gary_deal

Well, if I'd actually known anything about offest printing plates at the time the answer to my original question may have been a bit more obvious. Now that I've read through a few patents I know a little more about it and can say that the chief differences are that the silver image remains within the anodized layer rather than being located on top of the surface or being etched through further processing, and that as far as I can see there's no resulting areas of differing hydrophilic or hydrophobic surfaces - just an unbroken anodized surface.

 

As a matter of fact, the substrate I used was stripped plate material.

 

I now see that the process has been used for many years to produce ID plates and a variety of other things (www.mtlphoto.com), though it seems to be primarily available as a specialized service or industrial grade kit using presensitized plates. I've probably missed the obvious so far, but from what I've found it doesn't apppear to be a regular "applied-to-your-parts" (not *those* parts!) service that you'd be able to get from an anodizing shop. Being a sort of interdisciplinary process (metal finishing versus hand-made photographic emulsions) this doesn't surprise me.

 

The idea was based in a current project (anodizing), which had aspects that I thought might utilize aspects of a previous project (home-made holographic emulsions), and based on the info I've dug up now it may be of use in both photgraphy and anodizing. Since I'm loosely associated with a group of small-time anodizers, such a process & procedure might allow those anodizers to offer an innovative service that may not be readily available elsewhere (even though it's not actually new), not to mention the possibility of metal backed images, dyed or not, and their potential archival qualities.

 

In fact, it's even possible that a diffraction grating could be incorporated into the anodized layer, producing that holo-rainbow effect you see on plastic films and such, without the poor wear characteristics of plastic film or the trouble of roll processing the metal, but that's a post for the holography forum.

 

I found one patent from the '70's that appears to provide almost all the information I was looking for, so I'll be writing myself up a set of formulas and procedures to follow to see what I get. Another patent provides a developer formula that I'll compare to other existing formulae to see what off-the-shelf developer is closest, or just go ahead and mix up. If that all works for me I'll have to get some pinacyanol blue to see about sensitizing the plate to red hene laser so that I can try the diffraction thing. Is there any "rainbow-anodized" stuff out there?

 

If I can get the process to work for me, I may post materials and procedures here (if anyone's interested).

 

Which of course reminds me, is sensitized aluminum sheet for photographers available? I now think I might have seen something like that once, a few years ago.

Cheers,

-Gary

I deposited silver within the anodized layer (between the actual aluminum and the surface) to form a photographic image, and it did not involve an emulsion applied to the anodized surface.

 

Found it was long ago patented in various forms and now should be in the public domain......

 

Ok Donald, here ya go:

 

The process involves anodizing an aluminum plate and inserting sensitization, exposure, and development/fixing steps between the anodizing and sealing steps. Basic anodizing is not difficult (http://www.focuser.com/anodize.html).

 

Having a basic anodizing setup already constructed, I lye-stripped a piece of aluminum printing plate (~.005") of it's coating and pulled it before any substantial etch could occur, then rinsed and anodized the piece at 24 amps/sq foot in sub-68 degree electrolyte (~20% w/w H2SO4) for 30 minutes. A second try using a plate etched at 9.25 A/sq foot at 75 degrees for 90 minutes produced less final image density, though other factors may have been involved.

 

Under safelight conditions, I rinsed the plate in distilled water, bathed it in a 6% silver nitrate solution, then in a 7.5% potassium bromide solution with approx. 0.1% ascorbic acid added to adjust ph, then rinsed briefly and allowed it to dry. Since the silver salts were not color sensitized and it was the middle of the night (needed UV but didn't have any), I sandwiched it with a negative and popped it ten times with an old starblitz flash (GN 210?) from about a half inch away.

 

Not having any Dektol at hand, I developed in double strength Xtol stock (because it was handy), for about five minutes, though development appeard to be complete by about three minutes.

 

A simple masked image was the most obvious (done specifically to show clearly whether the idea had worked or not), while a detailed image of a horse standing in front of pipe fencing was much less dense and took some work to see (but held detail nicely).

 

I then rinsed and fixed in 20% sodium thiosulfate, preferring to avoid anything at that point that might dissolve the anodized surface.

 

After an additional wash in tap water and a short rinse in distilled, I boiled the anodized sheet in distilled water for twenty minutes, a standard means of "sealing" the anodized surface. After a final rinse I hung it to dry until the next day.

 

When I say the image is "viable", I mean that you can see it and it doesn't disappear as opposed to there being no image or nothing left to show anyone the next day.

