Leica's IR-Cut Filters

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thanks a lot for the info Sean....Peter

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Thanks very much for the info, Sean....Peter

[lars_bergquist]

Just a short notice and question. On the official German Page from BW (the product overview pdf) there are no 486 MRC coaded filters. All listed 486 Filters are normal coaded.. ? Now Am I'm right or is this pdf wron and there actually are some MCR coaded 486 Filters ?

 

The IR cutting coating of these filters is a special kind of multicoating. They neither should nor can try to put an extra coating on top of it!

 

The old fogey from the Age of Flashpowder

[gravastar]

There's a very interesting Olympus interactive tutorial on Interference Filters and how they are constructed and work here.

 

If you have java enabled there is an interactive diagram where you can see how the filter transmission changes with angle of incidence.

 

I noticed this comment:

 

"Another drawback is that interference coatings often produce polarized light at high incident angles, an effect that is not always desirable."

 

Perhaps this is something we should check when photographing blue sky with a wide angle and 486 type filters.

 

Bob.

[alain]

question from reven:

 

if you go on the Schneider-Kreuznach home-page to INDUSTRIAL FILTERS you can see that the industrial 486 are allways MRC !!

Hope this answers your question.

 

Alain

[gravastar]

question from reven:

 

if you go on the Schneider-Kreuznach home-page to INDUSTRIAL FILTERS you can see that the industrial 486 are allways MRC !!

Hope this answers your question.

 

Alain

Can someone clarify the google translation of this statement on the german page: Tipps u. Tricks: UV-IR Sperrfilter B+W 486 , Jos. Schneider Optische Werke GmbH

 

"To note it is however that contrary to measure-colored (through-colored) filter glass the UV-IR band elimination filter is based on thin-film technology. It contains than 30 vapour-deposited interference layers on a side more and is recompensed on the opposite side MRC."

 

Are they saying the filter is only MRC coated on one side opposite to the multilayer filter, or are both sides MRC coated?

 

Bob.

[alain]

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see this link for english version:

http://www.schneider-kreuznach.com/tipps/uv-ir_cut_filter.htm

 

hope it works

Alain

[Venkman]

Are they saying the filter is only MRC coated on one side opposite to the multilayer filter, or are both sides MRC coated?

Bob.

 

Zu beachten ist allerdings, dass im Gegensatz zu massengefärbtem (durchgefärbtem) Filterglas das UV-IR Sperrfilter auf Dünnschicht-technik basiert. Es enthält auf einer Seite mehr als 30 aufgedampfte Interferenzschichten und ist auf der Gegenseite MRC vergütet.

 

Please be advised that, opposite to "mass colored" (solid colored) filter glass, this UV-IR filter is based on "thin layer" technology.

It features more than 30 layers of vacuum-metalized interference layers on one side and is MCR coated on the other side.

 

Rough translation, but I hope you'll get what they mean

 

P.S. Ok, I wasn't that far off....

 

Dirk

[k_g_wolf ✝]

>> Robert

 

 

thx for this LINK.

 

Cudos to OLYMPUS for visualizing these filtereffects. Makes things much easier to understand.

 

 

 

Best

[gogopix]

If the interference is to work,it cannot be interfered with (pun intended!)

that means, the 30 coatings that cause the IR to be reflected are on one side and operate to keep the UV and IR refelected out (makes sense that this may be on the outside)

 

Then the MRC needs to be on the opposiet side, where it keeps internalreflections from affecting image.The glass in between should not become part of the interference filter (unless it is designed that wayas some birefringent filters are. then the glass is VERY thin i believe

 

so the explanationis clear. it only matters now how the filter works best. MRC IN or MRC OUT

 

the properties of the glass will the affect how both operate.

 

Sea,n you might want to see, withan IR target (one of those patented "black poly jackets") and also see which direction is ore effective.

[gravastar]

I did check to see how the amount of cyan/green compensation needed might change with polarized light. There is a noticable effect on the filter's transmission when the angle of incidence of the polarized light is very large.

Edited to add: As the amount and plane of polarisation changes so does the required cyan/green compensation. In practice this might mean under certain conditions refective surfaces in the corners of a wide angle picture could still have a color cast after compensation.

