What causes black flare?

[Poco]

I've uploaded an image to the technical gallery that has me scratching my head. What would cause the black flare above the big white square section of the building? I shot doubles and the flare is present on both sheets, so it's not processing, ... definitely flare. Now I've seen flare that shows up as light spots before, but never as dark spots and I'm wondering what causes this reversal. Ideas?

 

[wfwhitaker]

I can't see it on my monitor. But if I use my imagination, maybe I can see something which resembles industrial exhaust. Any stacks located behind the building?

What film/processing did you use?

 

[Poco]

Will,

It's not exhaust. It's one of those things that you can spot better by not looking directly at it. It's one of those typical faceted blobs you get from sun reflection (much more obvious with PS manipulation) ...only it's dark, instead of light. I came across this once before on a B&W shot where it was much more obvious, but convinced myself I'd screwed up processing since the phenomenon made no sense. But I now know it's very real, if rare, that flare will sometimes reverse itself. I'm just wondering why.

Film was 160 NC in regulare C41

 

[Dave Parker]

Hmmm, I can't see it on my monitor either???

Dave

 

[pentaxuser]

I eventually could see it after about 5 mins! It's hardly black. More of a very, very light brown and as near as I can make out, it isn't quite the classic hexagonal flare shape either. I've only had this once on a B&W shot taken with the sun just to one side of the viewfinder. For all the world it's as if you had the lightest of tea or coffee splashes you get if a drop falls on a picture and spreads and you quickly mop it up but inevitably leave just a trace of stain. Reason? Haven't a clue, I am afraid.

If the mark on the print is just as faint, test it on your friends and see how many spot it. Very few I'd be willing to bet. It's a nice shot

 

[Poco]

Okay, I photoshopped the crap out of it (but I repeat myself) and it should be obvious now.

Thanks, Pentax, for confirming I'm not nutz. It DOES sometimes happen.

 

[Helen B]

Why do you think that it isn't a processing effect? Exactly how were the sheets processed? Is the dark patch completely identical on both sheets, or just similar?

It's difficult to tell from the JPEG even with the contrast boosted enormously, but the dark patch does not look like a perfect pentagon or hexagon or whatever-agon. How many blades does your aperture have? Is it a perfect pentagon or hexagon on the original? I could imagine a situation in which flare was caused by light reflecting off the aperture blades, in which case the opening could appear as a dark patch.

Best,
Helen

 

[Konical]

Good Morning, Poco,

Doesn't show up for me, either.

Konical

 

[Dave Parker]

I can now see a shadow above the building, it does not seem to have the normal characteristics of what would be considered flare, it looks more like an inverse reflection off the white side of the building, perhaps black reflection from a high contrast situation and black asphalt on the ground, but again, it looks more like a shadow of some sort being reflected.

Dave

 

[Bob Carnie]

If the black spot is in the identical spot in both negatives I would think it is flare caused by a reflection in the lens or lens hood.
When printing , if you have a burn card with white paper on top and a burn hole cut out, standing beside your print, I have sometimes seen a plus density or black mark on the print that mimics the hole in the burn card.It could be something as simple as a dark piece of dust causing a minus density reflection on the negative.

If the black spot is in a different position then I would then agree with Helen and assume it is improper agitation in the development of the negative.
Processing errors are most evident in large expanses of nuetral tones like skys and grey background.

 

[Poco]

I dunno, the facets are very suggestive of the typical aperture flare spot ...and the fact they're not normal looking (as clearly defined) doesn't surprise me since we're obviously talking about some atypical reflective thing going on, either within the lens or between it and the center filter, that reverses the flare.

Helen, I actually took 4 shots of the scene (I was obsessed with getting the water ripples uniform ) and the spot is absolutely identical on all of 'em. No way can it be a processing artifact.

 

[Helen B]

OK, so it might be slightly out-of-focus reflection from the aperture blades or the dust shadow as suggested by Bob.

Best,
Helen

 

[David A. Goldfarb]

I don't see the facets. I know you said it wasn't exhaust, but you're sure it's not something like heat waves rising from the building?

 

[Poco]

David,

You looking at the pushed contrast version? Maybe I have beveled eyeballs.

I dunno, I'm absolutely certain it isn't exhaust or from development. That spot is exactly the same on all 4 negs.

Oh well, the effect is pretty rare and probably nothing that can be guarded against.

 

[Bob Carnie]

Poco

At this point I would shoot a grey card with your normal setup and mimic the lens apeture ect. that you used that day.
develop the film and see if the spot is on the film

 

[Poco]

Thanks, Bob. Believe it or not, I don't think the flare is from the sun itself (off to the right) but from that big white wall on the building which was made of painted steel and perfectly angled to reflect a whole lot of light right back into the lens. As an imperfect (more diffuse) light source, it was probably responsible for the fuzzy rendering of aperture blades on the flare.

I've photographed with that lens/filter combination many times without problems, though never a gray card.

I guess I'll just chalk it up as an interesting anomaly.

 

[rbarker]

My vote goes for atmospheric defraction caused by heat waves rising from the expanse of wall.

Just swim over, climb half way up the wall, and then see if it's hot, Poco.

 

[Poco]

As much as I'd like to demonstrate my athleticism <snort>, I think I'll pass, Ralph.

Besides, I'm pretty sure I figured it out: This isn't a case of flare at all, but of the lens taking a picture of itself (complete with darkened open aperture) as reflected off the inside of the center filter. That explains why the aperture blob is fuzzy (lens not focused closely enough, obviously) and why it's dark instead of light. I can't think of any other explanation, so I'll go with it.

 

[gnashings]

I always thought the Black Flare was caused by uncontained raw sewage and rampant rat population...