Test Request: pre-asph 35mm Lux with a pre-asph Cron hood

[russell]

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http://www.l-camera-forum.com/leica-forum/leica-m8-forum/114120-filter-summilux-35-pre-asp-2.html

 

Over on the M8 forum we've a theory we want to test. If someone has a M9, a pre-asph 35mm Lux and a pre-asph 35mm Cron hood, then we'd like to know if it vignettes on the M9.

That's to say is the vignetting any worse than using the normal hood?

 

RichC might be on to something. The big knock on the Lux is the flare. But he might have tamed the beast?

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[adan]

Tested it last fall - no vignetting. Not surprising, since the exact same shade is also sold with the 28 Elmarit ASPH and does not vignette even on that substantially wider lens.

 

Only downside on the preLUX is that there are no slots on the lens to catch the tangs on the lens shade, so the only thing that keeps it from rotating freely (and possibly vignetting corners if rotated too far) is the friction from the spring clips themselves.

 

And the fact that the 35 'lux pre-asph uses its dedicated hood as a filter holder. So with a different hood - no filter use is possible.

 

As to flare - the 35 Summilux pre-ASPH has two kinds of "flare". The "Leica glow" around highlights caused by severe aberrations at f/1.4, which a hood won't help.

 

And the bright rings and artifacts caused by light just outside the image area, which I tracked down to a bright reflection at the intersection of the front element and the lens barrel. Don't know if either shade helps those - but stopping down to f/2 does, because the aperture blades then hide that reflection source.

[lct]

Lot of flare when shooting against the light as well. A hood will do very little to fix that. The glow at f/1.4 and f/2 is a quality if you like it. Otherwise better use a later design. Don't ask me which though as both current Leica and CV 35/1.4 lenses suffer from focus shift. Same for the Sonnar 50/1.5 i've been told but i have no experience of it. The next Summilux will solve this issue hopefully.

[russell]

And the bright rings and artifacts caused by light just outside the image area, which I tracked down to a bright reflection at the intersection of the front element and the lens barrel. Don't know if either shade helps those - but stopping down to f/2 does, because the aperture blades then hide that reflection source.

 

This is exactly the flare that I see as problematic. Thanks for your comment.

Can you provide more color around that point? Intersection of the front element and the lens barrel? What happening there?

And the cron hood doesnt improve that? Hmm... That's exactly the flare I'd hope the cron hood would tackle.

 

Others?

[adan]

Traded my 35 'lux for a cron, mostly for the closer focusing, so I can't snap a picture. (But I drew one)

 

But what I saw, looking through the lens from the back with my eye where the film or sensor would be, was a bright reflection of just-out-of-frame lights at the edge of the glass of either the first or second element - where it meets the barrel. And opposite the light source (since lenses invert the world)

 

Leica paints the edges of lens elements black, but that wouldn't help an internal, prismatic-like reflection: Total internal reflection - Wikipedia, the free encyclopedia

 

BTW - a similar reflection, but off the inside of the barrel behind all the glass, is the source of the veiling flare that turns up in 90mm TeleElmarit-M lenses occasionally - even ridged matte black paint will reflect light if the angle is flat enough.

 

As to shades - the problem is that shades and lenses are 3-dimensional. To absolutely block any light outside the image area from hitting ANY part of the 1-2" wide front element, without causing some vignetting, the shade has to be really long and also wide. Like those bellows shades Hollywood uses. So a shade compatable with "small-camera Leica M" photography will necessarily be a compromise.

 

Since Leica also uses the 35' cron shade for a 28mm lens, it is wide enough to not block light (vignette) within a 28mm field of view. So any light source outside the FoV of a 35mm lens but inside the FoV of a 28mm lens will not be shaded at all. Even on the 'cron.

 

That is theoretical, of course - like you, I await some practical experience from users.

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