Light gathering aspects of M6/rangefinders in general

[dayton_p._strickland]

I just started using the Leica M-system again. I've had the camera for

a while, but haven't taken it out on assignment until last week and

I've noticed something that baffles me only because it makes no sense

in the usual photographic world. The camera seems to gather more light

than my Canon EOS system does. Using Fuji Press 800 film, 28mm lens

and available light, the Leica just seems to show more shadow detail

and doesn't wash out the highlights like the Canon does. Is this magic

or something to do with the way rangefinder lens are manufactured and

their relationship to the film plane. By the way, the lens is a Voigt

28/1.9. Maybe some non-voodoo types out there have an answer.

P.S. It reminds me of the digital television images I see on the local

stations when I have covered the same event they did, but the scene

seemed much darker than what the

[jackflesher]

Stated simply, I think you have discovered (or discerned) the magic

of Leica glass. I don't know that I'd say Leica gathers more light

than others, but IMO there is a broader range of tonality present in

Leica images.

 

<p>

 

:-),

[ralph_barker]

Your experience may be the result of the microscopic pyramids that

coat the inside of the M6, preserving the detail in the light as it

passes through the air between the lens and the film. ;-)

 

<p>

 

Or, it might be that your Voigtlander 28mm (and most Leica lenses) are

less prone to detail-robbing flare than many other lenses. Or, it

might be a difference in how you are metering the scene, resulting in

better exposures. Or, perhaps some combination of the above (excluding

the mythical pyramids, of course).

 

<p>

 

There is no voodoo in the amount of light any lens collects (a given

focal length and aperture will all be the same), but there is a

certain amount of voodoo to lens design and what the lens does to the

light passing through it. Zeiss lenses on other cameras employ similar

voodoo in other formats.

[andy_piper2]

Dayton: you didn't mention which Canon lenses you're comparing to, but

if you're using zooms they have a lot more glass elements (NOT

pyramids!) 8^). Each air/glass and glass/glass interface reflects and

refracts light instead of passing it on to the film as image.

 

<p>

 

Prime lenses have fewer elements, on average, than zooms, and

rangefinder lenses often have fewer than SLR primes (e.g. the Elmarit

90 has four pieces of glass vs. five-six for Nikon's 85-105 lenses, and

maybe 9-12+ pieces in a 28-105 or 80-200 SLR zoom).

 

<p>

 

Leica makes a big deal out of keeping the number of elements down in

their designs (one reason why they are emphasizing aspheric surfaces in

their newest designs - each ASPH surface does the work of two normal

surfaces in terms of making optical corrections, and with half the

light loss to reflections.)

[richardvanle]

<i>I think you have discovered (or discerned) the magic of Leica

glass</i><p>

Er... in this case it should be the magic of Voigtlander glass.

[dayton_p._strickland]

Thanks for all the insight. After posting this I dug through some old

magazines and came across an article in the September 2000 issue of

Popular Photography that might shed some light on this. In talking

about how rangefinders are better in many aspects over an SLR, Herbert

Keppler talks about the distance from the rear of the lens to the film

plane. An SLR must add extra distance for the mirror to clear, in some

cases as much as 20mm's more. That same issue also has a review of the

Hexar RF so his piece might have been a little slanted toward

rangefinders, but everything he says makes sense. As for more info on

this, my Canon lens is a 2.8 zoom and the light readings from both

cameras were identical. By the way, if your work, like mine, requires

you to use an SLR, I highly recommend the Canon EOS-3. It's metering

is the best I have ever come across. ---------------------------------

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[david_killick]

Re Andy's point, I'm not sure if number of elements is the whole

story, although zooms are definitely prone to more flare. Old pre-WWII

Leitz lenses used to have far more elements and glass/air interfaces

than Zeiss. Leitz lenses had better resolution, Zeiss had better

contrast. Today's Leica lenses are more contrasty through use of

multi-coating, but still have six or seven elements. Another very

simple but highly praised lens today is the Zeiss Tessar found on the

tiny Yashica T5, which (I think!) has just four elements. It's praised

for being sharp and contrasty. I think there are heap of highly

complex factors which need to be taken into account. Lens expert Erwin

Putts at www.imx.nl is the guy to check out.

[douglas k.]

Andy raises a good point concerning primes vs. zooms: years ago I

purchased an old 135mm f2.8 lens which had, I believe, six elements.

To test it out, I mounted a camera to a tripod, and used both the

135mm and a 70-210 zoom set at 135mm to shoot some test slides. To

make a long story short, the comparison showed that the zoom's true

f-stop (I think they call it a "T-Stop" in motion picture camera

lenses) at a given setting was considerably smaller -- about 1/2 stop

-- than the indicated setting. At 135mm, the zoom's setting indicated

f4 as max aperture, but it was effectively about f4.8, or a half stop

slower, a fact I only discovered by comparing the readings to those

derived using the prime lens. I surmised the difference to be

accounted for by the zoom's larger # of elements (about 11, I think)

diminishing the light as it traveled down the lens. Even well-coated

lenses will lose some light to flare.

 

<p>

 

In practice, it means that good prime lenses may be even faster, in

comparison to zooms, then indicated by their published maximum

apertures.

[maurice_tepper]

Someone showed me a picture of a cat's face in 1966, with each

whisker in the Black and White print sharply defined. It convinced

him to give up his well-known SLR. When it comes to Leitz...or now,

Leica, you can use all kinds of lens studies to prove a point, but

it's really magic. Don't question it, just use it, just like

photographers have been doing since 1925, with the same fabulous

results. I use a Leitz V15 enlarger to cast an even sharper spell.

Zap....magic, plain and simple.