n_dhananjay3

Just to put some of these worries in perspective. I took a picture

using 8x10 lith film. The film was slightly oversize and bowed out in

the holder, but I was just shooting some tests to figure out a

developer problem. I was using an old Gundlach rapid rectigraphic -

its not even an anastigmatic lens. The resultant pictures when

contact printed were still (my subjective opinion, mind you) sharp,

whatever the hell that means. Lith film is VERY sharp film and 8x10

is forgiving of a lot of sins, so I'm not for one minute trying to

say film flatness is not an issue - it is. Could the picture have

been even sharper than I got? Of course! If the film had lain flat,

the picture would have been sharper. The point I'm trying to make is

that sharpness is a cumulative issue.

<p>

Some of these issues need to be tackled in some order of priority.

Spread functions are cumulative functions. That is, sharpness is a

function of an entire system and worrying about film flatness is

pointless if other elements of the system have slop in them. I would

argue that your lenses need to be extremely sharp and contrasty

(we're talking modern, multicoated designs used fairly open in the

magnification range they were designed for). Your tripod needs to be

steady as a mountain. You need to expose and develop with precision.

Don't stop down to where diffraction is the ceiling. Etc etc etc.

<p>

As indicated in answers above, I would start with assessing whether

you have a sharpness problem to begin with (that actually affects

your images). Then tackle sources of sharpness degradation in the

order which will give you the biggest bang for the buck. I would look

at technique, tripod, ground glass position, lenses, developer and so

on and probably in that order. Although that is based on my

subjective experience. If you are absolutely convinced that film

flatness is the problem, sure go ahead and experiment with the glue -

I'm guessing a prewash might help remove it but you'll have to

experiment. Or spend the big bucks for a vacuum holder (are these

even available or do they have to be designed?)

<p>

Lastly, IMHO, you do need to make a call on where you want to expend

your energies. I've concluded that for the kinds of pictures I want

to make (contact prints from 8x10 negs), as long as it looks sharp to

the eye and folks are able to tell what the heck the darn thing is,

other things about the picture matter more to ME. The search for

better sharpness is an endless quest with diminshing returns. How

important those incremental gains in sharpness are, only you can

decide. For the kind of work I do, landscapes with old lenses

typically stopped down to about f/22 or even further, I've concluded

that I'm better off concentrating on making pictures and working on

things like technique and seeing. Could my pictures be sharper? Of

course! Would it matter? I doubt it - my pictures are likely to fail

on other counts first. YMMV, FWIW etc etc etc.

<p>

Good luck, DJ.

Another good option for a lightweight, inexpensive rig is the Wehman.

And it comes with a Plexiglass, unbreakable GG. Cheers, DJ.

I use Pyrocat HD both in trays and for rotary processing. Times are

obviously different between the continuous agitation of rotary

processors and the intermittent agitation of trays. I've experienced

no trouble with rotary processing - I've read about the excessive

oxidation and 'bombing out' with PMK, but I've never experienced this

problem. I use about 300ml of working solution per 8x10 sheet (the

usual 1:1:100, no increase in A solution etc). Maybe the problem

turns up with the smaller amount of solution used in 4x5 film - the

increased A solution should do the trick in that case. Good luck, DJ.

I use one with my 8x10 - and I do backpack. Very nice, stable tripod -

I believe it is made of ash. You would probably want one of their

lighter models though, if it is for a 4x5 - maybe the Kadette or

therebaouts. Cheers, DJ.

I think manufacturers recommending high CI for sheet film (even using

identical processing methods) is a relic of bygone eras when sheet

film was typically contact printed and roll film was enlarged (if

you're contact printing, you typically need to develop the film

slightly longer than if you were enlarging). I don't think that is

relevant to 4x5 when the end use is for enlarging. Cheers, DJ.

I'm curious - is this really the case? I have always asumed that

these differences reflect the fact that we agitate roll film and

sheet film in different ways. I remember Kodak's recommendations were

based upon intermittent agitation for roll film but tray developing

(i.e., constant agitation by rocking the tray) for sheet film. In

other words, differences in time are merely to offset the differences

in agitation. Or is there more here than meets the eye? I know some

emulsions are different (e.g., TriX in sheet film is different from

that in 35mm) but leaving things like that aside, identical

processing of similar emulsion should require similar times....

