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10-29-2008, 03:34 PM   #16
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Interesting. I can only guess the spot chosen was *not* what you think. The one you thought was metering off a black object may have actually been using the white object next to it, and vice versa. I don't have enough experience with spot metering to know for sure how tight that spot really is.

10-30-2008, 12:21 AM   #17
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I use spot metering, mainly when taking macros. The point is that you also have to use AE-L to lock the exposure after metering before recomposing your shot(eg. rule of thirds).

If your subject is in the center then you might get the result as you wanted, but the spot metering is very narrow (about 2-3 %, I have not found exact value for Pentax) and thus, as Marc said, you easily measure a wrong point. Especially if you are shooting moving objects. To make it easier, you can set the camera to automatically lock the exposure when AF locks, but then you have to use the center AF point.
10-30-2008, 03:04 AM   #18
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I agree with Marc that most of the samples shown are actually 'correct' given the metering mode in the EXIF. The last couple of pictures of the globe are however pretty weird. As suggested it might a recompose issue but is doesnot look like since you more or less reproduced the same scene three times.

The posts on Flickr do not help much since you stripped then of all the exif data. You might think "I mentioned the most important stuff here !", but that's not what I'm after. A full EXIF can tell me exactly what the camera actually metered, and not just in the spot area if you used spot metering.

It looks like this:



So put the jpgs on flickr with all exif data in it and I can have a look at it.

lock
10-30-2008, 07:18 AM   #19
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thanks for the helpful information.
I will stick with center weighed for time being.

one thing I observed is spot metering is very bad in outdoor shooting compared to indoor.

lock2nl
how do I post these EXIF values? a separate txt file?
I have all the raw files. so tell me how to extract the values.
thanks for your help.

10-30-2008, 08:44 AM   #20
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What I meant was to upload a jpg.picture with full exif in flickr. If I download your flickr picture, there's no EXIF data at all.

But here's the way to do it yourself.
First download photome at PhotoME - Exif, IPTC & ICC Metadata Editor and install the exif reader. It reads RAW so you do not have to convert anything.

Start up Photome and open your globe pictures.
All segments metered "AE metering segments", are listed and displayed graphically in LV's.
Save the screen dump as a reference.
Also check out the 'effective LV'.

But first tell me about the exif readings shown in flickr. They all say 1/100 sec at F/6.7, iso 640 . That would bring me an effective LV of a bit above 9. Did you really use the flash (as said on the flickr page) in manual and still used spot metering ??? Or are these exif readings all bull ?
10-30-2008, 10:19 AM   #21
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lock2nl

I think most of the information is correct.
Yes it was flash fired, It was Sigma 100-300 lens. It was at 300 mm and F 6.7, ISO 640.
(The same lens I used for the pictures in my signature.)

Even after that I got pretty dark pictures.
but the same settings also produced the other bright pictures.

Not only with this set, I did the same with three other set and all of them were like that.

As I told I am still learning.
thanks for the help.
I will post the things tomorrow. right now I do not have them with me. it is on other PC.
10-31-2008, 09:02 AM   #22
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Here are the pictures. expecting experts to comment.
thanks
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10-31-2008, 02:44 PM   #23
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QuoteOriginally posted by istDL-K10D Quote
Here are the pictures. expecting experts to comment.
thanks
If those pictures are saying what it looks like they are saying, something is seriously wrong. Unless the light changed from the first two the the other photos, the values in the various boxes should be pretty consistent across all the shots. But right now the first two are reading as having produced *much* lower meter readings practically across the board. Are you sure nothing else changed between the "white" and "black" photos?

10-31-2008, 03:55 PM   #24
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This is tough one...pretty inconsistent LV values I would say. Apart from the MS-M one, most LV series should be more or less similar. I suspect it might be sticky aperture blades. But it could also be that the short distance is poorly handled by the flash. Need some time here.
11-01-2008, 09:28 AM   #25
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marc
there is no change in light between the shots. I sat at the same place and took the shots.

As I told earlier it can be a lens issue too. how can I clean (if possible) the lens?
can we fix the sticky blades??
11-01-2008, 09:31 AM   #26
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I'm missing the effective LV's. That's what camera uses to calculate the 'correct' exposure, and deal with the flash. You used F6.7 with 1/100 meaning the EV is about 12. To get back to LV, you have to substract the number of stop over iso 100, which is 2 2/3. As I said, it will be effective Lv should be around 9 1/3.

To give you an example, with a flash picture the camera chose (Av mode) 1/100 at F/5.6 with iso 400. The actual EV is 11.6. Minus 2 for the iso 400 means LV was about 9.6. Indeed, effective LV was metered at 9.5.

Something about the top 2 pictures: The metering of the spot area does not make sense.
The value in the spot area of the left one should be less than on the right side, but they are the same. I do not think you metered , locked the metering and refocused. I suspect this could happen when the aperture is not opened fully when metering.
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