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vikasmg

Default shoot at -2/3 compensation on an M8?

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If over-exposure is recommended when shooting at higher ISOs, for the sake of lower noise, that seems to contradict the technique of UNDER-exposing at high ISOs and recovering in the converter, e.g., 320 at -1 comp = 640, yielding less noise than 640 at 0 comp.

 

What am I missing?

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I think the M8 metering is pretty accurate and consistent and hence easier to make an exposure judgement quickly. It does need practise.

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If over-exposure is recommended when shooting at higher ISOs, for the sake of lower noise, that seems to contradict the technique of UNDER-exposing at high ISOs and recovering in the converter, e.g., 320 at -1 comp = 640, yielding less noise than 640 at 0 comp.

 

What am I missing?

A fair point, Stan, but I think that we're approaching the threshold of sensitivity, where the behaviour of the photodiodes becomes non-linear.

 

Under normal light conditions we can expect a reasonably linear relationship between input and output, which means that the more light you shine on a photodiode the more voltage it will produce (to create a pixel).

 

But as light levels decrease there will be a point where the voltage produced by the photodiode is less than expected for the light entering it. So we need to increase the amount of light entering the photodiode to produce the same level of voltage and this can done by overexposing as Jamie advised earlier.

 

The level of voltage is important because it also relates to the signal to noise ratio, which we see as noise when the ratio is too low. Each photodiode inherently produces a very low level of noise and when the voltage (or signal) produced by the photodiode is small enough the processor will find it hard to distinguish between the inherent noise and the actual signal.

 

Raising the ISO level artificially increases the processor's signal sensitivity because it lowers the level of voltage (signal) that the processor would normally ignore and permits voltage levels that it would normally not need. But this means that the processor will now accept input that also contains a portion of inherent noise so the signal to noise ratio is degraded.

 

Logically ISO 320 at -1 should produce the same amount of noise as ISO 640 +0 but it seems that the action of exposure compensation is 'heavier' than adapting the sensitivity through the ISO settings and forces the processor to accept a lower voltage level, which will contain more inherent noise. By using ISO 640 and overexposing you're 'drowning' the noise a little more effectively.

 

My apologies for the long response but this is the best way to describe what I think is happening.

 

Pete.

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When I process my RAW files they always seem over exposed and I have to subtract the exposure in Capture One or ACR by half a stop. I then set my M8 to -1/3 compensation but never quite sure if it is my own poor technique or some issues with my camera. I feel -2/3 from personal experience is more appropriate but left it at a more conservative -1/3 nonetheless thinking it was my fault somehow. I am glad this is not just me.

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When I process my RAW files they always seem over exposed and I have to subtract the exposure in Capture One or ACR by half a stop. I then set my M8 to -1/3 compensation but never quite sure if it is my own poor technique or some issues with my camera. I feel -2/3 from personal experience is more appropriate but left it at a more conservative -1/3 nonetheless thinking it was my fault somehow. I am glad this is not just me.

Do you print any of your images? If you do do they match what is on your monitor as far as brightness?

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Do you print any of your images? If you do do they match what is on your monitor as far as brightness?

 

Yes I convert the images to b/w and print them on the Epson R2400. I adjust the curves to get a slightly brighter image to get a proper print with shadow details. But as far as I know that is a different issue with the M8 exposure compensation. It is not that the zero compensation default setting is giving me bright images, it is from the obviously blown high lights. I am still a novice at this and so far this process has been working for me but I am here to learn so will appreciate any insights. Best, Ray

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The main thing to get used to isn't that the M8's meter is center-weighted, but that the meter pattern changes with focal length: With wide-angles it's closer to an averaging meter, with longer lenses it moves more toward a spot pattern.

 

Are you sure this is right? I thought the area metered would remain the same, as far as the percentage of the field of view being used to make the reading? I have heard that the Mamiya 7 rangefinder meters as you describe (actually, reverse to what you describe), because the meter reading is taken at a fixed angle (ie. not through the lens), so a wide angle lens meters more like a spot, as the field of view of the image is much greater than that of the meter, and with longer lenses, the image fov. is similar to that of the meter, and so it is more like an average reading. The M8 meters through the lens doesn't it, isn't that what the light grey shutter blade is for??

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Are you sure this is right? I thought the area metered would remain the same, as far as the percentage of the field of view being used to make the reading? I have heard that the Mamiya 7 rangefinder meters as you describe (actually, reverse to what you describe), because the meter reading is taken at a fixed angle (ie. not through the lens), so a wide angle lens meters more like a spot, as the field of view of the image is much greater than that of the meter, and with longer lenses, the image fov. is similar to that of the meter, and so it is more like an average reading. The M8 meters through the lens doesn't it, isn't that what the light grey shutter blade is for??

