{"id":78,"date":"2009-03-08T09:59:25","date_gmt":"2009-03-08T14:59:25","guid":{"rendered":"http:\/\/existentialmonkey.com\/blog\/?p=78"},"modified":"2019-01-27T05:41:46","modified_gmt":"2019-01-27T11:41:46","slug":"on-light-meters","status":"publish","type":"post","link":"http:\/\/existentialmonkey.com\/blog\/on-light-meters\/","title":{"rendered":"On Light Meters"},"content":{"rendered":"

Someone I know just bought a vintage Yashica TLR and was met with the realization that we’ve become all too accustomed to our cameras all having built-in light meters these days. So what do you need to know when it’s time to consider a light meter?<\/p>\n

A side note: You’ll find people ’round the web that just say “you don’t need a light meter, you’ve got one built in to your DSLR, just use it.” Here’s my list of why that doesn’t always work out so well.
\n1) If the DSLR is in the vehicle, or at home it’s of no use.
\n2) It’s awkward as hell to use one camera just to meter a scene then set up the other camera for the shot. I’ve done it (did it yesterday, in fact) but it’s still a pain in the neck.
\n3) Built-in meters are reflective. If you want to do an incident metering (read on for explanation) forget it. Flash metering, forget it.
\n4) If your DSLR ISO range doesn’t go where you need to match the film you’re using in the film camera, you’ve got to compensate and adjust accordingly. It’s not a huge deal, and you should know how to do it, but if you goof, you’ve blown the shot.<\/p>\n

Close side note. On with the post.<\/p>\n

Excluding things like cinematographic and color temperature meters, light meters basically fall into two groups: reflective and incidence.<\/p>\n

Modern cameras utilize reflective metering. They meter the light reflected from the subject through the lens and onto the metering sensor. Obviously a scene can have different levels of light coming from different parts of the scene. Back in the old analog days, the most basic camera meters just averaged out all the light hitting the sensor. Higher end sensor systems would either totally ignore parts of the scene and only meter an area in the middle, or would average the entire scene, but bias the average toward the light in the center (center-weighted metering).<\/p>\n

Now on to a modern camera. Nikon calls their full-frame scheme Matrix metering. Canon refers to it as Evaluative metering. These are more advanced than basic full-frame averaging in that they look at the entire scene, but then do some magical computer-camera stuff to arrive at the “perfect” exposure. The D300 manual recommends it \u201cin most situations\u201d, but I don\u2019t use it much. Any time the camera is doing “magical computer-camera stuff” I feel left out. I tend to use center-weighted metering or spot metering.<\/p>\n

Imagine the situation where you are trying to shoot a subject with very dark skin wearing light-colored clothing in front of a very light background. Using full-frame, or even center-weighted metering will result in the dark skin tones being very underexposed since it will try to meter the lighter clothing and background for perfect exposure. This is where spot metering comes in. Set spot metering, put your focus point on the subjects face and it will meter for those levels. Obviously everything else will now be over-exposed, but the subject\u2019s face will be nicely exposed.<\/p>\n

Incidence metering is different in that you meter the light at the subject, as opposed to the light reflected from the subject. Flash meters are incident meters. With an incident meter, you stand with the meter detector facing the camera position and meter the light falling on the scene. Many will have a semi-spherical, semi-translucent cover over the sensor to detect a more 3-dimensional coverage of light instead of the light coming directly at the sensor.<\/p>\n

The most critical choice factor for reflective vs. incidence metering comes down to whether or not you can physically get at the subject. A landscape or any other distant subject requires reflective metering. For a portrait you could use either reflective or incidence metering.<\/p>\n

When metering for flash, if you’re not using a flash meter, you’re pretty much limited to automatic control of the flashes for the camera and flashes working together to set exposure and flash levels, or you’ve got to shoot and review the shot (preferably with the histogram<\/a>) to see if you need to make adjustments.<\/p>\n

So on to hand-held meters.<\/p>\n

When it comes to buying a hand-held meter, your first choice is whether to get a vintage or modern meter.<\/p>\n

Vintage meters are cool and there are people that collect them just like vintage cameras. The main drawback to vintage meters is that most used a selenium cell to operate. Selenium is photo-voltaic and generates a voltage proportional to light exposure. Over time however, the selenium degrades to the point that the meter no longer works. Repair at that point is cost-prohibitive. They still look cool, but they’ve given up their functionality at that point. It is significant to continue looking cool though.<\/p>\n

There is a ton of great information on various vintage meters at James’ Light Meter Collection<\/a>. Lots of good background on lots of cool vintage meters.<\/p>\n

eBay is a good place to get vintage meters<\/a>, and the prices tend to be reasonable. I would recommend buying meters only from people that understand what they are and how they work, and confirm the meter is in functional condition, though there’s nothing to guarantee that a meter that works today won’t die next month.<\/p>\n

I have a General Electric DW-58<\/a> that I paid $20 for in an antique store. That was definitely more than it was worth, but with no shipping costs and being able to test it right there, I decided to get it because I needed a meter to travel with my Yashcia Mat. It will do both reflective and 2D incidence metering and is within about 1\/3 stop of being correct when checked against my D300.<\/p>\n

If you don\u2019t want the hassle of a vintage meter and the fact it might be dead next month, modern meters are the way to go.<\/p>\n

One advantage to a modern meter is that most offer flash metering as well. The digital meters respond quickly enough to the flash and have a digital readout that\u2019s not limited by an analog needle. I\u2019ve recently read a discussion that made the point that metering flash is completely unnecessary because modern cameras do everything automatically and blah, blah, blah. I\u2019m personally not a huge fan of \u201call-automatic\u201d because I like to know and control everything in my shot. Full-auto (through-the-lens, or TTL) flash metering has it\u2019s place, and I use it sometimes, but it\u2019s not my mainstay. Plus, if you\u2019re using manual studio strobes, or want to work with a vintage camera, then you\u2019re back to flash metering.<\/p>\n

I use a Sekonic L-358 Flash Master<\/a>. $259 at B&H<\/a>. It will do reflective, incidence, and flash metering and I’ve been happy with it so far. The reason I bought the L-358 instead of the less expensive L-308S<\/a> is because the L-358 will calculate flash\/ambient ratios and will also allow aperture priority metering.<\/p>\n

If you just want a very basic analog reflective \/ incidence meter, the Sekonic L-208 Twin Mate<\/a> is the least expensive I know of at $99 from B&H<\/a>. I had considered one of these until I decided that I wanted flash metering capabilities also and it wouldn\u2019t do much more for me than the GE DW-58 I already had.<\/p>\n

They also make reflective spot meters<\/a>, but they are pricey. My D300 has spot metering and I figure if I\u2019m ever in need of a spot measurement when I’m using something besides the D300, I can pull it out of the bag and use it to meter. If I don\u2019t have it with me, I\u2019ll do my best using the meters I have and make my best eyeball estimate from there.<\/p>\n

All metering aside, in a pinch (and at no cost), you can always use the Sunny 16 rule. Brian Auer has very nice explanation<\/a> at his blog Epic Edits.<\/p>\n

Further reading:<\/p>\n