Light meter iphone and Fuji x100s

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gabrielcik

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Hello,

I installed on my iphone the pocket light meter app with the idea to use it for metering my Leica IIIf.
I tested the measurement on my Fuji X100s and the photo were coming quite underexposed.

So I decided to use the measurement of the Fuji for to take photos with the Leica...
I got the film few days ago and well photo appear to be overexposed :D

So my question:
is it normal that the correct light meter settings change according to the camera? (maybe according to the sensor size?)

I just wonder why the settings offered by the iphone would return a correct exposition on the leica and a completely underexposed result on the fuji...

Thank you:)
 
What measurement is each taking?

Spot, evaluative, incident, reflective & others. Both phone and camera set the same way? Same time both photos made?

I use film for black and white only. Quite a bit of leeway with so many variables. Although, for color, I use RAW capture for digital which, I find, has a fair amount of leeway.
 
gabrielcik said:
Hello,

I installed on my iphone the pocket light meter app with the idea to use it for metering my Leica IIIf.
I tested the measurement on my Fuji X100s and the photo were coming quite underexposed.

So I decided to use the measurement of the Fuji for to take photos with the Leica...
I got the film few days ago and well photo appear to be overexposed :D

So my question:
is it normal that the correct light meter settings change according to the camera? (maybe according to the sensor size?)

I just wonder why the settings offered by the iphone would return a correct exposition on the leica and a completely underexposed result on the fuji...

Thank you:)
Click to expand...

I briefly used the app Lightmeter but have given up on it as it was highly unreliable. Weird as it uses the iPhone's camera's light meter as it's own. The phone takes properly exposed pics, which shows the defect is with the app.
 
gabrielcik said:
Hello,

So my question:
is it normal that the correct light meter settings change according to the camera? (maybe according to the sensor size?)

I just wonder why the settings offered by the iphone would return a correct exposition on the leica and a completely underexposed result on the fuji...

Thank you:)
Click to expand...

Yes, this is entirely normal. Different brands, as well as different models from the same brand, will evaluate light differently.

I suspect the similarity to your phone App and the film result was a happy coincidence.

There are several reasons for theses sort of differences. Details below.


While photographers think of ISO solely in terms of light sensitivity, ISO stands for International Organization for Standardization whose *headquarters are in Switzerland. The International Organization for Standardization defines performance standards for a wide variety of products in many industries besides camera manufacturers. The International Organization for Standardization published procedures for how ISO is defined and measured for film and for sensors. The film and digital standards are completely unrelated and are not intended to correlate with each other.

The Japanese camera industry conforms to completely different ISO standards defined by the Camera & Imaging Products Association, CIPA, guidelines. These guidelines state members of CIPA must measure sensitivity using either the Standard Output Sensitivity (SOS) or Recommended Exposure Index (REI) methods.

At the risk of causing further confusion, DX0 instead uses yet another measurement, based on so-called saturation based sensitivity, which is not approved for use by CIPA.

Here's a useful article on how come comparing ISOs is usually frustrating.
 
gabrielcik said:
So my question:
is it normal that the correct light meter settings change according to the camera? (maybe according to the sensor size?)

I just wonder why the settings offered by the iphone would return a correct exposition on the leica and a completely underexposed result on the fuji...

Thank you:)
Click to expand...

Light can be measured in a number of ways, in various units of measurement.

In the old days, one either measured light for photography with an incident meter or a reflective meter. That means you either measured the light reflecting off your subject or the light as it falls on your subject.

Later, in-camera metering became available, and from there, many ways to measure the light reflected from your scene.

From simple averaging to specific 'spot' metering, things only got more complicated from there, as modern-day cameras incorporated computer power to calculate 'correct' exposure based on many variables and fit them into predefined algorithms. For example, unless overridden, your camera might calculate exposure for a landscape differently than it would meter a portrait, even given the same amount of light reflecting back into the camera lens.

This would tend to explain your circumstances; two devices measuring light differently based on different algorithms. A light meter app *should* simply measure reflected (or incident) light, and that could also explain the differences you experienced. Also, I tried an app the other day and noticed that the ISO was easy to change to another value without meaning to. Perhaps the ISO was set incorrectly.

For those new to photography who have never had to deal with the complexities of light measurement, I would recommend trying to learn some of the basics, perhaps with the use of the manual settings on their camera and the use of a dedicated light meter, even if just to get the basic hang of it and a good feel for what to expect when your camera or your phone meters light for a camera.
 
I've used Pocket Light Meter on my iPhone 4s, and on an iPod Touch, on and off for about 5 years and found it to be very reliable - if anything, it tends to "expose for the shadows" a bit in a way that works well for b&w film & old cameras. I've not used it for more demanding applications.

Note that the recommended exposure does change depending on where in the frame the little orange focus point box is placed - if you try it again, try to place the box on a mid-tone.

I've retired iPhone metering in favor of the Voigtlander VC ii, which is one of the best photography purchases I ever made.
 
I use the app and it's important the area covered when metering, the lens on the iPhone is a 28mm equivalent.
It seems to agree with my X-E1 when metering carefully
I have both normal and Pro versions and use it for pinhole too
 
I'll now say something that Fuji fans wont like to hear:

In the 3 months that I've owned my x100s, I've screwed up half of my photos due to wrong exposure. Still not sure what it is: my guess is that the Fuji center spot is _very_ narrow, and depending on the scene you can get 5 stops or more exposure error by only slightly moving the camera. Not what I am used to from my other film or digital cameras. That combined with the fact that the x100s exposure compensation dial is really easy to move accidentally, makes the camera a pain to use. I now am trying to shoot in A mode with wider, center-weighted metering, hope it will improve.

In a nutshell: trust your iphone, not the Fuji. Occasionally, verify with sunny 16.

Roland.
 
In my X-E1 (Fuji) the metering is very good.
I use multi mode normally and spot ocassionally.
Of course, depending on lighting, I have to use exp comp from multi metering
But I'm always using the EVF and seeing what's going on... not sure what you mean...
And using spot metering, moving the camera will result always in a significant change, because it is narrow, as it has to be...
 
ferider said:
In the 3 months that I've owned my x100s, I've screwed up half of my photos due to wrong exposure. Still not sure what it is: my guess is that the Fuji center spot is _very_ narrow, and depending on the scene you can get 5 stops or more exposure error by only slightly moving the camera. Not what I am used to from my other film or digital cameras. That combined with the fact that the x100s exposure compensation dial is really easy to move accidentally, makes the camera a pain to use. I now am trying to shoot in A mode with wider, center-weighted metering, hope it will improve.
Click to expand...


The X100S does not have a center weighted metering mode.

Sounds like you were using spot metering (2%) and have switched to multi mode.

Are you using the DR200 or DR400 modes? If you are and shooting RAW with a RAW developer that ignores those settings you need to apply a 1 or 2 stop boost to the files.

The XP1s metering isn't quite to the level of my Nikons but it certainly does better than 50% of the time.

Shawn
 
I used Pocket Light Meter on my iPhone 5, and it agreed with my Luna-Pro and my Leica-Meter MC, but not with my dad's old Sekonic L-6. I just got an iPhone 6s, and I haven't tried it on the 6s yet. I hope it's still accurate on the new hardware.

Scott
 
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I compared the iPhone light meter apps (using the iPhone camera, no diffusor) to my camera. Pointing into the exact same direction, I'm getting:

EV 6.3 -- camera meter
EV 6.5 -- LUMU iPhone app
EV 7.5 -- Luxi iPhone app
EV 8 -- Pocket Light Meter app

Lumu is always spot on. Don't forget that you can always calibrate the app.
 
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