posted September 17, 2014 Share #9 Posted September 17, 2014 Thank you for posting this - fascinating! Quote Link to post Share on other sites More sharing options...
pgk Posted September 17, 2014 Share #10 Posted September 17, 2014 So in essence the lens sits against a flat port and the area between the front element and the flat port is filled with (sea?) water the same as outside the port. An interesting solution. I wonder if there are any underwater images from it available anywhere to look at? Quote Link to post Share on other sites More sharing options...
MarkP Posted September 17, 2014 Share #11 Posted September 17, 2014 (edited) Not the same lens but I did find these: LEICA Barnack Berek Blog: LEICA UNDER WATER Blankdl, I note that on the discussion at the bottom of this article someone claimed to have the immersion lens. Was this you, or the owner of 251-0001? http://leicarumors.com/2011/09/05/rare-leica-underwater-housing-for-m4-rangefinder.aspx/ Edited September 17, 2014 by MarkP Quote Link to post Share on other sites More sharing options...
pgk Posted September 17, 2014 Share #12 Posted September 17, 2014 Actually looking at the pdf and your lens that you have photographed, the lens that you have photographed is different in that it has a 'dome port' whereas the pdf shows an 'immersion' system which has no such dome. Does the lens you have disassemble so that the dome port can be removed and the immersion system put onto it instead - this might make sense if it was a prototype where Elcan were comparing the two systems - although usually a lens system placed behind such a dome is designed for use in air rather than water. Does your lens show any code from Ecan (XXX-XXX)? Quote Link to post Share on other sites More sharing options...
luigi bertolotti Posted September 17, 2014 Share #13 Posted September 17, 2014 Not the same lens but I did find these: LEICA Barnack Berek Blog: LEICA UNDER WATER Blankdl, I note that on the discussion at the bottom of this article someone claimed to have the immersion lens. Was this you, or the owner of 251-0001? Rare Leica underwater housing for M4 rangefinder | Leica News & Rumors Yes, the US Navy underwater housing for M4 is not unknown... (btw, the article quotes the lens as a 90mm 2,8, which i doubt it is... on the front ring, imho the writing "90" does refer to angle of taking.. a small tele like a 90mm has little sense underwater) ; but seems to me that, even if the "customer" was probably the same, the OP item isn't strictly related to the underwater housing... it seems made for a camera to be used in a "normal" submersile environment, attached to a glass window. 1 Quote Link to post Share on other sites More sharing options...
pgk Posted September 17, 2014 Share #14 Posted September 17, 2014 Yes, the US Navy underwater housing for M4 is not unknown... (btw, the article quotes the lens as a 90mm 2,8, which i doubt it is... on the front ring, imho the writing "90" does refer to angle of taking.. a small tele like a 90mm has little sense underwater) ; but seems to me that, even if the "customer" was probably the same, the OP item isn't strictly related to the underwater housing... it seems made for a camera to be used in a "normal" submersile environment, attached to a glass window. 90 degrees is the Field of View of a ~20mm lens. Its also about the widest angle which gives fairly good corners behind a reasonably small spherical dome when used underwater. It makes good sense to quote the Field of View as the underwater focal length would obviously be different from an above water one, and quoting Field of View might just help to avoid confusion. I agree though that the pdf doesn't look like it relates to the photographed lens. Quote Link to post Share on other sites More sharing options...
blankdl Posted September 18, 2014 Author Share #15 Posted September 18, 2014 Let me make a feeble attempt at answering some of the issues raised regarding this lens. First, yes, I am the same person who posted on the Leica Barnack Berek Blog. I should also note that the dome lens pictured in his blog was an Elcan 240 series and my lens is an Elcan 251 series. I concur that the lens does not seem to exactly match the schematic in the Elcan pdf file. There is a release show in my pictures but, frankly, I don't know what it does. It's possible that it has some control function over the perfusion liquid or it's possible that it releases the front part of the lens. If the latter, it doesn't come off easily and I'm not willing at this time to exert any excessive force to loosen it up. Nevetheless, the Elcan brochure refers to the series of my lens, Series 251. Serial number is 251-0002. I feel lucky to even have the Elcan brochure. Wish I had a user manual. Does anyone think it's possible that this was a lens designed to compare the dome lens (where the external lens is exposed to seawater) with the description in the Elcan pdf where a fluid of chosen refractive index is perfused into the interior of the lens. I really don't know enough about optics to know if that's possible to do in a single lens like this. I should note that there is about 1/2 inch of thread on the internal surface of the housing. I thought it might hold a filter or protective glass, but it's possible it was for mounting on an underwater housing. It may also have been for mounting on a threaded ring attached to a porthole of a submersible. Look forward to any comments. 1 Quote Link to post Share on other sites More sharing options...
MarkP Posted September 18, 2014 Share #16 Posted September 18, 2014 Hi Blankdl, can I ask how you came into possession of the lens? Is there any way to get more information about that way?? Quote Link to post Share on other sites More sharing options...
