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Author Topic: Using Spot Metering and Exposure  (Read 2324 times)

maxshafiq

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Using Spot Metering and Exposure
« on: February 01, 2017, 06:30:19 PM »

OK folks I have a spot meter and exposure question.

I have an indoor scene where the sun is shining through the window and hitting some furniture. It casts a nice ray of light across the furniture.
I am trying to shoot the scene where the highlights are not blown out, and yet the darker parts are not lost either.

Here are the scenarios:
1/ If I meter only the highlight (100 ISO, 1/250s, F5.6) and expose for this in camera, the highlights come in nice but everything is dark. When I try and pull the dark in software I see noise.
2/ If I meter the mid tone (100 ISO, 1/15s, F5.6) , then the highlights get blown out.
3/ If I meters the dark areas (100 ISO, 1/4s, F5.6), then highlights still blown.

What technique (spot metering) could I use to get perfect exposure? I am using a Sekonic meter.

Thanks

 
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BAB

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Re: Using Spot Metering and Exposure
« Reply #1 on: February 01, 2017, 06:37:04 PM »

you need two or three exposures or you need to add fill flash if not you can only expose for your cameras DR and do the rest in post!
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maxshafiq

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Re: Using Spot Metering and Exposure
« Reply #2 on: February 01, 2017, 07:11:36 PM »

I understand the flash option and let's assume I want to keep it all natural light.

If I go the 2 to 3 readings route, how do I know/calculate which reading to use for the camera? I am assuming I have to calibrate my camera/sekonic meter to each other?

Thx
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Slobodan Blagojevic

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Re: Using Spot Metering and Exposure
« Reply #3 on: February 01, 2017, 11:11:50 PM »

.... If I go the 2 to 3 readings route, how do I know/calculate which reading to use for the camera?...

If you do 2 or 3 readings, you'd do 2 or 3 exposures at those readings and then combine them in post.

Depending on your camera's dynamic range, you might be able to get away with just one exposure. Your 6 f-stops scenario shouldn't be such a big deal for modern cameras, especially for Sony sensors.

razrblck

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Re: Using Spot Metering and Exposure
« Reply #4 on: February 02, 2017, 02:15:16 AM »

You can use a reflector to bounce some light in the shadows. If the highlights are too strong and they come from a window, try using a big diffuser (or a white, opaque cloth) to bring them down.

On the exposure side, ETTR might help minimize shadow noise.
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BrownBear

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Re: Using Spot Metering and Exposure
« Reply #6 on: February 02, 2017, 05:56:28 AM »

Quote
...fill flash....

Quote
...reflector....

I've done a lot of this kind of shooting, and those are the quick and easy solutions that just flat work all the time. One big proviso on both- you have to avoid reflections off the window glass if the window is visible, especially if any outdoor scenery is visible through the window.

Another option is to ND gel the window to reduce the intensity of the highlights while "bringing up" the ambient indoor light. (gel sheeting is available from larger photo supply stores).

Speaking of gels, you could also CC gel the windows to match indoor light sources and crank up the indoor light to reduce the difference from outdoor. In architectural shoots an array of larger incandescent light bulbs (to sub for originals in a room) and rolls of CC and ND gels were critical accessories in my location kits.

You might also consider moving the furniture.

Given options on time of shooting, there's one more approach that can be even more pleasing when any outdoor scenery is visible through the window: I also adjust my shooting time until outdoor ambient light is lower and more compatible with indoor light, especially when spill light from windows elsewhere in the room helps illuminate the scene. Best results for me are when there's no more than about 2 stops difference between indoor ambient and window-sourced highlights on your subject.
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pegelli

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Re: Using Spot Metering and Exposure
« Reply #7 on: February 02, 2017, 07:02:00 AM »

2/ If I meter the mid tone (100 ISO, 1/15s, F5.6) , then the highlights get blown out.
jpg or raw? (of film?)
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pieter, aka pegelli

maxshafiq

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Re: Using Spot Metering and Exposure
« Reply #8 on: February 02, 2017, 08:55:08 AM »

RAW
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maxshafiq

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Re: Using Spot Metering and Exposure
« Reply #9 on: February 02, 2017, 08:56:30 AM »

If you do 2 or 3 readings, you'd do 2 or 3 exposures at those readings and then combine them in post.

Depending on your camera's dynamic range, you might be able to get away with just one exposure. Your 6 f-stops scenario shouldn't be such a big deal for modern cameras, especially for Sony sensors.

Yup Sony sensor...was trying to avoid the HDR route for the time being :-)
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pegelli

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Re: Using Spot Metering and Exposure
« Reply #10 on: February 02, 2017, 09:06:49 AM »

Yup Sony sensor...was trying to avoid the HDR route for the time being :-)
Very strange you can't get 6 stops of DR from the camera, my 2010 Sony does better then that.
How do you determine the highlights are blown out in your second and third scenario? Are you using raw digger or are you judging by the default conversion of your camera in your raw conversion software?
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pieter, aka pegelli

SZRitter

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Re: Using Spot Metering and Exposure
« Reply #11 on: February 02, 2017, 10:01:31 AM »

Yup Sony sensor...was trying to avoid the HDR route for the time being :-)

HDR isn't the only way to combine images. I sometimes prefer to hand paint in areas, or you can use a technique like luminosity blending. Or any combination of techniques.

