Gossen Profisix Problems. . . ?

Jmqx · Aug 22, 2009

Hi all,

I have recently acquired a gossen profisix light meter which I intend on using with my Spotmatic F, however I have come across a problem:

Following the instructions to take an incident reading I set ASA speed, then point and take a reading, then turn the outside dial to match the exposure needle to the correct exposure.

However, should I then not be able to vary f-stop and shutter speeds and receive corresponding movements on the needle as to the exposure - such as can be done on the camera itself? currently the only needle movment i get corresponds to movement of the outer ring, none of the others seem to do anything. Of course I am doing all of this during the 30 second limit, and the same applies when taking a continuous reading.

Am I missing something here?!

If you can help, please do!

gmikol · Aug 22, 2009

Jmqx said:
Am I missing something here?!

Yes, you are missing something...the manual.
http://www.gossen-photo.de/pdf/ba_profisix_e.pdf

Here's the condensed version: Once you have the needle reading "0", then look at the how the shutter and aperture rings line up. Every single possible equivalent exposure is displayed for you there. Pick an aperture, read the corresponding shutter speed. Pick a shutter speed, read the corresponding aperture. Need +1 stop exposure? Turn the dial so the needle reads +1, and then pick your shutter/aperture combination.

Hope this helps.

--Greg

Jesper · Aug 22, 2009

I may have misunderstood your question, but it seems to me that your meter is working correctly.

Step 1. Set the ASA speed
Step 2. Take the measurement (direct or incident doesn't matter)
Step 3. Turn the outer wheel so that the needle matches the 0 in the middle.
Step 4. Read the exposure time for the selected f-stop or the other way around.

Remember that the numbers 1-3 on both sides of the 0 does not indicate full stops but 1/3 stops.
If you prefer to set the needle exactly at 0 or if you set it to time/f-stop close to it and read the 1/3-stops from the display is a matter of personal preference.
Hope this helps. The Profisix is an excellent meter.

chriscrawfordphoto · Aug 22, 2009

Nope, thats not how handheld meters work. The needle points to a number, you turn the dial to that number then it presents a range of aperture/shutter combinations that all give the correct exposure. Choose one based on how much depth of field or action stopping capability you need, shoot photo.

AgX · Aug 22, 2009

Jesper said:
Remember that the numbers 1-3 on both sides of the 0 does not indicate full stops but 1/3 stops.

The digits are representing full stops.
The dots are representing 1/3 stops.

AgX · Aug 22, 2009

Chris,

The Profisix works differently than the meters you refer to.

chriscrawfordphoto · Aug 23, 2009

AgX said:
Chris,

The Profisix works differently than the meters you refer to.

Isn't it the same as the Luna Pro? or is it the one with the null-metering needle like the Luna Pro SBC?

Ian Grant · Aug 23, 2009

Chris the problem is that sometimes confusion arises because Gossen sold the same meter with one name for the US (North American) market and another in Europe & elsewhere.

The Profisix is the Luna Pro SBC, I have one, as well as a plain Luna Pro which is quite different.

Ian

Jesper · Aug 23, 2009

The Profisix and Lunapro does not work in the same way. You have the same kind of EV scale that you find on Lunasix, Lunasix III and Luna Pro as well but most owners of Profisix read the time/f-stop combination (unless they shoot Hasselblad).
Basically the Profisix works just like any older meter but what I think may be somewhat bewildering is the markings of 1-2-3 next to the needle instead of 1/3 -2/3 - 3/3 which would be easier to understand. It is easy to see the numbers as full stops and not 1/3.

You can easily check this by taking a measurement, setting the needle to 0, read the time for your selected f-stop and then turn the needle to 3 and read the time once more. You will find that it is one step from your first reading and not three.
At least this is the way mine works.

Mick Fagan · Aug 23, 2009

Jesper, I don't think you may have explained it quite correctly, maybe you are misunderstanding the Profi-six meter and the dial(s) on the unit.

AgX is correct in that the numbered lines are full stops and the dots are 1/3 of a stop.

I just measured my LCD computer screen which is showing this thread. The reading at 100 ASA with the meter nulled to the 0 is 1/60 at f4, moving it across to 1 on the right side it reads 1/60 at f2.8, moving across another line to 2 it reads 1/60 at f2 and finally across to 3 it reads 1/60 at f1.4.

The little dots in-between the numbered lines refer to 1 DIN increments, which is the German system that was still fairly dominant when this meter first came onto the market. Three DIN numbers equal 1 full stop, which is why (I assume) nearly all light meters give measuring increments in 1/3 of a stop, they just do not explain that this also is 1 DIN.