 

The reason that I ask about pre-existing processes is that the image I got didn't have all that much contrast or density, and if someone else has already done the work to produce a more refined method it would be much simpler for me to do some reading instead of starting from the beginning. Better to read a book on photographic processes than to start with salted paper and work forward.

 

I'd done a number of searches through the patent database, but nothing before 1976 can be text-searched (pat no or classification only) so I needed to find a recent patent that referred to earler patents. I finally hit upon the right search string tonight, and it looks like I've got some reading ahead of me.

 

Check out US patent # 4,092,169, it's got plenty of referenced patents to start with including one from 1938, the period where I would have expected this to first be discovered.

 

If you're unfamiliar with the online patent database, go here:

http://patft.uspto.gov/netahtml/search-bool.html

Then enter the patent number, select "1790 to present" from the drop-down menu, and hit search. For pre-1976 patents you'll have to hit the "Images" link.

You can learn all kinds of stuff reading patents....

 

From quickly scanning a couple of these patents, it appears that the cool tip for this is to use a 30% - 50% silver nitrate solution with about 0.5% gelatin, apparently just enough to keep the silver salts within the pores, and to allow it to dry before subjecting it to any of a number of halogenating baths.

 

Ok, looks like that's plenty long enough and tells more than most would ever want to know.

Don't stay up too late reading patents.....<div></div>

Does anyone know of a process that produces a silver image embedded in an anodized layer on an aluminum substrate? I

managed to get a viable image about three this morning and it's held up to rubbing and sunlight.

Any links or references would be appreciated, this has an interesting look and should have pretty good permanence (being

embedded in what amounts to a layer of sapphire...)

 

Searched the forums with no luck, might have missed something though...

 

-Gary

When I got my Pressman, I was afraid to open it because I could hear the bellows crackling with every small movement. Not having any better ideas I fed armorall into the folds over the course of several days, then opened it a little and fed it some more. It suppled up nicely and has seemed fine for 10+? years, but lately I notice it's making a little noise - I'll have to try the lemon Pledge trick.

 

Standard 4x5 filmholders of pretty much any kind will work, from old wooden ones to nice new ones. I like the Studio Pro holders because of their metal slides, but I don't like paying for them. Buy some used plastic ones and you should be fine.

But, you can read and post without being a registered user, as I just did. *shrug*

Robert's right, a few extra bucks is worth a bit less hassle.

 

Assuming it's like the one I have here, it's got a metal box body that won't break if you drop it, even if it's not as pretty as a busch pressman. :) It's also got a lensboard just short of 4" square and the front standard has a 3" hole, so you should be able to stick fat lenses on it (beats the pressman there). The front standard has rise, tilt, and shift, as well as a drop bed, and while the back won't do those things, the one I have here has a rotating back. This one has a spring back, but it looks like it wouldn't be hard to swap on a graflok or other back if you're handy (and get hardcore). The focusing hood door appears to be attached to the back, and the focusing rack has a little friction lock on the side (useful). No focal plane shutter in there, but I doubt that will matter.

 

I think I paid about $75 for this one, but it's got some holes in the bellows, some peeling outer leather, and it came with a Rathenow Dialytar and a quaint looking Perle Rapid shutter that's decorative but amusingly sluggish on the slow speeds.

 

The deal sounds ok to me for a starter camera (you didn't think you'd stop there, did you?), and if that 101mm lens will cover the film reasonably well you'll have fun with it. It appears that the trick for short lenses with this one is to drop the bed, loosen the rise/tilt knobs, slide the little tabs at the bottom of the lensboard in, tilt the bottom part out, push the tabs back out, and then tilt it back so that the tabs are against the front standard. The lensboard then appears to be reasonably parallel to the back then, but you'll have to adjust the height to center the image and remember to keep those tabs set against the standard (if you're not using tilt).

 

Now you need more stuff....

Wow, Mars looks an awful lot like Kansas (or vice versa), except there's some kind of hill on the horizon - I don't have that here.

Raymond, here's a photo of what I've got. I'll be the first to admit that this is an odd modification, but I got it this way - the Linhof 5x7 back is probably worth more off the camera. I can't tell if the lens covers the corners of the format because there's a 5x5 mask cast into the body. I've also got the shutter assembly (not installed in this picture), it might be operable, but the curtains are missing so it's non-op. I haven't shot with it because I've never bothered to get any 5x7 film to go in it or fit a shutter to it (nor attached it to a view camera)

 

The one in the auction appears to have the mounting flange attached, so attaching it to a lensboard would probably only involve boring a large hole and drilling for the mounting bolts. Focusing would involve screwing the lens in and out of the mounting flange - the threads are pretty fine so if you don't mind it it's not too bad.

