Spotmeter through a filter or use filter factor.

[David M]

Yes, I was sceptical of the merits.
If you have seen the Picker video of him taking pictures, he doesn’t meter a variety of different colours in the scene. In fact he uses a very simplified version of Zone System metering. Nevertheless, he seems to have influenced a whole cohort of photographers.
Presuming that there is a difference, for at least some filters, between factorial and direct measurement readings, can this amount to more than our normal experimental error. As you say, the negative is very forgiving.

 

[David M]

I’ve read an account of how to make filters, both graduated and plain, from unexposed but fixed plates, by simply dying them. Graduation was produced by slowly withdrawing the plate from the dye solution. When sufficiently coloured, the plates were dried and varnished.
I’m afraid I’ve lost the reference and the names of the dyes.

 

[thronobulax]

Yes, I was sceptical of the merits.
If you have seen the Picker video of him taking pictures, he doesn’t meter a variety of different colours in the scene. In fact he uses a very simplified version of Zone System metering. Nevertheless, he seems to have influenced a whole cohort of photographers.
Presuming that there is a difference, for at least some filters, between factorial and direct measurement readings, can this amount to more than our normal experimental error. As you say, the negative is very forgiving.

As an aside ...

I spoke to Picker once after he'd retired and found him to be a thoughtful, kind and inquisitive man, fascinated with photography in all its aspects. This often didn't come through in his newsletters and published works which tended to run to absolutes and occasional bombast.

To give him his due, he gave people a fast onramp to ZS style exposure and development controls. As always, some people see an approach like his and turn it into holy doctrine. But I've found that to be true among the Adam's acolytes, the unsharp masking bunch, and the Barnbaum "everything needs ferricyanide" devotees. Oh, and have you ever encountered a BTSZ True Believer?

Picker was a decent teacher for beginners. His company many many useful tools. Brillliant graded paper was probably the most beautiful paper I've used across 50 years of printing. 'Shame it wasn't properly carried into the VC era, where Zone VI seemed to just rebrand some generic VC stuff found laying about in industry.

 

[David M]

I have all the newsletters and as you say, he seems extremely confident of his own opinions. Others on this forum have mentioned how he was different in person.
I have one of his 5x4 cameras and it’s solidly made and functional, although I use a different one now. When I needed a small replacement part, it arrived promptly, by (trans-Atlantic) return post, and free.
I also have an unmodified Pentax meter and haven’t found it wanting. Although I rarely use filters, I’ve used both methods of compensating the exposure and found no practical difference. Until now, I’d never thought of side-by-side tests, but curiosity-driven research is always welcome. My own greatest variable is incompetence. Always an anxious moment when the film comes out of its final wash.

Could it be the case that for a single scene, there’s little practical difference - the Forgiveness Principle, if you like? Under different lighting conditions there may be a noticeable difference. Consider the effect of a yellow filter in both noon light under a clear sky and warm orange sunset lighting. Tungsten lighting would generate an even bigger difference.

 

[Jonathan Hotopf]

I've done a little bit of experimentation regarding meter readings with an R25 filter metering off a grey scene my Reveni labs show a -1.5 stop reduction in light indicating a factor of 5.65 compared to a quoted 8 factor generally given. Will have to try my Minolta and see what I get off that.

 

[thronobulax]

I've done a little bit of experimentation regarding meter readings with an R25 filter metering off a grey scene my Reveni labs show a -1.5 stop reduction in light indicating a factor of 5.65 compared to a quoted 8 factor generally given. Will have to try my Minolta and see what I get off that.

Small point of mathematical order:

A factor of 5.65 would be a -2.5 stop reduction not -1.5 stop.

A -1.5 stop reduction would be a factor of 2.83.

In general...

To convert from stops to factors:

Factor = 2^Stops

To convert from factors to stops:

Stops = log Factor/log 2

 

[Alan Klein]

The simple way I do it is to divide the ISO by the factor number. So if the filter has a factor of 4 and I'm using ISO 200 film, I divide by 4 and set the meter to ISO 50.

Or if the meter is set to the film speed of 200, I just add 1/2 the filter factor in stops. So filter factor of 4 divided by 2 = 2 stops. Add 2 stops to whatever the meter says.

 

[Jonathan Hotopf]

The late Fred Picker, who has been mentioned here before, sold a modified Pentax spot meter, which was claimed to give “correct” metering with filters. Some people were enthusiastic, some were not. The unmodified meter was once the weapon of choice for LF photographers, because of its light weight and convenient operation.
It might be worth looking up any references you can find. Nobody has repeated the project, although this may be no reflection on the meter itself.

As it happens I've just got one of the Zone IV meters, it appears to have a filter thread so might be handy for colour filter use in B&W, if I could get some cheap small diamter filters.

 

[Alan Klein]

Over thinking, I will agree with that, I definitely have read more photography books than I need to and concentrated on theory instead of practice. I need to get out of my armchair and make more photographs.

Don't forget your filters.

 

[Jonathan Hotopf]

Don't forget your filters.

Got those filters now and used one of them earlier in the week with the yellow Y2 filter. All my meters match now to the Pentax. The metering looks accurate from some 5x7s I developed. (Did an initial "scan" with my mobile)