Perhaps it is in the fine print of the manual. However as my manual is in German because I bought the meter in Germany, I cannot read the fine print. Also I have had the meter for around 25 years and really don't consult the manual anymore.

The DIN measurements are actually what I use, they give you a real possibility of getting more accurate film speeds with the readings allowing you to adjust your aperture scale on the lens, to a setting that is as close as possible to your metered, or desired, shutter speed f/stop combination.

Mick.

Jesper · Aug 23, 2009

I've only had mine for 10 years but it has worked flawlessly all the time.
Since we are both getting correct exposure (I don't think you would have continued yours for 25 years if you didn't).

One easy check is to take one reading, move the needle to 3 and you will see that you have moved 1 stop and not 3.
Maybe I have another version, but that is the way mine works.

Mick, I have no reason to doubt your measurements and if so, then the numbers on your meter really are full stops.
But I know what I get from my own meter, and on that one the numbers really are 1/3-stops. Doing the same kind of test that you did veryfies this.
I bought my meter second hand so I have not had it since it was new. Maybe Gossen made different meters or you could have this changed later.

It is definetely more logical to have the numbers represent full stops but it is hard to argue with the evidence you hold in your hand. Maybe we have someone from Gossen on this forum who can shed some light on this matter. I have alwasy assumed that my Profisix worked the way others did (mine is serial # 3D98261).

Ian Grant · Aug 23, 2009

Mick's right about the 1/3rd of a stop increments and I remember using German LF lenses that had 1/3 stop click's on the aperture setting. In contrast only one of my Copal shutters (on my Gradagon 90mm) has markings for 1/3 of a stop.

Sorry Jasper but you are quite wrong the numbers either side of the 0 used for the null reading are whole stops, and clearly marked as such in the meter's handbook. See attached

Ian

Mick Fagan · Aug 23, 2009

Jesper, as a result of your last post I backtracked and downloaded the Profi-six manual, for which a link was provided earlier.

On page 27 there is a scene brightness range explanation, which, as the manual states, covers 6 f/stops, which are subdivided into 1/3 f/stops.

Somehow I think you either have a different or doctored scale, or your meter is a bit different to any other Profi-six meter I have seen.

My serial number is 5D28106 and I bought it in southern Germany at the start of 1985 so it's only 24½ years old, not 25

You and the OP, may like to know that the various accessories available for this meter are brilliant and well thought out. Having the odd one or two attachments greatly enhances the capability of the meter, as well as making some things more easy when measuring.

Mick.

Mick Fagan · Aug 23, 2009

Ian, brilliant!

That is page 27 of the manual, I wish I had the computer nouse to enable me to find something like that and post it.

Mick.

Jesper · Aug 23, 2009

As I wrote, I do not doubt Mick's readings. However, when I do the same test it supports my previous posts.
Either Gossen sold two diffrent versions, or you could have this changed later. Since I have not seen anything about two different versions in the Gossen documentation I assume it has been modified later.

I have used my Profisix since I bought it. Mostly in combination with a Minolta Spotmeter (I am mostly shooting 8x10). Both meters have been giving me accurate readings (as far as you can compare a spotmeter with a 30degree meter) and the negatives confirm this.

I could post a film of the way my meter works, but I would have to get some kind of digital camera first. It is however quite simple, move the needle three steps and the time/f-stop scale will have moved one step.
It would be nice if we could get someone from Gossen to explain this.

Ian, it is nice to have click stops at 1/3 stop on your shutters, but it has very little do do with the way a Profisix works.

Ian Grant · Aug 23, 2009

Jesper said:
Ian, it is nice to have click stops at 1/3 stop on your shutters, but it has very little do do with the way a Profisix works.

They were designed to work together, the Profisix had a TTL probe for LF cameras, the German Compur shutter had 1/3rd click stops.

So it has everything to do with how a Profisix can work

Ian

Jesper · Aug 23, 2009

Sorry Ian. The fact that both the shutter and the meter are having 1/3 stops is not evidence that the needle can only have numbers representing full stops. I have a Zeiss 21/2,8 that also has 1/3 click stops. Does that also prove the same point, or a different one?

1. There is no post claiming that the Profisix does NOT do measurement in 1/3 stops.
2. The question now is if it is another version or if it is a modification after sale.

The meter I have is in all outer aspects the same as the one in the manual and in the old prospects and that is why I assumed that it works like all others. The scale is the same.
The movement of the needle however is not the same as it moves to three when the time is changed one step.

