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Jeff Polaski
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 17, 2005 - 06:06 am: | 
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Sounds like Gossen USA should look at it. They wil be on the BogenUSA web site. |
Glenn Middleton
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Votes: 0 (Vote!) | | Posted on Wednesday, August 17, 2005 - 04:37 pm: |
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The Luna-pro f is known in UK as the Lunasix f.From your description I would say that there is nothing wrong with the meter,just the way you are using it or expecting it to work.The meter has three modes of operation;1,instantaneous 2,continuous 3,flash.
In 1, on release of the large red button, the circuit does not switch off for at least 30 secs.So technically you have 30 secs to null the meter.Can be useful if you are hanging onto the top of a 50ft ladder,I know!
In 2,the red operating button is locked in and after nulling the needle,you can point meter at high/low lights and note the under/over exposure values indicated on needle scale.When the red button is unlocked,the meter will give an instantaneous reading of whatever it was pointing at when button was released.It is an odds on certainty that 90% of users will not have the meter pointing at the subject under the continuous measurement.Hence the 'stored' reading is not considered in mode 2.
However you cannot set the electronics to read under/over the ideal exposure.All the rotating dial does to the electronics is null the needle.To increase or decrease exposure you physically set the desired EV/EI on the compensation dial,but all this does in reality is alter the ASA rating of the film.It is a purely mechanical thing,nothing to do with electronics.The meter just gives the correct electronic reading when needle is nulled,you then decide to set a factor on the outer dial.
When set to the flash mode,the meter measures the light from a test flash and you null in same way.Reading the dial is slightly different to the ambient light setup.Within certain parameters the meter will compute the aperture for a number of firings.Allowing a lesser powered flash to illuminate a large room etc.
When measuring ambient light,the meter does not use the 'memory' in this way.
I have and use a number of Lunasix f and S models.All are within less than 1/4 stop agreement and none have needed calibration.
If you do have this meter serviced,send it back to Gossen USA.They replace various bits and pieces gratis.Well Gossen Germany do,ie back plate,dial screw insert,battery door etc.I cosmetically refurbished two of my meters after 20 odd years of hard work.Gossen supplied the parts for free and the meters look like new.I call that really looking after your customers.
A point worth noting is that Gossen cannot service the Grey (gray) cased Lunasix/pro models anymore.They no longer hold spares for these models |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 18, 2005 - 07:07 am: |
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I do not quite agree with this description. The Luna Pro F looks pretty similar to the Profisix (german distribution name) plus flash measurement.
Both the Luna Pro and the Profisix have a scale with readings from -3 to -1, 0, +1 to +3. If you want to over- or underexposure your shot, you can turn the dial until the needle points to the EV correction value desired. This works in both continous and stored measuring (on the Profisix you press the button for stored measuring and latch it by turning for continuous measurement).
On my Profisix it is also possible to do EV compensation mechanically by turning two dials against each other to positions defined by an extra scale on the dial, so you don't have to bother with moving the needle off the 0 position - just do the correction adjustment on the dial and null the needle as usual, the readings will include the correction value (did this by mistake several time - but there is a red warning mark which appears as soon as you 'misalign' these two dials). There seem to be several variations of the Profisix/Lunapro dial, so you probably don't have this feature on all items.
I think this is Panu's problem: he wants to move the needle to the EV correction position by turning the dial, and this seems to be far too slow in his case. On my Profisix, the needle follows the dial movement almost immediately, with little delay due to electronic dampening. The EV correction scale does not show values up to -5 or +5, I think Panu rotates the dial just 5 EV off the nulling position and then the needle seems to follow.
However, the Profisix circuitry is quite complex and I would not dare to work on it (with a degree in instrumentation and years of experience in electronic design). You'd better have it professionally serviced. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 18, 2005 - 09:57 am: |
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Whilst not wanting to open an electronic slanging match,it should be pointed out that the -3 to +3 EV scale has nothing to do with over/underexposure of your shot.This scale is to allow you to measure contrast of your subject/scene.This only works when you have obtained the null point for the exposure.You then just point the meter at the high/low lights and note the scale readings.You do not alter the 'computer' dial from the original null value!If you doubt me see the relevant manuals
All compensation is done by resetting the 'computer' dial.On meters without the zone setting you increase/decrease the EV setting as required.
The Profisix will give almost immediate needle movements with dial movement-from the null position.The Lunasix/pro f does not do this,or at least my three examples do not,unless you start a new reading.Something to do with sensitivity I suppose.Also circuits are quite a bit different,something I found to my cost when I thought a Lunasix f would provide enough bits to repair a Profisix with a damaged board.The dial variable resistor is soldered into the Profi board,you have to unsolder before separating case halves.On f type resistor is located by three pin plug,very simple.Person I got the Profi off, had tried to pull case apart by brute force-damaging circuit board!
So Panu's meter may need a service,but I still maintain that he is expecting it to perform in a way that it was not really designed to do.All I can say is that I have depended on my Gossen meters in very hostile working environments and using as I describe,they have always delivered.Photography associated with forensics or accident investigations is very unforgiving. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 18, 2005 - 02:10 pm: |
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Thanks for giving an explanation for the -3 to +3 EV markings. However, I found they can be used for over/underexposure on purpose, too. I have the downloaded manual somewhere, maybe some day I should read it... AFAIK it must be used when using the non-dedicated tele attachment (the dedicated spot attachment has some plugs which set the circuitry accordingly), you have to set the needle to the -3 position or something like that.
BTW I managed to remove the board of the Profisix without damage. I bought it as non-functional on a camera swap, the battery contacts were rotten. I decided to replace them the proper way by soldering new wires to the board. The circuitry of the Profisix is built around a rather simple LM324 quad op-amp and seems rather tricky. I was glad I did not have to mess with the four or five adjustment pots. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 18, 2005 - 06:37 pm: |
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Sorry,and these are my last words on the subject,the EV compensation for non dedicated attachments is set on the outer computer dial.The one with red indicator on it,that shows it is set on a compensated setting.
My 'standard' meter is a Gossen calibrated Lunasix 3S,which I use to set up my calibration lamps.As stated all my meters are within +1/4 stop of each other.Prior to writing this I had a play with my Profisix and one of my f types.Using the +2 as the nulling point the Profi was reading 1 stop under and the f 3/4 stop over,when compared with 3S.Well within modern film latitudes but not what I normally would expect.
As Gossen never mentioned using any other reading point other than the 0 null point,I have never given it much thought.Resetting the outer dial is second nature to me.However as you have made accurate exposures using the needle dial,I will have a play around when I set my test lamps up at the weekend.I have a couple of A1s to calibrate. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 19, 2005 - 12:20 am: |
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I also don't want to stress this issue any more - I think I already mentioned I haven't read the manual yet, and so probably my remarks on the EV markings on the scale were pretty premature.
However, it seems pretty logical to me that turning the dial +1EV has the same effect as 'nulling' the needle at the +1 marking - it should make no difference whether you make this compensation by the dial or by using the +1EV marking. On my Profisix, when turning the dial + or - 1EV, the needle goes precisely to the +1EV or -EV markings.
If you want to use 'compensated' values for a longer period, of course using the 'dial method' will be more useful, since you once set it and just null the needle as usual. Using one of the EV markings on the scale is prone to errors. |
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