Cause of enormous flare?

After purchasing a used 480mm Schneider lens with a Copal shutter

for my 8x10, I was surprised to find the enormous flare in the

middle of some of my images. The first one was taken at about 8:30

AM at Sequoia National Park under a clear sky, but the sun had not

hit the trees or the camera at this point. It's about a 2 minute

exposure at f64, spot metered.

 

The second one was taken the evening before in much lower light, a

10 minute exposure at f 64.

 

I'm trying to figure out the source of this anamoly. I've checked

the lens, shutter and lensboard for light leaks. The camera does

not leak, either, brand new Tachihara.

 

I have used other 480mm Schneiders with no problems. I did not use

any filters with either version of the lens. Any ideas????

 

Thanks.<div></div>

Well, I can clearly tell you that you should not have used the flash with the first image! I cant see what your talking about. Do you have a scanner? or maybe just take the image without the flash.

 

Sun flare does NOT always have to come dirrectly from the sun shinning INTO the lens.

 

Ryan McIntosh

It almost looks as though you have a pinhole in the darkslide. That is a pretty strange looking spot, don't know how you could get it right in the middle without their being something obvious with the lens. No holes in the lensboard, right?

 

Isaac

Does not look like a lens problem to me. Too intense in a small area.

 

IMHO it is a light leak. Could be a small hole in the slide, or a small hole in the lens board.

Or it was caused during loading/unloading the holder.

Who processed it? Could have happened then also.

Maybe the lens was stopped down to f32 or more to focus and you pulled the darkslide before re-adjusting for exposure causing a double exposure? Been there..done that.

A shutter problem? The shutter does not close completely? In the shorter exposure the effect would be larger than in the longer exposure due to the fact that the light leak is stronger in brighter light. Definitively some sort of light leak.

I think that Ryan is the only one who is on the right track here. No holes in the holders, the shutter is tight, not a processing problem. The flare happens, even in the second image, but not as intensely. I think shading the lens might help, as it becomes more pronounced as you point the camera towards more ambient light.

Michael,

 

If it was flare, you would see it while composing and focusing.

 

Think about it. Flare would only happen for the same amount of time as your exposure. So if it was that bright in the final image, (relative to the rest of the image) you couldn't miss it while focusing. So this must be happening for a longer period of time than your exposure. Therefor it can't be flare.

 

Nor can it have anything to do with the shutter, since a shutter that didn't close all the way would result in a blurred image and over-exposure.

 

Have you had this happen with film in different film holders?

 

What type of film are you using? If you're using Readyloads the problem could be in the holder.

If he was doing a 10 minute shot, then he would NOT have been able to see any flare on the ground glass because clearly the ammount of light was very soft when making the image.

 

A light leak in the lens board or anywhere in the camera, would have slightly fog the whole film, not just a small exact spot right in the center. Because the lens was open more for the second image, there would of been MORE flare in the second, you would think.

 

I would recommend just going out in your backyard and make a negative and see what happens. Make a few negatives with the bellows and lens extented to different lengths. I had this problem with a old Ektar lens on a 4x5 Graphic. The closer my lens was to Invinity, the worst it was, but when I would extend the lens out to focus more closly... it would go away. It was a problem with the possition of the lens and I belive reflection inside the camera that was causing a weird spot on all my film.

 

Ryan McIntosh

Ryan,

 

I did point the camera indoors at a bright source, while having the ground glass removed, and noticed that a lamp above the lens was producing a reflection, or flare, within the rear element of the lens, so I suspect this IS a flare of some sort, but not enough to become clear on the ground glass.

 

The first image in this posting is the WORST manifistation of the flare. The flare is actually present in the second image, but to a much lesser degree. I think the reason for this is that the sun was more behind me and had already set behind the mountains. In the first image, the sun was higher in the sky, and more to the right and front of the camera, thus producing more of a flare.

 

I think exposing some chromes outside would be a good idea, both WITH and WITHOUT extra shade around the lens, to see what happens.

 

Besides a flare, my other theory is that the light reflects from the film, back to the rear element of the lens and back again, but if that were the case, it would do it to the same degree in all shots.

 

At any rate, I don't understand why this happens on this particular 480mm because I've used the same model lens with no problems before.

 

Again, this is NOT a problem with film holders. All the holders are in excellent shape, and the same flare shows up to one degree or another, regardless of which holder I'm using. I have not quite ruled out a light leak, but, like you said, they tend to fog entire areas of the film, without any focus.

 

Mike

"If he was doing a 10 minute shot, then he would NOT have been able to see any flare on the ground glass because clearly the ammount of light was very soft when making the image."

 

If light levels were so low that he couldn't see that bright a flare, he couldn't have seen the image to focus. So, unless this is one of those new autofocus 8x10 cameras, it ain't flair. It's a light leak.

I'm sorry, but that last comment makes NO sense at all.

 

Yes, it was a 10 minute exposure, but at f64. My light meter gave me a "4" and I was shooting Velvia, pushed one stop to 100. I had NO trouble with seeing the image on the ground glass. There are no light leaks in this camera. I've used other lenses with it with no problems, it's a brand new camera.

