How do you determine if a Sekonic L28c2 light meter is accurate

[bob_dean]

I've had this meter for some time and it has always been in the case when not used.  I have used it when shooting with an old Nikon F with no light meter.  Knowing that the selenium cell can break down over time I would like to figure out if this one still works.  I have tried comparing it with metering results from a recently restored FE and come up with some really different values. I'm not sure if this is due to the different metering functions between the FE and the Sekonic.  Any thoughts?

Thanks

PS - I am currently shooting landscapes and so I'm also not sure that this meter can even properly function for the job.  If not would a Sekonic 308 work?

Edited October 19, 2022 by bob_dean
Clarification

[Niels - NHSN]

The Nikon will do a reflected light reading and the Sekonic will do an incident light reading.

To establish if these two readings are in alignment, you will need a surface of 18% reflectance and measure light reflected off that with the Nikon, and measure the light hitting that surface with the Sekonic.

If you don't have a gray card, you may use a (green) grass lawn for a rough estimation.

[c_watson1]

I'd be reluctant to trust a nearly 50 year-old selenium meter. Working meters aren't always accurate meters, especially this type, this old.

The Sekonic 308 is a great little incident meter. Have one and never had accuracy worries. The 500-600-700 series Sekonic spot/incident meters are also worth a look.

[bob_dean]

I just tried that experiment using what little green grass I have.  I pointed the Nikon at the grass and obtained a reading of between 1/30 and 1/60th of a second at f/8.  Next I took the Sekonic and held it close to the grass with the Lumisphere pointing up toward the sky and had to put in the H filter and then obtained a reading of between 1/250 and 1/500th of a second for f/8.  So then I took the H filter out and held the Sekonic close to the grass, ~12" off, and had the Lumisphere pointed towards the grass and obtained a reading of between 1/30 and 1/60th of a second for f/8.  

So is it correct to assume that the Sekonic is measuring accurately if my second measurement with it was the right way to do the experiment?   If so, I'm not sure how I would use the Sekonic for landscape photography.  Take lots of readings of the area with the Lumigrid and average it out??

Thanks for any help.

[John Seaman]

I don't know anything about your meter but I recently sold a Sekonic L398 which may be similar. It's a very old design based on the earlier Norwood Director. It responded strongly to light but I never got around to working out how to use the various attachments or interpret the various scales and markings, even though it came with the manual. So I was never able to confirm its accuracy - I sold it on this basis and the buyer was happy with it. I much prefer a simple meter, and have a number of old selenium meters which are easy to use and still accurate. There are of course plenty around which aren't accurate, or don't work at all. Here is the L398 kit I sold:

 

 

[bob_dean]

John, the 398 is just a slightly updated version of the L28c2. Basically the same thing with a couple of small differences.

So from what others are saying, there is no telling how accurate the L28 (?)is and maybe I should go and get a 308.  My question at this point is, will one of these incident meters work for landscape photography?  Or are they only for portraiture photography?  Being retired I do not have a big budget for the latest and greatest equipment so that is why I'm looking at older used equipment for film.

Thanks

[AJG]

A working incident meter should be fine for most landscape photography.  I haven't had a Sekonic L28 c2 for quite a while, but it was always reliable for me when I had it, including for shooting reversal color 16 mm movie film which is very exacting.  I have several other 1950's vintage selenium cell meters that still are reasonably accurate so I wouldn't discount them entirely except for low light conditions where they just aren't sensitive enough compared to modern silicon blue cell meters. My current studio mainstay is a Sekonic L 718 that I have used for the last 20 years.  I replace 2 AA batteries once or twice a year, but other than that no problems.  It also measures flash, so if that appeals to you at all it would be a good choice.  There is a 5 degree spot attachment for it, but that might be harder to find at this point.  You should be able to find one for around $100 used in decent condition from the usual sources.

[Niels - NHSN]

18 hours ago, bob_dean said:

I just tried that experiment using what little green grass I have.  I pointed the Nikon at the grass and obtained a reading of between 1/30 and 1/60th of a second at f/8.  Next I took the Sekonic and held it close to the grass with the Lumisphere pointing up toward the sky and had to put in the H filter and then obtained a reading of between 1/250 and 1/500th of a second for f/8.  So then I took the H filter out and held the Sekonic close to the grass, ~12" off, and had the Lumisphere pointed towards the grass and obtained a reading of between 1/30 and 1/60th of a second for f/8.  

So is it correct to assume that the Sekonic is measuring accurately if my second measurement with it was the right way to do the experiment?   If so, I'm not sure how I would use the Sekonic for landscape photography.  Take lots of readings of the area with the Lumigrid and average it out??

Thanks for any help.

Assuming both were set to same ISO, there appears to be a discrepancy, however I am not familiar with the exact meter and the H filter you mention, So I can't out-rule a user error.

You should definitely not point the dome towards the subject but at the source of light, typically relative to the placement of the camera.

A perhaps easier way to quickly check if either meter is off, is to use the Sunny16 rule. 

Set meter to ISO 125, A reading in direct sunlight (sun hitting the dome) should read around F:16 1/125.
Point your Nikon, also set to ISO 125, to a sunlit scene - the reading should be about the same.

There is generally no problem using a Incident meter for landscapes if the light at your position is the same as what hits the scene. If you are in the shade, and the scene is in the sun, you can use Sunny16 to compensate. In the opposite situation you can create shade over the meter - further compensation may be needed depending on brightness around the meter, but that is easily learned with experience.

