Phone light meter app

jusxusfanatic · Aug 5, 2016

How do I use it? Look at the picture I attached, it was done in my room, and after I inserted the numbers on my dslr to see what it's gonna look like, I just see a black screen as I already predicted it's gonna be like that. How does the app work? Thanks
Did it on my dslr first so that I won't mess up the whole roll

The way I look at it:

250 = shutter speed
ISO 100 (of course)
EV = exposure value = F stop

Andrew O'Neill · Aug 5, 2016

Just downloaded the same app. Set the ISO. Tap the little red button at the top right. What you are pointing your phone at will appear in the white dome in the middle of the meter. You can zoom in and out with the little slider sticking out at the bottom. Zoom in on the area you want to measure and press the measure button. It'll make a shutter clicking sound, the dial will move a bit giving you you shutter/aperture combos. Simple.

jusxusfanatic · Aug 5, 2016

Andrew O'Neill said:
Just downloaded the same app. Set the ISO. Tap the little red button at the top right. What you are pointing your phone at will appear in the white dome in the middle of the meter. You can zoom in and out with the little slider sticking out at the bottom. Zoom in on the area you want to measure and press the measure button. It'll make a shutter clicking sound, the dial will move a bit giving you you shutter/aperture combos. Simple.

Ahh so you have to take a pic no wonder. Thanks

AgX · Aug 5, 2016

Exposure value is NOT F-stop

Exposure value is a relation between exposure time and F-stop, representing the object luminance.

EV 0 = 1sec @ F-stop 1

or

EV 0 = 2sec @ F-stop 1.4

or

EV 1 = 1/2sec @ F-stop 1

etc., etc.

jusxusfanatic · Aug 5, 2016

Andrew O'Neill said:
Just downloaded the same app. Set the ISO. Tap the little red button at the top right. What you are pointing your phone at will appear in the white dome in the middle of the meter. You can zoom in and out with the little slider sticking out at the bottom. Zoom in on the area you want to measure and press the measure button. It'll make a shutter clicking sound, the dial will move a bit giving you you shutter/aperture combos. Simple.

Yea I know the aperture, but which one's the shutter!

jusxusfanatic · Aug 5, 2016

Oh so Exposure Value is also the shutter in this case?

AgX · Aug 5, 2016

Neither.
It is just a one-number representation of the object luminance. Today it enables us to speak in easy terms of the object luminance, or of the sensitivity of a meter (eg. EV-2 @ ISO 100 @ 1.4 lens)

In the past many german leaf shutters had an EV-dial. You brought over the EV-reading from the meter to that dial and by this mechanically the appropriate ratio between time and F-stop at the shutter was automatically set. By this you could set either of the two without bothering for the other or to look again at the meter-scale.

jusxusfanatic · Aug 5, 2016

AgX said:
Neither.
It is just a one-number representation of the object luminance. Today it enables us to speak in easy terms of the luminance, or the sensitivity of a meter (eg. EV-2 @ ISO 100 @ 1.4 lens)

In the past many german sghutters had a EV-dial. You brought over the EV-reading from the meter to that scale and by this the appropriate ratio between time and F-stop at the sutter was automatically set. By this you could set either of the two without botheering forv the other or look again at the meter-scale.

Alright thanks!

goros · Aug 5, 2016

Also, the red button at the top right corner switches from incident (I) to reflected (R) light reading. The reflected light measure is done through the phone camera, but the incident light measure is done through the sensor that adjusts the screen intensity, so the smart phone must have that functionality.

jusxusfanatic · Aug 5, 2016

goros said:
Also, the red button at the top right corner switches from incident (I) to reflected (R) light reading. The reflected light measure is done through the phone camera, but the incident light measure is done through the sensor that adjusts the screen intensity, so the smart phone must have that functionality.

Yep I know!

Helinophoto · Aug 5, 2016

I would recommend that you use the "Pocket light meter" app on the iPhone.

It shows you -live, how the shot will look like, and the corresponding values.

Easy as pie.

jusxusfanatic · Aug 5, 2016

Helinophoto said:
I would recommend that you use the "Pocket light meter" app on the iPhone.

It shows you -live, how the shoot will look like, and the corresponding values.

Easy as pie.View attachment 161332

Wow that's nice Shame that I use an android

jusxusfanatic · Aug 5, 2016

Oh they have it on android thanks

etn · Aug 9, 2016

A quick side note:
I compared those apps to my spot meter and was amazed that the readings were in general within +/- 1EV
of what the spot meter said. So plenty accurate enough for B&W or color negative film.
If you shoot slide you might want something a bit more accurate (such as a spot meter).

Helinophoto · Aug 9, 2016

I saw that as well, when I compared the "Pocket light meter" to my spot meter on my Canon 1v, spot on on a white wall in a room.

