Vacuum easels...recommended?

[Jon Wilson]

Who uses or has used vacuum easels? What are your thought/recommendations on using them or not? Problems, if any, you encountered? Positive findings? Thanks.

[Peter De Smidt]

In my experience, the biggest problem is the vibration that passes from the the vacuum motor to the easel. The second issue is the noise of the vacuum.

[Jim Jones]

Decades ago I made one powered by a vacuum cleaner for up to 11x14. The small holes were spaced at 1/2". Pegboard might have worked as well. It flattened most papers, although thick fiber paper sometimes didn't pull down completely flat in certain conditions of humidity. The hose to the vacuum cleaner eliminated vibration. A remote location for the vacuum moter could have reduced the considerable noise. The easel was lost in a darkroom fire, and I went back to using Speed Ez-els.

[Drew Wiley]

No vibration will get to the easel if you use the right kind of vacuum pump. Do not use
a peristaltic or diaphragm pump. You need something with a rotary action which is
continuous. If you can't afford something quiet and specialized, you can always put
the vac in an adjacent room and run the hose thru a hole in the wall to isolate the
noise, with a remove on/off switch. It doesn't take much vac draw to pull film flat. In
fact, the biggest mistake people make is to apply to much vac. So unless you own a
variable power unit ($500 up), you will need a bleeder valve. Used graphics equip
suppliers are likely to have all these things at reasonable prices. Correctly made, a
vac easel will improve things quite a bit with squirrely papers that tend to curl, or with
long exposure times which make certain papers heat and buckle. But the easel itself
needs to be thoughtfully designed... a more extended topic.

[Greg Blank]

I use a vac easel as my preferred easel. I bought mine from Omega when they moved and were selling or throwing stuff. It was like 20 usd for a 20x24 easel. One could easily make such a device. My vac I also clean house with its an old canister type. Its loud using in the darkroom so a remote set up would be better. The long flexible hose does not transfer vibration..that I can see and I am picky :)

[Gary Beasley]

I have mine piped into an adjacent closet so the noise is very minimal, and no dust stirred up in the darkroom by the blower. I have to use cover sheets on the empty part of the easel to retain vacuum but otherwise great performance.

[Bill Burk]

I have a 20x24 Bychrome and matching pump with extra long hose.

I have no regrets buying it, but don't use it on the enlarger. My standard size print is 11x14 and an old Kodak easel holds paper flat enough for this work.

It hangs on the wall of my darkroom with the pump under the sink. I use it for copy work.

There are plenty of situations where the vacuum easel could come in handy.

-borderless
-20x24 or 16x20
-horizontal enlarging

[Jon Wilson]

I appreciate everyone's responses. Good food for thought. Keep them coming. :)

[Mark Sampson]

They aren't necessary unless you have a horizontal enlarger, or are making prints larger than 20x24. They are great for 30x40s. It's relatively easy to make your own but remember that they have to be masked off perfectly around the paper, no air leaks, or they won't work at all.

[Bill Burk]

...they have to be masked off perfectly around the paper, no air leaks, or they won't work at all.

I suspect that is a problem with home-made vacuum easels. The Bychrome and matching pump never needs masking. It might be the gauge of the holes or the strength of the vacuum. Also, though I haven't taken it apart, I believe the interior is baffled to direct the vacuum advantageously.

[Jim Jones]

. . . I believe the interior is baffled to direct the vacuum advantageously.

Baffles may be necessary to keep the air pressure difference between inside and outside from flexing the paper supporting surface rather than to direct the vacuum. There is little air movement as the easel finishes drawing down the paper.