 

Looks like the price went a bit high, maybe it's time for me to dismantle this one and sell the parts.

Great posts Emmanuel!

 

 

>>Gary: Thanks a lot. What was the source of your equations? Can we find them anywhere?

 

I had to do some searching, but the original set came from June 1988 issue of Popular Photography. It was the same Rayleigh limit equation noted at Norman Koren's site, but I don't have the other calcs I found.

 

Since repeated calculations are simpler for me now that I have a computer instead of a cheap calculator, and since many won't want to do the math, here's the results of the Rayleigh limit equation:

 

 

F#...................Disc Dia(mm)........Theoretical Resolution, lpm

 

1......................... .000671.........................1490

 

 

1.4..................... .0009394.......................1064

 

 

2......................... .001342.........................745

 

 

2.8..................... .0018788.......................532

 

 

4......................... .002684.........................372

 

 

5.6..................... .0037576.......................266

 

 

8......................... .005368.........................186

 

 

11...................... .007381.........................135

 

 

16...................... .010736.........................93

 

 

22...................... .014762.........................67

 

 

32...................... .021472.........................46

 

 

45...................... .030195.........................33

 

 

64...................... .042944.........................23

 

 

90...................... .06039...........................16

 

 

128................... .085888.........................11

 

 

The hazards of small apertures should be obvious.

When considering the theoretical resolution above, don't forget to consider your film's resolution limits - you don't need it if the film (or final print) can't reproduce it. Also remember that those are *theoretical* - not what your lens can actually produce, they're just the upper limits for a particular aperture. And last but quite important, consider final enlargement size, a 35mm frame printed at 8x10 will turn 135 lpm into 16 lpm. But that's one of the reasons we like big cameras, isn't it?

Of course, there's also final viewing considerations as well, a 35mm shot may look fine on a billboard if you're not the guy putting it up.

 

Around the time I originally read this I was shooting micro on 35mm, with a reversed 13.5mm f1.4 lens at around 100 - 150mm extension. At f5.6 the diffraction blur was very obvious and I had to shoot all those images at f2.8. Depth of field was *extremely* shallow. Which reminds me, what the heck happened to Ektar 25 print film?

 

 

>>A physicist chum who is also a photographer assured me years ago that d-o-f is constant for a constant f.l., stop and final image size, so you don't actually get more d-o-f by starting out with a smaller negative.

 

Um, yeah, a 150mm lens, at a particular aperture, would show the same depth of field regardless of film size. The reason there seems to be more depth of field with smaller formats is because the "normal" lens used for smaller formats is a shorter focal length than that used for larger formats. On 35mm that would be around 50mm, while on 8x10 that would be around 300mm. They'll both produce about the same field of view on the film, but at identical apertures the 50mm will show more depth of field than the 300mm. My digital camera has a zoom range "equivalent" to ~35 - ~512mm on a 35mm camera, but the actual imaging area is substantially smaller so a "normal" shot has far more d-o-f than I'll get from a 50mm on a 35mm film frame.

Twenty years ago I spent about a week working calculations supplied to me for figuring theoretical resolving power and diffraction limitations (ever work up a sweat with a calculator?) and regardless of focal length, it always came down to this:

 

To avoid diffraction problems, avoid stopping the lens down beyond an f-number that's one quarter it's focal length (in millimeters).

So, avoid stopping a 50mm lens down below f11 (f12.5 to be exact), but your 135mm should be ok down to f22, maybe up to f32 (f33.75 would be the numerical limit), etc. (non-theoretical lens qualities aside) You should be able to work out the rest. 8)

 

If you don't want to process all the math, use the above as a rule of thumb. Try some testing and see if this bears out on the film. Be sure to use high magnification when checking.

I'm 45 and have been nearsighted since about 2nd grade. In the past decade, my near vision has deteriorated, and I've got that sharp field about seven inches from my eyes. This is ok for overall viewing of 4x5, but not 8x10. In addition, it's not very good for looking really closely at the groundglass, and the glasses interfere with the usual magnifiers.

 

I tried using the viewing hood from my hassy and it was pretty good, so I got one of the old hassy chimney finders that focuses and that's great. If I want to leave my glasses on I can focus it for that, or take them off and turn the wheel a bit and bring it into focus. Ahh, adjustability. Does this qualify as a diopter adjustment?

 

While the chimney finder is great, I like things I can stick in my shirt pocket and not worry about and the chimney doesn't fit very well. The Hassy WLF fits, but if I drop/step on/lose it, I'll be upset. So, I just got a russian WLF for $17 on fleabay and when it arrives I'll see how well that works. If it works, and I inadvertently step on it, it'll just add character.

