Why shiny aperture blades?

[maciek_stankiewicz]

<p>I was wondering; While all lens makers since the fifties are doing research and coating lenses with multiple layers, nano-layers, <strong>Why for God's sake aperture blades in some cameras are made of shiny metal that reflects light like hell?</strong> Is it make sense? (Wow, God and hell in the same sentence? :)<br />While it's not good idea to paint them black why not choose mat-grey or black metal?<br />I can see that modern lenses have dark-mat aperture blades but we are discussing<br />Classic cameras here:)<br />Did You noticed flare due to shiny aperture blades? Any Thoughts?<br />Thank You, Best Regards,</p>

<p>Maciek</p>

[mnpd]

<p>I've got some lens with shined up blades too. For me it's the older lens, and I've always thought that the shine was caused by heavy use... the blades polish each other each time the aperture is activated. The shining seems more prounounced with SLR lens where the camera opens and closes the aperture very fast... accelerating the polish. On older rangefinders where the aperture is set much more slowly by hand, the polishing effect is far less pronounced.<br /><br />That's my take, for what it's worth. I never thought that camera manufacturers produced lenses with shiny aperture blades... I've always thought they just wore that way in time. In fact, I've always judged the use a lens has had by determining the amount of shine on the blades. If you'll look carefully, you may see where the polished area begins and ends, which coincides with the contact positions of the blades.</p>

[steve_levine]

<p>Tolerances are tight between aperture blades ,and paint would take up space, and wear off causing a mess.</p>

[maciek_stankiewicz]

<p>Thanks for the responses.<br />Steve, as I said, any paint is a BAD idea, I would expect dark mat metal similar to one used in modern lenses. Now I have Russian Helios 50mm f2 lens in mind... I am alergic to Russian cameras but some non-russian cameras in my collection got aperture blades made of regular, shiny metal... I'm sure it will lower lens' performance in a sunny day... Any experiences? <em>M.S.</em></p>

[tomscott]

<p>Maybe I'm not thinking about it correctly but, I can't see where it would really matter. The aperture is basically just the hole that is left by the opening or closing of the aperture blades. The blades themselves, at least in theory have no actual part in the photographic process, only the size of the hole that the light shines thru. If the blades were to reflect light, the reflection would be forward and not in the direction of the film. I suppose there could be a small amount of light reflected forward to one of the front elements but, then where would it go that would cause any damage?</p>

[maciek_stankiewicz]

<p>I was thinking about <strong>flare</strong> due to multiple reflections inside the lens.</p>

[tomscott]

<p>I realize what you are saying and I can see for instance why the inside of a lens hood is a flat or matte black to reduce flare, because of the direction that it would cause the light to reflect if it were shiny. I don't know, I'm just giving some random thoughts. Too much geometry involved for me to have a definite answer. I've never had a problem caused by this (that I know of).</p>

[leighb]

<p>They're smooth because they have to move against one another quite rapidly, which mandates minimal friction.</p>

<p>Rough surfaces which move against one another will eventually become smooth, and all the material which is removed in the process becomes dust running around inside the lens.</p>

<p>- Leigh</p>

[frank.schifano]

<blockquote>

<p>older rangefinders where the aperture is set much more slowly by hand, the polishing effect is far less pronounced.</p>

</blockquote>

<p>No. It doesn't have to snap closed and open again every time you actuate the shutter. Set it and forget it. It stays where you put it.</p>

[chuck_foreman1]

I'd say generally I've never noticed a problem. Some older cameras while not black are suffciently dark (tarinshed) and in the high friction areas perhaps a bit shiny. I do have a russioan Sonnar which I bought as a defekt becasue of scratches. It's blades are a very shiny copper color. Again I didn'T notice any flare, but this struck me too as way too shing and likely to cause problems. With the exceptions I mentioned here, almost all my older cameras have black blades if not a dark metallic blue-black color.

[j.p._dahl_n]

<p>Both Deckel and Gauthier (The makers of Compur and Prontor and other shutters) took this seriously. Their early shutters have aperture blades of matte black paper and some have plastic shutter blades. They are delicate and easy to damage during cleaning and repair. Their later shutters have polished metal blades, chemically treated to a grey colour.</p><div></div>

[murray_kelly]

<p>Brian Sweeney on RFF has a thread about this. he has blackened the blades of his Helios 103 lenses and has before/after pictures to show the improvement under rear lit scenes. He uses a felt pen.<br>

Murray</p>

[bob_miller4]

<p>Anything that could slow down the moving blades could do more harm than good. I would not worry about treating or dulling a particular set of blades unless I experienced a real-life problem that could not be solved in another way.</p>

[mnpd]

<p><em>"No. It doesn't have to snap closed and open again every time you actuate the shutter. Set it and forget it. It stays where you put it."</em><br>

Sure it does. With full-aperture metering --- the SLR standard for decades --- the aperture blades always stay fully retracted. As the shutter is fired the aperture blades snap shut to the appropriate opening, stay closed for the duration of the exposure, then snap back fully open. With manual cameras the aperture blades are opened and closed by hand. The only "set it and forget it" aperture I'm familiar with are jammed lenses. :)<br>

<em> </em><br>

<em> </em></p>

<p> </p>

[tomscott]

<blockquote>

<p>The only "set it and forget it" aperture I'm familiar with are jammed lenses. :)</p>

 

</blockquote>

<p>Apparently you are not familiar with a rangefinder then, which is what the statement was made about. With a RF since you are not looking thru the lens, the aperture is set to wherever you set it, and that is where it stays until you readjust for a different exposure. There is no need to have it stop down at time of exposure because most RFs that have meters either have the meter cell in front of the lens, or built into the body. No need for full aperture metering like you have with most SLRs.</p>

[mnpd]

<p>Sure, I own dozens of rangefinders and use one regularly. I think you may be talking about the process of changing the aperture for proper exposure and/or the differences in how SLR's and rangefinders frame and focus... which I completely agree with. I was merely referring to the mechanics of <em>how</em> the various lens apertures are activated.</p>

<p>With full-aperture metered SLR cameras, the camera opens and closes the blades... very rapidly (snap!). With many rangefinders, the user handsets the lens aperture (slowly). Look at an old Leica or Argus C3/4/44. Of course some rangefinders do the opening and closing of the lens, i.e the old Electro 35 and others, which requires an mechanism similiar to that used in the SLR's.</p>

<p>Anyway, I don't want to clutter up the poster's thread by continually repeating myself. I know what I'm talking about and if you are equally convinced that you are too then we are both happy. :)</p>

[leighb]

<blockquote>

<p>With full-aperture metered SLR cameras, the camera opens and closes the blades...</p>

</blockquote>

<p>Hi Thomas,</p>

<p>Aperture control is not limited to metered cameras. <br>

All SLRs use full-aperture viewing to maximize viewfinder brightness. Hasselblad is a good example.<br>

The same technique is used in view cameras, for the same reason.</p>

<p>- Leigh</p>