B+W Cut/IR Filters - For which lenses?

[bherman]

All;

I have a Leica M8.2 and the following lenses:

28mm F/2.8 Elmarit ASPH 6-Bit
35mm F2 summicron ASPH 6-Bit
50mm F/2 Summicron (not coded)
90mm F/2.8 Elmarit (not coded)

Will I need a 486 Cut/IR Filter for each lens or just the 6-Bit Coded lenses?

Thanks
Brad

[DRabbit]

You'll need them for all lenses. You're not using them to correcting vignetting (which is what the coding is about). You need to to compensate for the fact the M8 is ultra sensitive to the infrared spectrum of light.

[bherman]

So, if I get a filter for each lens, do I essentially remove the B+W UV and use this filter all of the time? I mean, if I'm shooting landscapes up in the mountains, should I remove the Cut IR filter and replace it with the UV, or should I just keep it on all of the time and forget about it?

Thanks

Brad

[Ben Z]

Those cut filters are UV+IR so you don't need a UV filter ever, really. You can just leave the UV-IR filter on all the time and either discard the original UV-only filters, or do as I did and put the UV filter back on in front of the UV-IR. Those UV-IR filters are expensive so I'd rather not clean them any more often than I have to. Sure there's even more risk of flare, but I haven't had it happen to me even at night under street lights (but it's not a problem to take the UV off for that kind of shooting).

[geesbert]

stacking two filters is not such a great idea. the increased flare i got with one of them is annoying enough!

[kbg32]

Keep the filters on all the time.

[Roger Hicks]

Originally Posted by geesbert

stacking two filters is not such a great idea. the increased flare i got with one of them is annoying enough!

Easpecially as there is no extra filtration effect, and the UV/IR filters are pretty damn' tough.

Tashi delek,

R.

[DRabbit]

I wouldn't stack them either. And yes, just leave the UV+IR-cut filter on there all the time.

[furcafe]

I answered in the parallel thread on photo.net:

http://photo.net/leica-rangefinders-forum/00T7IP

[Benjamin Marks]

Probably more important for color than B&W work, although I suppose there is an argument that filtering out IR will lead to more sharpness as all image-forming light will be focusing at the same plane. I have slowly been acquiring them and use them when I can.

Ben Marks

[yanidel]

On all lenses, it will be a good protection ....
only time I take them off is some night shots with many light sources as you might have ghosts all over the picture.

[ruslan]

Any glass plate is UV filter, even bottle glass.

[Al Kaplan]

Most lenses don't focus all visible light to the same plane. Apochromats supposedly do. The others just focus 'em "close enough".

[Ben Z]

I admitted that stacking a UV on top of a UV+IR is asking for increased flare in theory, but so far in lots of practice it hasn't happened, not even in the kind of situations that promote it. My UV's are all B+W MRC coated and never gave me one whit of flare when I used them alone, so it doesn't really surprise me they don't add any flare when stacked. The B+W and Leica UV+IR filters are not MRC coated, so if anything will cause flare it will be those, even if they are alone. But you can't take them off without waking the magenta monster.

Roger I have to disagree that the UV+IR filters are tough, at least not the B+W 486's and definitely not the Leica's, not from my experience anyway. They are very susceptible to cleaning marks if you're not meticulous (and I tend to clean my B+W MRC's with my shirt, because digging in the bag for a microfiber cloth usually means missing a few shots). The Heliopan UV+IR filters (which most of mine are) are a lot tougher, and also much better coated against reflectivity (can be seen just playing the filters around under a light, the Heliopan's barely reflect anything compared to the others). Some say they don't give the same color results as the 486 or Leica filters, but I haven't noticed a problem.

[jaapv]

Originally Posted by ruslan

Any glass plate is UV filter, even bottle glass.

Umm- I have a couple of UV pass filters- those are glass as well....
Leica developed a special lens kit, Absorban, to stop UV light passing through their lenses. My Summarit 50/1.5 is an excellent UV lens with a near 100% UV transmission, but I can assure you that the lens is made of glass. So this is clearly not correct.

