Is my incident meter correct?

marcmarc · Feb 25, 2013

Hi Everyone,
I've been using a Sekonic L508 for years. I've noticed that it reads 1/2 stop slow when comparing it to "sunny 16" i.e. it will read f16 and 1/2 at 1/125 rather then an even 16 when I use FP4. However, when I take the iso down to 100, it then reads an even f16 at 1/125. The difference between iso 125 and 100 is about 1/3 of a stop correct? So is my meter under exposing? I normally down rate my film at half the box speed anyways but still my negs look a little thin in the shadows. Thanks for replies.
Regard,
Marc

nicholai · Feb 25, 2013

To my best knowledge, sunny 16 applies to ISO 100, so your meter should be good?

markbarendt · Feb 25, 2013

Couple thoughts.

Your negatives are only thin in the shadows if they don't let you print the shadow detail you want, how does it look on paper?

Sunny 16 assumes a front lit subject, if the subject is instead cross lit, backlit, or the sun is really high in the sky, like a Lahaina Noon where the sun is directly overhead the meter should indicate differently.

Jim Noel · Feb 25, 2013

Sunny 16 applies to films of any speed.
It is not unusual for a meter whether incident or reflective to disagree with it. Like all other rules in photography, rules are meant to be broken. Clouds, atmospheric haze, smog and other abnormalities in the air will alter the amount of light falling on the subject. If your negatives please you, don't worry about the meter. If the readings are close to the Sunny 16 rule you are OK. If it begins to vary a lot then you need to worry about it.

benjiboy · Feb 25, 2013

The Sekonic L508 light meter is more likely to be accurate than your sunny sixteen.

Chan Tran · Feb 25, 2013

My meter would read f/11 and 2/3 @ 1/125 with ISO 100.

marcmarc · Feb 25, 2013

Thanks for the quick replies. I always side with the meter and my thin negs could just be shutter variances of course. Here in LA where it's mostly bright and sunny throughout the year, sunny 16 I figured would be a starting point to see of my meter might be off.

marcmarc · Feb 25, 2013

I forgot to add that this meter has been around the block quite a bit and has been dropped once or twice so I have no idea if something has been knocked loose which may affect its reading.

Marc B. · Feb 25, 2013

Speaking of light meters, living in the LA/Hollywood area, you're lucky.
Contact the folks at 'Quality Light Metric' for light meter repairs/calibration.
Word has it, they do a lot of work on photog's meters at the studios.

Quality Light Metric Co
7095 Hollywood Blvd # 550
Los Angeles, California 90028

Ph# (323) 467-2265

Peltigera · Feb 26, 2013

If Sunny 16 were both accurate and reliable, no one would use a meter, would they? If the meter was several stops away from Sunny 16 I might worry but not for part of a stop.

Also, in LA, I would expect Sunny 16 to overexpose somewhat as "sunny" is going to be a lot brighter than in a northern state or in Europe.

marcmarc · Feb 26, 2013

Thanks for the additional replies Marc B and Peltigera. I'll contact Quality Light Metric just to be safe. If my meter checks out OK, then I know it's a shutter variance.

BrianShaw · Feb 26, 2013

There are many factors, a lot of which have been already mentioned, that makes Sunny-16 only approximate. It isn't just shutter variation that will cause what you are experiencing. But getting shutters checked is as easy (maybe even easier) than getting your light meter checked.

Check this out for more details on exposure approximation factors:
(there was a url link here which no longer exists)

benjiboy · Feb 26, 2013

marcmarc said:
Thanks for the additional replies Marc B and Peltigera. I'll contact Quality Light Metric just to be safe. If my meter checks out OK, then I know it's a shutter variance.

Or failure of your sunny sixteen guestimate.

George Collier · Feb 28, 2013

To benjiboy's point - I think the sunny 16's biggest variation is in our own judgement of the conditions - the only sure condition is "bright sun", as soon as there are clouds, the conditions get gray (pun intended).
As an inappropriate aside, the other day (I was using a d*****l camera) I was shooting in an empty church, lights low to balance intensity with late afternoon window lighting. ASA was 200, I was exposing manually with a 28PC Nikkor. Took a reading with my trusty old Sekonic L-398 Studio. The exposure was f/16 at 5 seconds, and although I had expected to make an adjustment, the image was perfect.
As a variation on Deming's well known saying, "In incident we trust, all others be careful."

Jim Noel · Feb 28, 2013

I live in San Diego.
Through testing I have discovered that except during Santa Ana winds, it is closer to Sunny f11, than Sunny f 16.
As several have said, it is only a ball park estimate at best.

Poisson Du Jour · Feb 28, 2013

The Sunny 16 rule is an approximation only, at best, an estimation which must be used with experience.

BTW, is the meter set to 0.3 or 0.5 stop reading in its custom functions? Customised readout is one of the biggest causes of confusion with Sekonics because there is no visible warning on the display that a core metric has been altered, other than to realise the exposure steps at wider or narrower. Having said that, it is most unlikely that the Sekonic is at error with its metering: it is very fine and precise instrument. People really should move on from these cute, clubby, "rules of thumb" that only provide for increasing risk and failure and not refinement of metering technique that is so much a calling when armed with a Sekonic.

John Koehrer · Mar 1, 2013

Another factor to consider is your EI. if you haven't determined it. the film/developer/exposure combination can be off too.
Rather than equipment problems I'd consider exposure/development first. If the exposure is consistently a bit under It may be you're using too high a film speed.

As far as Sunny 16 being an approximation. so is any system is until tested and proven.

cliveh · Mar 1, 2013

marcmarc said:
Hi Everyone,
I've been using a Sekonic L508 for years. I've noticed that it reads 1/2 stop slow when comparing it to "sunny 16" i.e. it will read f16 and 1/2 at 1/125 rather then an even 16 when I use FP4. However, when I take the iso down to 100, it then reads an even f16 at 1/125. The difference between iso 125 and 100 is about 1/3 of a stop correct? So is my meter under exposing? I normally down rate my film at half the box speed anyways but still my negs look a little thin in the shadows. Thanks for replies.
Regard,
Marc

Without experience of using your meter with camera/ lighting ratio of what you photograph and the processed shots you produce, I would suggest this is an impossible question to answer.

benjiboy · Mar 16, 2013

George Collier said:
To benjiboy's point - I think the sunny 16's biggest variation is in our own judgement of the conditions - the only sure condition is "bright sun", as soon as there are clouds, the conditions get gray (pun intended).
As an inappropriate aside, the other day (I was using a d*****l camera) I was shooting in an empty church, lights low to balance intensity with late afternoon window lighting. ASA was 200, I was exposing manually with a 28PC Nikkor. Took a reading with my trusty old Sekonic L-398 Studio. The exposure was f/16 at 5 seconds, and although I had expected to make an adjustment, the image was perfect.
As a variation on Deming's well known saying, "In incident we trust, all others be careful."

I've always thought George that the human eye is a very poor instrument for judging changes in light intensity because it reacts to changes so imperceptibly without the person noticing them.

Is my incident meter correct?

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