Light meters with reflective, incident and spot metering

138S · Jan 17, 2021

Sirius Glass said:
I never disputed why the dome is needed for incident readings and I have pointed out that some situations are best handled using incident readings.

+1

I totally agree, because of that some Sekonic meters are made to operate both spot and incident. Still a particular photograher may have prefer one mode or the other in some particular situation. Often, if shot is complex and important, we may even consider both readings to take a wise decision.

Sirius Glass said:
My point is that all of ones light meters should be calibrated for accuracy and consistency.

Yes... but regarding Apps using the on-screen light sensor we have a "problem", some phones have a diffuser on the light sensors and deliver a reading that's always very close to the one a (say) Sekonic incident would deliver, while other phones lack that diffuser and is reading is very directional, being very extra sensitive to the rays that come quite perpendicular to the screen, and less to the others rays.

Alan Edward Klein said:
In fact, if you select the wrong 1 degree to read, you'll get a worse reading than if you used center metering or matrix metering.

Of course, spot mode usually requires inspecting several spots and taking a decision, or spoting a well selected 1 degree, plus adding a correction. For example we may spot a very light caucasian skin and then adding two stops for the key illuminated cheek.

Sirius Glass · Jan 17, 2021

138S said:
+1

I totally agree, because of that some Sekonic meters are made to operate both spot and incident. Still a particular photograher may have prefer one mode or the other in some particular situation. Often, if shot is complex and important, we may even consider both readings to take a wise decision.

Yes... but regarding Apps using the on-screen light sensor we have a "problem", some phones have a diffuser on the light sensors and deliver a reading that's always very close to the one a (say) Sekonic incident would deliver, while other phones lack that diffuser and is reading is very directional, being very extra sensitive to the rays that come quite perpendicular to the screen, and less to the others rays.

Of course, spot mode usually requires inspecting several spots and taking a decision, or spoting a well selected 1 degree, plus adding a correction. For example we may spot a very light caucasian skin and then adding two stops for the key illuminated cheek.

Basically so-called smart phones are expensive and light meters are cheap, I would rather have high end light meters which meet my needs and leave the phone to be used as a phone ===> such a concept. Besides I can send my light meters off to be calibrated but I will not send my phone off.

Arthurwg · Jan 17, 2021

Lachlan Young said:
I really have no idea why people want to make metering as difficult as possible - they should be able to get a more than sufficiently accurate exposure with one meter reading, two if they really need to know the contrast range.

Reminds me of fly fishing. It's much easier to catch a trout with a worm, but that's too easy. Tying flies in winter with keep you busy, and using them in the spring will prove that you are smarter than the fish.

Arthurwg · Jan 17, 2021

BTW. Hasselblad's meter prism PME 45 provides reflective, spot and incident readings. It even has a dome on top. Mine cost me a good deal of money but packed up and can't be fixed.

138S · Jan 17, 2021

Sirius Glass said:
Basically so-called smart phones are expensive and light meters are cheap, I would rather have high end light meters which meet my needs and leave the phone to be used as a phone ===> such a concept. Besides I can send my light meters off to be calibrated but I will not send my phone off.

At all, we don't need a phone or the incident reading, an spot reading on a piece of R-27 gray card is a perfect incident metering, it is the way I have used a lot.

But, personally, I've the phone always in my pocket. I also use it to take notes of the image, I also take a shot with the phone, then I edit that image to write on it the over/under exposure of the spot metered areas, I use an stylus (for touch screen). I also write the scheduled N+/-, which I also write in a label on the holder.

After developing the negative sometimes I check densities in the metered areas and I also write that density in the digital image with the stylus. This is quite useful to me when learning a new film/processing.

That way I get very good and convenient feedback. Describing the spot metering in a paper sheet takes a lot of literature, easily annotating the spot reading on the image is a joy compared, so this way I also take more notes.

Alan Edward Klein · Jan 17, 2021

Arthurwg said:
Reminds me of fly fishing. It's much easier to catch a trout with a worm, but that's too easy. Tying flies in winter with keep you busy, and using them in the spring will prove that you are smarter than the fish.