 

Now I'm wondering if I can use the Hassy meter head on the GG and get accurate, or at least consistent (i.e., -1 stop) readings. Anybody doing this?

Thanks Jim, that sounds promising. Any idea if it comes in quart (or smaller) cans? And, do you have a handy source for it? Otherwise, I'll be picking brains and catalogs at the hardware stores for a special order - some things are hard to find out here in the middle of nowhere.

Thanks for the suggestions, there's at least one or two I haven't tried.

 

The WD-40 is no joke, it's an excellent solvent for crayon, say when nitwit children scrawl obscenities on neighborhood mailboxes - wipes right off. I've also used it to remove two part industrial paints from my hands and parts, once the paint is dissolved, boraxo for the hands and acetone for the parts cleans everything right up.

 

Regarding the torch, I have considered heat. Light application of a propane torch had no effect, but since the uneven heating would be likely to crack the lens, I've considered baking the front element at a high heat. That would involve starting and finishing with a cold oven, probably a ten hour process.

 

The thing is, there's two lenses, and I'm using the smaller one for all the extreme methods. The small one looks like a 165mm f8 JML process lens, and while it looks like it would have quite a bit of coverage, those are pretty easy to acquire cheaply. It's partner is a 272mm f16 that has a protruding rear element, and front and rear elements that are three inches across. The assembly is over four inches long measured from the glass. It's a sizable lens, and I expect it's coverage will be quite large. I'm probably going to have to modify my garage in order to measure the image circle.

So, while I'm not particularly concerned with the small lens, I'd like to get the bigger one cleaned up. If I never get around to making any of the giant box cameras I've thought of, it might serve one of you ULF guys.

 

The problem is definitely on the glass surface, the front element is easily removable. (I forgot that lye eats anodizing and bleached the front of the housing with the oven cleaner)

 

Steel wool would work, but I hope to never have to deal with this coating again and as I said, I'd like the lens to be usable in the end. Although brass or bronze wool might work, it probably wouldn't remove every last bit and there's the original coating to consider. It's frustrating seeing it under the transparent gunk.

 

I don't think I've tried limeaway. I've tried brake fluid, but not for an extended soak. That's probably worth a try. I've heard of using Bon Ami to polish glass (here, I think), but again there's the original coating to consider. I let it soak overnight in extra strength bleach, no change. A trip to the parts store might turn up something - I've heard of something referred to as liquid freon that was a solvent, but that's probably long gone. Carb cleaner, gun cleaner, starting fluid, tried all those.

 

Since the stuff appears to be some sort of epoxy or hard plastic, I think I'm going to have to go after it chemically. I have yet to try soaking it in armorall to impregnate it and then trying to attack that with solvents or acids, hoping to collapse the matrix around the armorall. I think I've soaked it in one of the citrus cleaners, no luck. Nitric acid is pretty iffy, but I recall a procedure for making it. Benzene is pretty hard to find these days. I can generate bromine gas, I could give that a try with some preparation. What else eats plastics?

 

I've got it soaking in one of those recent adhesive removers, if that doesn't work an extended soak in brake fluid and then MEK will probably be next on the list. I've been working on this for about a year now.

 

Thanks for all the suggestions everybody, and for anyone that might think this is a joke, it's not.

If I do manage to get the stuff to come off, and it's not too exotic, I'll try to remember to post.

I may eventually give up and just see what happens with Bon Ami.

I've gotten a few secondhand lenses from the infamous auction site, and while most of them have been beautifully clean and

clear, some have had some sort of haze. Some of these cleaned easily, one or two was difficult, and two have been impossible.

 

The easy ones were a matter of simple lens or at most, glass cleaner, and any required dis/reassembly. Not a problem.

 

The difficult ones shed the usual cleaners with a shrug, and remained clouded. One of these, an Apo-Gerogon that one or more

of you may have owned before me, resisted *everything*. I did finally get that front surface clean, but I did it with

concentrated sulfuric acid. It was a last resort, nothing else so much as touched the fog. Needless to say, this is a very nasty

material and not for the meek or clumsy. To my surprise, it left the coatings intact, and all it has now are the few wipe marks

it accumulated before it arrived in my hands.

 

I have two lenses that have resisted everything, including concentrated sulfuric acid, pure methylene chloride (paint stripping

component), acetone, MEK, WD-40, hydrochloric acid, various alcohols, water, ammonia, lighter fluid, bleach, oven cleaner

(with

lye), and a variety of the usual alternative solvents. The gunk on the lenses does *not* appear to be fog. Instead, it appears

to be a coating that was carefully applied, wiped on and spread around to cover the entire front surface of the lens. The

reason for this application I can only attribute to someone wanting to make the lenses unusable, because that's what it did.