[jaapv]

Originally Posted by Ben Z

I admitted that stacking a UV on top of a UV+IR is asking for increased flare in theory, but so far in lots of practice it hasn't happened, not even in the kind of situations that promote it. My UV's are all B+W MRC coated and never gave me one whit of flare when I used them alone, so it doesn't really surprise me they don't add any flare when stacked. The B+W and Leica UV+IR filters are not MRC coated, so if anything will cause flare it will be those, even if they are alone. But you can't take them off without waking the magenta monster.

Roger I have to disagree that the UV+IR filters are tough, at least not the B+W 486's and definitely not the Leica's, not from my experience anyway. They are very susceptible to cleaning marks if you're not meticulous (and I tend to clean my B+W MRC's with my shirt, because digging in the bag for a microfiber cloth usually means missing a few shots). The Heliopan UV+IR filters (which most of mine are) are a lot tougher, and also much better coated against reflectivity (can be seen just playing the filters around under a light, the Heliopan's barely reflect anything compared to the others). Some say they don't give the same color results as the 486 or Leica filters, but I haven't noticed a problem.

I am sure you are not having problems, Ben, but be aware that adding extra surfaces is not just adding to the flare, it is multiplying the flare. The two surfaces of an extra filter multiply the chance of flare by four.

[Ben Z]

Originally Posted by jaapv

I am sure you are not having problems, Ben, but be aware that adding extra surfaces is not just adding to the flare, it is multiplying the flare. The two surfaces of an extra filter multiply the chance of flare by four.

That's true of course Jaap, but the coating on the B+W MRC is so good at preventing reflections that for all intents and purposes it transmits something like 99.9%. If you hold one parallel to the floor, in one hand, and any other filter (eg. a 486 or Leica UV/IR) in the other hand, and play them around a little, you'll see how the MRC filter reflects much less by comparison

That said, if I'm shooting in a particularly flare-prone situation I can always take the UV filter off. The sad part is, in those flare-prone situations the major offender is the UV/IR filter, and that one has to stay.

[HenningW]

Originally Posted by Al Kaplan

Most lenses don't focus all visible light to the same plane. Apochromats supposedly do. The others just focus 'em "close enough".

Apochromats focus three wavelengths to the same plane. How far off the focus plane the rest of the wavengths focus is not defined. For process lenses that can be quite far and make the lenses essentially unuseable for general use, but for Leica's apochromats that's mostly a small amount.

'Apochromat' doesn't automatically define outstanding optics. A good achromat will beat a mediocre apochromat. Achromats focus two wavelengths to the same plane.

Henning

[HenningW]

Originally Posted by Ben Z

That's true of course Jaap, but the coating on the B+W MRC is so good at preventing reflections that for all intents and purposes it transmits something like 99.9%.

Unfortunately, that's not true. The transmission for some wavelengths is much less than 99%, let alone 99.9% and the doubling of the filters can make that obvious.

There is no reason to have a UV filter on the lens at the same time as any other filter. The fact that we have to have a UV/IR filter on the lens at all times is bad enough.

Henning

[Ben Z]

Originally Posted by HenningW

Unfortunately, that's not true. The transmission for some wavelengths is much less than 99%, let alone 99.9% and the doubling of the filters can make that obvious.

There is no reason to have a UV filter on the lens at the same time as any other filter. The fact that we have to have a UV/IR filter on the lens at all times is bad enough.

Henning

I'm sure you're scientifically theoretically 100% correct. Empirically however, my actual hands-on experimentation in thousands of flare-inducing shots made with and without the MRC-UV, and shooting over a year with the UV on top of the UV/IR, has convinced me that theory, no matter how correct it is, can safely be ignored in this case. However, far be it from me to suggest that anyone else adopt the practice if it makes them uncomfortable.