 

Sam,

 

that is how I understand it too...

regards

andy

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Are you sure this is right? I thought the area metered would remain the same, as far as the percentage of the field of view being used to make the reading? I have heard that the Mamiya 7 rangefinder meters as you describe (actually, reverse to what you describe), because the meter reading is taken at a fixed angle (ie. not through the lens), so a wide angle lens meters more like a spot, as the field of view of the image is much greater than that of the meter, and with longer lenses, the image fov. is similar to that of the meter, and so it is more like an average reading. The M8 meters through the lens doesn't it, isn't that what the light grey shutter blade is for??

 

Actuall ALL built into camera meters are like this. No matter what camera maker they are from or how many points it has that you can select from.

The meters that are built into any camera can only meter on what the lens sees. With a wide angle lens it sees a wide area, with a telephoto lens the meter sees a smaller area. Just like the picture you are taking.

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.......despite what Chris says.......... Use the force ......meter on something bright,.....

 

....point the center of the camera on something that you want visible detail in... ...set the camera so that you are between a half stop and a couple of stops "overexposed." A good starting point is the center dot is lit but so is the right arrow. If you count, the shutter goes up/down in half stops. So the maximum I'd do this is "four clicks" .....

 

Jamie - Well I'm new to photography, I've only been serious about it for 30+ years; and that's with 30 years of using manual mid-grey metering technique successfully; so highlight metering is rather alien to me. However, I tried your highlight technique, and I see where I will use it rather than mid-grey technique. I'd take some persuading to forget about the M8 histogram, even though with Nikon manual metering I'm happy to - but thanks for giving the useful technique.

 

May the Force be un-blown. Jim. As we know it. etc.

 

.............. Chris

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Actuall ALL built into camera meters are like this. No matter what camera maker they are from or how many points it has that you can select from.

The meters that are built into any camera can only meter on what the lens sees. With a wide angle lens it sees a wide area, with a telephoto lens the meter sees a smaller area. Just like the picture you are taking.

 

Ed,

 

You have the correct answer here. The area metered remains exactly the same in proportion to the image area framed,regardless of lens used. The "zoomed" effect of the metered area with a longer lens is due to the cropping effect of the focal length, but the portion of the image area metered still remains the same whether you are using an 18mm or a 135mm lens.

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Jamie - Well I'm new to photography, I've only been serious about it for 30+ years; and that's with 30 years of using manual mid-grey metering technique successfully; so highlight metering is rather alien to me. However, I tried your highlight technique, and I see where I will use it rather than mid-grey technique. I'd take some persuading to forget about the M8 histogram, even though with Nikon manual metering I'm happy to - but thanks for giving the useful technique.

 

May the Force be un-blown. Jim. As we know it. etc.

 

.............. Chris

 

LOL!! Sorry--just having a bit of fun. But the histogram on the camera is still relatively new-fangled, and I don't think many people realize it's just measuring a JPEG interpretation of the exposure

 

And if folks (not Chris) need a film metaphor here for exposure, think slide film, where you would shoot exactly the same way, to preserve detail in the highlights... digital is a lot "like" that, IMO... If you just dial in -1/3 EV and shoot "anything" there will come a time when it just doesn't work and you hit the noise floor too quickly.

 

FWIW, I've mostly preferred incident metering techniques than mid-gray reflective techniques--on any kind of film--for precisely these reasons... but of course there are times when a spot reflective meter comes in very handy

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Jamie, that hits the spot. Thanks!

 

One more area of question for those of us wanting to shoot weddings -- fill light.

 

I believe you posted recently that you use -1 2/3 stop for fill light outdoors. I take it that you'd follow your rulle above at 1/2 to 2 stops overexposure and then set the flash on auto at -1 2/3 stops. Do I have that right?

 

I have noticed that there is so much flare under a white tent that a flash is mandatory for shots under the tent. Where would you set the flash for fill in this situation.

 

And a million thanks in advance.

 

Regards,

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I think the M8 meter the light perfect. I don't use the compensation. I prefer to choose where I meter the light and block it, depending on every picture and what I want. But I can change my way depending on the light conditions and what I am shooting, using the different possibilities of my camera.

 

I agree. That's exactly the way I use the M8 meter.

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Are you sure this is right? I thought the area metered would remain the same, as far as the percentage of the field of view being used to make the reading? ...

sam--

No, I haven't taken the time to check out my claim; I'm repeating what Leica's lecturer told us at the M8 training session in Irving, Texas just after initial introduction of Lightroom.

 

Clearly the meter sees a wider area with a wider lens, but the percentage covered _will_ vary with the lens design. (That's why the M5 required a meter cell baffle, if you recall.) As you move toward wider angles, the fact that light from a greater angle strikes the cell means that the cell's pattern tends to become wider _if_ you don't use a baffle as was incorporated in the M5's meter.

 

More importantly, the instruction manual's representation of the metering pattern is only approximate, since it shows a pattern symmetrical across the field, while the M8's reflective shutter blade is angled.

