Pentax Zone V completely off

[PatrickMarq]

I sometimes forget: bellows factor, and reciprocity factor exposure correction, reciprocity development correction. stopping down. ASA setting on the meter, etc. Way too many things to remember. I don't even try to use CC filters to correct for color shift with long color exposures. How old is the battery in the Pentax V? I have had to replace the battery before. I have two of these meters and I compare their exposures values with each other.

Bellow factors not so mutch a problem as I stay between 90mm and 150mm
Reciprocity always check the app when I have 1 sec.
Development correction, I have one undeveloped sheet with a paper of pull 1 stop (not going to do this now).
I was constant going between 12 and 80 ISO but still
I’ll meter always with a filter on the lightmeter, except with the R72 filter.
No idea how old the battery is I’m sure more then two years.

[PatrickMarq]

At the end it was not so bad, thanks to my habit of 1/2stop metering problem :-)

One Rollei IR that have come out of the holder in the development tank SP-445, man that film is thin !


For this one I have to go back, the catacombs are really nice.

All the other ones you can see here:
https://www.largeformatphotography.i...=1#post1691269

[Robert Opheim]

You need to verify that the meter is accurate with another meter that is accurate. The battery is probably the issue. I always check bellows factor with a small tape measure. I do use a 75mm, 90mm 92mm, 112mm, 135mm etc. I made 3-1/2x5 cards for each lens - for bellows factor. For reciprocity I use charts made by the film manufacturer. I was taught in a week long photo class that metering thru a filter is not accurate - except with the Pentax spot meters adjusted by Zone 6 - mine are not so I used the manufacturers filter factors - I just write the correction on a piece of paper in the filter case. I have been using 200 ASA for both Tri-X and for HP5.

[PatrickMarq]

It seems I have to wait some day’s because my photographer shop does not have the correct batteries

[PatrickMarq]

You need to verify that the meter is accurate with another meter that is accurate. The battery is probably the issue. I always check bellows factor with a small tape measure. I do use a 75mm, 90mm 92mm, 112mm, 135mm etc. I made 3-1/2x5 cards for each lens - for bellows factor. For reciprocity I use charts made by the film manufacturer. I was taught in a week long photo class that metering thru a filter is not accurate - except with the Pentax spot meters adjusted by Zone 6 - mine are not so I used the manufacturers filter factors - I just write the correction on a piece of paper in the filter case. I have been using 200 ASA for both Tri-X and for HP5.

Robert,
Could you explain more about metering through a filter is not accurate ?
I have always done that and always with good results.

[Doremus Scudder]

Robert,
Could you explain more about metering through a filter is not accurate ?
I have always done that and always with good results.

Patrick,

Let me take a stab at it. First though, you should know that I, too, meter through my filters.

The problems come from the meter's spectral response being different than that of the film. So, when you limit the meter reading to one small part of the spectrum, like happens with the stronger filters, the film's response can be quite different that the meter's. Note that with the "weaker" filters, like #8 yellow or #11 green, the problem isn't so bad. With a #25 filter, you'll almost always get a significant discrepancy. If you use dark green (#58) or a #44 cyan or even dark blue filters (#47) then the same problem comes up.

Also note that the discrepancy can go different ways with different films.

The answer is to do a few tests and come up with some factors for reading through your filters. Test your strongest filters with the films you use first. For example, if you have a filter kit that included a #8 yellow, #11 green, #15 orange and #25 red, you should start by testing the #25. Then, if move to the next strongest and continue from there.

Another issue is that film, when exposed to a narrow bandwidth of light often exhibits different development characteristics. For example, 320Tri-X and the #25 filter requires a reduction in development time for me that is almost one whole Zone (e.g., N becomes N-1 in Zone-System parlance).

Testing that is needed to if you want or need to keep your negative density ranges close to a particular value.

Hope this helps,

Doremus

[PatrickMarq]

Patrick,

Let me take a stab at it. First though, you should know that I, too, meter through my filters.
Hope this helps,

Doremus

Yes, I have done my own test and the metering through my filters are quite correct.
I was just curious, and as always you have given a quite detailed explanation.

Patrick

[PatrickMarq]

So I have replaced the batteries, put the arrow where it belongs (screw and test button)

Did a metering test with a grey card:
Digital camera ISO 100 and f16 as expected.
Pentax ISO 100 but 15,5 not 15 - 1/2 stop off.

[BrianShaw]

Can you try the experiment again with a more similar metering system as the comparison?
How can you be sure which is giving the truth?

Those results, though, are pretty good considering that in the OP you wrote of 1-2 stop errors. This should make you feel much better!

[neil poulsen]

You can calibrate you meter by exposing a uniform target 4 stops under at various settings on the meters 'ASA' dial.
Keep notes and the processed negative that cuts out 1/3 stop of light (compared to blank frame) when placed over the meter, is the correctly exposed negative. That frame's 'ASA' is your meter's 'ASA' setting for that film.

I suppose. But, I think that it's better to get the meter professionally calibrated, versus aligning an uncalibrated meter to the film being used.

And, Richard Ritter at www.lg4mat.net can calibrate it for you. He does an excellent job.