Leica v Heliopan IR filter anti-reflective coatings

[mmk60]

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I took the attached photo with a Leica UV/IR filter on my 21/2.8. I had sun going down at about 60 degrees to the right. There is a quite large red "dot" that seems to be a reflection from the filter which has a light redish tint on it.

 

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The photo is straight from a DNG file with a simple white balance adjustment.

 

Has anyone see this?

 

Cheers

 

PS; Please ignore the grid lines. My trial with Lightzone has expired...

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[ho_co]

Mashu--

 

Definitely looks to me like sun-induced flare.

 

Any filter can produce flare when hit by light at the proper angle, but then so can most lenses under some circumstances. The UV/IR-cut filters improve one aspect of the IR issue, but there are times when filters do cause flare.

 

It would be interesting if you had made a second shot, but without the filter.

 

A not always easy solution is to keep the unwanted light from the front of the lens by blocking it with a hand or a shadow.

 

(But I think you already knew all that! )

 

--HC

[mmk60]

Mashu--

 

Definitely looks to me like sun-induced flare.

 

Any filter can produce flare when hit by light at the proper angle, but then so can most lenses under some circumstances. The UV/IR-cut filters improve one aspect of the IR issue, but there are times when filters do cause flare.

 

It would be interesting if you had made a second shot, but without the filter.

 

A not always easy solution is to keep the unwanted light from the front of the lens by blocking it with a hand or a shadow.

 

(But I think you already knew all that! )

 

--HC

 

Howard -

 

Thanks for your comment.

 

Yes, it is a reflection from the filter and luckily I got one photo without it. I have been using a UV filter on all of my lenses and have had some bad reflection/flare on some occasions but this one is a bit different. It is RED:eek:

 

Oh well. I still love my M8

[ho_co]

I ... have had some bad reflection/flare on some occasions but this one is a bit different. It is RED:eek:

Yeah, I don't know why it's red, either. I was wondering about that aspect. My first thought was that it might be sunlight reflected off some red surface, but it looks as if it's coming directly from the sun, so that explanation won't work.

 

Maybe a kind of prismatic effect from some part of the lens, ending up mainly red?

 

These UV/IR-cut filters are new to all of us, of course, so you may be the discoverer of a new effect.

 

Is the lens coded? How did you have the camera set in regard to lens and filter detection?

 

Grasping at straws here--maybe the camera was trying to correct for cyan but you didn't have any cyan, so you got red instead?

 

With luck, someone who knows what he's talking about will jump in on this!

 

 

Lastly, the job these filters is really doing lies outside the human visible spectrum so it is hard to judge the performance of filters without technical equipment. When people talk about "stronger" or "weaker" filters, what do they mean? That the width of the passband is different? That the rejection outside of the passband is different? The undefined adjective has no meaning.

Harry--

I agree. When I used the terms 'stronger' and 'weaker,' I was quoting what I think Guy said in his Leica Akademie thread.

 

That is, somewhere (and I think it was there), I read that Leica decided to put extra layers of coating on the E60 and E67 filters because their standard filter wasn't 'strong' enough. And I believe that I read on Reid Reviews that Leica had reduced the number of interference layers in their other size filters as compared to Schneider/B+W.

 

I may be wrong in what I think I remember, and it certainly doesn't clear things up when I or anyone else uses so vague a term to describe a technical issue we don't understand.

 

Thanks for reminding me!

 

 

Vinay--Didn't mean to hijack the thread.

 

--HC