I took up 4x5 large format photography this year. Harder than fly fishing. It's a pleasure when I go on vacation, I just take my little P&S, switch it to "P" auto mode, and shoot away. My pictures come out great and I make a wonderful slide show when I get home. Well, that part is like tying flies.

wiltw · Jan 17, 2021

138S said:
At all, we don't need a phone or the incident reading, an spot reading on a piece of R-27 gray card is a perfect incident metering, it is the way I have used a lot..

To wake the ogre asleep in the cave...a grey card is NOT necessarily consistent in the reading it produces!
Here the gray card can provide different brightnesses, as captured with one f/stop and shutter speed!

From two different camera angles (two different 'scenes' at 180 degrees to one another, but both at the same location -- my backyard-- and same time of day with consistent lighting)...this points out the need for some degree of consistency in how the card is angled.

Nevertheless, 138S, a great methodology to use modern tools to assist with a arduous task of documenting your techniques behind a photo, using your phone. especially if you can exploit the speed of voice input of text!

Mainecoonmaniac · Jan 17, 2021

Alan Edward Klein said:
I know what you mean. But to clarify it for those who might not, spot meters andother meters all have the same "precision". The meter provides readings that are at the same accuracy. All spot meters do is narrow how much area they are reading to let's say 1-degree wide angle. That doesn't make them more precise. In fact, if you select the wrong 1 degree to read, you'll get a worse reading than if you used center metering or matrix metering.

That’s for your elaboration! The reading is so granular, it could be erroneous.

Sirius Glass · Jan 17, 2021

Alan Edward Klein said:
I know what you mean. But to clarify it for those who might not, spot meters andother meters all have the same "precision". The meter provides readings that are at the same accuracy. All spot meters do is narrow how much area they are reading to let's say 1-degree wide angle. That doesn't make them more precise. In fact, if you select the wrong 1 degree to read, you'll get a worse reading than if you used center metering or matrix metering.

Ah, that is why one needs to look through the eye piece and aim at the same place.

Lachlan Young · Jan 17, 2021

It's also a whole lot easier to take an incident reading or a highlight indexed spot reading than it is to get a sufficiently accurate reading off a grey card!

Sirius Glass · Jan 17, 2021

Lachlan Young said:
It's also a whole lot easier to take an incident reading or a highlight indexed spot reading than it is to get a sufficiently accurate reading off a grey card!

I have used incidence, reflectance and spot meters, even metered of my hand while taking snow photographs but I never used a grey card [never even owned one] but then I have only been doing this for 60+ years.

Lachlan Young · Jan 17, 2021

Sirius Glass said:
I have used incidence, reflectance and spot meters, even metered of my hand while taking snow photographs but I never used a grey card [never even owned one] but then I have only been doing this for 60+ years.

The only real reason to have a grey card is for certain specific repro/ reference purposes - and even then, a Q-13 or Q-14 are often more useful.

Sirius Glass · Jan 17, 2021

Sirius Glass said:
I have used incidence, reflectance and spot meters, even metered of my hand while taking snow photographs but I never used a grey card [never even owned one] but then I have only been doing this for 60+ years.

Lachlan Young said:
The only real reason to have a grey card is for certain specific repro/ reference purposes - and even then, a Q-13 or Q-14 are often more useful.

For that I would use a color card instead of a grey card.

Alan Edward Klein · Jan 17, 2021

That gray card test done above raises an interesting question. If you can get so many exposure settings from the same reflectance object, how do you know you're getting the right reading from the object in the actual space you're measuring?

Lachlan Young · Jan 17, 2021

Sirius Glass said:
For that I would use a color card instead of a grey card.

Yes - hence the Q-13 etc - it makes life much, much easier when handed art repro transparencies for example.

Lachlan Young · Jan 17, 2021

Alan Edward Klein said:
That gray card test done above raises an interesting question. If you can get so many exposure settings from the same reflectance object, how do you know you're getting the right reading from the object in the actual space you're measuring?