Cheers, DJ.

Neither. You need to ensure you have a sufficient quantity of

developer for the amount of film (sq in) that you have. A roll of

35mm film has about 80 sq inches. An 8x10 film has about 80 sq

inches. So you would need the same quantity of developer for one 8x10

sheet of film as for a whole roll of 35mm film. Cheers, DJ.

Not to pour oil on troubled waters but my understanding of Ctein's

conclusions was as follows. I don't think he was saying the plastic

is problematic. Resin coated paper uses titanium dioxide as part of

the white paper subbing layer instead of barium oxide which is used

in fiber based paper. He concluded that the titanium oxide layer was

at war with the plastic base, and exposure to light hastened the

battle. Keeping a print under glass seems to exacerbate the problem.

As stated in a previous post, selenium toning and treatment with

Sistan seems to help the problem. As for how they look, heck,

whatever looks good to you is the only criterion that can be used.

Was it Weston who said he didn't care if the print was made on a

bathmat as long as it was a good print? Cheers, DJ.

Diffraction is only one aberration that contributes to lack of

sharpness. And this gets worse with increasing stopping down. In

contrast, other aberrations tend to be improved by stopping down. In

practise, what this means is that most lenses have a sweet spot where

other abberations have been reduced but degradation due to

diffraction has not yet increased intolerably. So stopping down

further does not reduce the other aberrations but increases

degradation due to diffraction. This is the idea of a diffraction

limited lens i.e., the other aberrations have been corrected to a

sufficient degree that the only thing that contributes to image

degradation is diffraction, as one stops down further and

further.Where this sweet spot is for any lens depends on the design

and construction of the lens - in other words, based upon how bad the

other aberrations are. Some lenses may need to be stopped down

considerably to bring the other aberrations down, while other lenses

may be sufficiently well corrected that stopping down a couple of

stops will be sufficient. Within a lens line, problems with centering

and quality control can provide some variance in the corrections.

<p>

I'm not sure I understand what you mean by long lenses should hit

optimum at smaller stops. In an ideal world, all lenses would be

diffraction limited wide open. Then stopping down is only a function

of DOF requirements i.e., when DOF does not dictate, one can operate

at wider apertures and still get pictures limited only by the

diffraction at that f stop.

<p>

I haven't seen any data pertaining to differences as a function of

different shutters, due to thickness of the blades etc. I doubt there

is much variance there.

<p>

Cheers, DJ

As mentioned above, I would be suspicious of the readings. Reflection

densitometers include a light source that shines on the paper and the

cell measures the light reflectde back from the sample. Which means

what you will be measuring through a setup with the light table will

include 1) light from the light table (some of which has been stopped

by the opacity of the negative) AND 2) light from the densitometer

source reflected back by the negative. There is no way to tell a

priori how much has come from the light table alone (because any

density will both stop light from the light table and simultaneously

change the amount of light that is reflected back) i.e., any reading

will be confounded. If you are determined to go this route, I guess

you could try some calibration exercises, but the game doesn't seem

worth the candle, IMHO.

Cheers, DJ.

As indicated above, in photography, diffraction is purely a function

of f number. Diffraction is related to the physical size of the

aperture (and would be defined that way in physics textbooks).

However, diffraction are angular apread functions. So a 300mm lens at

f/16 may have a larger physical aperture than a 75 mm lens at f/16.

However, the distance between the nodal point of the lens and the

screen will be longer for the 300mm lens, which gives the diffraction

from the larger physical aperture of the 300mm lens a longer travel

distance over which the angular spread function can spread. WHn you

do macro work, it is very obvious that diifraction is a function of

the effective f stop and not the marked f stop. Which sort of proves

that it is a combination of the f stop plus the linear distance over

which light can spread that contributes to diffraction (which is the

definition of the f stop in normal photography).

<p>

Strictly speaking, diffraction is also a function of wavelength of

light etc. Diffraction patterns looks like concentric rings. The Airy

disk referred to above is the central, brightest ring (which is an

order of magnitude brighter than the outer rings).

