Greetings, All:

Forgive my ignorance here.

Spinning the aperture dial on the 35mm lens, and looking at the diaphragm blades, there is an extra click beyond each of the marked extremes that affects the blades as expected. Are there 1/4-or-so stops (guessing the number here) beyond the stated aperture range that are "valid"?

Matt Sachs mattsachs@attbi.com

-- Matt Sachs (mattsachs@attbi.com), April 10, 2002

Answers

they are half click stops, not 1/4 click stops...

-- Matthew Geddert (geddert@yahoo.com), April 10, 2002.

The click stops in between full aperture markings are half stops. But some Leica lenses apparently open up a bit more than the widest aperture. For example my 2/35 aperture opens to about 1.8-1.9, after the click marked 2. Leica is supposed to calibrate the aperture scale exactly and has some leeway to be sure to always get the maximum aperture, so some lenses open up a bit wider. I suppose the same applies in the smaller end though my lens does not really close beyond 16.

Ilkka

-- Ilkka (ikuu65@hotmail.com), April 10, 2002.

My 35mm Lux Asph and 90 SAA are the same.

-- Kristian (leicashot@hotmail.com), April 10, 2002.

"Valid" is a relative question. One of my meters reads in 1/10 stops. Lenses are usually clicked in 1/2 stops, and film speeds, shutter speeds, and lens openings traditionally progress in 1/3 stops. Shutter speeds are variously accurate across brands, specific cameras, and speeds within a single camera (Leica high speeds are notoriouly off, usually). Cameras which automatically bracket exposures, and people who do the same manually when they shoot, usually work in 1/2 stops, which should tell you something (though I'm sure someone will pop up who says he brackets in something like 1/50 stops, and can tell the difference in each frame--this is a *Leica* forum, after all, with all the attendant nonsense!)

-- Michael Darnton (mdarnton@hotmail.com), April 10, 2002.

Ah, and I see I totally missed the point of the question! I'd go with what the company set, and if you want to know if there's a difference, test your individual sample and see if you see a difference.

-- Michael Darnton (mdarnton@hotmail.com), April 10, 2002.

At the wide open end, no: the maximum aperture is limited by the diameter of the baffle in the barrel, opening the blades further into it won't affect anything. At the small end, the blades probably are overtraveling slightly as you go past the click, but it's probably not enough to be of any use photographically.

rick :)=

-- rick oleson (rick_oleson@yahoo.com), April 10, 2002.

Matt was not asking about the 1/2 stops between the markings but about the extra ammount that some lenses open for example 'chron 35/2 just a tad more towards 35/1.4.

This is because every lens is individualy adjusted to be precise 35/2. How much is this extra "opening" depends on the lens but it is neglectable little.

Best regards,

-- Boris BRECELJ (boris@brecelj-op.si), April 11, 2002.

It varies from lens to lens just how much extra you 'get' - but it's never enough to make for significant 'extra' speed or 'extra' DOF - my 35 f/2 opens up to about f/1.95 and stops down to f/17 or so.

Large-aperture long lenses (90 f/2.0, e.g.) often have more visible change at the wide-open end - but it's still actually adding only an insignificant amount of light compared to the huge size of the f/2 aperture itself.

The 21 f/3.4 I'm experimenting with is the opposite - it has a full clickstop between f/4 and f/3.4 - same spacing on the ring as from f/4 to f/5.6. But the aperture blades disappear completely by the time I turn halfway from 4 to 3.4. The actual hole in the glass is f/3.4 even though the blades behind it move to f/2.8 or some such.

Stopping down from f/3.4 to f/4 nothing happens until just before the f/4 click stop - then a sliver of blade sneaks into the opening at the last second. It's taking a little practice to get used to the idea that 'stopping down' a half click from f/3.4 is still f/3.4. =8^o

-- Andy Piper (apidens@denver.infi.net), April 11, 2002.