 

For me it has been more difficult to learn the M8's metering as compared to that of the M5 or M6, simply because the technology is so different.

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Jamie, that hits the spot. Thanks!

 

One more area of question for those of us wanting to shoot weddings -- fill light.

 

I believe you posted recently that you use -1 2/3 stop for fill light outdoors. I take it that you'd follow your rulle above at 1/2 to 2 stops overexposure and then set the flash on auto at -1 2/3 stops. Do I have that right?

 

I have noticed that there is so much flare under a white tent that a flash is mandatory for shots under the tent. Where would you set the flash for fill in this situation.

 

And a million thanks in advance.

 

Regards,

 

Hey Bill--

 

There's two separate thoughts here...

 

First, let me say that I prefer not to use fill flash out of doors, and I'd almost rather use anything else (like a reflector). But when I have to use flash, I will

 

So then I generally use natural light as the key light and the flash is just getting rid of shadow I don't want or adding some sparkle to folks' eyes. I try to make it look like flash has not been used at all

 

But under those circumstances, I carefully place the main daylight exposure with the meter, then underexpose the flash as necessary--from -1/3 to -2 EV, depending on what needs fixing. Remember, the flash should only fill shadows or spark up people's eyes, and so shouldn't affect the overall exposure technique very much.

 

Under a (light-coloured) tent, it all depends.

 

If it's during the day, then the flash is "fill" but later on when it's dark (and there's often bad (overhead) lighting evident), then flash becomes "key" or main and then everything gets reversed: ambient is up to 2 stops below where I'd normally put it and flash is pushed high and bounced (or preferably, remotely triggered from my position).

 

Make sense? If the flash is your key light you expose for that (with an aperture setting) while maintaining ambience a couple of stops under (with the shutter).

 

If the sun (or the tent in daylight) is your key then you expose for that and the flash stays under the ambient and fills in shadows.

 

Good luck! It's always a challenge to make it look natural, but it can be done

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Actuall ALL built into camera meters are like this. No matter what camera maker they are from or how many points it has that you can select from.

The meters that are built into any camera can only meter on what the lens sees. With a wide angle lens it sees a wide area, with a telephoto lens the meter sees a smaller area. Just like the picture you are taking.

 

Actually, in the example I gave, this is not the case. The meter in the Mamiya 7 is not through the lens, it is a fixed angle meter that reads from an outlet near the rf window (iirc), which was why I gave it as an example.

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sam--

No, I haven't taken the time to check out my claim; I'm repeating what Leica's lecturer told us at the M8 training session in Irving, Texas just after initial introduction of Lightroom.

 

Clearly the meter sees a wider area with a wider lens, but the percentage covered _will_ vary with the lens design. (That's why the M5 required a meter cell baffle, if you recall.) As you move toward wider angles, the fact that light from a greater angle strikes the cell means that the cell's pattern tends to become wider _if_ you don't use a baffle as was incorporated in the M5's meter.

 

Now that is interesting! I didn't know that about the M5, but I understand your point about the lens design (rather than the focal length) impacting on the meter reading. Presumably if the reading was taken off the film plane then this wouldn't mater, but as the reading is taken in front of that plane (off the shutter), then the design (eg. symmetric vs. rectilinear) of the lens will have an impact. Have I understood correctly?

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Now that is interesting! I didn't know that about the M5, but I understand your point about the lens design (rather than the focal length) impacting on the meter reading. Presumably if the reading was taken off the film plane then this wouldn't mater, but as the reading is taken in front of that plane (off the shutter), then the design (eg. symmetric vs. rectilinear) of the lens will have an impact. Have I understood correctly?

sam--

Yes. That's one reason the M6 and M7 are so easy to meter with. The meter cells look at the light reflected back from a circular white spot on the shutter, which is as near as practical to the film plane.

 

The M5 has something that looks like a spiral spring over its swing-out meter cell. The 'spring' is a couple millimeters deep and serves to block rays from too broad an angle, so the M5 can meter with any lens that doesn't stick too deeply into the body.

 

With the M8 we've got a slanted white panel that runs the full width of the frame. Because it's slightly slanted top to bottom, the meter pattern isn't symmetrical side-to-side. Because it runs the width of the frame, lens design can influence its pattern. With a tele, light is basically concentrated in the center of the reflective shutter blade. But with a wide angle lens, light tends to be more spread out; and since the reflective surface will reflect just about any light striking anywhere across its width, the M8's effective metering pattern changes based on lens design as you said.

 

I haven't tested this out. It's based on the local M8 introduction seminar. I have no idea how much difference retrofocal designs as compared to classical designs would make, or how much difference wide-angle vs telephoto would make. I do feel that the M8's meter is trickier than earlier designs.

 

That's the advantage of threads like this one: A lot of both practical and technical information.

 

 

Oh. I just realized I had overlooked greeting you and welcoming you to the forum! Glad to have you aboard!

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