Free light meter iphone app

[goodgollymissmolly]

Doc, not to be repetitive, but don't worry about it because it will not function as an incident light meter. There are a number of places on the internet (try Rays, he might have it) that describe how to use a reflected light meter to estimate incident light. It requires that you measure off a white surface and set your camera to a specific aperture and use the recommended shutter speed to go to a table giving you incident light. Since you can not set the iPhone camera exposure manually or even see its exposure settings, then you can not do this.

This is a way more complex subject than you all are making it. You know that old saying, "....is bliss".

[BikerDoc5968]

Originally Posted by goodgollymissmolly

Doc, not to be repetitive, but don't worry about it because it will not function as an incident light meter. There are a number of places on the internet (try Rays, he might have it) that describe how to use a reflected light meter to estimate incident light. It requires that you measure off a white surface and set your camera to a specific aperture and use the recommended shutter speed to go to a table giving you incident light. Since you can not set the iPhone camera exposure manually or even see its exposure settings, then you can not do this.

This is a way more complex subject than you all are making it. You know that old saying, "....is bliss".

Yes, I know about using my camera. I used to use my Nikon F2 because I could set the ASA (ISO) to 25 as instructed in a book addressing this topic. the newer digital cameras don't go that low, so you have to adjust f stop and/or shutter speed to extrapolate the number.

[goodgollymissmolly]

Doc you're right except for two things. You can manually set the exposure values on the new digital cameras just as on your old film camera, but that isn't my point. What is being discussed here is an iPhone app.You cannot manually set or even see what the exposure settings are on an iPhone (or any other cell phone camera)...so you can not do what is being suggested in this thread. I hope I'm being clear, but I'm wondering.

[Phalguy]

For those like me on Android, the application exist! ;-)

Pocket Light Meter For The applications - Android

Claude

[BobInBonita]

I understand the difference between reflected and incident light, but do not understand why folks say the app won't work.

I think all you have to do is point the iPhone / Android / camera at a white sheet of paper (so the paper fills the field of view). You need to make the ISO or f-stop adjustments ONLY if you are using a camera. The app already reads in footcandles, so you shouldn't have to worry about that part.

If I'm wrong, please explain so I can understand.

[Amanda L]

That's awesome!!! Now if only my ipod touch had a camera!! Oh well, I guess I need to buy a new iPod! Hehehehehehe

[natasha]

i have installed both iphone app mentioned here but i have no idea how to use them... anybody can teach me how???

[ohho]

1. Click the lower left button to set the lock to Aperture or Shutter speed
2. Press + - to find a preferred Aperture-priority or Shutter-priority value
3. (optionally) set the ISO film speed
4. point the iPhone to a scene
5. watch reading changes, or touch the screen to freeze reading

[goodgollymissmolly]

Bob, because the camera meter is telling you what it sees. That's dependent on the aperture that is used for light measurement, but that is always less than the actual reflected light because even at wide open it's still dependent on the size of the hole.

However according to the post by ohho, you can see the aperture and shutter speed and possibly pick a value for one or the other. If that's true, then this will work at least to the extent that an SLR can be used to approximate incident light. Remember that even in the SLR case it is an approximation of incident light, but it might be useful for orchids since exact measurements are not necessary. It's an approximation because you need to be careful what you measure off of and it's properties. For example, white paper usually contains "whiteners" which are chemicals that absorb UV and re emit it as visible light. That makes the paper look whiter. Also there are some basic differences between incident and reflected meters that make them unique to each other. Nevertheless, if you can actually see the aperture and shutter speed, this might give you a usable value.

[Donald]

Well it works for me.