zone system test with filter on lens?

Phil Lamerton wrote:

Since I will eventually be using the camera in the portrait studio
with a yellow/green filter, would it be wrong to do the testing with
the filter over the lens?

Remember that you need a spot meter capable of reading flash light (not
every meter can do it) if you intend to use ZS in studio with normal
eletronic flashes. ZS is of quite limited use with an incident flash meter.

Severi S.

What 'camera and lenses'?

Koni Rapid Omega with 90mm and 180mm lenses. I'm uncertain as to why
you should ask this?

rgds, phil lamerton

Severi Salminen wrote in message ...
Michael Scarpitti wrote:

Since I will eventually be using the camera in the portrait studio
with a yellow/green filter, would it be wrong to do the testing with
the filter over the lens?

What 'camera and lenses'?

How would it affect your answer if you knew the camera and lens in
question? Most filters work quite similarly no matter what camera or lens...

It matters a great deal. Is this medium format? Large format? 35mm?

Michael Scarpitti wrote:
: (Phil Lamerton) wrote in message . com...
: I'd like to photograph a gray card outside on an overcast day, in
: order to do some zone system testing with my new camera and lenses.
:
: Since I will eventually be using the camera in the portrait studio
: with a yellow/green filter, would it be wrong to do the testing with
: the filter over the lens?
:
: Thanks in advance for your advice on this.
:
: phil lamerton

: What 'camera and lenses'?

What difference could the camera or lens possibly make?
--




Keep working millions on welfare depend on you
-------------------

Severi Salminen wrote:
: Michael Scarpitti wrote:

: What 'camera and lenses'?
:
: How would it affect your answer if you knew the camera and lens in
: question? Most filters work quite similarly no matter what camera or lens...
:
: It matters a great deal. Is this medium format? Large format? 35mm?

: Umm, how does it matter? Does light behave differently between various
: formats? Does a certain filter affect light differently on different
: camera body?

: Let me ask like this:

: 1. Would it be wrong to do the testing with the filter over the lens
: using (35mm) Canon EOS 30 with a 50mm f/1.8 lens?

: 2. Would it be wrong to do the testing with the filter over the lens
: using (6x7) Mamiya RB 67 Pro-S with a 180mm f/4.5 lens?

: 3. Would it be wrong to do the testing with the filter over the lens
: using (4"x5") Toyo Field 45AII with a Schneider 150mm f/5.6 lens?

: How would the answers now differ? In what cases it _IS_ wrong to do the
: testing with filter in place? And why is it wrong? I'm just curious to know.

It would be wrong for you to use any camera but a leica.
--




Keep working millions on welfare depend on you
-------------------

(Phil Lamerton) wrote in message . com...

What 'camera and lenses'?

Koni Rapid Omega with 90mm and 180mm lenses. I'm uncertain as to why
you should ask this?

rgds, phil lamerton

1. First of all, because zs is unsuited to roll film.

2. Because some cameras have the shutters in the lenses, and thus each
lens has to be calibrated.

3. Because leaf shutters are less efficient at high shutter speeds and
large apertures. It takes time for the blades to open all the way, and
thus the full aperture is not available during the entire exposure. At
lower shutter speeds and small apertures, the percentage of time
during which the entire aperture is used is much higher. Electronic
flash is so quick that this does not matter, and thus your exposure
will not be the same.


In addition:
Reciprocity failure may affect flash pictures differently than normal
shutter speed images.

Michael Scarpitti wrote:
1. First of all, because zs is unsuited to roll film.

Actually ZS is very usable with roll films. There are of course some
limitations as per frame development is quite difficult to do but ZS can
be used (at least to some extent) with roll film cameras. And in studio
environment (as in Phil's case) it is quite easy to have and change
different backs/rolls for different development times. But Phil
obviously didn't ask if ZS is suitable or not, but about using a filter
when testing.

2. Because some cameras have the shutters in the lenses, and thus each
lens has to be calibrated.

But that has nothing to do with Phil's question about testing with
filter in place. It doesn't even matter if one uses ZS or not: the
photographer should allways know the accuracy of his/her shutters.
Otherewise it is quite hard to make correct exposure with _any_ technique.

Focal plane shutter is not allways a solution as aperture blades/scale
can also be a bit off. So some basic testing is allways beneficial.

3. Because leaf shutters are less efficient at high shutter speeds
and large apertures. Electronic flash is so quick that this does not
matter, and thus your exposure will not be the same.

That is true - allthough the difference might or might not be of any
importance. But that is a phenomenon that must be considered allways.
Phil asked only about testing with/without a filter - which you didn't
even bother to answer

Regrads
Severi Salminen

Thanks very much for all the advice.

Please could anybody clarify something? If I calculate my film speed
and development time for N outdoors, with the filter in place (and for
each of my lenses), how different are the results likely to be from
those of the same test conducted indoors using electronic flash
lighting?

Also, in studio portraiture I am unlikely to place any essential part
of the image on the toes region of the film's characteristic curve.
Doesn't this mean I could safely use the film speed determined in my
outdoor test?

TIA - phil lamerton

Severi Salminen wrote in message ...
Michael Scarpitti wrote:
1. First of all, because zs is unsuited to roll film.

Actually ZS is very usable with roll films. There are of course some
limitations as per frame development is quite difficult to do but ZS can
be used (at least to some extent) with roll film cameras. And in studio
environment (as in Phil's case) it is quite easy to have and change
different backs/rolls for different development times. But Phil
obviously didn't ask if ZS is suitable or not, but about using a filter
when testing.

2. Because some cameras have the shutters in the lenses, and thus each
lens has to be calibrated.

But that has nothing to do with Phil's question about testing with
filter in place. It doesn't even matter if one uses ZS or not: the
photographer should allways know the accuracy of his/her shutters.
Otherewise it is quite hard to make correct exposure with _any_ technique.

Focal plane shutter is not allways a solution as aperture blades/scale
can also be a bit off. So some basic testing is allways beneficial.

3. Because leaf shutters are less efficient at high shutter speeds
and large apertures. Electronic flash is so quick that this does not
matter, and thus your exposure will not be the same.

That is true - allthough the difference might or might not be of any
importance. But that is a phenomenon that must be considered allways.
Phil asked only about testing with/without a filter - which you didn't
even bother to answer

The filter bit is actually irrelevant, or at best, the least of his
worries, but he was unaware that these other issues will mess up his
measurements completely.

Why?
1. An electronic flash exposure make with a leaf shutter does not
suffer from inefficiency. All shutter speeds will give the same
exposure (not counting ambient light) with electronic flash.
Existing-light exposures made with different combinations of apertures
and shutter speeds, using a leaf shutter, will not be equivalent,
because slow speeds and small apertures will give more total exposure
than the nominally equivalent exposure with large apertures and high
shutter speeds.

2. A certain amount of reciprocity failure is possible with electronic
flash, the duration of which is often much less than daylight
exposures.


Regrads
Severi Salminen

(Phil Lamerton) wrote in message om...
Thanks very much for all the advice.

Please could anybody clarify something? If I calculate my film speed
and development time for N outdoors, with the filter in place (and for
each of my lenses), how different are the results likely to be from
those of the same test conducted indoors using electronic flash
lighting?

This cannot be done in the way you suggest, because of shutter
inefficiencies at large apertures and fast speeds that affect
existing-light exposures but not electronic flash exposures. This is
hopeless. You must calibrate using the same set up (electronic flash),
and separately for each lens.


Also, in studio portraiture I am unlikely to place any essential part
of the image on the toes region of the film's characteristic curve.
Doesn't this mean I could safely use the film speed determined in my
outdoor test?

TIA - phil lamerton