[John Bowen]

I have a 16x20 vacuum easel I use for contact prints. For enlargements I use speed easels. I mask the contact prints with 2ply mat board to improve the vacuum when working with 8x10 or 7x17 negatives

[Drew Wiley]

I've made plenty of them. I would consider them absolutely essential for really sharp prints if the paper itself does not tend to lie completely flat or if long printing
times tempt the paper to heat and buckle. This is stated in relation to how I often prefer to use enlarging lenses at optimum apterture, or relatively wide for shallow depth of field upon the primary emulsion itself, and not what lies on either side. Internal distribution of how the air draws things down can be important. I also like to combine the function of the perimetergasket with that of the border, i.e., the masking blades. It's very important to design the internal struts not only to optimize
the intended air flow, but to prevent the easel itself from becoming distorted by
vacuum. These are fun projects if you like shop work. Take your time and do it right.
Forget the pegboard route. My last one of these was a precision pin-registered one to match a 20 by 24 film punch I recently refurbished.

[Bill Burk]

I can look in where the vacuum hose connects to the Bychrome and clearly there is a two-inch wide path blocked off the sides (with a few holes in the sides) and top (just below the vacuum surface) that opens to the center -- so most of the vacuum is sent to the center to hold down smaller pieces.


I have a 16x20 vacuum easel I use for contact prints. ... I mask the contact prints with 2ply mat board to improve the vacuum...

Masking will help/is required for contact printing.

[Drew Wiley]

The idea of channelling vacuum first to the center is probably related to where you want it to "tack" the film first, so that you spread the draw logically and evenly once the valves are open, rather than just accommodateing smaller prints. Conversely, if you design a vac easel for pin-registered work, you want it to obtain draw adjacent to the registration bar first, then gradually spread downward and out away from it.
Although this only takes a couple of seconds, it is very important for eliminating
bubble-like islands or air pockets which would affect overall registration.

[Peter De Smidt]

In my experience, the biggest problem is the vibration that passes from the the vacuum motor to the easel. The second issue is the noise of the vacuum.

Just FYI, the model I had was a Bychrome 20x24", along with it's pump. I did use the long hose/remote starter solution. I still had vibration in the easel, which could easily be felt by placing your hand on the print, and so I expect that it wasn't a rotary pump as Drew talked about.

[bob carnie]

Hey Bill

I just got a couple of Bychrome big easels, how do you like them and where do you get vacuums for them?

Bob

I can look in where the vacuum hose connects to the Bychrome and clearly there is a two-inch wide path blocked off the sides (with a few holes in the sides) and top (just below the vacuum surface) that opens to the center -- so most of the vacuum is sent to the center to hold down smaller pieces.



Masking will help/is required for contact printing.

[bob carnie]

Posted too quick. so there is no way to get rid of the vibration??

Just FYI, the model I had was a Bychrome 20x24", along with it's pump. I did use the long hose/remote starter solution. I still had vibration in the easel, which could easily be felt by placing your hand on the print, and so I expect that it wasn't a rotary pump as Drew talked about.

[Jim Jones]

Posted too quick. so there is no way to get rid of the vibration??

If the vibration is due to fluctuations in the vacuum, a small air tank in the vacuum line might cure it. Soft rubber hose should eliminate the transmission of vibration from the pump to the easel.

[Jim Jones]

The idea of channelling vacuum first to the center is probably related to where you want it to "tack" the film first, so that you spread the draw logically and evenly once the valves are open, rather than just accommodateing smaller prints. . . .

This is also efficient when contacting with large negatives. A vacuum table tends to draw down the interface between film and paper (or film) at the edges first, sealing them so the center does not draw down. Even with the advantage of drawing down the center first, the vacuum tables I once used required many minutes to draw down 32x40 film sufficiently for good 133 dpi halftones.

[Drew Wiley]

Hmm ... It's been awhile since I used my own 30x40 wall easel. It's been tossed. The
30x40 vac easel I now use is beautifully machined tank of a unit cannibalized from a
22ft long process camera. It has various sets of retractable registration pins and a variety of channel options. I added the masking blade system. The vac holes are quite
small. The unit is so efficient that I can draw flat even a 30X40 in just a few seconds
using only a 12V little cordless vac.

[Jim Jones]

My 11x14 printing vacuum easel drew down almost instantly. The contact frame for duping 30x40 halftone negatives onto diazo film had a much more difficult task. We had two quite large 5000 Watt metal halide lamps close to the frame. Any bit of air trapped between film and negative degraded those 133 dpi halftones. For the most even exposure on critical jobs we dodged the center of the frame while exposing. Duping onto litho film with a small more distant light source took perhaps seconds for adequate draw-down. In each darkroom we had a fairly powerful pump.