Acetone had a small effect, but the majority of it remains and acetone has no further effect

 

So, does anybody have any ideas or suggestions? On a glass working site I've seen an "epoxy remover", which must be an

unpleasant material because epoxy is notoriously difficult to dissolve or remove. I'll get around to buying some shortly, but in

the meantime any suggestions would be appreciated. (I don't have any trichlorethane handy)

I recently received a Linhof Kardan Super Color 4x5 as sort of an "extra" - it was attached to the 300mm Fujinon I wanted. Since the bellows is completely trashed (and amazingly so), I kind of have the same problem.

I also happen to have a couple of Calumets, and I've checked the boards for fit.

 

The following assumes you have essentially the same camera I do....

 

The Good News:

Both boards are 6 and 3/8 inches square, so the height/width is right for the Calumet board to fit the Linhof.

 

The Bad News:

The thicknesses are wrong. The Calumet board is about 1/8 inch thick, plus some paint. The Linhof board is about .077" thick, or a few shades more than 1/16".

 

The Problem:

While the Calumet boards will fit into the Linhof frame dimensions (and the corners are more rounded on the Calumet boards, so that's not a fitting issue), the two clips at the bottom and the big clip at the top won't accept a board that thick.

 

Solutions?

Get a Calumet bag bellows. Have someone machine the thickness of the mounting plates in the areas of the clips down to something acceptable for the Linhof. (extremely judicious use of an end-cutting endmill in a drill press would work, but be slightly less neat, or... use a dremel) Do something about potential light leaks around the edges, since the light baffle setup is different - maybe some of that black adhesive backed felt, or some thin black foam weatherstripping. Pop it on the Linhof, check for leaks, and smile about the $300 you can spend on something else.

If you know any hobbyist machinists, you can probably get something slightly more elaborate made that doesn't involve altering the original bellows frames.

One possible problem:

My Calumet bellows frames are plastic, while my Linhof frames are metal. Shaving the plastic that thin may cause problems, like breakage. If you've got spare metal Linhof lensboards and don't mind taking the bellows apart, go for it.

 

Wait, *I* should do this! Except, the 4x5 calumet is basically mint in the box since I've only used it a few times since I got it ten years ago and I don't want to modify any of it's parts (this week). As I've cleaned and adjusted the Linhof, I'm finding that I really like it's operation, amazing how a really nice piece of equipment will do that. Too bad I didn't search/destroy that Linhof bellows that closed on fleabay two days before I received this camera, but I do have the bellows endplates so I'll see about scaring up something that I can splice in until another shows up.

 

I kind of deal in really thin leather, and the idea of sewing up my own bag bellows has occurred to me, any comments on that?

My old Burke & James has a sheet of what looks like flashed opal glass in it, white side down. Don't know if it's original. I'd think you need a more or less white sheet to allow illumination to pass without being able to see through it, as well as something that wouldn't show textures or detail that's not in the neg.

I saw that camera, took a look on the cambo site, and concluded that it was home-built, at least as far as those L shaped standards go. No movements aside from focusing? Bummer. Are the standards metal? Depending on how the front and rear are attached, and what parts may be missing, you might be able to gather up the necessary pieces on ebay but I don't envy that project. Or, are whatever movements there may be just thoroughly locked down? Stick a lens on it and shoot with it, you won't be bothered by all those "other" adjustments......

I've had the same problem, they're weird, where can I get them - and when you can find them, they seem to run between $25

and $50 depending on condition (and the bottom end really is the *bottom end*).

So I made my own. The first was painstakingly created from aluminum plate with stuff like a hacksaw, file, sandpaper, and a

compass with a blade stuck in it. Needless to say, this took a horribly long time. Later I started working with industrial

engraving machines, and I was able to make another while management was on vacation. The use of actual power tools greatly

sped the process.

That was years ago. Now, I have my own machine and am getting the photo hardware back out again, and was considering that

I should make a few more of them to a) Use on my Pressman, and b) Sell.

At this point the project is only in concept stage, but I've done this before so it shouldn't be difficult. The pirmary problem

will be lead time (and perhaps aluminum stock, I don't think I have the right thickness on hand, but I may have brass), as I

have lots of other projects in progress.

If you're interested, email me and I'll set your email aside for when I get that project going (and yes, I'm afraid I'll have to

charge for the things). Oh, and sorry for the wordy post...

 

<p>

 

-Gary