M240 light meter oddity

[Hookeye]

Advertisement (gone after registration)

When using a hand held light meter I found my M240 images became slightly underexposed.

 

My curiosity drove me to take reflected light readings off a uniform gray wall. First with the M240, then with a Gossen Digiflash light meter and finally with a Gossen Lunasix (my trusty analogue meter from the 80'ies). All set to ISO 200.

 

I was not surprised to see the two Gossen meters in perfect agreement, but to my surprise the M240 was off by a full EV value. I.e. the M240 wanted a shutter speed of say 1/45s whereas the two hand held meters suggested a shutter speed of 1/90s for the same f-stop. I then switched to "advanced metering mode" on the M240 and tried again. I got exactly the same result here as in the "classic" mode

 

I have used the M240 for a while now and find my camera built-in meter gives correct exposure in most settings. So it seems as if the camera light meter is properly calibrated versus the sensor characteristics. But it also seems as if the M240 is living in a world of its own, being a full EV value out of synch with the rest of the universe.

 

I have now set a 'correction' value of -1EV on both my handheld light meters to get them into agreement with the M240.

 

Has anybody else made a similar observation? I am curious if this is "normal" for the M240 or if it is only my specimen that behaves like this.

[pedaes]

Have not tested against hand-held meter, but have found camera meter very accurate when used properly (i.e.. recognising central weighting pattern). Did use "Advanced" multi-field for some night shots and found it extremely accurate. It might have been worth trying incident light readings to see if these more accurate values were same as in- camera meter. If you are happy with the exposures why worry.

[theno23]

Not sure if its related, but I've found that I have to underexpose digital cameras compared to negative film. For negative film I tended to overexposed by about 2/3 of a stop relative to meter readings, and for digital under by 1/3. Transparency I shot at the reading.

 

That would give the same 1 stop difference you're seeing, but not if you used to shoot negative film with those same lightmeter settings.

[Hookeye]

Not sure if its related, but I've found that I have to underexpose digital cameras compared to negative film. For negative film I tended to overexpose by about 2/3 of a stop relative to meter readings, and for digital under by 1/3. Transparency I shot at the reading.

 

That would give the same 1 stop difference you're seeing, but not if you used to shoot negative film with those same lightmeter settings.

 

What you say is true. But it is not really related. In fact my M240 likes to be OVERexposed one full step (relaive to hand-held meters) which runs contrary to what we all know about digital sensors. I find this pretty strange.

 

It is just as if the ISO values of the M240 are not standard ISO but one step ahead. I.e. what is ISO 200 on my M240 is not really ISO 200 but ISO 100.

[Hookeye]

If you are happy with the exposures why worry.

 

Well if it is only my M240 - I can probably live with it. But if this is true for ALL M240s it puts a strange light on the observation that there is less noise at high ISO with the M240 than e.g. the M9. Because what my camera seems to do is to "pretend" it is shooting at (say) ISO 1600 when in fact it is shooting at 800..

[jaapv]

You need to read the ISO sheet on exposure to understand the difference between digital and film. ISO values are conceived for film and narrowly defined with densities etc. Digital "ISO" values are supposed to be equivalent to the corresponding film values without a rigorous method being prescribed, leaving the camera makers a fair amount of leeway in the definition of the value.

It leads to this type of discrepancy. For instance ISO 160 on the M8 was equivalent to a film value of 200 on an external exposure meter, whilst the Canon 5D of the time was far less sensitive at the same setting.

 

As it is, digital photography does need a different approach. On the M I have a habit of dialing in an -0.3 or even -0.7 exposure compensation, depending on the subject and light, as the camera has a habit of overexposing the red channel, leading oversaturated reds and to a magenta shift in bright red highlights. And to endless colour discussions on this forum...

The RGB histogram is very useful in this context.

[theno23]

Advertisement (gone after registration)

What you say is true. But it is not really related. In fact my M240 likes to be OVERexposed one full step (relaive to hand-held meters) which runs contrary to what we all know about digital sensors. I find this pretty strange.

 

It is just as if the ISO values of the M240 are not standard ISO but one step ahead. I.e. what is ISO 200 on my M240 is not really ISO 200 but ISO 100.

 

Ah, I see, yes. I misread your post - that is odd.

 

I will test my 240 against a meter, I don't generally use one, so I probably wouldn't have noticed.

 

I did test my 240 against my M9, and found them to be more-or-less the same (the meter patterns seem different, so they're not identical for the same scene), but I so rarely shoot with a handheld meter that the M9 could have been off by the same ammount without me noticing.

 

I have noticed that the 240 meter is fooled less by extreme lighting than the M9 one though. I use compensation for backlighting for e.g. a lot less.

[thighslapper]

On the M I have a habit of dialing in an -0.3 or even -0.7 exposure compensation, depending on the subject and light, as the camera has a habit of overexposing the red channel, leading oversaturated reds and to a magenta shift in bright red highlights. And to endless colour discussions on this forum...

 

I agree ..... and intense yellow can be a problem too...... is the M metering system insensitive to red ??? ...... using a 90 ..... which effectively means you are spot-metering ... red flowers etc are always blown and need a good -1ev compensation to render normally....

[mjh]

Red flowers are always problematic, for most cameras. Unless the metering sensor doesn’t differentiate between the brightness in the three colour channels (as for instance Nikon’s does), the camera only sees the total brightness and will happily overexpose the red channel when the green and blue channels are much darker. I have seen lots of pictures of plasticky looking red roses, taken by all kinds and makes of cameras, due to excessive clipping in the red channel.

