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06-01-2009, 03:22 AM   #16
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https://www.pentaxforums.com/forums/pentax-dslr-discussion/59306-k10d-sigma-1...g-problem.html <-- my metering issue with sigma 10-20, also caused by the split focusing screen I believe..


Last edited by PiratStian; 06-01-2009 at 04:59 AM.
06-01-2009, 10:23 AM   #17
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QuoteOriginally posted by 5teve Quote
...are you still using the split screen?...
No i am not using it anymore. But not because of metering. It had problems with shims and alignment in k200d. Since didn't wanted to bother solving this, i sold it to k10d user where it fit fine.

You can easily learn how much compensation to apply when in aperture priority mode, zooming the lens in/out some distance.
If you're pointing the camera at something more or less evenly lit (like a blue sky) the exposure shouldn't change that much. By evaluating the scene in such way you can observe how much EV you need to dial in. Actually i always meter around the scene, even in matrix mode to see how the shutter speed changes, what dynamic range the scene has and which is the best exposure reading to lock on.

And BTW. For me the Chinese screen underexposed a bit @ 70mm, was fine somewhere in the middle (150-200) and over exposed at the tele end. But it depends on the lens (what angle the light has after the rear element).
It may also be because the lens isn't constant aperture. At 70mm its F4, but it is F5.6 at 300mm, even if the blackout cant be seen with eye (as you can' t easily see original screen getting darker when zooming from 18 to 55mm with kit lens either), the meter may start to get too dark readings from split prism and micro prism collar (doughnut).

Last edited by ytterbium; 06-01-2009 at 10:29 AM.
06-01-2009, 03:00 PM   #18
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QuoteOriginally posted by 5teve Quote
spot metering i understand... except that using that it does work... sometimes!
Well, sure, it works if you are pointing it at something that is 18% gray in value. Was that the case in these pictures? Doesn't look like it to me.

QuoteQuote:
the multi segment.. well as i have said previously... i will guarantee that there is no exposure compensation or bracketing turned on... i have double checked on the exif, but until it was mentioned on this thread i hadn't even thought of using it! (let alone know how to do it!)
All the more reason why people are wondering if you didn't hit the button accidentally - easy enough to do. Although one of the pictures looks as much like lens flare as overexposure to me - probably some of each. I take it you weren't using a hood?

Anyhow, posting pictures with EXIF intact would help.

QuoteQuote:
the camera seems to be playing much more nicely now.. from what i can see on camera screen.. whether or not it is the same on the PC i will find out shortly!
If it looks fine on the LCD, it's fine, I mean, it might not be *perfect*, but it's probably within the normal range of what should be expected.
06-01-2009, 05:51 PM   #19
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QuoteOriginally posted by ytterbium Quote
No i am not using it anymore. But not because of metering. It had problems with shims and alignment in k200d. Since didn't wanted to bother solving this, i sold it to k10d user where it fit fine.

You can easily learn how much compensation to apply when in aperture priority mode, zooming the lens in/out some distance.
If you're pointing the camera at something more or less evenly lit (like a blue sky) the exposure shouldn't change that much. By evaluating the scene in such way you can observe how much EV you need to dial in. Actually i always meter around the scene, even in matrix mode to see how the shutter speed changes, what dynamic range the scene has and which is the best exposure reading to lock on.

And BTW. For me the Chinese screen underexposed a bit @ 70mm, was fine somewhere in the middle (150-200) and over exposed at the tele end. But it depends on the lens (what angle the light has after the rear element).
It may also be because the lens isn't constant aperture. At 70mm its F4, but it is F5.6 at 300mm, even if the blackout cant be seen with eye (as you can' t easily see original screen getting darker when zooming from 18 to 55mm with kit lens either), the meter may start to get too dark readings from split prism and micro prism collar (doughnut).
yeah i think the river scene with dark water and bright sky probably didnt help... neither with the boat rocking.. like i say they were quick snaps taken while driving so couldnt take too much care.. experience i'm sure has lots to do with it... hence the thread title..

interesting you note about the 70 and 300 lengths as it is something i observed.. hence my reason for thinking about the split prism / micro prism causing the exposure issues.. (and my inability to read the scene!)

QuoteOriginally posted by Marc Sabatella Quote
Well, sure, it works if you are pointing it at something that is 18% gray in value. Was that the case in these pictures? Doesn't look like it to me.



All the more reason why people are wondering if you didn't hit the button accidentally - easy enough to do. Although one of the pictures looks as much like lens flare as overexposure to me - probably some of each. I take it you weren't using a hood?

Anyhow, posting pictures with EXIF intact would help.



If it looks fine on the LCD, it's fine, I mean, it might not be *perfect*, but it's probably within the normal range of what should be expected.
Hi Marc thanks for the reply also!

nope i doubt i was spot metering against an 18% grey object either..

my apologies for the exif being stripped out of the pictures, i didnt realise picasa albums did that... the included link above each image allows you to view and there is a link on the viewing page to download the image (complete with exif)

I understand about the +/- button and understand that for an inexperinced guy like me that all things no matter how simple need to be eliminated! the exif shows that none was added, and i honestly didnt even think about using it before it was mentioned! i was learning one step at a time!

Regarding the hood, im afraid i was using one... the one that came with the 70-300... maybe its just the fact its a cheapy lens.. but i do always use the hood regardless as the sun is always pretty intense over here.

Yeah have now reviewed the pictures from yesterday and they are all quite nice.. well exposure wise anyway! i'll carry on experimenting and see how i go.. but as a side note.. yesterday i was playing with the +/- to alter the exposure, it is very easy to adjust and something that im sure i will end up using too..

again i appreciate all your help and comments.. i will now keep the Original screen in for a while and see how many pictures i lose to overexposure! then when time allows i may do a direct comparison between the screens and exposure, life is just a little too busy at the moment to have time to do that..

