Who repairs and calibrates S.E.I. photometers ?

[spookyphoto]

Anybody know anyone that repairs, calibrates or who have spare parts for S.E. I. photometers ?

Thanks in advance

 

[Bill Burk]

I tinker with them. Some of mine are only good for parts. The selenium cell is a weak part. I only have one good cell. The filter assemblies are also dicey. I probably have only one with a good set of filters. The battery chamber and bulb is a reliable part. I only have one bad one, the rest are fine.

What’s off with yours?

 

[koraks]

The selenium cell is a weak part.

I've never owned a SEI Photometer, but I always understood these to be extinction meters that do not rely on any cell, but instead use a calibrated light source (tiny bulb) and filters as a basis for visual comparison with part of the scene.

Maybe the same manufacturer also made later models that were regular meters based on a photocell?

Some online resources on the SEI Photometer as I know it and refer to above:

SEI Photometer - ROBERTSUOMALA.COM

robertsuomala.com

www.robertsuomala.com

James's Light Meter Collection: SEI Photometer

A few words about the SEI Photometer.

www.jollinger.com

 

[spookyphoto]

I tinker with them. Some of mine are only good for parts. The selenium cell is a weak part. I only have one good cell. The filter assemblies are also dicey. I probably have only one with a good set of filters. The battery chamber and bulb is a reliable part. I only have one bad one, the rest are fine.

What’s off with yours?

Getting ready to pick one up this afternoon. I used to have 3 of them 50 years ago but stupidly let them go. At the time I think i might have gotten the last anti flare tube and bulb housing that was available. I'll let you know how it goes after I pick it up

 

[Bill Burk]

I've never owned a SEI Photometer, but I always understood these to be extinction meters that do not rely on any cell, but instead use a calibrated light source (tiny bulb) and filters as a basis for visual comparison with part of the scene.

Maybe the same manufacturer also made later models that were regular meters based on a photocell?

Some online resources on the SEI Photometer as I know it and refer to above:

SEI Photometer - ROBERTSUOMALA.COM

robertsuomala.com

www.robertsuomala.com

James's Light Meter Collection: SEI Photometer

A few words about the SEI Photometer.

www.jollinger.com

They use a calibrated light source, true.

The bulb gets electricity from one regular D size 1.5 volt battery. In some models you are expected to remove the outer paper wrapper. I use a cheap D to AA adapter carved to be small enough to fit the chamber. A rheostat in the bottom cap adjusts bulb brightness. The selenium cell (always weak or dead) points down at the bulb, and is wired to the ammeter on top. Once you adjust bulb brightness to the standard mark, it's ready to use.

From then it's a "grease spot comparator" with a tiny dot of yellowish light (or blue by a filter) that you make darker or lighter over 1.0 density range by turning the handle. There are two opposing graduated neutral density filter strips that move in and out by a gear. The whole unit can read over 3.0 density range because of ND filters you kick in and out between the bulb and spot, and in front of the scene image.

The scene is upside down in the "telescope".

For my meters which can't reach the standard mark, I'll draw a new standard mark (or tape a sticker on the glass) lower than the original. For the ones that don't work at all, I'll use an external "standard" light source, dial in the known luminance on the scales and then adjust bulb brightness to match.

I tend not to use them "in the field" but more around the house, in the back yard to look at the moon. For example, I take three working SEI and measure the moon, and come back to the light source and match the light... then meter the light with a Sekonic spotmeter.

 

[koraks]

That's so cool! Thanks for sharing @Bill Burk

The whole unit can read over 3.0 density range because of ND filters you kick in and out between the bulb and spot, and in front of the scene image.

Yeah, I can also imagine it's this bit that's sensitive; either the mechanism locking up and/or filters going bad due to environmental conditions. Is that indeed what tends to happen with these?

 

[Bill Burk]

The filters get wrinkly for sure, and I have to assume fade over time. One of mine the filter switching mechanism is stiff, but the others are reliable. One had a battery corrode in the chamber which really made a mess of things and I believe yellowed the opposing neutral density wedges. The prism with mirror spot is pretty reliable, only one of mine has missing silver in the spot. I was able to swap out that section with a better one, but not every unit is compatible some of the screw holes and meters are arranged differently.

 

[spookyphoto]

I lucked out. Picked up one an hour ago from an ad in marketplace for $ 50. Figured it didn't work but I would take a look anyway. When I looked at it I couldn't get any movement of the calibration needle. I couldn't get to the bulb to check if the problem was the bulb or the sensor. Decided to buy it anyway as it was essentially mint. I took it home and took it apart and with a little cleaning of the contact points it now works perfectly. Can get the needle to the calibration point easily.
50 years ago when I was in school at I.U. I was reading the book "Exposure Manual" by Dunn & Wakefield who were the developer of the meter. I asked my prof. if he had ever seen one before. The next day he marched into my darkroom and handed me 3 of them and said "Just go ahead and keep them. I about fell on the floor. After leaving school and a few years later I decided to give them back to him. It was just too nice a gift. I've been kicking myself ever since

 

[Bill Burk]

Well great news! I would still confirm the calibration against a light source/ other meters because the selenium cell could easily be weaker than it used to be, making you overdrive the bulb a little past a true calibration. Pencil mark on scotch tape will make an easily movable substitute mark as you try a few different estimates