[jayabbas]

A Durst Gravaku vacuum board is a big , precision chunk of engineering that might be worth researching for your needs. It has individual vacuum zone control for all the popular sizes 8x10, 11x14 and so on up to 20x24.

[Jon Wilson]

I sure appreciate everyone's posts.

[Bill Burk]

Noise is the same as a typical household canister vacuum cleaner.

With the Bychrome I never thought there was vibration, but now I feel what Peter J. De Smidt reported. I don't think it's motor vibration. It kind of feels like grinding. I think it's turbulence.

[ROL]

They aren't necessary unless you have a horizontal enlarger, or are making prints larger than 20x24. They are great for 30x40s.

I don't believe vac easels are necessary for prints larger than 20X24. Nice, but not essential. If you are able to level your film stage, lens, and printing platforms (as with the use of a laser alignment tool), depth of focus with this degree of enlargement should allow for some amount of imperfectly flat roll papers.

[Asher Kelman]

This is also efficient when contacting with large negatives. A vacuum table tends to draw down the interface between film and paper (or film) at the edges first, sealing them so the center does not draw down. Even with the advantage of drawing down the center first, the vacuum tables I once used required many minutes to draw down 32x40 film sufficiently for good 133 dpi halftones.

Jim,

Did you use a vacuum gauge and an automatic bleed to keep the pressure constant?

Asher

[Asher Kelman]

I don't believe vac easels are necessary for prints larger than 20X24. Nice, but not essential. If you are able to level your film stage, lens, and printing platforms (as with the use of a laser alignment tool), depth of focus with this degree of enlargement should allow for some amount of imperfectly flat roll papers.

ROL,

How do you calculate that? What assumptions lead to this difference that no vacuum board would be needed for prints of 40x60 or 720x50 etc? It seems intuitive the getting the paper as flat as possible would tend to give a sharper print. The larger the paper size, coming from a large roll, the more likely it's not lying flat.

My consideration is for photographic imaging directly on to Harmon or Ilfochrome paper with no negative.

Asher

[Jim Jones]

Asher, the guages usually peaked at maybe 24lbs vacuum, and the pumps continued to run during exposure. I don't remember anything limiting the vacuum.

[Asher Kelman]

Asher, the guages usually peaked at maybe 24lbs vacuum, and the pumps continued to run during exposure. I don't remember anything limiting the vacuum.


Thanks Jim!

I appreciate your reply. That value should be the same for any size board if the holes are the same size. So what are the size of the holes and the spacing?

Asher

[bob carnie]

I completely agree. I like vacuum easels for contact work but have found for murals there is no issue if every thing is leveled.

I don't believe vac easels are necessary for prints larger than 20X24. Nice, but not essential. If you are able to level your film stage, lens, and printing platforms (as with the use of a laser alignment tool), depth of focus with this degree of enlargement should allow for some amount of imperfectly flat roll papers.

[Jim Jones]

Thanks Jim!

I appreciate your reply. That value should be the same for any size board if the holes are the same size. So what are the size of the holes and the spacing?

Asher

The little 11x14 vacuum easel I made had 624 small holes on a 1/2 inch grid. I don't remember the hole size; probably less than 1/32 inch. The size isn't critical as the volume of air moving through them is low. Large holes and high vacuum could cause dimpling of thin paper. The vacuum cleaner I used could pull only a few lbs of vacuum.

The 32x40 inch vacuum tables used at work years ago had a heavy glass top that hinged up for access and sealed against the table frame in use. They drew the vacuum through canvas, so the hole size and pattern wasn't visible. I believe the hose to the vacuum pump was well under an inch inside diameter.

[Herb Cunningham]

I use a Nuarc with their pump, works like a champ for contact printing for large negatives, especially large digital negatives.

You should try local photo shops. They quite often have them sitting around in the back, be glad to get them out of the house.