<p>

Basically, as you stop down the lens, the central undiffracted AREA

(pi*r squared) of the lens reduces much more rapidly than the

peripheral, diffracted PERIMETER (2*pi*r). In other words, while the

diffracted perimeter formed a negligible part of the image forming

light when the lens was wide open, it contributes a significant part

of the image forming light when the lens is stopped down. Which is

why it is recommended that stopping down be contained to the bare

minimum that will accomodate DOF requirements.

<p>

Cheers, DJ

Another option is to use one of those barndoor type shades with a gel

filter holder. Good for backpacking - its light, cheap, doesn't take

up too mcuh space, has the barndoors to provide some shade on the

lens, and will hold 3" gels like the Kodak Wrattens. Cheers, DJ.

Considerably cheaper and safer to use one of the following methods.

Buy a bunch of marbles and add them to the solution till the solution

reaches the brim. Or hold your breath as long as you can and exhale

the carbon di oxide into the container to displace the oxygen. Or put

up the money for the Prtectan. Cheers, DJ

I would urge you to also look at the Wehman closely - it is a very

interesting design and works great in the field. DJ

Pinakryptol was introduced by Konig and is a family of dyes - the

formulary sells yellow, green and white versions. Green is said to be

the least effective, can cause staining with some MQ developers but

can be used as either a forebath or mixed into the developer. Yellow

is more active in reducing panchromatic sensitivity and more

compatible with MQ developers but can only be used as a forebath as

it is destroyed by sulfite. White is used in the developer.

Pinacryptol is probably preferred to older desensitizers like Scarlet

N, especially for modern emulsions. Olders desensitizers also tend to

stain film.

<p>

With regard to FX2, the story in The Film Developing Cookbook is that

Crawley found that PY offered somewhat better discrimination (than

conventional restrainers and anti-foggants) between exposed and

unexposed grains. Apparently, he also suggested that it should not be

used for T grain film. So, it sounds like it has restraining

properties in addition to the desensitizing property when used as a

forebath.

<p>

Cheers, DJ.

You might want to look out for a 141mm or 183mm Protar V (not to be

confused with the Protar VII convertibles). The Protar V was a wide

angle lens. It covers 8x10 with ease (especially once you stop down a

bit - they are meant to be stopped down to f:32 or smaller for use).

The lens list in Henney and Dudley indicates coverage of 100deg. They

are not coated but you might prefer it because it only consists of

two cemented doublets and so coatings are less of an issue. I have a

141 and it covers 8x10 without too much trouble. It is incredibly

tiny - an 8x10 backpacker's dream. They are fully corrected for

color. Bausch & Lomb made the lens under license from Zeiss. Good

luck. DJ

Sorry for the typo at the end of my second paragraph - those are

reasons to 'aim at grade 2', not to 'not aim development at grade 2'.

DJ

There are some valid reasons to aim neg development at about grade 2.

But leaving that aside for just a moment, you raise a good point. In

fact, when Kodak first introduced different grades of paper, it was

for the purpose of dealing with errors in development. Try a simple

exercise. Assume for the sake of simplicity, that all our transfer

functions (film curves and paper curves) are linear - I know they are

not actually linear but let's start there. Pick a subject luminance

range and try plotting them on a tone reproduction cycle. You will

find that as long as you pick matched slopes for the film and paper

curves (i.e., low slope film with high slope paper and vice versa),

your final tone reproduction will be identical.

<p>

Now, in actuality, films and papers have toes and shoulders and that

does change the tonal gradations. Also, many of the points made

earlier are absolutely valid. Working with higher contrast papers is

a pain in the neck. Burning and dodging is hideous, grain tends to be

exaggerated by the higher local contrast and as you approach high and

low contrast, you have less wiggle room, which is another reason one

might not want to aim neg development towards #2.

<p>

But I've often thought that the best system would be to minimize the

toes and shoulder areas of the curves - that would give us the

longest possible straight line section with clean gradation - no

tonal distortions. The reason platinum looks so good is exactly for

this reason. Platinum actually has a lower Dmax but the neg is

developed to a higher CI and the paper accomodates such a neg. The

reason it looks good is because in the overall transfer function,

most of the function is a straight line - the toe and shoulder have

been reduced as much as possible. Most of the overall transfer

function is pretty close to a straight line. (And no, an

appropriately scaled neg on a silver print will not look the same

becuase the silver system will have longer toe and shoulder areas).

