How to calibrate a Gossen Luna Pro

<p>Remove Batteries, Zero meter. RE insert batteries. Remove aluminum cover plate with a double edge razor blade or with a sharp point knife. Take your time and don't bend or mar the cover. Don't loose the meter zero adjusting screw. It is the gray plastic one. it's a good idea to remove the neck strap.<br>

Remove the four brass screws as shown in photo.  Now turn the instrument over and carefully remove  the front half of the of the meter. Take notice of the diffusion cover and remove it and the black shield with a round hole in it  where the cds element is. When you press the low light part of the rocker switch, do it slowly and watch the transparent mirror not to let it fall out.</p>

<p>if you have purchased my magic disc and battery kit and have placed them in your unit as described you are ready to adjust and calibrate your meter. You already have zero ed the meter and now check the battery switch and and see where the level is. With new batteries it should read to the right end of the RED zone. If it doesn't<br>

turn the adjusting screw (potenciometer ) listed as (1) in the photom and set it to the far right in the red. You<br>

must turn the screw very, very slowly.<br>

Now you are ready to check for accuracy with an accurate meter, a digital camera is a good source.<br>

This is not for the faint of heart, you must be extremely patient. It takes me about 30 minutes.<br>

The two POTs on the left are for low light readings. The two on the right are for Hi light readings<br>

These work together to get the accurate readings.  If your low light reading is high, turn the inner POT very<br>

slowly and notice if you are going in the correct direction to get you reading. It is a good idea to make a chart<br>

with EV-3 and 2 Low..... Ev6 and 11 Hi   for the low end, Ev8 and 13.....Ev16 and 21 for the HI end.<br>

Adjust the low light to these readings and the high light to these readings. You may notice that when you adjust the POT you need for the reading you want and check the other end it has changed on you . YOu must go back and forth adjusting until you get it right. I was ready to pull my hair out before I finally realized what was going on.<br>

I finally got me a flouresenct light buld and a box and cut some filters out of 120 film blank and measured the<br>

light coming through the filters until I had four reading EV3, EV6, Ev8 and Ev16 and adjusted that way. Now if you mess up  don't blame me, send me your unit and I will adjust it for you. With a total of 11 units adjusted<br>

I am fairly capable to do the job.<br>

Now take a look at the photos.</p><div></div>

<p>Next Photo</p><div></div>

<p>More Photos</p><div></div>

<p>Hi Ron,<br>

Which Gossen light meter do you think is the best? I've never used handheld light meters before but I've been meaning to get one since I have some cameras that don't have meters built in or they are non functioning.</p>

<p>Al;<br>

I've used a good deal of meters and to say which is the be would be an overstatement. For me it would be one that was not too expensive, complicated and accurate. What fits the bill is the Gossen Luna Pro. It is two meters in one. For low light is where the Luna (moon) light come into play. It will read very low light, almost where you may stumble and fall the light is so dim. The other meter is for average day light. I have some what near a half dozen Luna Pro units. Three of which I have recalibrated to take the Silver Oxide 1.55v batteries, and it would be tough for me to give up any of them. I shoot with so many cameras that I will leave a unit in each case so I don't have to look for one.<br>

Minolta is another good meter. Sekonic is a must for me in the studio.<br>

You can find a good Gossen Luna Pro on the auction bay for about 25% of what one would cost new. The main reason they are so cheap is the Mercury battery problem. That problem has been solvel with battery adapters of which I have on the bay for sale now. Hey Al, I gotta go, Fed-ex is here with another Gossen<br>

Luna Pro meter. And by the way in my instructions above, that should read a Single edge razor blade. When the Germans made the Gossen they had real close tollerences on the back plate.</p>

<p>Argh! I took apart my meter and, typical of my efforts, some parts fell out that I can't figure out how to put back. One is the part shown in the photo, which would seem to fit in the slot between the opening in the meter housing and the sensor lens. It won't fit there, though, without binding the meter switch. the other are two tiny washers or spacers. They're quite small (smaller than the heads of the four long screws that hold the halves of the meter body together), sort of a clear amber color, and they seem to be made out of silicone. Can you offer any help on how to get these parts back to where they belong?</p>

<p>I'll try it again!</p><div></div>

<p>Do you know how to adjust a Luna Pro F? It uses a 9V battery.<br>

Thanks.</p>

<p>The part you have shown is the diffused glass mirror and in the bottom right corner is a slot that must go to the top right as you are using the meter. The bronze arm of the rocker switch goes through it. In order to get it on you must push the low light rocker switch about 3/4 way and turn the mirror straight up to get it on the switch arm. Now ease off on the rocker switch and place the corner of the mirror in the groove it goes in and as you ease off the rocker swithch guide the mirror to the left until it drops into place.</p>

