Question to Sean Reid re his M8 Update Postit-Review

[wparsonsgisnet]

I have just re-upped for my ReidReviews subscription (and again, for the second year in a row, it's the best $30 I've spent on photography). The current, new posting is a rolling update of Leica M8 news and in this case discusses the IR-cut filters at great length.

He is testing the Leica version of the IR-cut filters along with the B+W filters that many of us are using and he plans to test the Heliopan filters.

In the review he notes that these filters have been coated to reduce both IR and UV light. He also states that it doesn't matter which side of the filter either coating is on, that is, the IR side can be the "in"side or the "out"side. However, he states that the UV coating is more durable than the IR coating.

My question is how can we ascertain for ourselves which side has which coating.

I know this has been stated in a thread on the Forum, but I think it would be useful to let all know again how to verify this.

And, for the record, the new posting/review is exceeding clear and helpful.

Regards to all.

[BTW -- to all ReidReviews subscribers, check the renewal rates.]

[dhsimmonds]

Can anyone say what colour the IR cut filters are, either B & W or Leica please? I have visions of some ghastly red, orange or pink glass screwed on to the front of some very expensive lumps of Leica glass!

[wparsonsgisnet]

Dave, the IR-cut filters look mostly clear to me. I have the B+W 486 filters. These are UV and IR-cut filters with one side multi-coated for IR-elimination and the other side multi-coated for UV removal.

When I look thru them, they seem to me to have a slight cast to them, but they are supposed to have a light transmission factor of 1.0 (that is, no loss of light).

If I place them on a dark surface (I set them on a microfiber cloth to see this) and view them from a 45-degree angle, the filter looks reddish. When mounted on the lens, I can also see the reddish tint by tilting the lens agains the light.

They work very well. There is some flare in difficult situations, but, after all, those are difficult situations. They make a big difference with color rendition. This sensor, with the thin cover glass that M Leica's require, passes more IR light than dSLR's do.

I guess if we had to make do with a filter on our lenses, then having to use one like this is not so bad. It does not reflect as much as solid color filters, I believe.

[wparsonsgisnet]

Sean, any comments?

[sean_reid]

Hi Bill,

In an area with good lighting (your desk?) place the corner of a piece of white paper against the filter and note whether the colored reflection begins right at the glass or if it starts after a slight gap. Someone else on this forum invented this method but I'm afraid that I can't recall who.

Bill mentioned a few points and there's more information about the filters in the new rolling M8 update article (which I'm sure won't be quoted <G>). I interviewed one of the 486 filter designers.

Regarding filter color: clear seen straight on, cyanish when seen at certain angles. In addition, if the filter is reflecting IR from some source, one will see (from some angles) that reddish reflection. Much has been made of this by some but I've been using the filters since late October and the colors they reflect, etc. don't seem to have any affect at all on my photography of people. My take is that its a curiosity but means little when actually working with the camera. If someone notices the color of one's filter, he or she has already noticed the camera.

Cheers,

Sean

[scott kirkpatrick]

I've done the corner test with B&W 486 filters obtained from Foto-Huppert. One had the IR-cut side in and the other had it out. At the time that suggestion was posted, others were seeing both orientations. It's a bit puzzling that the possibility of ghost reflections is apparently the same whether the IR-reflective surface is in or out, since it does cut a little (< 10 per cent) of the visible light at well, but there are no bare glass-air surfaces in this filter. I understand Leica's decision to keep the anti-reflection, anti-scratch coating on the outside as concluding that the cost of replacing scratched filters under one of their stronger warranties is likely to be greater than the cost of dealing with angry owners who see unexpected reflections. Now both events should be rare.

scott

[sean_reid]

Originally Posted by scott kirkpatrick

I've done the corner test with B&W 486 filters obtained from Foto-Huppert. One had the IR-cut side in and the other had it out. At the time that suggestion was posted, others were seeing both orientations. It's a bit puzzling that the possibility of ghost reflections is apparently the same whether the IR-reflective surface is in or out, since it does cut a little (< 10 per cent) of the visible light at well, but there are no bare glass-air surfaces in this filter. I understand Leica's decision to keep the anti-reflection, anti-scratch coating on the outside as concluding that the cost of replacing scratched filters under one of their stronger warranties is likely to be greater than the cost of dealing with angry owners who see unexpected reflections. Now both events should be rare.

scott

Hi Scott,

That wasn't Leica's decision, per se. Schneider believes that to be the best orientation.

