Leitz filter factors

[Sean Moran]

Hello folks,

I have two old-ish 39mm Leitz Filters in satin-chrome type mounts.

One is marked 'Or' which I assume means orange. I compensate when using it by opening up two stops and that seems okay.

The other one is very pale yellow and is matked 'O' or possibly '0' (the letter O or zero - it's hard to tell). I rarely use this because I'm not sure of the filter factor. Half a stop compensation seems okay, but HP5+ in Perceptol has such tolerance it's hard to know if this is accurate. Has anyone any idea of the 'official' filter-factor for these two filters?

Also, the 'Or' one is good for darkening blue sky and bringing out clouds and stonework on fine old Belfast buildings, but what would be a suitable application for the paler one?

I'm off to India over Christmas [unneccesary bragging 😉 ] and I would like to make best use of my minimalist kit of M2 & 50mm Summicron, the two filters & much HP5+.

Cheers,

Seán.

 

[back alley]

do you have a handheld meter to put behind the filters?
or a built in meter in a camera?

i have a couple of old canon yellow filters that are much more pale then contemporary filters. not sure if they just faded or were made that way.

joe

 

[Sean Moran]

That's a great idea, Joe. It hadn't occurred to me.

I have a Gossen Lunalite, but I suppose I'll have to wait for daylight to try your suggestion.

Cheers,

Seán.

 

[richard_l]

I get around 1.5 to 2 stops for the Leitz Or. The filter factor really depends on the dominant colors in the scene. Scenes with mostly cool colors like green and blue might need more compensation than those with lots of warm colors like browns and yellows. I don't know what the official filter factor is, but 2 stops would probably be close enough. My Leitz yellow is a 1, not a 0, and it's between 0.5 and 1 stop. C-41 type B/W films don't have the peak in blue sensitivity that most silver films have, so a yellow filter for C-41 would be roughly equivalent to an orange filter with conventional B/W film.

Richard

 

[Doug]

Richard makes a very good point... and you cannot assume correctly that the meter's spectral response is the same as the film's; depending on the meter type, it's likely to have greater sensitivity to the red end than the film. And relying on the meter reading will then lead to some underexposure with reddish light or with a warm-color filter. Just compensate in the plus direction, maybe a half stop or so.

Also my experience with the chromogenic B&W films is that they're more red-sensitive than, say, Tri-X or probably HP5, and will give more density to blue skies, about like using a pale yellow filter with Tri-X. So any warm color filter will have a slightly more effect, with slightly less filter-factor, and more closely matches the meter...

 

[back alley]

i find it's usually close enough - as close as using a filter factor alone anyway.

 

[richard_l]

i find it's usually close enough - as close as using a filter factor alone anyway.

Probably even better. Filter factors don't take into account the dominant colors in a scene. Just to simplify things when exposure accuracy is critical, as with Scala B&W slide film, I use the Leica M6, which has TTL metering. Of course, the M6 meter is also biased toward one color or another, but life is too short; one has to trust something, or else go nuts. 🙂

 

[Sean Moran]

Some (not very scientific, but a little surprising) empirical results:

Here in Belfast on a slightly hazy Sunday morning (8.20 am), the Or (orange) shows a mere 2/3 stop difference and the 0 (pale yellow) about 1/3 stop. This doesn't seem to be affected by indoor/outdoor; pointed horizontally/tilted down; pointed towards distant landscape/pointed towards nearby buldings.

The meter is a Gossen Lunalite, which has an SBC sensor.

Cheers,

Sean.

 

[richard_l]

Some (not very scientific, but a little surprising) empirical results:

Here in Belfast on a slightly hazy Sunday morning (8.20 am), the Or (orange) shows a mere 2/3 stop difference and the 0 (pale yellow) about 1/3 stop.

Is that using reflective or incident mode? Incident mode may let additional light get to the meter sensor from sideways underneath the filter (due to the the 180º dome if your meter works that way). Best to use reflective mode for comparison.

Richard

 

[Sean Moran]

Good point, Richard.

Reflective mode (ie dome pushed out of the way; filter as near as possible to the sensor - thereby covering it)

Sean.

 

[richard_l]

Good point, Richard.

Reflective mode (ie dome pushed out of the way; filter as near as possible to the sensor - thereby covering it)

Sean.

Then I would go with the filter factors you get. I think even Leitz filters vary according to when they were manufactured. They probably obtained their colored glass from Schott, Hoya, or Schneider, so there was no direct control over the source.

That's great about your trip to India over Christmas. That should be a photographer's dream! I would probably also take only the 50mm Summicron.

Richard

 

[peter_n]

Seán this is said very much with tongue in cheek, but would the filter factor of an Or or Grn depend on where you are in the city? 😉 😉 😉

 

[Sean Moran]

Very much so, Peter!

By the way, I shot Gerry Adams on the Falls Road about six weeks ago ... 1/250 @ f/11.

A couple of weeks ago I accidentally drove right into a Loyalist protest in East Belfast (burning barricades, police in riot gear - you maybe saw it on the tv?) and reached for the Leica ... but my girlfriend wouldn't let me get out of the car to take photographs. Just as well really: minutes later they started hi-jacking cars and vans and buses and torching them.

Things have quietened down now though. I've just returned from East Belfast to my apartment in the city centre and it's been a lovely quiet, peaceful Autumn afternoon. Long may it continue.

Cheers,

Seán.

 

[peter_n]

Long may it continue indeed Seán. 🙂