Lightmeter vs. R9 (different readings my confusion)

[pridbor]

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I'm sure this issue has been dealt with years ago, and I used a Lightmeter when I was a teenager with reasonable success, so why do I have a problem now?

In some other thread(s) I noticed some of you swear to the use of a Lightmeter and I purchased one old analog such maybe close to a year ago.

I first managed to get hold of the correct type of Batteries for this old unit, Which looks and feels like new, and got them installed, and voila "it works"! 

Now I tried to point towards the same object, my big white car, and I was expecting to get the same, or sort of the same, measurement from the R9 as from the Lightmeter, and thus my choice of Shutter speed and Aperture choices; but no, there's a big difference. For e.g. Aperture 11, I got a Shutter speed of 1/4Sec from my Lightmeter and 1/60Sec with the R9 in A mode.

Could someone please educate me in what I do wrong here? (and I'm sure that it's my not understanding in using these deices as it's been a long time since I used the Lightmeter, but I have gotten some decent Photos from the R9 in A mode this last year, so I'm a bit confused as to which device to "listen to 🙂

Thanks

Preben

Edited July 21, 2019 by pridbor

[lykaman]

Different Angle of view, different Baseline for both Camera & LightMeter, have you adjusted ISO? Film Speed? Which Lens are you using? Have you used a Grey Card to check readings? --- L

Edited July 21, 2019 by lykaman

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[spydrxx]

Disconcerting...yes, meaningful...hardly. It is 1/2 of an f stop. I think Lykaman hit it on the head. There could also be other factors...relative age of the batteries, fine adjustment/calibration of the lightmeter. You did say it was an old analog, and most of them occasionally needed a slight tweaking of the needle....even my old Leica ones.

[lykaman]

11 minutes ago, spydrxx said:

Disconcerting...yes, meaningful...hardly. It is 1/2 of an f stop. I think Lykaman hit it on the head. There could also be other factors...relative age of the batteries, fine adjustment/calibration of the lightmeter. You did say it was an old analog, and most of them occasionally needed a slight tweaking of the needle....even my old Leica ones.

He could always Bracket...

[masjah]

 

Spydrxx, perhaps you misread the OP's original message (because of a lack of a space in the text)? I did exactly that on first reading! It's 1/4 sec versus 1/60 sec, which is 4 stops.

Preben, as implied above, the first thing to check is that you are metering the same thing. You need a uniformly illuminated surface large enough so that the field of view of the camera and meter are completely within the image, then you can be sure that both the meter and the camera are recording the same thing. If you still have a discrepancy, then you have to accept that most probably the sensor (of whatever type) of the meter may be ageing and losing its accuracy - this does happen.

 

[earleygallery]

Too many variables here to give an answer but possibly, as your example is a white car, I’d suggest that your R9 has centre weighted metering and is trying to expose for the white of the car correctly, whereas the handheld meter is giving an average for the whole scene in front of you.

The handheld meter probably has a much wider field of view than the lens you were using?

Your example - if I’m correct - is one example of why I think it’s an essential accessory!

[ramarren]

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With any meter, in-camera or hand-held, you have to test to be sure what its calibration is. For instance, I have two Sekonic incident meters (L358 and L478): their calibration in identical reading circumstances differs by 1 EV. They're both within a reasonable range of "correct" exposure, but one is obviously biased to a typical exposure I use for transparency film and the other for negative film. Once I measured their calibration, I knew what to expect. 

Reflected light meters, like the one in your camera and hand-held meters in reflected light mode, are additionally influenced by field of view ... making sure the two are 'seeing' the same thing is critical to understanding what the meters are reading.

A test rig with a gray card or a tri-tone card is essential to measuring these calibrations to determine how in-sync, or not, they are. A tri-tone card is a superb tool for doing calibration measurement along with a digital camera and its histogram overlay...

[spydrxx]

5 hours ago, masjah said:

 

Spydrxx, perhaps you misread the OP's original message (because of a lack of a space in the text)? I did exactly that on first reading! It's 1/4 sec versus 1/60 sec, which is 4 stops.

Preben, as implied above, the first thing to check is that you are metering the same thing. You need a uniformly illuminated surface large enough so that the field of view of the camera and meter are completely within the image, then you can be sure that both the meter and the camera are recording the same thing. If you still have a discrepancy, then you have to accept that most probably the sensor (of whatever type) of the meter may be ageing and losing its accuracy - this does happen.

 

Tanks Masjah - that lack of a space and aging eyes did mislead me...apology offered. I still think it may be a meter calibration issue if both readings cover a similar field of view.

