Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
m00dawg
Actually exposing the film as well made sense although I don't think I have the tools to do it properly. I do have a few (mechanical) LF lenses I could perhaps figure out how to mount to my enlarger. I was going to say I was worried the mechanical lens wouldn’t be accurate, but as long as it's accurate for the same 5 test exposures it should be ok? (e.g. if 1/2" speed is more like 575ms instead of 500ms).
Once I have those though, the conclusions drawn from it when you start looking at ISO and development start to get hazy and I got totally lost when having to map the zone system on-top when looking at expansion/contraction. Makes me wonder if there is a local informal class I can take (we have an art college here) so it's more hands on. I have had some AHA! moments but mostly with the paper and geometric sequences.
I suspect I'm getting stuck on the "B" part of BTZS because I should probably get a handle on what AA described in The Negative first.
Maybe I could sell you a copy of my booklet (free):
http://beefalobill.com/imgs/20150812...dAttention.pdf
Do you have any old "electronic" SLR cameras in your arsenal? For example a Minolta X370 would give you a good (quartz-controlled) 1/2 second time.
Consistency is the name of the game here. Not so sure the V54 can give that to you though. Do you have another enlarger, maybe one that takes regular light bulbs?
The B of BTZS is for "Beyond" and means "using an incident meter". The nice thing about BTZS is that it covers the Zone System pretty well... then takes you Beyond.
You can treat them as different chapters and grapple with them one at a time.
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
Pere Casals
My guess is that the ISO Norm that enlights the more is ISO 2721:1982 for internal (TTL) meters, still applicable to film cameras but not to digital cameras (that have ISO 2721:2013).
The ISO 2721:1982 document has to be payed, but here it is quoted mentioning the
x10 factor, so 1.0H,
please see here page 4:
http://dougkerr.net/Pumpkin/articles...alibration.pdf
https://web.archive.org/web/20170213...alibration.pdf
The standard for internal meters it has less "complications" because it's a direct reading of the light that is to reach the film, without having to guess the lens transmssion or the good reflectance value.
Ah, yes... The 1.0H would be in a standard for the meter (or camera) calibration.
Now if you remember my story where I didn't perfectly confirm 1.0H but found slightly less, the fact my OM-4 missed by about 0.03 makes me think a couple things could be at play. The OM-4 has off the film metering so it could give exactly the right amount of exposure if it wanted to. But maybe its calibration was reduced 0.03 to match "everything else", Olympus wanted people to get the same results whether they used the auto exposure or they used one of their trusted light meters.
For example, the best light meter calibration might place the meter point at 1.0H from the speed point but due to transmission loss, in a camera the light hitting film falls about 0.03 less.
So Olympus made the automatic exposure hit 0.03 less to match.
So maybe 1.0H is the meter calibration constant, but the film is expected to receive 0.97H
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
Bill Burk
For example, the best light meter calibration might place the meter point at 1.0H from the speed point but due to transmission loss, in a camera the light hitting film falls about 0.03 less.
Bill, perhaps that 0.03H shift may also be of spectral nature, just another possibility.
A perfect BW meter should match the same spectral sensitivity than in the particular film we are using...
But in practice we have a chain of spectral transformations. First there is the light source spectrum, then we have the subject's spectral reflectance (a gray subject may not have a flat response, but a balanced response)...
Then the Zuiko lens (praised because of his colors) also it may transform a bit the spectrum, and finally we may have some different spectral sensitivity in each meter sensor.
Anyway a 0.03H shift is not much in practice...
My view is that we always may need some safety factor for the deep shadows we want to record. If our metering/exposure is very accurate then this safety factor is way narrower...
...for example if we have no shutter tester for our LF shutters then our good safety factor may grow remarkably...
This may be irrelevant for many shots, but IMHO some shots may require that we squezze all the film capability. And Velvia always wants precision !
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
Bill Burk
The Kodak tables you quote in your pdf (and an idea of time/ CI curves - manufacturers data is not the worst starting point) + flare correction (as you discuss) + an incident meter or spot meter are about all that is needed to really get a handle on exposure & development... That people want to make it so wilfully difficult and obscurantist never ceases to amaze me. I think a lot of it has to do with a poor analytical & artistic understanding of the visual (as opposed to sensitometric) behaviour of the materials - which is often solved by making more negatives & printing them...
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
interneg
I think a lot of it has to do with a poor analytical & artistic understanding of the visual (as opposed to sensitometric) behaviour of the materials - which is often solved by making more negatives & printing them...
interneg, you are right in that. I don't think that Sally Mann has calibrated the sensitometric curves of the wet plates, while she is exhibiting right now one of the most powerful works in decades. Perhaps she calibrated his process, I've no idea, but I'm pretty sure that his work does not depend on that.
Anyway sensitometry is an straight way to learn how the medium works, to nail exposures, to learn the effects of manipulating the process, and also it's a precise tool that's extremly useful in some situations.
IMHO it's more important learning what BTZS says than using calibrations. There is a lot of gossip around about films and processing. Having the BTZS knowledge one may discriminate what is worth and what is gossip.