For instance, and I am by no means as good at interiors as even a quarter of the guys in here, but to overcome window light vs incandescent, I'll typically make two conversions of the RAW, one aimed at each sources temp, then layer the two conversions in Photoshop. With the image that is my base (i.e. predominant light source) on the bottom, I'll mask out the other layer and start painting it back in. It's time consuming, but it has worked for me. Obviously, doing it at the time of the shoot would be better, but not all of us have that luxury.
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scyth

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Re: Using Spot Metering and Exposure
« Reply #12 on: February 02, 2017, 10:17:05 AM »

OK folks I have a spot meter and exposure question.

I have an indoor scene where the sun is shining through the window and hitting some furniture. It casts a nice ray of light across the furniture.
I am trying to shoot the scene where the highlights are not blown out, and yet the darker parts are not lost either.

Here are the scenarios:
1/ If I meter only the highlight (100 ISO, 1/250s, F5.6) and expose for this in camera, the highlights come in nice but everything is dark. When I try and pull the dark in software I see noise.
2/ If I meter the mid tone (100 ISO, 1/15s, F5.6) , then the highlights get blown out.
3/ If I meters the dark areas (100 ISO, 1/4s, F5.6), then highlights still blown.

What technique (spot metering) could I use to get perfect exposure? I am using a Sekonic meter.

Thanks

use camera's spotmeter and use rawdigger to find out how your camera's spot-metering is calibrated (rawdigger website has article with instructions)... then expose so that important lights where you still want details will be within say 1/2 EV to clipping in raw channel (most probably greens based on your illumination)...  you absolutely do not need to bother with Seconic, albeit 1 degree spot metering is nice (if your model has that)
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maxshafiq

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Re: Using Spot Metering and Exposure
« Reply #13 on: February 02, 2017, 10:58:45 AM »

I've done a lot of this kind of shooting, and those are the quick and easy solutions that just flat work all the time. One big proviso on both- you have to avoid reflections off the window glass if the window is visible, especially if any outdoor scenery is visible through the window.

Another option is to ND gel the window to reduce the intensity of the highlights while "bringing up" the ambient indoor light. (gel sheeting is available from larger photo supply stores).

Speaking of gels, you could also CC gel the windows to match indoor light sources and crank up the indoor light to reduce the difference from outdoor. In architectural shoots an array of larger incandescent light bulbs (to sub for originals in a room) and rolls of CC and ND gels were critical accessories in my location kits.

You might also consider moving the furniture.

Given options on time of shooting, there's one more approach that can be even more pleasing when any outdoor scenery is visible through the window: I also adjust my shooting time until outdoor ambient light is lower and more compatible with indoor light, especially when spill light from windows elsewhere in the room helps illuminate the scene. Best results for me are when there's no more than about 2 stops difference between indoor ambient and window-sourced highlights on your subject.

Some interesting techniques using GELS!! that I had not thought off :-)

Moving the furniture around to suite the style I am looking for is always an option.

Thanks
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maxshafiq

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Re: Using Spot Metering and Exposure
« Reply #14 on: February 02, 2017, 11:02:18 AM »

Very strange you can't get 6 stops of DR from the camera, my 2010 Sony does better then that.
How do you determine the highlights are blown out in your second and third scenario? Are you using raw digger or are you judging by the default conversion of your camera in your raw conversion software?

Just by looking at them after default conversion and zooming in. There is nothing but white...no data.
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scyth

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Re: Using Spot Metering and Exposure
« Reply #15 on: February 02, 2017, 11:11:04 AM »

Just by looking at them after default conversion and zooming in. There is nothing but white...no data.

dear, you need to use tools that can show clipping in raw - rawdigger, fastrawviewer or converters that can do the same like rawtherapee or rpp
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Slobodan Blagojevic

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Re: Using Spot Metering and Exposure
« Reply #16 on: February 02, 2017, 11:13:55 AM »

Just by looking at them after default conversion and zooming in. There is nothing but white...no data.

Just looking at them is not good enough. You would be surprised just how much data is still present in the area that looks totally white.

SZRitter

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Re: Using Spot Metering and Exposure
« Reply #17 on: February 02, 2017, 11:19:15 AM »

Just by looking at them after default conversion and zooming in. There is nothing but white...no data.

Just to back up the other two who posted before me, on my main digital camera, I know that right as my white clips, I still have one stop I can bump up and recover data while maintaining color accuracy. This will vary by camera, so you just have to test.
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pegelli

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Re: Using Spot Metering and Exposure
« Reply #18 on: February 02, 2017, 11:42:39 AM »

Just by looking at them after default conversion and zooming in. There is nothing but white...no data.
I agree with the others before, white at default conversion doesn't mean there is no data. It's very likely your raw converter has only pushed that data over the edge in its default jpg conversion. Probably another example of "it's not the tool, but the ......"  ;)
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pieter, aka pegelli

EricV

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Re: Using Spot Metering and Exposure
« Reply #19 on: February 02, 2017, 12:52:42 PM »

If you cannot use your meter or camera histogram to find the right exposure, just take several bracketed exposures and figure out later which one is right.  Your scene is not moving, and there is no special prize for capturing the image in a single perfectly calculated exposure. 

In cases where the brightness range is extreme, there may be no single exposure which keeps highlights below clipping and simultaneously provides enough light in the shadows for adequate post-processing.  In that case, you will have to combine multiple exposures in post-processing.  This will let you do what you have already attempted (brighten the shadows), without the noise penalty.
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