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[OM] Lens hot spotting and flare [was 24/2 vs 21/2 vs 24/2.8]

Subject: [OM] Lens hot spotting and flare [was 24/2 vs 21/2 vs 24/2.8]
From: Moose <olymoose@xxxxxxxxx>
Date: Fri, 22 Oct 2010 15:36:15 -0700
On 10/22/2010 8:55 AM, Brian Swale wrote:
> Wayne wrote
>> Don't recall noticing any problems with the Zuiko 35/2, but the tamron 
>> 90/2.5 and Nikon series E 50/1.8 were the worst of the ones I tested.  By 
>> the way, once I'd identified the problem lenses I retested with film and yes 
>> the effect can be detected when using film.
> I have a Tokina 24-40/2.8 lens I bought more than 5 years ago for my OMs.
>
> For the first time I experienced hot-spotting with a lens. It's a very sharp 
> lens, but the unpredictability and severity of the hot-spotting has resulted 
> in me hardly using it on OM since discovering the problem. I haven't tried it 
> on an E-thing, but should give it a trial then sell it.  I'm not much good at 
> selling but this one is a prime candidate for sale. It would find sky to 
> reflect in the most unlikely places.

I think you may be confusing two different problems.

Hot spotting is, as illustrated in Wayne's link, a bright spot near the center 
of the image. It may be larger or smaller 
than his examples, but is generally close to neutral in color.

There are two kinds of lens flare. One is a brightening, even blowing out, of 
the edge of the image where a bright light 
source is just out of the frame. When that source is the sun, the flare leans 
toward warmth.

The second is one or more 'echos' of a bright light source elsewhere in the 
image, often taking the form of the lens 
aperture and/or round or slightly oval shapes of round lens elements. Often 
there is repetitive series of them, of 
diminishing brightness. They may be various colors, depending, I think, on 
coating reflection colors.

This second kind in nicely illustrated in Ian's recent posted image of two 
people on a hill below a cloudy sky with the 
sun breaking through. The flare is on the lower left. Your comment "It would 
find sky to reflect in the most unlikely 
places." leads me to suspect that you are referring to this type of lens flare, 
not to hot spotting.

I have a Tokina AT-X 24-40/2.8, which I would guess is the same lens you have. 
I have not seen hot spotting with it, but 
have seen flare, although at the moment, I only specifically recall the first 
kind. The lens hood is round and has to be 
wide enough to avoid vignetting at full WA, so it's not effective at longer 
focal lengths. A hand, hat, etc. is a useful 
way to control flare at longer focal lengths, both with this and other lenses.

Moose
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