[masjah]

Of course, with the R9, you have a choice of spot. multifield or centre-weighted metering. If you meter a uniform and uniformly lit subject, such as a grey card, and get similar readings on your R9 in all three metering modes (which you should if the grey card fills the viewfinder frame) then that ought to be a good basis. You can then take your handheld meter and try to replicate that reading by ensuring that the card fills the meter's viewing angle. That should give you some sort of feel as to how the meter is reading.

[pridbor]

Thanks all for your valuable inputs. One thing I did do wrong was to have the R9 metering set to centre-weighted metering (Rectangle with spot in center I think), when I should have used multifield (Rectangle?) instead I now believe, as pointed out by masjah. ISO was set to the same on both devices and I used a 50mm Cron on the R9. Batteries fresh, and compatible with the original Mercury batteries i.e. 1.35V and the Meter shows that they are in good shape.

I do know a bit about Electronics being in Aerospace Computer design for most of my life, so yes aging is not only for us but Electronics suffer it too 🙂 From what I read though the meter is a fairly simple device, not many and simple components so I had hoped that it would still be good. It looks and behaves perfectly well, but it might just need that Calibration, but I'm in need of a calibrated source. Don't know if it's worth my time or buying a modern lightmeter is the solution. I just like the feel of this device in my hands, reminding me of my father's meter of yesteryear.

Lacking a grey card, will buy one shortly, I have decided to take a number of my Camaras, R4,5, and 9 and the SONY A7R2 and put them on a tripod pointing at the same white cat door, again just for a quick sanity check.

I might have failed to add that I have had some level of success with the R9 mostly with B&W, so I assumed that it was to be trusted, at least to a degree where the results are usable 🙂to me at least.

Thanks again for your insights and recommandations

Preben

 

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[Michael Geschlecht]

1 hour ago, pridbor said:

Thanks all for your valuable inputs. One thing I did do wrong was to have the R9 metering set to centre-weighted metering (Rectangle with spot in center I think), when I should have used multifield (Rectangle?) instead I now believe, as pointed out by masjah. ISO was set to the same on both devices and I used a 50mm Cron on the R9. Batteries fresh, and compatible with the original Mercury batteries i.e. 1.35V and the Meter shows that they are in good shape.

I do know a bit about Electronics being in Aerospace Computer design for most of my life, so yes aging is not only for us but Electronics suffer it too 🙂 From what I read though the meter is a fairly simple device, not many and simple components so I had hoped that it would still be good. It looks and behaves perfectly well, but it might just need that Calibration, but I'm in need of a calibrated source. Don't know if it's worth my time or buying a modern lightmeter is the solution. I just like the feel of this device in my hands, reminding me of my father's meter of yesteryear.

Lacking a grey card, will buy one shortly, I have decided to take a number of my Camaras, R4,5, and 9 and the SONY A7R2 and put them on a tripod pointing at the same white cat door, again just for a quick sanity check.

I might have failed to add that I have had some level of success with the R9 mostly with B&W, so I assumed that it was to be trusted, at least to a degree where the results are usable 🙂to me at least.

Thanks again for your insights and recommandations

Preben

 

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Hello Preben

Keep in mind that if you do the test that you suggested & get a set of readings that all more or less match.

And set the reading on any of your cameras/lenses.

And take a picture of the white garage door.

The door will come out more or less 18% reflectance gray.

Since the purpose of meters is to provide a reading so that when that reading is set on a camera/lens: The resultant subject will be produced as an 18% reflectant gray subject.

Which, in this situation, would mean a reasonably dark "white" door.

Best Regards,

Michael

Edited July 22, 2019 by Michael Geschlecht

[Michael Geschlecht]

Hello Again Preben,

If you look in the WIKI at the top of this page & go to the section on "R" Digital cameras.

And go to the R9.

And then to the R9 instruction book: You will find on that on page 121 (Illustrated on page 119.), it writes:

The spot is selective metering.

The rectangle is center weighted metering.

The rectangle with the spot in the middle is multi-field metering.

Best Regards,

Michael

[pridbor]

I misunderstood/misquoted Masjar's writing so thanks for the clarification Michael , and by chance I thus had it in the correct position. 

And also thanks for your insight on "My quick and Dirty" measuring test! My objective with the test however, was to see if there was any significant difference in the Shutter speed between the different cameras; I had them all on the same Lens, Aperture, and ISO. I did the test today but didn't take a shot, which I will do tomorrow when I will most likely have the same 100+ F (40+ C) temperature, and my white Car door is really really white. I used the same 50mm lens on all cameras R3,4,5,9, but not on the Sony, which will be corrected tomorrow.

Not quite sure what to make out of the 18% reflectant gray subject means? sorry for asking this question, which I'm sure you all understand, but I have never heard of this topic before. Why wouldn't it render a white door? I will buy the Grey Card I now need to find out how to make use of it. Must be somebody on YouTube explaining this.

