What causes black flare?

[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...