jean_marie_dederen

<p>Bravo! Well said! I have certainly learned a thing or two.</p>

<p>And here is the device mounted. Admittedly it does look a little silly.</p><div></div>

<p>And now I see where the canon AUTO-UP and super-NOOKY got their inspiration from: the Leica ADVOO close up device for the IIIg. Also without wipers!</p><div></div>

<p>Great ad JDM.<br> - somebody must have leaked my design.... :(</p>

<p>Digital monochrom. Never really understood the meaning of it. Why go for a simulated image when you can get a real print? :/</p>

<p>That's a real macro device then. Surely there's a distance scale on the nooky (knowing the german sense for prezision!) ? Your summitar's dark blue coating looks in good nick! I had two. The one had a cracked element in it and you needed iron man to turn the focusing ring (totally glued up). But the few colour films I shot with it produced great results. They surely don't build them like that anymore.</p>

<p>Jim - Leaving it permanently on probably means that it does not affect shooting 'in normal mode'? Does the extension piece not affect working with the distance scale on the lens? </p>

<p>Now you make regret I gave my summitar away!<br> Lucky I kept the summar. Your still life concepts are stunning. Can't believe you manage those little eyepieces on the IIIc though. I suppose the 'Nuke' device magnifies and makes things easier to see. Stll for a blind bat like myself...</p>

<p>Jim: how accurate is the focusing with that device? The summitar is very sharp in the centre, so I suspect the results will be stunning if properly focused.</p>

<p>Like this one:</p><div></div>

<p>I personally think a leica mit brille is uebercool!</p><div></div>

<p>GOGGLES never understood why users hate and collectors undervalue them?</p><div></div>

<p>Amazing. Never seen anything like it; thanks for sharing. Even ze red box with golden lettering is a leica-like.</p>

<p>You got the cheap model JDM; the de luxe model has wipers!</p>

<p>Thanks Steve - I only knew about the blue and purple coatings on the pre 1970's lenses.</p>

<p>Been looking for a way to improve on the tiny view/rangefinder on my Leica III. It's not yet perfect but then again...it's only a prototype! Any suggestions are welcome.</p><div></div>

<p>Whoops, forgot this one:<br> <em>It was noticed by Dennis Taylor in 1896 that some lenses with glass tarnished by age counterintuitively produced brighter images. Investigation revealed that the oxidation layer suppressed surface reflections by destructive interference.</em></p>

<p>Had no idea oxidation inspired lens coating:<br> Harold Dennis Taylor, <em>A Method of Increasing the Brilliancy of the Images Formed by Lenses.</em> United Kingdom Patent #GB29,561 (1904); granted 23 November 1905. (from Wikipedia)<br /></p>

<p>Pics with repolished lens came out normal by the way. Maybe my multicoated ND4 helped.</p>

<p>James - You're right. Just started checking and found a reference to a discussion of lens coatings in the 1983/1 issue. Any comments on the following thread:<br> <em>Some vintage (prior to WWII) lenses that left the factory uncoated but because of age and oxidation during these years have developed "bloom" which acts somewhat like a coating. Regarding lenses with a "bloom", I seem to remember reading that the idea for deliberately putting coatings on lenses happened when it was observed that old lenses with such a "bloom" tended to perform better than new lenses without one. Some types of optical glass develop some superficial corrosion over time. And sometimes this layer of corrosion has optical properties similar to that of coating. In some cases, intentional "forced" surface corrosion was used instead of coating.</em><br> <em> </em></p>

<p>Thank you James and Gus. Pity there is so little data available on coatings in the Leica literature.Zeiss, pioneering coating technology, including multi coating, was quite verbose about it. The Japanese manufacturers who were eager to imitate, I mean compete, made it a selling point in their adverts. Leitz just never made it much of an issue.</p>

<p>Gus, James:thanks; what exactly is 'lubricant regassing'?<br> Is each element coated? If I hold the lens up and stand under a tubelight, I see different colours: I thought the orange-yellow was caused by the glass type, and that only the violet/purple and blue were coatings: the latter seem to be limited tothe front and back elements only?<br> Lastly: one of the elements in front of the diaphragm seems to have a mark that runs along the barrel of the lens. What is going on there?</p>

<p>Do they wear because of age? Fade because of exposure to light? What happens to the coatings inside?</p>

<p>James - Thanks. I thought the coating was limited to the front and final back element only. Your early summicron would have had a light blueish coating, not much different from the coating that was put on uncoated prewar lenses in the late 40's and early 50's?<br> If this sample I borrowed was polished they sure did a good job, looks as good as new. I want to hold next to another summicron 35 so that I can see the difference.</p>

<p>Borrowed a cron35 (goggled) 1959 vintage. Lens looked almost too good to be true: couldn't see any blemishes or cleaning marks or hairline scratches.... Took it out to do some BW landscape. After a closer inspection I can see why there is no damage to the coating: it doesn't seem to have any! (at least not on the front element). Hate to think what I will develop over the weekend!<br> I suppose that 1959 front element coating is of the kind that rubs off over the years? But surely it wouldn't rub off completely? How do you see that a lens has been repolished? </p>