Cheers,

Sean

[scott kirkpatrick]

Originally Posted by sean_reid

Regarding filter color: clear seen straight on, cyanish when seen at certain angles. In addition, if the filter is reflecting IR from some source, one will see (from some angles) that reddish reflection.

That's what happens, but the explanation isn't quite right. Put a piece of white paper under the filter and it will look slightly cyan at angles more than 10-15 degrees from vertical. But if there is a white object (sky, wall, etc) reflected in the filter surface , that object will look a little pinkish at first, becoming a strong light crimson at angles of 30 degrees of more. It doesn't involve IR, which we still can't see, but is just the shift of the reflectivity cutoff down into the visible reds. So cyan in transmission, red in reflection, if the angles are sufficient.

My take is that its a curiosity but means little when actually working with the camera. If someone notices the color of one's filter, he or she has already noticed the camera.

I think this one got started with Joseph Wisniewsky's comment that he was hassled by security guards when carrying his filtered Nikon D1 because the color reminded them of a rifle scope. Obviously they had already noticed the camera, but their reaction to it was not that I would expect of most folks on the street.

regards, time to go outside and shoot with new M8. 1250 and 2500 are most impressive, when compared with my GR-D.

scott

[rvaubel]

Originally Posted by sean_reid

Hi Scott,

That wasn't Leica's decision, per se. Schneider believes that to be the best orientation.

Cheers,

Sean

I think the filters should be anti-reflective coated on both sides AND anti-scratch coated on both sides . I believe this is the case with the Heliopan filters. I could give many reasons but one of then is that Schneider can't seem to keep track of which way to mount the glass to get consistent results. It seems that half the time the IR coating is on the lens side and the other....well you get my point.

Rex

[marknorton]

The filters Schneider are making for Leica will be to Leica specs, let's hope they've had the good sense to require the filter glass to be put in the mount in a consistent way.

[scott kirkpatrick]

Originally Posted by marknorton

The filters Schneider are making for Leica will be to Leica specs, let's hope they've had the good sense to require the filter glass to be put in the mount in a consistent way.

From Sean's interview, it appears that Leica will specify a particular orientation. And there's an easy test that will let us check, the gap or lack of it between a corner of a white piece of paper and its pink reflection on the filter. Finally, it seems that these facts and specs are really coming from Schneider, with Leica asking them simply to do the right thing (my interpretation).

scott

[chrism]

Using a B&W 486 last night I managed some lovely green reflections when photographing a chandelier. After my initial concerns about green blobs had been cleared by proving they weren't there if the filter was removed, I tried reversing the filter as my IR side was outermost - still there just the same.

Chris

[wparsonsgisnet]

Originally Posted by rvaubel

I think the filters should be anti-reflective coated on both sides AND anti-scratch coated on both sides . I believe this is the case with the Heliopan filters. I could give many reasons but one of then is that Schneider can't seem to keep track of which way to mount the glass to get consistent results. It seems that half the time the IR coating is on the lens side and the other....well you get my point.

Rex

Rex, as I understand it, if the UV and IR-cut coatings are applied to the same surface, the IR-cut effect is canceled. Is seems the the UV and IR-cut coatings must go on opposite sides of the filter.

[sean_reid]

Originally Posted by rvaubel

I think the filters should be anti-reflective coated on both sides AND anti-scratch coated on both sides .

Rex

Hi Rex,

Take a look at my article to see why that isn't possible.

Cheers,

Sean

[sean_reid]

Originally Posted by marknorton

The filters Schneider are making for Leica will be to Leica specs, let's hope they've had the good sense to require the filter glass to be put in the mount in a consistent way.

Hi Mark,

As I mentioned in the article, all of the "Leica" 486 filters I've tested have been oriented correctly.