Thanks

Steve

06-01-2009, 09:54 PM   #20
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QuoteOriginally posted by 5teve Quote
the first shot of the boat shows the following...

AE Metering Segment 1: 9.8*LV (center)
AE Metering Segment 2: 9.9*LV (center edge)
AE Metering Segment 3: 9.6*LV (upper, mid-right)
AE Metering Segment 4: 9.5*LV (upper, mid-left)
AE Metering Segment 5: 9*LV (upper, right)
AE Metering Segment 6: 8.9*LV (upper, left)
AE Metering Segment 7: 9.9*LV (mid-right)
AE Metering Segment 8: 9.8*LV (mid-left)
AE Metering Segment 9: 9.8*LV (right)
AE Metering Segment 10: 10*LV (left)
AE Metering Segment 11: 12.1*LV (lower, mid-right)
AE Metering Segment 12: 12*LV (lower, mid-left)
AE Metering Segment 13: 12*LV (lower, right)
AE Metering Segment 14: 11.8*LV (lower, left)
AE Metering Segment 15: 9.1*LV (top)
AE Metering Segment 16: 13.1*LV (bottom)

how does this look in your opinion?
I haven't been watching these numbers closely on my own photos to get a sense of how they apply to different scenes, so take this with a grain of salt, but I do have some impressions...

In a similar image (in terms of relative light levels) that I have, blue sky is around 13.5LV. The sky in your boat image is saturated, but not as completely blown as the bottom foreground. I'll assume it's something white-ish that's reflecting sun, in which case it should be registering in the 14-15LV range, but the camera has the the bottom segment at 13.1. That seems dimmer than it should be.

The segments to the right of the boat in the center are measuring around 9.8LV, so we'll take that as normal for the water/grass/trees combination. The far left segment is reaching 10, which is appropriate because it has a bit of light-colored car and driveway in the mix. Now the center and center edge segments are over a white boat and yellow buoy, both highly reflective, and so should be measuring above the left segment -- instead they're both in the 9.8-9.9 range, which doesn't seem right.

So I'd say the entire scene is metering dimmer than it should be, and the center area is being thrown off. I've never used a focusing screen other than the stock one, but that behavior seems to fit with the issues others are describing.
06-01-2009, 10:47 PM   #21
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QuoteOriginally posted by Quension Quote
I haven't been watching these numbers closely on my own photos to get a sense of how they apply to different scenes, so take this with a grain of salt, but I do have some impressions...

In a similar image (in terms of relative light levels) that I have, blue sky is around 13.5LV. The sky in your boat image is saturated, but not as completely blown as the bottom foreground. I'll assume it's something white-ish that's reflecting sun, in which case it should be registering in the 14-15LV range, but the camera has the the bottom segment at 13.1. That seems dimmer than it should be.

The segments to the right of the boat in the center are measuring around 9.8LV, so we'll take that as normal for the water/grass/trees combination. The far left segment is reaching 10, which is appropriate because it has a bit of light-colored car and driveway in the mix. Now the center and center edge segments are over a white boat and yellow buoy, both highly reflective, and so should be measuring above the left segment -- instead they're both in the 9.8-9.9 range, which doesn't seem right.

So I'd say the entire scene is metering dimmer than it should be, and the center area is being thrown off. I've never used a focusing screen other than the stock one, but that behavior seems to fit with the issues others are describing.
Thanks for your thoughts...

to answer some of your queries..

the bottom segment was water.. the river water. it was a green blue colour but reflecting the sky which was pretty stormy! there was a bit of sunshine but nothing too bright.

from what i gathered on the matrix readings the centre seemed to be dimmer than it should of been..

so now i have thrown the darkish coloured water.. does that confuse things more?

Thanks

Steve
06-02-2009, 12:29 AM   #22
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QuoteOriginally posted by 5teve Quote
QuoteOriginally posted by 5teve Quote
the bottom segment was water.. the river water. it was a green blue colour but reflecting the sky which was pretty stormy! there was a bit of sunshine but nothing too bright.
The pure white bottom 1/4 of that image is water?! That's quite a reflection...

QuoteQuote:
from what i gathered on the matrix readings the centre seemed to be dimmer than it should of been..
Yeah, that's my impression as well, and matches what people describe split-prism screens as doing.

QuoteQuote:
so now i have thrown the darkish coloured water.. does that confuse things more?
Well, it's certainly confused me. Best I can come up with is that the angle of sun->water->camera was perfect to blow it out ahead of the sky. The camera exposed for ~11.5LV, so it would have left the bottom nearly blown anyway (apparently the matrix decided it wasn't as important as the rest of the scene), but I'm thinking it was about 2 stops off.
06-02-2009, 03:14 AM   #23
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QuoteOriginally posted by Quension Quote
The pure white bottom 1/4 of that image is water?! That's quite a reflection...



Yeah, that's my impression as well, and matches what people describe split-prism screens as doing.



Well, it's certainly confused me. Best I can come up with is that the angle of sun->water->camera was perfect to blow it out ahead of the sky. The camera exposed for ~11.5LV, so it would have left the bottom nearly blown anyway (apparently the matrix decided it wasn't as important as the rest of the scene), but I'm thinking it was about 2 stops off.
Yep surely is dark green water reflecting dark clouds! certainly got it wrong eh?

its off by a fair way to the point where there is no detail.. how many stops i'll trust you on!

so i'll leave it there and thank you guys very much... and watch how it goes! any more issues i'll report back!

thanks

Steve

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