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10-14-2008, 11:29 AM   #1
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what a difference blocking the view finder makes!

getting to know the camera better i realized the other day how BIG of an impact having the viewfinder open to light has on exposure, with sometimes as much as a 3 stop difference working off a tripod!

just by blocking it with my thumb i see the readings change drasticly.

my next purchase item will be a cupped eye-piece to eliminate light streaks during regular use.

10-14-2008, 12:33 PM   #2
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QuoteOriginally posted by Gooshin Quote
getting to know the camera better i realized the other day how BIG of an impact having the viewfinder open to light has on exposure, with sometimes as much as a 3 stop difference working off a tripod!

just by blocking it with my thumb i see the readings change drasticly.

my next purchase item will be a cupped eye-piece to eliminate light streaks during regular use.
didn't your camera come with a small slide over cover? all my pentax cameras came with one.

The best solution I have seen to this however is very old. My Ricoh XR-2s had a built in shutter over the viewfinder, with a small activation lever.

Maybe pentax is listening
10-14-2008, 12:38 PM   #3
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ohh it came with it, i have it at home somewhere

but i mean i didnt realize it had such an impact, nothing some EV compensation wouldnt fix

but no, i get a much richer histogram, its awesome.

and its a bit bothersom to take off the rubberized hood, and slide that thing on, i just used my thumb, lol.
10-14-2008, 12:41 PM   #4
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QuoteOriginally posted by Gooshin Quote
getting to know the camera better i realized the other day how BIG of an impact having the viewfinder open to light has on exposure, with sometimes as much as a 3 stop difference working off a tripod!

just by blocking it with my thumb i see the readings change drasticly.

my next purchase item will be a cupped eye-piece to eliminate light streaks during regular use.

Thats a great point. It's one of those things that I think I "knew" but never used.

I shoot alot without the camera to my face. I think I'll start using the view finder cover.

I also shoot sometimes while wearing glasses. Wonder if this changes the exposure?

Maybe I should always wear contacts, and use an eyecup?

Somrthing to think about.

10-14-2008, 12:42 PM   #5
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I don't know if I can find any of the viewfinder caps I have. It seems I got one with nearly every Pentax I have ever owned. I'm with Gooshin - almost - I shade it with my hand so I don't get my messy thumb prints on the glass, when I need to use auto exposure on a tripod. Most of the time, I just use Manual Exposure, so it doesn't matter. I've seen some who use a piece of black cloth.
10-14-2008, 12:42 PM   #6
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I used a tripod last night, I forgot all about that....
10-14-2008, 12:56 PM   #7
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I've been wondering how much this matters when taking pictures of the night sky. Pretty much everything else is black and I'm using the bulb setting. Are there light leaks around the mirror when it's locked up or is this just a metering issue?

I ended up getting a rubberized eyecup because I'd been scratching my glasses with the stock viewfinder. Using the supplied cover is quite a hassle. Sometimes I wish the hotshoe cover would double as an eyecup cover.
10-14-2008, 01:10 PM   #8
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QuoteOriginally posted by smigol Quote
I've been wondering how much this matters when taking pictures of the night sky. Pretty much everything else is black and I'm using the bulb setting. Are there light leaks around the mirror when it's locked up or is this just a metering issue?
it's principally metering, but a strong back light might do something as I am not sure how perfect the mirror blocks off the view finder in the box of hte camera.

10-14-2008, 01:22 PM   #9
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Ha!

So, I am not the only one that has this problem! Some months ago I posted a similar observation and was smartly slapped down. Like you, I was working on a tripod and was getting inconsistent exposure.

I found that it is particularly true in AV mode using m42 lenses. I would meter with my eye to the finder, but expose with my eye away only to find that the exposures were way off. I finally noticed that the top LCD had a different shutter speed than what I metered to. The contribution of ambient light entering through the viewfinder is apparently more significant when the lens is stopped down.

Steve
10-14-2008, 01:23 PM   #10
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It only affect the metering if the surrounding are bright at the back of the camera, right?
10-14-2008, 01:24 PM   #11
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QuoteOriginally posted by Gooshin Quote
getting to know the camera better i realized the other day how BIG of an impact having the viewfinder open to light has on exposure, with sometimes as much as a 3 stop difference working off a tripod!

just by blocking it with my thumb i see the readings change drasticly.

my next purchase item will be a cupped eye-piece to eliminate light streaks during regular use.


Gooshin, forgive me, but I don't understand what you're reporting. It sounds as if you're saying that it makes a difference to the metering if the finder in the back of the camera is covered (say, because my face is pressed up against it) or not (as when I'm shooting on a tripod and NOT looking through the finder). Is that what you're saying? How could that be? The meter doesn't react to light coming in through the back of the camera does it?

I just did a quick test here. I held the camera up by a window. It's bright outside and dark inside. I pointed the camera toward the inside of the room (dark) with the finder pretty close to the window and thus getting hit by the bright light from outside. In P mode, I get the same meter reading whether I cover the finder with my hand or not. This is with a K20D.

What am I missing here?

By the way, I do have an eyecup on the camera but I don't see how that would matter.

Thanks,

Will
10-14-2008, 01:26 PM   #12
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QuoteOriginally posted by vizjerei Quote
It only affect the metering if the surrounding are bright at the back of the camera, right?
what would you consider "bright"

i was observing this in both direct sunlight and inside a forest
10-14-2008, 01:28 PM   #13
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QuoteOriginally posted by WMBP Quote
Gooshin, forgive me, but I don't understand what you're reporting. It sounds as if you're saying that it makes a difference to the metering if the finder in the back of the camera is covered (say, because my face is pressed up against it) or not (as when I'm shooting on a tripod and NOT looking through the finder). Is that what you're saying? How could that be? The meter doesn't react to light coming in through the back of the camera does it?

Will
this is exactly whats happening.

i can cleary see the shutter speed change in AV mode on the top LCD of my K20D while covering it on and off.

now, i will note that this is with M42 lenses (as an above poster mentioned) perhaps this has something to do with the fact that i was stopped down to F8...


and for the record, i have always been a believer that light hitting the viewfinder does affect metering, i just always thought of it as insignificant.
10-14-2008, 01:35 PM   #14
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QuoteOriginally posted by Gooshin Quote
this is exactly whats happening.

i can cleary see the shutter speed change in AV mode on the top LCD of my K20D while covering it on and off.

now, i will note that this is with M42 lenses (as an above poster mentioned) perhaps this has something to do with the fact that i was stopped down to F8...


and for the record, i have always been a believer that light hitting the viewfinder does affect metering, i just always thought of it as insignificant.
it will always depend upon the ratio of light entering through the lens vs the light entering through the finder.

It might also be different between a penta mirror and prisim (I can;t comment on the penta mirror as I don't have a camera with one)

funny thing though, I can't find reference to the use of the cover in the manual. My Ricoh Manual does make specific note of the issue
10-14-2008, 01:43 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
it will always depend upon the ratio of light entering through the lens vs the light entering through the finder.

It might also be different between a penta mirror and prisim (I can;t comment on the penta mirror as I don't have a camera with one)

funny thing though, I can't find reference to the use of the cover in the manual. My Ricoh Manual does make specific note of the issue

well then that would make sense

at anything blow F4.0 i would think that the viewfinder hole is already bigger than the diaphragm, at f8 you would definetly get more light... and since M42's on a modern pentax are the only lenses that would showcase this, perhaps this is why its such a rare complain from people.
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