The L308 is a great reliable meter if the one you have doesn't work - and it does allow for a wide field reflected meter reading should you need it.

[AJG]

3 minutes ago, NHSN said:

Assuming both were set to same ISO, there appears to be a discrepancy, however I am not familiar with the exact meter and the H filter you mention, So I can't out-rule a user error.

You should definitely not point the dome towards the subject but at the source of light, typically relative to the placement of the camera.

A perhaps easier way to quickly check if either meter is off, is to use the Sunny16 rule. 

Set meter to ISO 125, A reading in direct sunlight (sun hitting the dome) should read around F:16 1/125.
Point your Nikon, also set to ISO 125, to a sunlit scene - the reading should be about the same.

There is generally no problem using a Incident meter for landscapes if the light at your position is the same as what hits the scene. If you are in the shade, and the scene is in the sun, you can use Sunny16 to compensate. In the opposite situation you can create shade over the meter - further compensation may be needed depending on brightness around the meter, but that is easily learned with experience.

The L308 is a great reliable meter if the one you have doesn't work - and it does allow for a wide field reflected meter reading should you need it.

That particular Sekonic meter (and its variants) required the high slide for use in bright sunlight since otherwise the needle went off the scale, so using it outside would be normal correct procedure.  That meter also could accept specific slides made for movie productions where you always knew your shutter speed (1/50 for most professional movie cameras) and the ASA/ISO so that it read directly in f/stops, a great convenience.  I still have my set of these slides somewhere, but the meter went to a friend who lost almost everything in a fire a long time ago.

[bob_dean]

Thank you for the replies.  I will do some more experimentation with the L28 and see if I can more correctly determine its accuracy.  I am going to use it to shoot B&W with the Nikon F.   I have used it in the past to try and do some family photos but the kids get way too antsy and say jeez dad how long is this going to take : -)  Those photos were not bad but I think I could have been not using the meter quite properly.

 

[rodeo_joe1]

FWIW, my Studio L398 measured almost exactly 1 stop over when I first bought it. I fitted a circle of 0.3 ND gel under the cell cover-glass to get it accurate. Or at least agreeing with an assortment of other meters. 

A second - used and half-wrecked - example bought dirt cheap was also similarly optimistic. 

Also, a brand new Sekonic Lux meter of similar design (based on the same cell and meter body) showed very poor linearity in its meter movement and didn't correspond terribly well with a digital Lux meter or other incident meters. 

In short, my experience so far with Sekonic's Selenium-celled meters has been totally negative. Give me something with a CdS cell or photodiode in it any day. Even if it does need a new battery every year or so. 

Edited October 23, 2022 by rodeo_joe1

[SCL]

Meters have always seemed a bit of alchemy to me, given their sometimes different responses to the same scene. Thankfully, for B&W, the film latitude covers a lot of the spread. I've used selenium, CdS, analog and digital, handheld and in camera over the years. The trick, at least in my case has been to clearly note the metering coverage and pattern. Ultimately, I prefer incident metering if I am using a meter, regardless of whether the subject is a landscape or portrait. If I'm too lazy to brin a meter or the camera doesn't have one, I use a variation of the sunny 16 rule (The Jiffy Calculator), which I keep a copy of in my wallet, in my car, and in my camera bag, and it's never let me down. I acknowledge, that depending on one's latitude and country, sunny 16 might be better described as sunny 11 or sunn6 22, as the actual intensity does vary by location. In the continental USA, Sunny 16 has worked for me almost everywhere. To see if your meter is "accurate" the old measurement of GREEN grass or an 18% card or a scrap from the inside of a cereal box is a good starting point. Do some reading up on what a meter measures, because often you may need to make a manual adjustment based on the reflectance of a subject (assuming you are using a reflectance meter), much less so with an incident meter. Also, remember that the developer strength, choice, time and temperature will have an effect on the final product. Sorry for the long winded response, but I hope it helps.

[rodeo_joe1]

On 10/23/2022 at 6:34 PM, SCL said:

Meters have always seemed a bit of alchemy to me, given their sometimes different responses to the same scene.

That was certainly true of meters from the last millennium, with Selenium, CdS and early photodiode sensors all having a quite different spectral response curve. And very few were doped or filtered to a normalised response, because makers and users valued sensitivity over accuracy. 

Specially doped or filtered photodiodes, low-noise integrated amplifiers and digital displays have changed all that. It's not difficult to find meters that agree closely with each other these days. You've just got to ignore the allure of attractive-looking antiques that only belong in a display cabinet.

Mmmm, nice. Hmmm, impractical - 

Edited October 29, 2022 by rodeo_joe1

[glen_h]

On 10/29/2022 at 5:07 AM, rodeo_joe1 said:

(snip)

You've just got to ignore the allure of attractive-looking antiques that only belong in a display cabinet.

Mmmm, nice. Hmmm, impractical - 

 

I have a Canon VI (bought by my dad when I was about one).

There is a selenium cell meter designed to work with it, and couples to the

shutter speed knob.  It is just more fun to use with that meter.

 

The original one died decades ago, but I got a used one.

It works some of the time, and when it doesn't, a tap on the side

(or two) usually helps.  So far, it is usually (close enough to) right,

or nowhere close.

 

The thing about selenium cells, is that there has to be contacts

to the cell.  And those contacts are very sensitive.