Archived posting to the Leica Users Group, 2000/09/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Please go to your local machinist and ask him to make up one.....no....make that a hundred 35mm focusing mounts (cheaper that way). Then go to your local optician and ask about having the lenses and prisms for a rangefinder made up. Rats, we are not even considering the mechanical parts! So go see your local watch maker for the rangefinder mechanisms. Then, after seeing the prices quotes, we will all get on our knees and thank our preferred diety(ies) that Leicas are so cheap.! I am in the old British car repair field and we encounter this sort of attitude all the time. When people bought Sunbeam Tigers, they bought fancy carbs, new HP air cleaners and threw away the original air cleaner housings. These things are now as scarce as hen's teeth. My apprentice came up with the, what seemed to him, brilliant idea of producing new air cleaners. It is a simple stamped steel item. The local foundry wanted $20,000 to make up the dies necessary! This for a car with a total production of under 5000 units and many of them were wrecked! Another customer brought in his 1932 Alvis Speed 20 for freshening up. The water pump casings and other small pieces were too corroded to save. We had to have moulds of the old parts made, new pieces cast and then machined. This was unbelievably expensive and easily added $5,000 to the total cost. We did not have the heart to add any profit for us for this special work. The Cosina "already" designed body had to have a second shutter put in front of the FM-10 et all shutter because it was originally designed to be used with a mirror. Do not forget the rangefinder had to be designed too. Why did they do it? Because their boss is a LTM nut and he told them too. If that boss left the company, I am sure all LTM production would stop and the lines would be used for more profitable equipment. We are very lucky to have such rich and diverse rangefinder camera products available. At least I am happy and grateful. John Collier > From: Walter S Delesandri <walt@jove.acs.unt.edu> > > I fully understand the operation of rangefinder coupled lenses. > However, the DESIGN of such compensating threads is difficult, > NOT the execution....cheap SLR zooms are much MORE complicated than > the different-rate helicals found in RF lenses....I worked on > all mechanical cameras (especially Leica and Nikon--plus medium > format--it was a pro shop, not many minoltas etc...) in the > late seventies and eighties.....I could NOT design the helicals, > but this design has been complete for more than 50 years... > the application shouldn't be any more expensive than designing > a NEW zoom...... > > Also, the rest of the Cosina was ALREADY designed, and costs SHOULD > have been amortized long ago.....hence the $300-400 street price > I stated....this allows another $100 or so PER CAMERA for the design > and implementation of the RFDR.....since the RF does the same > thing with ALL lenses (as you describe--it "thinks" it's focusing > a 50mm lens all the time)...the cost of a decent rangefinder AGAIN > is in the design....which has been around for, again, nearly 50 > years..... > > I think VF brightness/contrast is more important than accuracy... > most RF users would be content with lenses up to 90mm, f2.8..... > the shorter, faster lenses are very UNDEMANDING of the RF..... > as is evidenced by the fixed (fast) lens RFs of the seventies... > all of which focussed just fine, with their short base, cheap RFs > and their 45mm F1.7 lenses..... > > There will always be a place for the Leica....and the Rolex.... > what I'm talking about is the extreme need for a "SWATCH" RF so that > the real "shooter" can have 90% of the advantages of the Leica > RF without the ridiculous expense..... > > Best to U and URS for the weekend, > Walt in Denton, Tx. > > On > Fri, 15 > Sep 2000, John Collier wrote: > >> A rangefinder lens requires a focusing cam to couple with the camera's >> rangefinder. The camera's rangefinder is designed to couple correctly to the >> natural focus movement of a 50mm lens. All other focal lengths require a >> compensating mechanism to: increase the focusing cam's movement as compared >> to the wide angle lens' natural focusing movement; or, decrease the focusing >> cam's movement as compared to the long lens' natural focusing movement. If >> you are making an SLR lens into a rangefinder this will require designing a >> completely new focusing mount. As rangefinder cameras constitute a limited >> market, production numbers are fairly low. The Pentax "limited" production >> run of 2000 may well take many years to sell out. >> >> The problem with converting M lenses to LTM is that the M lenses were >> designed to be physically longer so that you could mount the shorter LTM >> lens on to a M camera using an adapter. You cannot just unscrew the M mount >> and screw on a LTM mount, the rear of the lens has to have 1mm machined off. >> That is not much but Leica has not been in the habit of designing in extra >> space just in case! So, again, a new focusing mount has to be designed and, >> again, demand will be low. >> >> The new mount designs required and low production runs mean higher costs. >> The Cosina/Voitlander lenses are often touted as low cost but that is only >> compared to Leica prices not regular SLR prices. Except, of course, in the >> super wide angles where you can design an uncoupled rangefinder lens to be >> much less expensive to produce than a complicated mirror clearing retrofocus >> SLR design. >> >> John Collier >> >>> From: Dante A Stella <dante@umich.edu> >>> >>> Just a thought >>> >>> Why are LTM versions of other lenses so expensive? Do the Summicrons >>> require >>> rengineering of the barrel body due to some problem with the difference in >>> film-flange distance that wouldn't allow you to switch the mount plates >>> (I've >>> never >>> disassmbled an M lens, so I can't tell)? (Why couldn't you just adjust the >>> focus >>> on the lens cells if that were the case)? Is this why the Pentax is so >>> expensive, >>> too (to say nothing of the Ricoh GR-1 lens and the Hexanon 60/1.2L)? Or is >>> it >>> milking the LTM user/collector / maven / afficionado / admirer? >>> >>> The actual lens mount in LTM is a pretty simple threaded piece of metal >>> that's >>> chrome plated, certainly something that seems like it could be made cheaply >>> by >>> a >>> competent machine shop (LTM ffd is 28mm +/2 0.2mm). Actually, with modern >>> CNC >>> equipment it doesn't seem like it should be that hard to make the "more >>> complicated" M mount, either. It would seem that to produce a short run of >>> LTM >>> wouldn't justfy the massive price increase like $400-500. >>> >>> By the way, has anyone ever converted an M lens to SM? >>> >>> It would be nice if you could specify LTM or M mount as an option. Think of >>> how >>> much new life could be breathed into so many old IIIgs and IIIfs. >>> >> >> >