Yet again I hear my "M3 Summaron" is "convertable"?

Greetings, I thought I had resolved my curiosity well enough sometime ago when someone had made the claim

that my M3 Summaron (35 f/2.8) could readily be used as a SM lens if I were to dismount it from the goggled

frame. It had taken place on here and many of you had voiced concerns or suspicions that it would work. My

curriosity got the better of me however and I did try it.. In my brief testing it had seemed to prove itself false.

While I felt a little foolish and frustrated, I did not wish to cause any embarrassment to the gentleman that voiced the claim with posting my results because he was quite sincere in his opinion. It helped that I had taken some precautions beforehand with remounting the lens back on the goggles as near precise as possible with the aide of a stero microscope. The

lens still seems to shoot and perform as it did before on my M2 and I considered the whole matter closed.

 

A few weeks back it all happened again while engadged in conversation with someone who was commenting

about the M2. He seemed to be quite a knowledge about Leica cameras and I introduced him to the rest of my

set up. He made similar claims about the Summaron lens based on it being an early run. I explained that I had

experimented on it and it did not work. He seemed surprised as well as a little doubtful that I had likely knew

what I was doing when I had tested it. He did not insist on it and the latter was more an assumption I got from

body language.

 

It has me somewhat curious again however and I'm not sure if my methods of testing were flawless. I did not

shoot any film but merely compared the distance findings on the lens with what my RF had indicated to be in

focus.I was using a "Voightlander" SM to M adapter with the lens and I did roughly half a dozen areas of

distance to which none seemed to match with the distance finding on the lens. I was also cross camparing it

with the distance findings I was getting from my Contax T and they did not agree. Was this enough to conclude

the question?

 

For what it might help, my M3 Summaron is an f/2.8 with SN:1678912. It has the "tiny" screw at the very base,

but I see this on several if not all. I can post photos if this will help anyone. Thank you for your time in reading as well as

any input you may contribute. Charles

<p>Of course, no Leica lens with goggles can focus accurately without the goggles (except for the dual-range Summicron in the non-closeup range.)<br>

The goggles change the magnification of the viewfinder, and put a wedge prism in the path of the rangefinder window. This makes the offset of the rangefinder roller that causes "coincidence" of the two rangefinder images at a particular distance different. The rangefinder cam on the lens moves at a rate that corresponds to the behavior of the rangefinder with the goggles on.<br>

This is easily demonstrated. Take two lenses, one made with goggles, one made without goggles. Set them at 5 feet on the focusing scale. Measure from the focusing cam to the lens mounting flange. The distance will be <em>different</em>.<br>

The only use of a goggled Leica lens with the goggles removed is as a scale-focusing lens. That's a pretty poor use of a Leica lens.</p>

<p>"The only use of a goggled Leica lens with the goggles removed is as a scale-focusing lens. That's a pretty poor use of a Leica lens"<br>

Actually, that's how most street photographers use their lenses. Set at 4 meters and f:16, everything is in focus from "near here to out there."</p>

<p>With my CV 35mm f2.5 PII lens attached to an M4-2 I still almost always scale focus outside in moderate to good light. Even indoors wide open I'll guess distance if I don't want to attract attention by bringing the camera up to my eye to focus. Much faster that way. Most of the viewfinder cameras I've have do not have a rangefinder and so I've become adept at estimating distance. You could try this with your Summaron and see how it works for you. You can get quite good with practice.</p>

<p>Yes, I understand that much street photography is done with Leica lenses by scale focusing. But most of the cost of a Leica relates the rangefinder, throwing that away is pretty poor financial planning.</p>

<p>I hope there is no misunderstanding of my post. I agree with John Shriver. The properly calibrated Leica RF is a marvel and I do use it with all my lenses whenever possible. As I noted, for much of the 40 years I've been at this hobby just about all my VF cameras have been scale focus so my perspective on this subject could be biased. I do still believe that learning to estimate distance is just another skill that can, on the proper occasions, enhance your chance to 'get the shot', so to speak.</p>

<p>Technically, a convertible lens is one which can be configured for several different focal lengths by using the entire lens, or either the front or rear portions (groups?) of the objective. This type of lens is usually for large format cameras in studio setups.</p>

<p>What I think is "convertible," however, is my non-goggle, bayonet mount 35mm 2.8 Summaron that has the tiny screw which, I believe, will reveal a screwmount thread if it is removed and the bayonet taken off. Did I say that correctly?</p>

<p>What I think is "convertible," however, is my non-goggle, bayonet mount 35mm 2.8 Summaron that has the tiny screw which, I believe, will reveal a screwmount thread if it is removed and the bayonet taken off. Did I say that correctly?</p>

<p>Here's the lense -- sorry</p>

Thanks Paul for that and it fills in a major blank. That helped me land some better search information about the "convetable" lens just with leaving out the word "goggles" in my request. While mine does have a near range serial number to the models I found online, I have to assume the tiny screw is what is confusing some into making this claim. The tiny screw seems to be on many of the early M3 Summarons with goggles. I can now at least rest my confusion as the screw itself does not necessarily indicate a Summaron is "convertable" unless it is without the goggles! Thanks again, and I thank the rest of you as well. Charles

<p>The convertible goggled version employs a totally different focusing cam than the regular version. It's easy to unscrew the ca.1mm set-screw on the side of the M-flange to reveal the LTM mount, HOWEVER Leitz had employed a different focusing cam on all goggled 35mm lenses compared to the one on the non-gogled versions.<br>

.<br>

Below shows the cam height in mm from the surface of the mounting flange (deduct 1.0 mm for the LTM to M adaptor from the values on the right column):<br>

.<br>

Distance m ... M-Mount... S-Mount (Convertible) <br>

0.7.......... 2.24.......... 4.00<br>

0.9.......... 3.36.......... 4.60<br>

1.2.......... 4.24.......... 5.20<br>

2.0.......... 5.40.......... 5.80<br>

5.0.......... 6.24.......... 6.40<br>

Infinity..... 6.52.......... 6.70 </p>

<p>As you see, they are so different that even the <strong>distance scale inscribed on the focusing collar could NOT be used for zone focusing.</strong></p>

 

The cam height is independent of the collar focusing scale. While the range finder would be well and truly out, infinity would still be at infinity and 1 metre at 1 metre settings, if either the goggles are removed (easy with the 3.5 version) or if the SM/BM adaptor is removed.

<p>I have the regular version as well as the goggled one, both the f2.8 version. The figures in the middle are from the regular one and the ones on the right are from the goggled version. One should not assume that the goggled version would be used on an M2 for example with no issues for focusing once the goggle is dismantled. Try it..</p>