Purple Fringing on Oly and Pany Bodies: Causes and Remedies

Started Jun 7, 2013 | Discussions thread
OP Anders W Forum Pro • Posts: 21,466
Re: Purple Fringing on Oly and Pany Bodies: Causes and Remedies
3

Laszlo13 wrote:

Anders W wrote:

walkaround wrote:

Anders W wrote:

texinwien wrote:

Any relation to the solution to the Panasonic 7-14mm & OMD EM5 purple flare problem you figured out?

Not such a bad guess tex. As a matter of fact, the explanation/solution I have now come across is at least in part a by-product of our go-around with "Mr. Fish" in this thread

http://www.dpreview.com/forums/post/51541995

a little while ago although the credit for making the observation that put me on the right track is, as that post reveals, certainly not his.

Ironically, this phenomenon (residual PF that in some important ways behaves like LaCA rather than LoCA) is one that I observed, and was puzzled by, already before the problem with purple flare with the 7-14 on the E-M5 surfaced. And in both cases, I was on the right track early on but incorrectly rejected the hypothesis due to not having/using quite the right equipment, as you can see here:

http://www.dpreview.com/forums/post/50380384

Looking forward to the answer. I fly out on vacation Sunday night, so tomorrow morning is my last chance to buy gear before I leave

So hurry up to that well-supplied camera store I am sure you have around the corner and ask them to replace the UV/IR-cut filter on the sensor on your E-M5 with its counterpart from the GH3 (which I think has quite the right size to fit ). If, against all odds, that would fail, just ask them to pick up one of those Wratten 2A or Wratten 2E gels I am sure they have laying around in a drawer somewhere since the last time someone asked about them 20 or so years ago. Then pick up some thin double-adhesive from the hardware store next door and you are all set to go.  

Dunno what the camera shops in Sri Lanka are like, but I'm guessing they're not that great.

Could conceivably be that they are not quite as well equipped as those in Vienna, but this is easy-peasy stuff so surely no problem.

Personally, I might have better luck. Flying out to LA on Wednesday for a trip to the Sierras together with my wife, our son, and our daughter-in-law. Possibly, I'll have to time to pass by Samy's and pick up one of those Wratten 2Es I see they have in stock. Good price too. Only 24.59 for a 3x3 sheet.

I'm a little slow... are you taping a pale yellow filter gel to the rear lens element?

That's what I originally did with my 7-14 before I implemented the alternative solution shown here . For the purpose of the sample images in this thread, I simply held the same type of filter (Wratten 2A) in front of the lens in order to study its effect on the PF.

Great thread.  So - what's the downside of using the 2A filters, on color digital images?  I imagine it helps with contrast as well, but any effect on purple colors?

While it may be of some help against haze (these are often called haze filters), the main reason for using them, as I see it, is to eliminate problems with purple flare (such as that caused by the 7-14) and purple fringing (of the specific kind described here) on cameras where the built-in UV filter is so weak as to cause problems in that regard, such as that of Oly cameras. As you can see here,

http://www.kolarivision.com/internalcutfiltertransmission.html

the Oly E-P1 cuts at about 390 nm versus about 430 nm for the Pany GF1, GF2, and G10, and there are reasons to think that this difference applies to Oly versus Pany bodies more generally. The Panys have a built-in UV filter about the strength of a Wratten 2E whereas the Oly filters cut at about the same point as a normal (i.e., rather weak) UV filter.

Of course, an advantage of the Oly solution is that it preserves a bit more blue light and that it might improve the rendering of blue/violet hues in some cases, but personally I think the price for that advantage is too high. And if you can accept the way Pany cameras render blue/violet tones, I see no reason why an Oly equipped with a 2E should do any worse.

As to the appropriate filter strength, it is clear by now that the two primary alternatives are 2A and 2E, with the advantage of the former being that it preserves a bit more blue light and the advantage of the latter being that it probably (I haven't tried one yet) eliminates the purple flare/fringing to a still greater extent. The one I used for the test in this thread, and the one I have permanently fitted on my 7-14/4 is the 2A, but it is likely that a 2E would have brought the results even closer in line with those you get on a Pany body.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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