The cool thing about the pocket light meter, is that you can select what you would prioritize and see how the skies go, when you lift the shadows.
If you then shoot c-41, you can gauge how far up the skies are and if they would be within the range, while keeping the shadows pretty detailed, i do this very often to avoid blocked shadows and underexposure with c-41.

Huss · Aug 10, 2016

I have found the Pocket Light meter to be very unreliable so I have stopped using it.
Here, the correct exposure is 1/60 at f4 at ISO 50. The app shows 1/1500 at f4. Missed by over 4 stops!... This is in open shade.

Helinophoto · Aug 11, 2016

Huss said:
I have found the Pocket Light meter to be very unreliable so I have stopped using it.
Here, the correct exposure is 1/60 at f4 at ISO 50. The app shows 1/1500 at f4. Missed by over 4 stops!... This is in open shade.

That is weird, you are aware that the pocket-lightmeter operates as a reflective reading and not incident metering?

Also you foot seems to be fairly close to the metering area, I think it's more center-weighted than sharply cut, as indicated by the borders of the metering area.

I've googled around a lot to see, and I have yet to find any discrepancies that are more than +-1 EV with this app. (on an iPhone)
What phone are you using, maybe it's related to that?

farmersteve · Aug 11, 2016

Funny this comes up. I just did a comparison to the Pocket Light meter against 2 analog and 1 digital camera and a real pocket light meter. Canon A-1, Canon Elan 7n and a Sony a6000 all similar lenses and f stops and they were all within less than a stop from each other on a variety of surfaces. I have about 3 light meters on my iphone and the Pocket Light Meter is my favorite since you can take a picture of the scene and store it for later to compare to the film picture you would take of the same scene with all the meter settings.

zanxion72 · Aug 11, 2016

I use the Pocket Light meter too. I have noticed that sometimes, rarely, it hangs (misbehaves, how to call it) and reports a way off reading. I restart it and it reads back normally.I use it on iOS 7.

jeffreyg · Aug 11, 2016

Plus another for the Pocket Light meter app. I used to take two light meters when traveling just in case. But with the accuracy of that app it has become the backup. Another good use for the phone camera is the gps recording of the location. I made a bracket to hold my phone on the hot shoe of my camera so I can conveniently take a shot of the location I captured on film.

http://www.jeffreyglasser.com/

TheFlyingCamera · Aug 11, 2016

Another vote for Pocket Light Meter. About the only scenario I wouldn't trust it in is extreme low light, and that may just be psychological bias and not based on any real world thing. It is always within acceptable variation of both my Sekonic 408 and my Minolta Spotmeter F.

DWThomas · Aug 11, 2016

(Still learning -- even at my advanced age ... )
Your screen shot looked different than what I have been seeing -- but now I discover I have the display set to "old style" instead of the wheels. (Didn't even remember there was an option!) Don't know if that has anything to do with anything!
The process of managing iPhone Apps via iTunes on the desktop seems needlessly obscure! ) But after a few gyrations trying to avoid albums of music, I finally found my Pocket Light Meter app appears to be version 9.3.3 -- and my apps are normally auto-updated so it should be the latest

In any event, I don't use the app all that much and have not tested it exhaustively, but when I have tried it, the results seemed reasonable. The log feature can be cool when wandering about, as it saves a view of what you were pointing the meter at, date, time, and even GPS location. (After all, my Perkeo II doesn't generate EXIFs!)

Huss · Aug 11, 2016

Helinophoto said:
That is weird, you are aware that the pocket-lightmeter operates as a reflective reading and not incident metering?

Also you foot seems to be fairly close to the metering area, I think it's more center-weighted than sharply cut, as indicated by the borders of the metering area.

I've googled around a lot to see, and I have yet to find any discrepancies that are more than +-1 EV with this app. (on an iPhone)
What phone are you using, maybe it's related to that?

1/ Yes, I am aware as to how it works
2/ If it read off my foot, the reading would still be over 4 stops off.
3/ Iphone 4s

Anyway, if others are happy with it, good for them. I've seen it give lousy readings occasionally which means I cannot trust it. So I don't use it.

jeffreyg · Aug 11, 2016

I notice your illustration is showing 6176 Kelvin. I am under the impression that most daylight color films are balanced for 5000 kelvin. Could that be the difference you are finding? My version doesn't show white balance or kelvin reading. It may be an older version and my tests against my spot meters and ultra pro are as others have reported are very close.
http://www.jeffreyglasser.com/

Huss · Aug 11, 2016

jeffreyg said:
I notice your illustration is showing 6176 Kelvin. I am under the impression that most daylight color films are balanced for 5000 kelvin. Could that be the difference you are finding? My version doesn't show white balance or kelvin reading. It may be an older version and my tests against my spot meters and ultra pro are as others have reported are very close.
http://www.jeffreyglasser.com/

The app uses the AWB of the camera phone so it will naturally warm up the image if used in the shade. As in this instance. You can turn it off in the settings.
Daylight colour film used in the shade will have cool tones etc etc etc

Phone light meter app

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