<p><i>The first one ... under a clear sky, but the sun had not hit the trees or the camera at this point.</i> Without direct rays from the sun reaching the lens, I have a hard time envisioning flare in the lens causing an effect as strong as seen in this photo. One time I got a flare image of the aperture from a cloudy sky which filled half of the view of the lens, but the effect was much, much weaker than this and the polygonal shape of the aperture was evident.</p>

 

<p><i>A light leak in the lens board or anywhere in the camera, would have slightly fog the whole film, not just a small exact spot right in the center</i>. I have seen other examples of light leaks that actually form an image. A small light leak will function as a pinhole and make a faint image. If this is a light leak, the hole would have to be larger because of the intensity of the spot and thus it wouldn't form a good image.</p>

 

<p>I agree with some of the others. The first example has such a strong amount of "extra" light that, if the extra light had been present while composing, Michael H. would have seen it -- the light spot is brighter than the image, so if he could see to focus, he would have seen the light spot. The other possibilities are that somehow the extra light changed during the exposure, or that it was added at another time.</p>

 

<p>Are the examples full crops of the films? Are the spots of extra exposure exactly centered? With a light leak, it would be hard to explain exact centering.</p>

 

<p>As a test for a light leak, I suggest focusing the lens, then closing the shutter and removing the dark slide from the holder. Next, move the camera around in direct sunlight so that sunlight strikes it in many ways. Finally, develop the film without ever having made an exposure through the lens.</p>

Assuming you didn't see this anomaly while focusing, how could it have come through the lens?

 

In other words, if it came through the lens, why didn't you see it?

Indeed. If it was flare at f:64, you would be able to count the aperture blades.

"brand new camera" does not always equal "no light leaks."

My guess is that with the 480mm you're at greater extension which is

stretching the bellows and causing it to gap somewhere. (pay particular

attention to all seams and attachments)

Let us know when you find it.

I agree that it is possible for a new camera to have light leaks. However, I have shot with this camera and a 500 mm lens as well with no problems. I have also double-checked for light leaks in the traditional manner.

 

However, there IS the possibility that a leak might originate with the lensboard, although I have checked for that as well.

 

I like the idea of the test without doing an exposure. That might be it. I will do one test in that manner and another one using "barn doors" around the lens, to see if that cuts down on the flare.

 

The top image is full-frame, the second one has a bit of the top and bottom cut off, but is more or less centered, with the full width of the original frame. Again, the bottom image DOES have the flare, but to a MUCH lesser degree.

 

Some of the images "in between" simply look more exposed in the center part, as if a center graduated filter may lessen the problem.

Peter is right- it's not flare. It's a light leak of some sort.

 

b.

I have a couple of questions that may sound silly, but I ask due to experience. Is the shutter new or used? What was the temperature when the shots were taken? Have you taken any shots at faster speeds, say 1/30 ?

The temperature was very comfortable, in the 50s for both shots. I don't shoot anything, ever, that's less than a 2 second exposure.

 

In regards to so many people saying it can't be a flare, it must be a light leak, I must ask how you know that? If it's a light leak, then why doesn't it happen with every shot? I'm not ruling a light leak out, and it doesn't LOOK like a flare, if I didn't know what I know, I'd say it was a leaky film holder. But, if it's a leak, then why is it CENTERED in the picture and perfectly circular? What would produce a leak like that in some pictures and not in others?

 

Thanks for everyone's thoughts...

I don't think it's a light leak. I've had light leaks from sun shining into film holders with the dark slide pulled, I've had light leaks from pin holes in the bellows, I've had light leaks when I didn't properly replace the standard bellows after using a bag bellows, and I've had light leaks from a tiny hole in the lens board (caused by the cable release thingy on a Linhof board falling off and my not thinking about the effect of the resulting hole in the board until it was too late). None of them produced results that looked like the first photograph.

 

It's true, as others have said, that flare isn't caused only by direct sunlight striking the lens. Flare is actually more of a problem when photographing in bright diffused light because you can't use your hand to block that kind of light. However, I wouldn't think the flare caused by that type of light would be as stong or as directional as the flare in the first photograph. So I don't know exactly what the cause is, maybe a defect of some sort in the lens, maybe light bouncing around inside the bellows, who knows, I just feel reasonably confident that it isn't a light leak in the lens board, film holder, or bellows.

We know it's not flare because flare is reflected light from the glass to air surfaces within the lens. It isn't light that passes through the lens without bouncing around, so to speak. That's why you can see either the aperture blades or the subject with flare.

 

For instance, if the sun is causing flare, and the sun is within the image, you'll see the sun in the image, just not positioned where it's supposed to be, and not as bright as it should be, but usually 180 degrees around the axis of the image from where it's supposed to be, along with the actual image of the sun positioned where it is supposed to be, and as bright as it is supposed to be.

 

If the sun is outside the image, it can still cause flare. If the sun is at 11 o'clock but outside the field of view, it can flare and put one or several reflected images of the sun on the film, in a line extending from the center of the image, towards the 5 o'clock position.

 

But they will be images of the sun, focused just as sharply as the sun would be if the sky is focused at infinity. There would probably also be reflections from the aperture blades, unless the aperture was fully open.

 

But unless there was an extremely bright source of light that was very out of focus, you would never get flare that looks like the anomaly in your images. That anomaly isn't in focus. If you get flare from a light bulb, you will often see the filament in the bulb. Your fuzzy bright area isn't an image of a thing, like the sun or a light bulb. Therefore it isn't flare.

Is it possible that it might be a processing problem? We seem to have eliminated everything else?

Michael,

 

Is there some exposed metal in front of the glass, like a ding, reflecting light at an odd angle?

 

best,

You know, there actually is a small ding on the back element ring. I would not think it was large enough to cause this problem, but right now, I think anything is possible.

 

Here is a picture of the rear element.<div></div>