If you use highlight/ shadow keying methods, all you're doing is attempting to reproduce the scene/ object as it appears to you (as will highlight/ shadow keying with an incident meter) - the problem with the grey card is that it's only 'correct' under a narrow aspect of use.

wiltw · Jan 17, 2021

Alan Edward Klein said:
That gray card test done above raises an interesting question. If you can get so many exposure settings from the same reflectance object, how do you know you're getting the right reading from the object in the actual space you're measuring?

Kodak come up with a very specific instructions to minimize the variability which I depicted earlier...few today are aware of the variability of brightness of the gray card, or the specifics of the Kodak instruction. (Unforunately, while I have the 1948 Kodak Gray Card and also a 1977 Kodak Gray Card, neither have the instructions on dealing with angle of the card to avoid card surface sheen.)

Someone put what was (as cliamed) Kodaks' instruction on Wiipedia. I cannot attest to the validity it is Kodaks recommendation:

"To establish the exposure for a photograph Kodak recommends placing the gray card as close to the subject as possible and "aiming the surface of the gray card toward a point one third of the compound angle between the camera and the main light. For example, if the main light is located 30 degrees to the side and 45 degrees up from the camera-to subject axis, aim the card 10 degrees to the side and 15 degrees up."

This is a Kodak Gray Card of 2007, and its instruction and illustration about aiming of the Gray Card seems to be consistent with the Wikipedia text.

https://www.zonephoto.it/images/pdf/kodak-grey-card1903061.pdf

138S · Jan 18, 2021

wiltw said:
To wake the ogre asleep in the cave...a grey card is NOT necessarily consistent in the reading it produces!
Here the gray card can provide different brightnesses, as captured with one f/stop and shutter speed!

Yes, but this is perfectly fine. If you tilt-swing an expensive Sekonic also under directional light then you'll also get the the shift in the reading. In fact you do that for portraiture to measure the key and the fill components, and you do both with the card and with the incident meter.

Both the Gray Card and the Incident meter have selective sensitivity to the orientation, the Gray Card is more selective, but this is not good or bad, for example when wanting to meter Key vs Fill the card provides better direct readings, but the card requires to be better oriented if we want a single basic reading.

While the incident meter reads worse the key/fill also the photographer may correct that from feedback, so problem is not big.

In the card instructions it is explained how to orient the card for a single basic reading, then we may tilt-swing the card to better understand the light nature we have. That variability in the reading is extremly useful to meter the diffuse vs directional components, to realize what light nature we have in the field, and to adjust light in the studio.

The Grey Card also provides the neutral color at the exposure level, while the white reverse provides neutrality at around +2.5. In a session it can be extremly useful to spend one shot with the card in the framing. A bare white sheet also is useful for that.

138S · Jan 18, 2021

Alan Edward Klein said:
how do you know you're getting the right reading from the object in the actual space you're measuring?

As wiltw mentioned, you have the instructions in the pdf, for a single basic reading.

A R-27 Gray Card is a reflectiveness standard, many of the finest photographers had always one at hand.

But as we all know illumination is a very complex mater. In practice we have several illuminations sources at the same time, with different directions and differently difussed, and this has an interaction with different face orientations in the subjects that can be more glossy or mate, beyond color intrinsics.

Both with an incident meter with a Dome or with the grey card we can get both the single basic reading or an advanced light nature metering (key vs fill, for example). The Incident meter is more convenient while the Grey Card is a more precise tool to explore the power in different directions.

The prestige Sekonic meters have accumulated speaks on their own, they are wonderful tools,

...but a R-27 Grey Card piece:

> substitutes perfectly an incident meter if not having one, or not wanting to haul it around in the field.

> a perfect choice for those wanting incident metering only from time to time, which are the most.

> it is lightweight.

> it is cheap, someone starting has perfect incident metering if he also has a $20 plastic SLR, or a DSLR.

> it provides a neutral reference (technically flat spectrum) at the metered exposure.

> it is a better choice for advanced understanding of the illumination nature.

Lachlan Young · Jan 18, 2021

Or you can just use the highlight index on a lightweight handheld 1o spotmeter to get reliable readings of highlight keyed exposure (same as incident) without wasting time fiddling with a grey card and TTL meters that are awkward to usefully index.