I will be back, and in the meantime thanks again for educating me, I really like these old R Cameras, to me they fell right/good in my hands, I have long fingers and would like to use them more and with a better understanding of their operaton. 

Thanks

Preben

 

[spydrxx]

"Not quite sure what to make out of the 18% reflectant gray subject means? sorry for asking this question, which I'm sure you all understand, but I have never heard of this topic before. Why wouldn't it render a white door?"

The meters can't tell the difference between black and white - only that their reflectance is different. So meters are designed to capture a range by translating whatever they are pointed at to approximately 18% gray...which generally encompasses the latitude of the film from black to white. If you meter a solid white card and a black card, and shoot at what the meter tells you in each case...you should get two shots which are 18% gray...identical. Shooting a typical scene which includes dark and light items gives you a full range on the negative. That is why, if a subject is particularly light or dark, you should compensate the reading your meter gives you. Hopefully this helps answer your question.

[masjah]

Spydrxx is absolutely correct. Put a slightly different way, suppose you were to meter a plain white subject (say a white card) on a very dull day, and then you meter a plain grey subject (say a grey card) on an extremely bright day, and you found (as would be perfectly possible) that the indicated exposures were identical. You take the pictures. How do they turn out, white or grey? The film will have received the same amount of light, and they will both turn out the same. The camera or meter manufacturer has had to take a decision that most images average out to an 18% grey, but as Spydrxx says, something like a snow scene would fool it.

One way round this problem is to use the meter in incident light mode (assuming the meter has a suitable diffuser to support this). You then measure the light falling on the subject, rather than the light reflected by it. I've got a (still accurate) Weston Master V which is very useful in this role.

 

[earleygallery]

Also........we are talking about a light meter that is approaching 50 years old, probably being used with batteries that aren't original specification. 

It may or may not have been recalibrated at some point. It may or may not be faulty. It may or may not require recalibration and servicing now. Add possible user error into the mix and we have a difficult situation. 

Don't test it with white doors and are areas which won't fill the frame of both meters. If you don't have a grey card you can meter green grass (as opposed to burnt straw like grass!) or something that's bright red - both are roughly equivalent of a grey card. 

 

[wizard]

vor einer Stunde schrieb earleygallery:

If you don't have a grey card you can meter green grass (as opposed to burnt straw like grass!) or something that's bright red - both are roughly equivalent of a grey card. 

Blue sky without clouds also works well (of course, make sure that the sun is not within the field of view). I used that blue sky measurement often when shooting slide film.

Cheers,

Andy

[pridbor]

One is never to old to learn!! Thanks all! 

 

Last night I spent more than an hour watching people on youtube explain how to do the measurements, but you guys added the why, and having eternal curiosity between my ears, I always try to figure out why. 

Thanks again, and be sure that I'm not afraid of asking dumb questions, and you have all been very patient and kind to answer them

Preben

P.S. so the only thing that I arrived at with my tests was that all my Cameras gave more or less the same shutter time, full white door in viewing area. My conclusion is that it's a cse of aging electronics, well it was just for fun anyway.

 

[masjah]

Preben, I always used to tell my students that there was no such thing as a dumb question (dumb answers are however something else!). Anyway, it's pleasing that you've been able to resolve the apparent inconsistency.

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[Michael Geschlecht]

Hello Preben,

to add a little to all of the information just above:

When meter manufacturers began building photo-electric light meters to measure exposures they had to choose standards to calibrate their meters to.

F stops & shutter speeds were common to all cameras & lenses. They could be laid out on adjustable scales on the meter

Film speed could vary significantly within the range of films produced. They could also be laid out on an adjustable scale.

This left SUBJECT BRIGHTNESS to be determined.

The subject of any individual photo might have a wide range of brightnesses. Depending on circumstance & composition.

In the days before INCIDENT LIGHT READING was used to measure exposures: Light  meters used a system that measured REFLECTED LIGHT.

But: Which/What reflected light?

Manufacturers studied all kinds of photos & all kinds of photographic situations. They came to the conclusion that many photographs were taken in situations where the major subject of interest had a net reflectivity of 18% of the light that fell on it.

So many manufacturers set their meters so that if a person using it measured the average scene of 18% reflectivity & then set the meter accordingly, then the transparency (positive/slide) material in the camera would produce an image after regular processing that would have an average subject reflectivity of 18%.

Negative materials are calculated somewhat differently sometimes.

Incident Light Reading, which was invented somewhat later, reads the light falling on the subject & calculates the exposure somewhat differently. With hopefully equivalent results. 

Best Regards,

Michael