...but I agree, one has to hit the boulder with a hammer to make a Pietà, in the darkroom this is having hands wet, and growing in determinaton after every pitfall. I'm a rookie printer, but I learned that the first day.
"Previsualization is where the Zone System really shines" (http://beefalobill.com/imgs/20150812...dAttention.pdf)
Re: "True film speed" vs just developing the film more?
I'm still trying to work out the relationship between film testing with the BTZS methods and how the film looks (e.g. films which are more contrasty vs less - so far book hasn't addressed that much). Be that as it may, even now I think doing tests will prove useful since, at the very least, it may help validate my own personal ISO and developing times to start and I can start filling in the gaps late.
That second issue (developing times) has me stumped though. The book suggests, and rightly so, to use BTZS tubes. I prefer to use a JOBO rotary tank (with a motorized rotary I built myself) with XTOL (Replenished) as my standard setup. Concern I have with the tubes is that it's not going to be a good way to evaluate development times accurately between it and my preferred solution because of agitation differences, etc. (right?). So the only way I can really determine dev times is doing a full development cycle with the methods I do use. Tedious at best and adds in some wiggle room when using replenishment that could skew fully accurate results.
Am I super off base in thinking that, or will using BTZS tubes theoretically get me close enough to extrapolate to a rotary? It's an expensive gamble to just buy the tubes and try it which is why I'm asking.
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
m00dawg
how the film looks (e.g. films which are more contrasty vs less - so far book hasn't addressed that much).
With normal development all films have same (or similar) contrast, this is a 0.62D augmentation for each 3.3 stops. I say "similar" because curves may not be exactly straight lines, so we may have slightly different flavours.
What influences the contrast in the negative is development time.
Quote:
Originally Posted by
m00dawg
That second issue (developing times) has me stumped though. The book suggests, and rightly so, to use BTZS tubes. I prefer to use a JOBO rotary tank (with a motorized rotary I built myself) with XTOL (Replenished) as my standard setup. Concern I have with the tubes is that it's not going to be a good way to evaluate development times accurately between it and my preferred solution because of agitation differences, etc. (right?). So the only way I can really determine dev times is doing a full development cycle with the methods I do use. Tedious at best and adds in some wiggle room when using replenishment that could skew fully accurate results.
The tubes and the jobo rotary have exactly the same effect, IMHO, so don't worry.
With tray development you may use diluted development and low agitation to provocate chem exhaustion in the highlights, so you prevent a bit blowing the highlights, so you have some compensating effect.
But any contiunous agitation processing (tubes or rotary) will renew well chem inside emulsion before it can be exhausted by intense development(in the highlights), so the tubes and rotary are same.
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
Pere Casals
With normal development all films have same (or similar) contrast, this is a 0.62D augmentation for each 3.3 stops. I say "similar" because curves may not be exactly straight lines, so we may have slightly different flavours.
What influences the contrast in the negative is development time.
The tubes and the jobo rotary have exactly the same effect, IMHO, so don't worry.
With tray development you may use diluted development and low agitation to provocate chem exhaustion in the highlights, so you prevent a bit blowing the highlights, so you have some compensating effect.
But any contiunous agitation processing (tubes or rotary) will renew well chem inside emulsion before it can be exhausted by intense development(in the highlights), so the tubes and rotary are same.
That's helpful thank you!!
Actually good point on trays since if I wanted to be both economical with time or money, tray is the only other option but seems like it's more akin to inversion processing? If I'm burning 5 sheets I should perhaps do it right. BTZS I bet will be nice if/when I start to do a lot of -/+ development (I suppose that's part of the point of the system heh!)
Conversation about curves is interesting though - I thought there could be, for instance, short toe and long toe films? This is where I kinda got confused because it implies that any film could look like any other film (speaking about contrast here) if you found the exposure and development settings where they produced close to equivalent curves?
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
m00dawg
if you found the exposure and development settings where they produced close to equivalent curves?
Please see manufacturer datasheets, they show the curves with different processings, for example you can compare TXP, HP5+, TMY, . Or TMX vs Delta 100 vs and (killed) Neopan.
In general all films are quite linear from -2 to +2. Beyond that interval the toe and the shoulder may have a particular footprint. If you ensure that your shadows are well exposed (say -2) then all films have same situation. Difference are more from grain structure (in small formats, specially) and spectral sensitivity, see also spectral sensitivity curves in the datasheets: Some see more deep red, some have a valley in the 550nm range that separates better skin tones, but filtration has a greater effect....
Re: "True film speed" vs just developing the film more?
Quote:
Originally Posted by
Pere Casals
Please see manufacturer datasheets, they show the curves with different processings, for example you can comapare TXP, HP5+, TMY, . Or TMX vs Delta 100 vs and (killed) Neopan.
In general all films are quite linear from -2 to +2. Beyond that interval the toe and the shoulder may have a particular footprint. If you ensure that your shadows are well exposed (say -2) then all films have same situation. Difference are more from grain structure (in small formats, specially) and spectral sensitivity, see also spectral sensitivity curves in the datasheets: Some see more deep red, some have a valley in the 550nm range that separates better skin tones, but filtration ha a greater effect....
Got it, thanks again Pere, that helps!
