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10-20-2008, 08:17 AM   #1
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DA 10-17mm Fisheye: Overexposure

Like several you, I have opted for the unusual performance characteristics of Pentax's great little DA 10-17m Fisheye lens. And I can vouch that it is a fun and creative piece of glass.

I have now used it on both my K10d and my GX20 and with some very interesting and pleasing results. The ability to stand in the middle of my back yard and shoot 180 degrees and get both sides of my 60" lot without photo stitching was amazing. (Have to be careful about those feet and elbows though!).

I have a question for those of you who have used this lens. I am getting about 50% overexposure from shot to shot. One exposure comes out sharp and contrasty and the next one might render milky and white with very soft contrast. This happens with both the K10d and the GX20, so I am inclined to think it is the lens (& me). Have any of you experienced this kind of inconsistency? It seems to be easly corrected by editing software which allows the shots to be transformed into very pleasant exposures. I have not noticed this inconsistency with any of my other Pentax or Tamron lenses. Could it be the design of the fisheye lends itself more readily to glare and tends to overexpose based on the particular angle of the shot and the prevailing light? I have a hunch this may be the case because when I shoot from say under a shade or porch cover, the shots are consistently sharp and well-exposed. It's when I'm out in the bright light and especially in bright overcast sunlite, I get the overexposures.

Anyone relate to this?

10-20-2008, 08:38 AM   #2
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Does not sound familiar.

When you change the F-stop in manual mode and leave the exp. time constant, changes the exposure as expected and can you see the aperture blades close?
10-20-2008, 08:38 AM   #3
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can you post any samples?
10-20-2008, 08:55 AM   #4
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QuoteOriginally posted by shutterbob Quote
Could it be the design of the fisheye lends itself more readily to glare and tends to overexpose based on the particular angle of the shot and the prevailing light?

...

Anyone relate to this?
That sounds like what would happen if you tried to use any ultrawide lens in spot meter mode. (A small change in camera angle makes a big difference in the location of the object you're metering from.)

Things to try:

-- different metering modes
-- AE Lock or manual-mode + green button
-- Select focal length, get close to your subject, meter, and move away to compose the shot

10-20-2008, 10:44 AM   #5
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QuoteOriginally posted by troyz Quote
That sounds like what would happen if you tried to use any ultrawide lens in spot meter mode. (A small change in camera angle makes a big difference in the location of the object you're metering from.)

Things to try:

-- different metering modes
-- AE Lock or manual-mode + green button
-- Select focal length, get close to your subject, meter, and move away to compose the shot
yea. These are good suggestions.
10-20-2008, 05:02 PM   #6
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QuoteOriginally posted by shutterbob Quote
(Have to be careful about those feet and elbows though!).
I'll 2nd that one! I was getting the opposite. Some very coming out underexposed. I was spot metering.

I have recently tried this too (unrelated). I mounted a cheap tripod head on a 5foot piece of thick dowel. I cabled tied a shutter release switch to the bottom of the dowel.
This way i can get the camera up very high... or even underneath things. Sure these shops aren't ones to post on here (yet) but make for very cool shots. The view of a fisheye from 3.5meters up is unreal.

mike
10-20-2008, 05:04 PM   #7
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I would stick to manual metering mode. Since you're capturing such a wide expanse of space, lots of areas to consider. My best bets using the lens have been to meter in manual mode and adjust from there - once I find a good exposure all-around then it stays that way unless the light changes.
10-20-2008, 06:11 PM   #8
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QuoteOriginally posted by shutterbob Quote
Like several you, I have opted for the unusual performance characteristics of Pentax's great little DA 10-17m Fisheye lens. And I can vouch that it is a fun and creative piece of glass.

I have now used it on both my K10d and my GX20 and with some very interesting and pleasing results. The ability to stand in the middle of my back yard and shoot 180 degrees and get both sides of my 60" lot without photo stitching was amazing. (Have to be careful about those feet and elbows though!).

I have a question for those of you who have used this lens. I am getting about 50% overexposure from shot to shot. One exposure comes out sharp and contrasty and the next one might render milky and white with very soft contrast. This happens with both the K10d and the GX20, so I am inclined to think it is the lens (& me). Have any of you experienced this kind of inconsistency? It seems to be easly corrected by editing software which allows the shots to be transformed into very pleasant exposures. I have not noticed this inconsistency with any of my other Pentax or Tamron lenses. Could it be the design of the fisheye lends itself more readily to glare and tends to overexpose based on the particular angle of the shot and the prevailing light? I have a hunch this may be the case because when I shoot from say under a shade or porch cover, the shots are consistently sharp and well-exposed. It's when I'm out in the bright light and especially in bright overcast sunlite, I get the overexposures.

Anyone relate to this?
I think you nailed it yourself. What you see is flare. Since you can't use a decent lens hood with this lens you must be careful when direct sunlight hits the front element. Try to shift position until the flare disappears.

10-20-2008, 06:33 PM   #9
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Need samples as-shot with exif. It is only guessing until then.

I don't recall having that described problem. Matrix metering in "P", mostly.
10-25-2008, 02:22 PM   #10
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10-17mm overexposure solved - thanks Troyz

I'm always impressed with the quality of helpful responses. I believe that TROYZ nailed it for me. He said:

"That sounds like what would happen if you tried to use any ultrawide lens in spot meter mode. (A small change in camera angle makes a big difference in the location of the object you're metering from.)"

I changed to multiple metering mode and the lens did a much better/more consistent job. I still need to learn to fine tune using some of Troys other suggestions, but I think I understand the difficulty of trying to use spot metering with a lens that can see such a wide expanse and different lighting conditions.

Some of you asked for examples of phots, but I have not learned to do that as yet. Thanks for all the helpful and informative responses and especially to Troy for his insight.
10-26-2008, 06:31 AM   #11
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Like Mike, I personally have not found this to be the case, actually found it was the other way around.

QuoteOriginally posted by schmik Quote
I'll 2nd that one! I was getting the opposite. Some very coming out underexposed. I was spot metering.

I have recently tried this too (unrelated). I mounted a cheap tripod head on a 5foot piece of thick dowel. I cabled tied a shutter release switch to the bottom of the dowel.
This way i can get the camera up very high... or even underneath things. Sure these shops aren't ones to post on here (yet) but make for very cool shots. The view of a fisheye from 3.5meters up is unreal.

mike


Thanks for the suggestion Mike (Schmik).
10-26-2008, 05:13 PM   #12
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shutterbob: I'm glad the simple fix worked.

mike (schmik): Fisheye on a stick? Cool!

Anyway, when you're ready to post some images, we'd love to see them on the fisheye fever thread

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/33549-fisheye-...ye-photos.html

It's been a bit slow lately and we could use some fresh material.
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