 

To analyze this it's easiest use a polarizer that's linear and not circular to produce the illumination. It is possible to use a circular one if you reverse it's orientation so that it's quater wave plate is the first thing the light source hits.

 

This needs testing under practical conditions with reflective surfaces/blue sky and wide angles to see if it's of any consequence, hopefully it's not.

 

Bob.

[sean_reid]

Sean,

do it get it right that cyan corners only appear with 28mm and wider lenses?

Does this mean that it shouldnt be a problem to use 35mm and longer with the filter all the time?

Cheers, Tom

 

Hi Tom,

 

35 mm and wider lenses. A 40 should be OK but I haven't tested one. The 50s are fine.

 

Cheers,

 

Sean

[tom0511]

Thanks Sean.

The thing which scares me is "Wegen dieser physikalisch bedingten winkelabhängigen Farbbeeinflussung ist das Interferenzfilter B+W 486 bei

Objektiven über 60° Bildwinkel nicht geeignet" saying the filter is not recommended for wide angle >60 degrees.

I just hope that Leica can fully manage to control the cyan cast problem.

[sean_reid]

Thanks Sean.

The thing which scares me is "Wegen dieser physikalisch bedingten winkelabhängigen Farbbeeinflussung ist das Interferenzfilter B+W 486 bei

Objektiven über 60° Bildwinkel nicht geeignet" saying the filter is not recommended for wide angle >60 degrees.

I just hope that Leica can fully manage to control the cyan cast problem.

 

I think they can. The existing firmware already corrects this to a degree, as you probably saw in the 28s article. I'll know more when I have 1.10 to test.

 

Cheers,

 

Sean

[sean_reid]

This is easy no brains correcting, use PTCorrect that is free plugsin to Photoshop. This have called Radial Luminants, you take /Options/ can chose number for R G B each one. After finding best numbers for each one lens this stay same for same lens always. Only problem is how to now what lens is make each one foto, because no EXIF, so this you must to remamber. Probly take after some experiants easy tell.

 

That's an important issue and it came up in a discussion on another forum. It seems that post-processing software probably could correct the cast but there are two aspects, that, in my mind, make me prefer the in-camera correction. I should explain that I may photograph 1000 frames during a shoot and am often under deadline to get work to clients.

 

1) In-camera correction eliminates the need for one to remember what lens was used for what picture. I myself use a lot of different lenses and my memory is not up to the task of knowing what was used for which when I'm editing 1000 + files.

 

2) In-camera correction means one less step one needs to take in preparing the final file for the client. I often take files from start to finish in C1 without any post work at all.

 

So, the desirability of a non-in-camera software solution for this task may depend a lot on how one works, how many lenses he or she uses, whether or not deadlines are involved, how much time he or she wants to spend in post, etc.

 

Cheers,

 

Sean

[brucek]

Easy way to check, take foto with filter hold in hand in front way and back way, see if any differents on black clothe. If no differents I will change glass of all mine filters so is IR face to inside. MRC coats is protect from when wipe out dort, I dont now IR coats is also same hard or no.

 

I just tried this very quickly and from what I can tell it's making no difference which side of the filter faces the lens. Either way the IR effect is removed. Good thing too, as I can't see any way to remove the filter in the holder in order to flip it.

 

Bruce

[lct]

...I'll get a 486 in an E40.5 to go on my M-Rokkor and let y'all know if it helps the old R-D1. That is, if anyone still cares...

As long as you don't put this thing on mine i don't mind at all.

[carstenw]

Hi Tom,

 

35 mm and wider lenses. A 40 should be OK but I haven't tested one. The 50s are fine.

 

Cheers,

 

Sean

 

The LFI article claims that 35mm lenses will need coding, but maybe they are being pedantic.

[loretdem]

As long as you don't put this thing on mine i don't mind at all.

I take it you're not too keen on this whole IR thing. The R-D1 has not failed me yet but I think I'll give it a try on a 40mm lens just to see if it makes much of a difference. Might be worth the small effort.

 

-Carlos

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Hallo,

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[lct]

I take it you're not too keen on this whole IR thing...

It's an euphemism my friend...

 

...The R-D1 has not failed me yet but I think I'll give it a try on a 40mm lens just to see if it makes much of a difference...

Would be easier to find out than a series 5 IR-cut filter for the non-coded Summicron 40/2 i guess.