Nick_S Posted September 18, 2014 Share #17 Posted September 18, 2014 I think I've uploaded three photos of this lens as well as a pdf file from the manufacturer. ... The field of view in water is listed in the Elcan brochure as 76 degrees. If this equates to the long rectangular dimension, then the lens with immersion liquid would appear to correspond to a 23mm lens on land. Nick Quote Link to post Share on other sites More sharing options...
pgk Posted September 18, 2014 Share #18 Posted September 18, 2014 (edited) Does anyone think it's possible that this was a lens designed to compare the dome lens (where the external lens is exposed to seawater) with the description in the Elcan pdf where a fluid of chosen refractive index is perfused into the interior of the lens. I really don't know enough about optics to know if that's possible to do in a single lens like this. Having thought about it I'd say that its almost certainly nothing like the lens shown in your pdf. Generally speaking, if a dome 'port' is incorporated into an underwater lens design, then the lens system placed behind it has to be designed to focus relatively close (this is because the virtual image produced by the dome in water is 4 x the radius of the dome from the centre of the dome for a subject at infinity (subjects are much closer than infinity underwater). The virtual image is also spherical so this needs to be taken into account (hence why fisheye lenses are popular for underwater use behind domes). So using a large domed front element means that either the lens is purpose designed for underwater use or that it incorporates a dome as the front element - either mean that the other optics within the lens are unlikely to work efficiently in other scenarios such as in the pdf. My guess is that you may have either an underwater lens system built to specification to fulfill an order (military, offshore, etc.) or you may have a prototype dome type design to compare with the system in your pdf. Either way its an interesting lens and must be pretty rare. It would be interesting to put it onto a digital Leica and see what it does (if anything) above water - it may simply not achieve focus at all in which case its probably a pure underwater design, or it may focus at close distances or even further away in which case its potentially a dome port optical system (you may need to use very small apertures even so and such tests are not definitive, just indicative). Often dome port systems use a correcting diopter (immediately behind the dome/in front of the lens behind it), to readjust for focus when using an infinity focusing lens behind the dome but a custom design may not and as the front element/dome shown is small it may only focus extremely close..... Edited September 18, 2014 by pgk 1 Quote Link to post Share on other sites More sharing options...
luigi bertolotti Posted September 18, 2014 Share #19 Posted September 18, 2014 Does anyone think it's possible that this was a lens designed to compare the dome lens (where the external lens is exposed to seawater) with the description in the Elcan pdf where a fluid of chosen refractive index is perfused into the interior of the lens. I really don't know enough about optics to know if that's possible to do in a single lens like this. I should note that there is about 1/2 inch of thread on the internal surface of the housing. I thought it might hold a filter or protective glass, but it's possible it was for mounting on an underwater housing. It may also have been for mounting on a threaded ring attached to a porthole of a submersible. Look forward to any comments. I think is quite probable... clearly the two projects can be dated around the same time, with any evidence for the same user (Navy) : nothing strange that the Navy's tender was both for a hand camera to be operated by divers and a camera to be operated from submarines : Leitz/Elcan, not surprisingly, based both systems around the Leica M (a camera well known to US military) with different approaches on the optical side. Me too don't know enough about optic design... but Elcan people (Mandler & C) DID.. ... If they proposed / prototyped that odd system of filling part of the lens' body with water, there was at least some evidence on paper that was a valuable solution... by logic (but am far from sure it is so) they adopted this approach to keep the same basic lens' design for the 2 systems... for the underwater housing, considering the need to keep the item as thin as possible, they made the lens with front element directly in contact with water ; for the "submarine version" in which you forcely had to operate through a window, they kept the same lens design.. still with front lens in contact with water, which was artificially injected in the assembly. Anyway, thanks again for this thread.... and your pictures : is a topic that could be worth a deep review from some historician related to the Elcan concern : just to start... I'd be curios to compare the lens' schema of the "90 2,8" lens of the KG24 with the one depicted in your pdf document (just to verify my above hipotesis... ) Quote Link to post Share on other sites More sharing options...
pgk Posted September 18, 2014 Share #20 Posted September 18, 2014 (edited) I should note that there is about 1/2 inch of thread on the internal surface of the housing. I thought it might hold a filter or protective glass, but it's possible it was for mounting on an underwater housing. It may also have been for mounting on a threaded ring attached to a porthole of a submersible. As it stands the lens pictured has no sealing system visible so I cannot see how it could be used underwater. Perhaps the thread mounts it on to a sealing system or maybe the lens as it stands is incomplete. Its puzzling because, although the lens could well be designed for use with the front element in contact with water it clearly can't be sealed. Is there a sealing 'O' ring around the periphery of the front element/dome (may be visible as a thin black line if viewing from an acute angle)? If so I would suggest that it might be a prototype which could be used for testing by lowering it vertically into a tank of water until the front is in water contact (trapped air might be a problem though). Another suggestion is to try it out against an aquarium ..... Lastly, does the lens cover 35mm or is it for cine? There are other possibilities. Without knowing its internal system its very difficult to say - looks as though it should dis-assemble to me but I understand your reticence to 'force' anything! Edited September 18, 2014 by pgk Quote Link to post Share on other sites More sharing options...
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