<p>

The best way that can be done is to develop towards a 45 degree

transfer function. Any variation from this will tend to increase the

toe and shoulder areas of the overall transfer function (note that

this would not happen with straight line transfer functions, its a

problem only when we have curves with toes and shoulders). Typical

procedures these days for negs is to develop to a CI of about 0.5 or

thereabouts, considerably less than the 45 degree line I referred to.

Typically one is likely to get better results in the midtones if one

aimed for a higher CI - that is, a neg aimed at grade 1 is likely to

yield somewhat cleaner midtone gradation. However, that leaves you

with no wiggle room. Any errors and you are sunk.

<p>

One reason so many folks like the way Azo looks, I suspect, is

because the final result has long straight line characteristics. That

reduces the distortions due to toe and shoulder - my subjective

opinion is that a neg aimed at Azo can be developed slightly longer

than one aimed at an enlarging paper. All of this is further

complicated by the fact that different manufacturers adopt different

methods of accomodating unruly negs. Some papers vary mainly in the

shape of the toes and shoulders. Others vary the slope of the

straight line section also. So given all of these complications and

associated problems alluded to by others, its probably preferable to

aim at the middle of that scale. Cheers, DJ.

The Ultra Spot has more bells and whistles. The Pentax seems more

intuitive and simpe, at least to me. Both offer full view of all

information in the viewfinder, which I think is crucial to a

spotmeter. The Gossen has more buttons to control all those bells and

whistles (all available at the touch of your thumb, conveniently

placed but still requires you to toggle back and forth sometimes).

The Pentax requires you to keep stuff in your head (not that it's a

big problem, but for what it's worth, the Gossen can keep a bunch of

readings in memory and display it in the viewfinder. In short, they

both are well designed and work well. I think it would come down to

things like how well does it fit in your palm, idiosyncratic

interactions between the interface and you and so on. I've heard

folks occasionally complain about non-linearity in early Gossens -

don't think that's a problemn now. FWIW, I got subjectively equally

good exposures from both. I would try playing with both, if possible

to see what fits. Cheers, DJ.

This page might provide you with some useful information. Dagors and

WA dagors would probably be your best bet. They have good coverage

and were made in longer focal lengths as well. Presuming you had

enough bellows, you could look at longer process lenses like the

Artars.

http://www.bostick-sullivan.com/Alt_cameras/large%20format%

20lenses.htm

Unlikely. The Artars have process lens characteristics. They are very

sharp but coverage is limited to about 45 degrees or so. So you would

need a focal length of at least the diagonal, preferably longer, to

cover a format. So for your 16x10, I would look at something in the

region of 28 inches or so. DJ

I've seen a photograph of him with his cat made by Wynn Bullock -

this was late in his years. Its heart wrenching, because you can see

the mask that Parkinson's has made of his face but his eyes have the

same eloquence in them that you see in all pictures of him. Must have

been a long, dark night of the soul. DJ

I doubt it. I suspect Anchell and Troop are referring to a supression

of edge effects when they refer to this, although I'm at a loss to

understand the mechanism for the same. But even if we agree with them

for a moment, the loss of edge effects only works because film is

never developed to completion. Paper is typically developed to

completion which renders such an argument moot for paper developers.

If I have misunderstood and they are talking about a supression of

resolution on paper, I would be very hard pressed to believe it

because most papers resolve way, way more than the eye can resolve

i.e., the limiting factor on resolution tends to be the

lens/film/enlarger lens system and not the paper. However, on the

whole, I agree that typically developers that need restraining have a

very high level of alkali and therefore reducing the alkali is a

better first line of attack than adding bromide or benzo. Cheers, DJ.

Hi Pete, alkaline fixers have a couple of uses. Especially popular

with pyro users because acid fixes apparently are not conducive to

the stain. Have also heard arguments for keeping paper processing

alkaline to enable going striaght from fix to Selenium toner (see

www.heylloyd.com and technical section for an interesting paper on

same). Cheers, DJ.