Contrast enhancing lens for focusing?

[jto555]

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I just saw this on Steve Huff's website for a contrast enhancing lens for focusing:

 

The Walter Leica Contrast Lens, an invaluable addition to your M | STEVE HUFF PHOTOS

 

I am a wee bit sceptical as I tried yellow len driving glasses which for me did not do any good. However am I right to be sceptical?

[mjh]

Just how exactly is this supposed to enhance contrast I wonder?

 

And btw: “Walter tells me that Leica themselves had a similar golden coating on some early M3 cameras, and that they actually used real gold so it became to expensive to implement.” A layer of gold so thin you can see through it would not be that expensive. You can see through gold leaf but that would still be too thick. Also if I remember correctly gold leaf held against light appears greenish, not yellow/golden.

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[bocaburger]

Apparently the guy had a brainstorm after noticing that some people wear yellow tinted glasses for driving/hunting/sports etc. claiming it increases contrast and acuity. Personally I never found it increased anything but annoyance. And definitely scews with color vision, like using an SLR with a yellow filter on the lens. Back in the screwmount days Leica made a slip on filter (it was red though) for the rangefinder window. But it didn't impede the viewfinder. (And it didn't really work either, I've got one). And adding an extra piece of glass in the optical path reduces contrast (probably not much if it's really well multicoated though).

 

Plus if you wear glasses this gizmo would make it harder to see the wide frame lines.

Edited August 3, 2014 by bocaburger

[wlaidlaw]

I have tried putting a yellow filter over the RF secondary window image on my M8 and I found it did make RF focusing easier, particularly in very flat light. Unfortunately I only had it stuck on with blu-tak and it fell off un-noticed. I did not have another very small yellow filter (it was one of the rear element filters to go on my Zenitar 16mm Fish-Eye lens).

 

I used to use yellow glasses when I was target rifle shooting, as they were recommended by my optician and also served as safety glasses. I am far from convinced the yellow tint made any difference at all. When I had a later prescription for untinted safety glasses, my scores did not seem to deteriorate.

 

France used to insist on yellow tinted headlights, as supposedly it penetrated fog and rain better. All it did was make the headlights dimmer, a bit like the civil servant who put the law in place. Totally abandoned now.

 

Wilson

[wlaidlaw]

I think this says it all. What applies to night driving applies to looking through a viewfinder. It is all perception not reality.

 

“Yellow ‘Night Driving’ lenses have been shown to provide no benefit in seeing ability at night. They are even hazardous, because they give the driver a feeling of seeing better, which no one has yet been able to explain. Studies have shown that they actually impair visual performance and retard glare recovery. Many promoters have made unfounded claims for the ability of amber to improve night vision. They have employed mass solicitation, usually by mail. The Federal Trade Commission has correctly ruled that such practices are illegal since the lenses do not perform as claimed.” – Forensic Aspects of Vision and Highway Safety”, Merrill J. Allen, O.D., Ph.D., Et al.

 

Wilson

[zlatkob]

I wonder how those yellow glasses are for distinguishing a red traffic light from a green traffic light when driving.

[jcraf]

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As someone formerly involved in the optical aspects of military aircrew, this is twaddle. Does Walter also sell used cars?................

[jaapv]

Has everybody forgotten OKARO and ORAKO ?

[TomB_tx]

Has everybody forgotten OKARO and ORAKO ?

Good point - but didn't these tint just one of the RF windows so the two images were tinted differently and thus easier to distinguish? This new lens on the eyepiece would affect both.

[bocaburger]

Has everybody forgotten OKARO and ORAKO ?

 

I mentioned it in my earlier post although I don't have the code words catalogued in my head. They were red, not yellow. I have the one that fits the IIIf. And yes, as I said, it only affects the rangefinder because it's a separate window. And if anything it makes it harder to focus for me because it darkens the view. Just like yellow or red lens filters, these have at least a 1 stop factor, meaning at best they halve the incoming light.

 

Now that I think about it, I do remember some Japanese rangefinder cameras of the 70s had a yellow rangefinder patch. I always thought it was just so it was easy to delineate, as they typically were round with soft edges, unlike the sharp borders of the Leica M patch (and why the latter can be used split-image as well).

[zlatkob]

Now that I think about it, I do remember some Japanese rangefinder cameras of the 70s had a yellow rangefinder patch.

 

The Canon Canonet: http://rick_oleson.tripod.com/rf-spot-view.jpg

[pgk]

However am I right to be sceptical?

Yes.

[jaapv]

I mentioned it in my earlier post although I don't have the code words catalogued in my head. They were red, not yellow. I have the one that fits the IIIf. And yes, as I said, it only affects the rangefinder because it's a separate window. And if anything it makes it harder to focus for me because it darkens the view. Just like yellow or red lens filters, these have at least a 1 stop factor, meaning at best they halve the incoming light.

 

Now that I think about it, I do remember some Japanese rangefinder cameras of the 70s had a yellow rangefinder patch. I always thought it was just so it was easy to delineate, as they typically were round with soft edges, unlike the sharp borders of the Leica M patch (and why the latter can be used split-image as well).

 

I have an orange one. Maybe it faded.

Edited August 4, 2014 by jaapv

[pgk]

Think about this for a moment. Yes, a coloured filter will increase contrast but only between certain colours just like a B& W contrast filter. So if you are wanting specific colours to have contrast enhancement then this will be so. Unfortunately this isn't often likely to be the ones seen in real life where we live in a multicoloured world.

 

Secondly, any colour filter reduces the light transmission so we are viewing at reduced light levels so contrast will be reduced because the dark areas may well merge into black. Lastly, the eye brain system is extremely sophisticated and will potentially compensate to produce 'known' colours thus skewing a view through a colour filter with unpredictable results which may even affect perceived contrast.

 

Yellow (or other colour) filters can be useful for contrast enhancement but only in controlled conditions or for very specific requirements. They are not a 'deliver enhanced contrast all the time' solution.

[farnz]

My OKARO worked very well with my IIIf because it highlighted in orange the edges of in-focus elements in a scene and made them stand out from out of focus edges. To be fair, it's a workaround for a rangefinder that needs a CLA but it works for me.

 

Pete.

[Paul J]

Shooters, racing car drivers, there are a whole host of athletes that use yellow lensed glasses for exactly this purpose so I'm sure it will make a good difference.

[bocaburger]

Shooters, racing car drivers, there are a whole host of athletes that use yellow lensed glasses for exactly this purpose so I'm sure it will make a good difference.

 

Can't speak for that whole host of athletes, but I'm in tight with shooters and auto racing folks and nobody I know still uses them, it's a myth that has been debunked.

[rramesh]

Isn't the intent of a yellow tint to neutralize the effect of blue which scatters easily and tends to reflect back at the eyes? This glare makes it difficult to see what is ahead of you. Hence the use of yellow usually in sunglasses and ski masks.

 

It helps you see better. Not sure about contract improvement though.

[jaapv]

But only when the light is diffused by fog, for instance.

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Hallo,

Look here: Leica M

[250swb]

But only when the light is diffused by fog, for instance.

 

Or snow? Seeing increasing detail and contrast in fallen snow can be important depending on the speed you are travelling downhill.

 

Steve