And unless you know what the midtone index of a particular meter is set to, you can be out by 1/2 stop - even if you hold the card correctly.

Realistically, a grey card is more useful as a perceptual midtone reference than as a means of determining exposure.

Alan Edward Klein · Jan 18, 2021

wiltw said:
Kodak come up with a very specific instructions to minimize the variability which I depicted earlier...few today are aware of the variability of brightness of the gray card, or the specifics of the Kodak instruction. (Unforunately, while I have the 1948 Kodak Gray Card and also a 1977 Kodak Gray Card, neither have the instructions on dealing with angle of the card to avoid card surface sheen.)

Someone put what was (as cliamed) Kodaks' instruction on Wiipedia. I cannot attest to the validity it is Kodaks recommendation:

"To establish the exposure for a photograph Kodak recommends placing the gray card as close to the subject as possible and "aiming the surface of the gray card toward a point one third of the compound angle between the camera and the main light. For example, if the main light is located 30 degrees to the side and 45 degrees up from the camera-to subject axis, aim the card 10 degrees to the side and 15 degrees up."

This is a Kodak Gray Card of 2007, and its instruction and illustration about aiming of the Gray Card seems to be consistent with the Wikipedia text.

https://www.zonephoto.it/images/pdf/kodak-grey-card1903061.pdf

Thanks for providing that information I have that same card and instructions somewhere in one of my cases. Here's the instructions from that card regarding using it in daylight:

ln daylight, orient the gray card the same way as recommended for artificial light using the sun as the main light. in shade, under overcast skies, or in backlighted Situations, use the brightest area in front of the subject, usually the sky, as the main light. in daylight, you can make the meter reading of the card located at the subject or at another position, such as near the camera, as long as the card receives the same illumination as the subject and is oriented correctly, the same way as you would orient the card at the subject position.

So my original question is repeated. If we need to orient the angle of the gray card to get the "correct" reading, would the angle of the natural object we're-reading also have different readings based on the angle to the sun? Would that reading be more affected by a 1-degree spot since you're only measuring one object rather than let's say center metering (assuming you've selected the correct center)?

Alan Edward Klein · Jan 18, 2021

To simplify my question. Would a reading of an object be the same with a 1-degree spot meter if the sun's angles are different? Could that change the setting you choose?

Bob S · Jan 18, 2021

Alan Edward Klein said:
Thanks for providing that information I have that same card and instructions somewhere in one of my cases. Here's the instructions from that card regarding using it in daylight:

ln daylight, orient the gray card the same way as recommended for artificial light using the sun as the main light. in shade, under overcast skies, or in backlighted Situations, use the brightest area in front of the subject, usually the sky, as the main light. in daylight, you can make the meter reading of the card located at the subject or at another position, such as near the camera, as long as the card receives the same illumination as the subject and is oriented correctly, the same way as you would orient the card at the subject position.

So my original question is repeated. If we need to orient the angle of the gray card to get the "correct" reading, would the angle of the natural object we're-reading also have different readings based on the angle to the sun? Would that reading be more affected by a 1-degree spot since you're only measuring one object rather than let's say center metering (assuming you've selected the correct center)?

Cardboard gray cards get dirty, can not be cleaned and some change color with time, heat and light.
The most accurate ones are the Zebra cards from Novoflex, and, since the base is a plastic, they are easy to keep clean and they can’t change color or hue.

Alan Edward Klein · Jan 18, 2021

Bob S said:
Cardboard gray cards get dirty, can not be cleaned and some change color with time, heat and light.
The most accurate ones are the Zebra cards from Novoflex, and, since the base is a plastic, they are easy to keep clean and they can’t change color or hue.

Doesn't plastic cause problems due to its reflectivity?

Bob S · Jan 18, 2021

Alan Edward Klein said:
Doesn't plastic cause problems due to its reflectivity?

Not with the finish on the Zebra. Go to the Novoflex site and learn about them

Light meters with reflective, incident and spot metering

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