<p>I haven't seen a luna pro F and would not have any idea on how to calibrate one until I get one cheap enough from the bayan tear into it.</p>

<p>I have a Luna Pro SBC that was off and there is one adjusting POT on the left front as you look at the back pointing it as if you were using it. The little screw in the center of the plate is the only one holding it on. The way I adjusted mine, I held it to a known light source that was measured with my digital Nikon D2x and while holding the measure button in I turned the adjustment until the center LED light up. that easy. It takes a 9v batt.</p>

<p>Thanks much for your help, Mr. Tincher. Now all I need to do is get three little dust "fuzzies" out of the dial!</p>

<p>Excellent, There are bunches on ebay now. I'm going to try and get one. I think it's ironic that the meter will give you a reading that you can't read unless you use a light to read it by!<br>

Thanks again Ron.</p>

<blockquote>

<p>How to calibrate a Gossen Luna Pro</p>

</blockquote>

<p>Send it to Quality Light Metric in Los Angeles.... </p>

<p>HI Ron</p>

<p>Thanks so much for this info and the pictures!<br>

I just came across this after posting elsewhere about an issue i have with a lunapro.<br>

It has a battery adapter kit for it. Its been working fine for a few weeks but yesterday i went to use it and it was giving me a reading in both low light and bright light settings in the same situation?<br /> I'm going to put a multimeter to the battery adapter tonight to make sure its not a voltage issue with the adapter but to behonest i would expect the metering to be off if the battery voltage was too low I wouldn't have expected the meter to produce a reading in either low or bright light settings.<br>

Would you have any idea what could be up with it?</p>

<p>thanks<br>

Brett</p>

<p>Igonre my question, i think i have the problem sorted ;)</p>

This is a pretty old thread. Today I was working on my Luna Pro, and its been years since I last worked on them. So I had forgotten. The meter switch on the right side opens a needle trap so the needle can swing freely. Once you take your reading you let go of the switch and the needle gets trapped at the reading you took. But here's my question I can't remember. Does that switch turn the meter on and off too? Or is the meter always on and depends on closing the case to preserve the battery? Thank you.

Oldie but goodie - glad to be reminded of it. My Luna-Pro could use little TLC

I've got a functioning Digital-Pro Digital, except I can't get the down button to work. The case clearly separates into two parts, but there are no screws holding them together and I'm afraid to insert a screwdriver and twist to separate the front and rear for fear of breaking the plastic pieces. Anybody have a hint?

The Luna-Pro is a real classic. Decades ago it was the "required" meter when I studied photo at RIT. I rebelled and used a Weston Ranger 9 that I truly loved, but it wasn't accurate and I got sub-par results much of the time. Shoulda went with the Luna-Pro. Much later I tried to calibrate it and discovered that a good calibration wasn't even possible. Better, but not as good as it should have been. IMO, the mercury battery problem hasn't been entirely solved in terms voltage accuracy, simplicity and long life.

 

My favorite meter these days is the Luna-Lux SBC. Super accurate, no stinkin' fragile meter to worry about and takes a common 9V battery.

Spell correction gets me every time. :D I'll try again. I've got a functioning Gossen Luna-Pro Digital, except I can't get the down button to work. The case clearly separates into two parts, but there are no screws holding them together and I'm afraid to insert a screwdriver and twist to separate the front and rear for fear of breaking the plastic pieces. Anybody have a hint?

Spell correction gets me every time. :D I'll try again. I've got a functioning Gossen Luna-Pro Digital, except I can't get the down button to work. The case clearly separates into two parts, but there are no screws holding them together and I'm afraid to insert a screwdriver and twist to separate the front and rear for fear of breaking the plastic pieces. Anybody have a hint?

No experience with that meter, SCL, but I've sprung apart a good many other fiendish plastic cases - some more successfully than others.

I think the 'key' to this one lies in the two rectangular recesses at underside front of the meter. I suspect that a small blade inserted and levered back (or forward) might spring a couple of plastic clips. Also examine the battery compartment for other clips or a screw.

 

Unfortunately, plastic 'spring' clips tend to get brittle over time, and even the action of initially pushing them together tends to weaken them. Therefore it's likely that levering the case apart might break one or more clips. So dismantling is entirely at your own risk.

 

All is not lost if the clips break, since most plastic cases can be held together with a contact adhesive like Evo Stik. This rubbery glue remains fairly pliable and can be slowly prised apart again if necessary. Or just tape around the edges of the case with adhesive tape.

 

Sorry, no surefire remedy here. But good luck!

Thanks Rodeo Joe - you nailed it! The bottom recesses are for attaching a lanyard and I hadn't thought that was a separation point for the case. My hat's off to you!

'Twas a lucky guess.