I will not turn this into "I am right, you are wrong" discussion (there are other forums for that). If you have constructive information please help us out (what serial do you have? do you know anyone else? Do you know anyone who is working with meter service or something like that who can shed some light on this?)

Jesper

Ian Grant · Aug 23, 2009

A far more likely explanation is that it's faulty, no-ones saying you wrong. Most good camera repair companies should be able to check and adjust a Gossen meter, but there are meter specialists, and Gossen in Germany offer their own repair & re-calibration service. It may just be a very simple adjustment is needed.

I use my Luna Pro SBC when I'm in the UK and I really like the simplicity of the scene brightness scale, it's useful, I use it with a 15°/7.5° attachment

My point about the 1/3rd stops is that these meter's are true precision instrument, and certainly German manufacturers often give us more control over exposure compared to some Japanese manufacturers.

Ian

Q.G. · Aug 23, 2009

I have never seen or heard of a Profisix that behaves like yours, Jesper.
So i tend to side with Ian's suspicion that your Profisix is faulty.

Jesper · Aug 23, 2009

Either it is a night scene or sun on snow it has given me correct readings all the ten years I've had it. One would expect it to be off in all but one (at least) type of reading if it is a faulty meter. That is why I am not totally convinced that it is a broken meter.

The only downside is that after the first reading I am likely to see the needle jump from one end of the scale when I move the outer wheel.
On the other hand I have more exact control of the exposure value with markings for 1/9 stop on the scale.

Remember that the needle moves corresponding to the current that flows through the spool that controls it, and that is done at a certain ratio to a comparison to the reading (very roughly speaking). Adjust the ratio and you have adjusted the movement.
The problem with this approach is that if you do not have the necessary precision in the first place all you do is multiply the error without gaining control.

As I said, I have no obvious reason to believe that my meter is faulty unless by sheer coincidence the fault only applies to the movement of the needle and that all readings are still correct. This scenario is not very likely. But on the other hand, if this is some kind of adjustment then there should be others with the same kind of meter.

Whatever it is, I must say that I prefer the added precision this has given. Wouldn't you?

Ian Grant · Aug 23, 2009

Unlike most meters where the intensity of light has a direct effect on the deflection of the needle a "Null" meter works differently.

According to Gossen the needle is powered by a differential amplifier, so while your meter at the null position may well be accurate, if the differential is off then the + or - readings would behave as you describe.

Because your meter has always been like that you don't appreciate just how useful & easy that scale and method of measuring the subject brightness range really is. It's those abilities that give the meter it's flexibility, and is why the initial reading is stored in memory for the comparisons to be made.

Ian

Jesper · Aug 23, 2009

It seems that we agree on the working principle (it was however a long time since "most meters" had a direct coupling to the incoming light).

The current generated by the incoming light is balanced against another running through the amplifier. If these two balances perfectly no current is running through the spool that moves the needle. The needle is in the middle (null) position.
If however there is a difference between the currents, this difference will be seen as a current running through the spool, generating a magnetic field that moves the needle accordingly. This by the way is linear and that is why the distance between the numbers isn't (but this is outside the discussion).

If a meter is electronichally faulty, this usually means that the voltage is not correct (using modern 1.5 cells in a camera designed for old mercury batteries fx). In this case no meter reading will be correct except total darkness (anything multiplied by 0 will still be 0).
If the voltage is correct but the amplification is wrong, the null position will work and the other settings MIGHT work depending on the change. If done correctly, and if the precision is high enough you can amplify the movement of the needle and be able to read a more exact result than otherwise.
This however relies on the precision of the original measurement (like enlarging a photo. At first more and more details will be seen but after a while it will only be a bigger and blurrier picture (a 50x enalagement will not reveal 5x more details than a 10x)).
I have, as I said, been using it like this for ten years and it really does show the right values, either at null or at +/- 1 stop.
The only difference being that I have a span of 2 stops divided in 1/9 stop whereas the normal meter has 6 stops divided in 1/3 stop.

I do, by the way not only use the null position. Usually I take a reading, put it in the null position, move the outer wheel to the nearest combination of f-stop/time and then read the offset on the needle.

If, by chance, this is the result of a fault I will not have it any other way.

Jesper · Aug 23, 2009

By the way, I would like to apologise to Jmqx who did his first post, asking for help, and got my bad mood and a slightly infected discussion about what can and cannot be done with a Profisix.
I hope the manual helped (I don't think that my posts did (though the first one was done with all the best intentions)).

Welcome to apug Jmqx.

Gossen Profisix Problems. . . ?

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