Lumu Power Meter Review

As I promised this is a quick review of the Lumu Power Meter from Lumu.

I had originally planned on doing an in-depth review of the meter but after I wrote the entire review I decided that I will let the test images speak for themselves.

Since I’m going to use this in my normal workflow I decided to take it in and tested in normal every day scenarios that fit my workflow. Each of the tests were done in places that I would normally shoot in and in lighting that I would normally encounter on a daily basis.

To make the testing easier, I am going to stick to the following equipment list:

  • Nikon D5
  • Nikon 24-70mm f/2.8
  • WhiBal cards in both pocket & medium size
  • x-rite ColorChecker Passport
  • Lumu Power Meter
  • Minolta Auto Meter Vf (flash) for ambient readings
  • iPhone 6 Plus (secondary device) also used for notes & voice recording
White Balance Cards

When it comes to white balance cards, the first thing you need to realize is that not all/most cards are truly neutral. Most cards advertise themselves at 18% grey for exposure and that they can be used for white balancing. Let me be perfectly clear, 18% cards are not for white balancing, they are for exposure readings. In order to properly white balance you need to have a truly neutral card. In order to be neutral, card needs to have all three RGB colors be exactly the same (or as close as possible) as this example shows.

Also, any card that has texture may skew the final results of the white balance. Also, any half-toning (example right) in the color of the card can also skew the final result. You want a WB card that is a smooth as possible. The WhiBal and xRite ColorChecker Passport are two examples of perfectly neutral cards that are smooth as possible (examples left) .

My normal workflow consists of getting the white balance reading either at the beginning or the end of my shoot, using the WhiBal card, and entering that white balance into Lightroom during editing. I have found this to be the quickest method since I do not have to worry about getting a white balance reading at different times unless there is a major shift in the lighting.

For these specific tests I used both the Lumu Meter and xRite ColorChecker Passport or the WhiBal card to demonstrate the consistency between the three. Since I trust the WhiBal card and the ColorChecker Passport to provide proper white balance, I knew that if the Lumu meter showed similar results that I could use it in my daily workflow. Also, if you use the ColorChecker Passport along with the Lumu you can also get a proper camera profile to help with coloring rendition.

The first test I did was for exposure metering. I found a Lumu to be consistent with my Minolta Vf. The Lumu required a small EV adjustment to equal the Minolta reading but I did not find this to be a problem as all meters should be able to be adjusted.

I did find that placing the Lumu in full-stop metering with decimal points showing was more consistent with what I was used to with the Minolta meter. But this is a personal preference that can easily be changed.

Before I start the testing I should note the following, the Lumu Power Meter app allows the green/magenta shift scale to be changed to any amount that you desire. This means that you can set the scale to any number that fits your workflow. Since my workflow consists of using Lightroom I have set the Lumu scale to +/-150 since that is white Lightroom uses in the green/magenta tint scale.

Since different camera makers use a different green/magenta scale you can change it to whatever your camera uses. For example, Canon uses a nine-point scale while Nikon uses different scales such as six-points for the older cameras and 24-points for the newer cameras. This is only necessary if you want to use in-camera green/magenta adjustments only.

All the RAW files used for the following tests will be available for downloading at the following link so you can test them for yourselves.

WB Tests RAW Files for Testing (462MB zip file)

Tests

Tungsten

This was a simple tungsten spot lamp at a restaurant.

All three methods determine the Kelvin temperature to be within 100-200K degrees of each other. The Lumu was consistently on the lower end while the WhiBal was the higher of the three.

Fluorescent & CFL

Unfortunately, there are hundreds, if not thousands, of fluorescent & CFL variations out there. There is no way to test them all. I have included three different ones that I have found on my daily workflow.

This is where the Lumu really shines. The Kelvin readings were almost exactly the same, and in some cases exactly the same, as the WhiBal and the ColorChecker Passport. Adding camera profile from the ColorChecker Passport really made the files come to life.

LED

LEDs are also so varied that it is impossible to properly test. I have heard from other users that there is an accuracy problem with the Lumu and LED lights. After my tests I cannot determine if this is a problem with the Lumu or the lights themselves.

First test was done at a high school gym that was recently upgraded to LED lighting. It is unknown what type or what the actual Kelvin temperature these lights are. But I did find a slight variance between the Lumu and the WhiBal/ColorChecker. The difference was about 400K. I find the Lumu to be more accurate but this could be a personal preference or bias. There is also a possibility that the proximity of the cards/meter to the floor cause a shift in color balance from the reflection of the floor. 

The second test was from conventional LED lightbulbs found at most retail stores. These lights are rated at 2800K with a CRI of about 80-85 (not the best color rendition).

The readings from all three were within a very close margin. Using the reading from the Lumu along with the camera profile created from the ColorChecker Passport created a very realistic image file.

Average scale (AVG)

The Lumu app has a feature called AVG (average) that shows a graphical scale of the color temperature reading for the time that you ran the test. I found it to be very useful to determine the best WB reading. I often used the average reading as the actual temperature reading fluctuated about 20-60K. This graph can be pinched-zoomed after you hit the “stop” on the meter function. It can zoom up to the smallest degree so you can really see the precise average.

Conclusion

I found the Lumu to be extremely accurate in the normal tests that I performed. These tests were done in a way to replicate my daily workflow and how I would use it to determine a WB. Since the Lumu came so close to both the WhiBal and the ColorChecker Passport, I will have no problems integrating it to my workflow.

Things I would like to see
  • The app has a note-taking feature. Notes take too long to create since they are a three-part process. I don’t mind keeping that but add a faster method where a simple photo is taken and, automatically, the data is added to it and either saved to Roll or iCloud or Google Drive.
  • The average WB scale gets lost sometimes, not sure if due to iOS or app. The pinch-zoom needs to reset every single time.
  • Be able to keep a screenshot, either in notes or by itself, of the average WB window. This is a very helpful feature.
  • Add camera specific G/M scales. Either by default or be able to create presets that can be edited/named.

 

FTC Disclamer: I paid for all items in this review and were kept after this review was concluded. None were provided to me or loaned. There is no relationship whatsoever with any of the companies mentioned in this review. No requests were made by any of these companies for a review. My review is based on my personal opinion and method of use is based on my own workflow and therefore may be different from yours.