Protective 'filters'?

[MarkP]

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I'll restrain myself from making the obvious dubious quip...

 

My words were very carefully chosen .

After all English is my first language .

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[mmradman]

One thing I meant to mention is that most (or all) of the occasions I have noticed the slight vignetting when using the 35 FLE I have also been using the hood. My suspicion has been that it is the hood that was causing this vignette but, being lazy and disorganised, I haven't yet run any comparison tests to determine if this is actually the case.

 

Hood is unlikely cause, same type is fitted to 24mm Elmar and 21mm SE. I didn't notice vignetting with 21mm SE at max aperture, but again didn't look for it.

 

Leica filters and also other compatible brands sit well inside the hood. As stated above wide fast lenses tend to vignette at max aperture.

[wattsy]

As stated above wide fast lenses tend to vignette at max aperture.

 

Yes, I know all this but the example I have shown isn't at maximum aperture (probably F5.6, maybe F4). The reason the phenomenon caught my eye (so to speak) was that it didn't have the usual hallmarks of optical vignetting.

[lct]

I don't see any difference at f/16 either.

[mmradman]

Yes, I know all this but the example I have shown isn't at maximum aperture (probably F5.6, maybe F4). The reason the phenomenon caught my eye (so to speak) was that it didn't have the usual hallmarks of optical vignetting.

 

Post #40, ever so slight, if I didn't look for it I would miss it, on the other hand going to Spec Savers springs to mind.

 

It might be the case of image circle barely making 43mm diameter - we now know that some (slow) R lenses will illuminate S sensor.

[Tonki-M]

Yes, I know all this but the example I have shown isn't at maximum aperture (probably F5.6, maybe F4). The reason the phenomenon caught my eye (so to speak) was that it didn't have the usual hallmarks of optical vignetting.

 

agreed. mine also isn't the gradual vignette like those normal optical vignette. this is more sudden, like it is caused by something. plus, my shots are at f/5.6-f/8. at these apertures, there should have been no vignette at all. Not sure how easily you can see it in this pic, but look at TOP LEFT and TOP RIGHT corner and you should see what i'm talking about.

This is 35 lux fle with Leica 46 uva filter.

 

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[lct]

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I don't see any difference at f/16 either.

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[wattsy]

Not sure how easily you can see it in this pic, but look at TOP LEFT and TOP RIGHT corner and you should see what i'm talking about.

 

Yes, I can see it. Looks exactly like what I have been trying to explain.

[Nicolas Soldati]

Yes, Leica started the trend for a neutral first element with the 280-4.0 APO. The reason was and is the price of the "real" front element, making a damaged lens less expensive to repair, but the flat front element is part of the optical formula, as opposed to a screw-in filter

 

Because the filter is placed before the refracting elements (where light beam is parallel), it has not to be part of the optical formula. There is therefore no difference with a screw-in filter. The only thing that matter is its intrinsic quality (flatness, transmittance, coating...).

 

I personally always put filters on my optic because I expect to use them life long and I PERSONALLY prefer, in the long term, to have a perfect old lens with a new filter rather than having a lens with a POSSIBLE aged front element without a filter. So I use B+W protective filter as well as color one for B/W photography.

[jaapv]

Incorrect. Leica indicated in the release notes of the lens (several ages ago) that both the front planparallel element and rear interchangeable filter were part of the optical formula. Outside the optical axis the refraction of a flat element will have an impact on the ray tracings.

That incoming light is parallel is a misconception. That may be true for a dot at infinity, but the rest of the light comes in from all angles. Both within the angle of view that forms the image and oblique rays that cause flare. The case is different with astrophotography where all objects are at infinity.

On lesser lenses this may be negligible, but we are talking about a full diffraction-limited optic here where the last nanometer counts.

[honcho]

If the lens is dropped or subject to some other impact damage on or off camera, a filter isn't likely to offer much protection to the front element and the direct cost of front element replacement is probably going to be limited only to insurance excess. The point, as a primary reason to use a filter and assuming the photographer has insurance, is moot imo.

 

I don't routinely use a filter but I often do use one, depending on the lens in use and the environment I'm working in. Some of my work involves photographing people, lots of them at close range and a protective filter is often useful and sometimes not. Some of my work is outdoors where a protective filter would often be a pointless hindrance and sometimes prudent.

 

There are relevant reasons both for and against using a filter for protection but no 'rules', so take insurance on your equipment and make your own decision.

[Nicolas Soldati]

Incorrect. Leica indicated in the release notes of the lens (several ages ago) that both the front planparallel element and rear interchangeable filter were part of the optical formula. Outside the optical axis the refraction of a flat element will have an impact on the ray tracings.

That incoming light is parallel is a misconception. That may be true for a dot at infinity, but the rest of the light comes in from all angles. Both within the angle of view that forms the image and oblique rays that cause flare. The case is different with astrophotography where all objects are at infinity.

On lesser lenses this may be negligible, but we are talking about a full diffraction-limited optic here where the last nanometer counts.

 

You pointed out! My reference is astrophotography. So I mistakenly assumed that it was the same in general photography. Thank you very much for your input, it is always nice to learned something. If you have have a reference to look at, that would be really appreciated! Thank you.

 

Nick

[semi-ambivalent]

If the lens is dropped or subject to some other impact damage on or off camera, a filter isn't likely to offer much protection to the front element

 

I have twice seen this refuted. As for insurance, the hassles of making a claim, and the time in the shop, does not make that a simple or easy alternative safeguard.

 

There are relevant reasons both for and against using a filter for protection but no 'rules', so take insurance on your equipment and make your own decision.

 

Absolutely correct.

 

Regards,

s-a