Cheers,

Sean

[sean_reid]

Originally Posted by scott kirkpatrick

From Sean's interview, it appears that Leica will specify a particular orientation. And there's an easy test that will let us check, the gap or lack of it between a corner of a white piece of paper and its pink reflection on the filter. Finally, it seems that these facts and specs are really coming from Schneider, with Leica asking them simply to do the right thing (my interpretation).

scott

That's right on the mark. The folks with expertise in this are Schneider, not Leica. Leica naturally wants the highest quality possible but, in case any here don't know of Schneider already, Schneider is itself a high-end optics company in Leica's league. My interview was with one of the engineers who designed the 486 filter and it is, IMHO, Schneider's expertise that is governing this.

And that's all as it should be. Leica needed a very good IR-cut filter and turned to a high-end company who know what they're doing. I'll do formal comparisons with the Heliopan but it does not seem to block IR as completely as the 486.

I'd rather not repeat my whole article here (and would ask that others don't do that either) but I think Leica made logical choices with these filters.

Cheers,

Sean

[Vivek Iyer]

Originally Posted by sean_reid

The folks with expertise in this are Schneider, not Leica. Leica naturally wants the highest quality possible but, in case any here don't know of Schneider already, Schneider is itself a high-end optics company in Leica's league. My interview was with one of the engineers who designed the 486 filter and it is, IMHO, Schneider's expertise that is governing this.

Sean, I am not sure that Schneider has the IR cut coating "expertise" and Leica lacks it.

Check the range of products offered by Leica and its subsidiaries (not only lenses and cameras). This IR cut stuff is totally within their expertise and the means are available to them as well.

Surveying equipment, riflescopes, etc made by Leica do have IR cut coatings applied on the glass.

[rvaubel]

Originally Posted by Vivek Iyer

Sean, I am not sure that Schneider has the IR cut coating "expertise" and Leica lacks it.

Check the range of products offered by Leica and its subsidiaries (not only lenses and cameras). This IR cut stuff is totally within their expertise and the means are available to them as well.

Surveying equipment, riflescopes, etc made by Leica do have IR cut coatings applied on the glass.

There seems to be a confusion between the various thin film coatings that can be applied. As I have always understood it, all coatings can be applied to one surface or both or any combination.

The types of coatings are

* IR cut
* UV cut
* AR
* Anti-scratch

It seems that the AR (anti-reflection) and anti-scratch coatings are confused. Maybe this is because they are only found on the most premium filters and generally come together.

The UV cut layer is really unnecessary but people expect it.

I have found that practically speaking the ant--reflection layer facing the lens like it theoritically should, doesn't do that much for reducing filter flare. But I have Heliopans which, I think, have AR coatings on both sides. The literature is confusing. I have heard diffierent people say different things. People say things like "its coated" instead of referring to the type of coating. When questioned I'm not sure if they know themselves.

Rex
still confused

[rvaubel]

Originally Posted by sean_reid

That's right on the mark. The folks with expertise in this are Schneider, not Leica. Leica naturally wants the highest quality possible but, in case any here don't know of Schneider already, Schneider is itself a high-end optics company in Leica's league. My interview was with one of the engineers who designed the 486 filter and it is, IMHO, Schneider's expertise that is governing this.

And that's all as it should be. Leica needed a very good IR-cut filter and turned to a high-end company who know what they're doing. I'll do formal comparisons with the Heliopan but it does not seem to block IR as completely as the 486.

I'd rather not repeat my whole article here (and would ask that others don't do that either) but I think Leica made logical choices with these filters.

Cheers,

Sean

Sean

But only Leica and Kodak know percisely what the IR cut profile is. They can supply it to Schneider but with the time frame I think they are just going to supply the IR cut filter they have been making all along. Which I suppose is OK since imperically people report it is working. But I seriously doubt Schneider is going to come up with a custom taylored coating that optimizes the IR supression required by the Kodak 10500 profile.

But if it works, I don't care.

Rex

[sean_reid]

Originally Posted by Vivek Iyer

This forum is totally bizzare in quoting a pay-per-view review on some site.

If the statement "However, he states that the UV coating is more durable than the IR coating." was indeed made somewhere it is simply incorrect. I would demand real proof for such assertions.

Reid Reviews is an annual subscription site, not a pay-per-view site. The site has subscribers, like a magazine. Beyond that, I'm not interested in debating an article with you that you haven't even read.