[120]

You need to read the ISO sheet on exposure to understand the difference between digital and film...

 

You have a copy of this now? You didn't before.

[edwardkaraa]

Well, that's a very interesting piece of info, because of true, it would mean that all the high iso advantage of the typ 240 is bogus.

[Guest tanks]

Not sure if its related, but I've found that I have to underexpose digital cameras compared to negative film. .

 

Interesting, most recommend exposing to the right for color digital when shooting raw "in order to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor."

[Hookeye]

Well, that's a very interesting piece of info, because of true, it would mean that all the high iso advantage of the typ 240 is bogus.

 

Precisely. It is also one that is easy to verify or refute. We just need a few more of us to compare reflected light readings fom an evenly lit surface using the M240 and a hand held meter set at the same ISO. So far, there is only my camera that exhibit this odd behaviour. Not much to worry about. For all I know it may apply to the M9 as well.. It would be interesting to see.

[algrove]

Well, yesterday I was shooting with my M in open shade. Used the WhiBal tiny grey card to set WB, moving the M cross hairs to select center of card, then pressed set. (Did you know how nicely this new setup works versus the M9?)

 

Then using incident metering for model shooting, used the meters reading only and ignored the M's meter. All came out correctly exposed for what I wanted. Seems to corroborate what you say although the 1 EV difference I did not check-too busy.

 

However, in recent weeks I found that the M meter worked beautifully in fully lit situations on its own without external meter.

[Rick]

DxO: Leica M240 ISO 200 setting measures as ISO 134. Which makes sense, the OP is about 1 stop underexposed when using hand held meter to set the M's exposure. In other words, you think you have ISO 200 film in the camera, but it is really closer to ISO 100 film. Go figure.

[theno23]

Interesting, most recommend exposing to the right for color digital when shooting raw "in order to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor."

 

The "expose to the right" thing is not a good bit of advice, it's based on a misconception about how sampling works, unfortunate that it's used at all, I hope it's not used by most people.

 

The Online Photographer: 'Expose to the Right' is a Bunch of Bull

 

- Steve

[edwardkaraa]

The "expose to the right" thing is not a good bit of advice, it's based on a misconception about how sampling works, unfortunate that it's used at all, I hope it's not used by most people.

 

The Online Photographer: 'Expose to the Right' is a Bunch of Bull

 

- Steve

 

That's only one reason, the other reason is that you screw up the colors if you ETTR. The best way to preserve the best colors is to expose correctly.

[dwbell]

This is a minefield that I've navigated before.

 

I have a -0.4EV compensation dialled into my Sekonic L358 incident meter. This makes each shot I measure the same amount brighter. I did this after realising that all my cameras were coming out darker than optimal (subjective call) and researching things a little. This article by Thom Hogan sums it up;

 

Meters Don't See 18% Gray by Thom Hogan

 

After calibrating my meter to my 5DII, I tested the other (less important) bodies and found a good match throughout. I haven't done thorough testing or profiling of the M240 yet, but when I incident meter with the adjusted Sekonic, my grey card spike is dead centre and exposure is good. Custom WB is a must I'm finding so far if you're using the RGB histo to judge channel clipping.

 

This is a deep, murky topic and I'm not going to get into discussions about it because everyone's an expert and there is no 'win'. It works for me, and I'm comfortable with why it does so.

[Robert Q Wong Jr.]

When using a hand held light meter I found my M240 images became slightly underexposed.

 

My curiosity drove me to take reflected light readings off a uniform gray wall. First with the M240' date=' then with a Gossen Digiflash light meter and finally with a Gossen Lunasix (my trusty analogue meter from the 80'ies). All set to ISO 200.

 

I was not surprised to see the two Gossen meters in perfect agreement, but to my surprise the M240 was off by a full EV value. I.e. the M240 wanted a shutter speed of say 1/45s whereas the two hand held meters suggested a shutter speed of 1/90s for the same f-stop. I then switched to "advanced metering mode" on the M240 and tried again. I got exactly the same result here as in the "classic" mode

 

I have used the M240 for a while now and find my camera built-in meter gives correct exposure in most settings. So it seems as if the camera light meter is properly calibrated versus the sensor characteristics. But it also seems as if the M240 is living in a world of its own, being a full EV value out of synch with the rest of the universe.

 

I have now set a 'correction' value of -1EV on both my handheld light meters to get them into agreement with the M240.

 

Has anybody else made a similar observation? I am curious if this is "normal" for the M240 or if it is only my specimen that behaves like this.[/quote']

 

It could be your meters.

 

I have three meters, a Sekonic and two Gossens, none agreed exactly with each other, but were within 2/3ths of a stop.

 

Sent from my iPad using Forum Runner

[Advertisement]

Hallo,

Look here: Leica M

[mjh]

Interesting, most recommend exposing to the right for color digital when shooting raw "in order to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor."

ETTR is good advice when shooting at a sensor’s native sensitivity (not so much at higher ISO levels as has been extensively discussed here). But then, ETTR means you have to keep an eye on the RGB histogram so you don’t overexpose – not even one out of the three channels. Dialing in a -1/3 EV correction as standard is sometimes recommended to prevent accidental overexposure when you are not checking the histogram. Both recommendations have their place; ETTR is generally the better advice but requires more care.