[Drew Wiley]

I would never, ever print even a 20x24 Cibachrome without vacuum. For one thing, its
a very dark heat-absorbing paper which often requires long printing times and will buckle; for another thing, it retains a degree of much greater degree of image detail
than paper media, so warrants nitpicky technique. By comparison, I notice that the
latest generation of Crystal Archive RA4 paper lies remarkably flat, even better than
the previous Super C, and of course the printing time for C papers in general is quite
fast. I haven't done anything on the new paper bigger than 20x24 yet, but basically
figured out I didn't need vacuum in this size. With the polyester-base rolls (Fuji CA
Supergloss), I'm sure I'll revert to vac regardless. The friend on mine who did the most
commercial mural work back in lab days simply tacked the paper coming off the vertical roll with two very long magnetic bars, top and bottom. But another friend
who specialized in high-end Ciba always always used vac for the big 60" Ciba rolls.
I figure my own work had to significantly exceed commercial lab quality; so vac
was a must with polyester-based stock, and still is with certain curl-prone black
and white papers (seems to be the papers I've had around just a little too long which
give me the most problems). So no right or wrong per se here, just intelligent options.

[Asher Kelman]

I use a Nuarc with their pump, works like a champ for contact printing for large negatives, especially large digital negatives.

I'll see if I can find one to look at. I want something v. large. 52"x76" or more for 50" Cibachrome paper and also for much smaller contact prints


You should try local photo shops. They quite often have them sitting around in the back, be glad to get them out of the house.

Yes, I should do that before spending any money on building one! Now often these are vertical. Is there any problem doing contact printing with the easel vertical?

Asher

[Asher Kelman]

But another friend
who specialized in high-end Ciba always always used vac for the big 60" Ciba rolls.


Is that 50" or do they also make 60"? I looked and B&H has 50" but not 60" rolls.

Asher

[Drew Wiley]

B&H is not an industrial distibutor. Big labs typcially bought from various manufacturers
like Ciba-Giegy, Fuji, Kodak, and even Forte directly. The products selection was way
bigger than what you'd find at any retailer, though these might have had on hand the
full price list for the sake of special orders. Now B&H, Freestyle, etc stock only min
amts of Ciba if any at all, and have an arrangement to have it shipped directly from
the importer. The overall selection of color materials has of course significantly diminished in recent years. An annoyance to me is that Crystal Archive is no longer
available in 30x40 sheets, and not even in 30-inch wide rolls. You have to buy it in
32" wide rolls, so that to fit my particular drum, I have to cut it twice, once for length,
and next two inches off width. I have the ability to do that, but it's a nuisance. Ilfochrome is still packaged in 30X40 sheets but has become quite expensive, mostly
due to the predictable raw materials and shipping inflation which has affected quite
a range of products nowadays. Anyway, I think Ciba was once available up to 6 ft
wide. Most seriously equipped big labs had XY cutters which could turn a roll into
any smaller size they wished. These cutters are still valued in for wide-format laser
printing, so are rarely a bargain even used. And they take up a lot of space.

[Drew Wiley]

Asher, another point - big Ciba prints require tremendous light output, esp given the
fact that to obtain good tonality it needs to be heavily silver masked, that is, unless
you known some pretty sophisticated tricks. So we're talking about true industrial scale colorheads and processing and all the nasty permits and health issues that come with that. If you really want to get into that, I know someone who has all the gear
for sale, but he won't offer it on the open mkt. But just to set this stuff up requires a
very serious investment. The more modern option, Fuji Supergloss, is unfortunately only
available in 32-inch rolls and not cut sizes at all. You can find other sizes for sale,
but they're all older material, not the current Type II. Maybe we can talk about this
more in person later in the month.

[Asher Kelman]

Asher, another point - big Ciba prints require tremendous light output, esp given the
fact that to obtain good tonality it needs to be heavily silver masked, that is, unless
you known some pretty sophisticated tricks.

Drew,

I'm planning to use 30,000 Watt.seconds for the flash.

At f22 I should be O.K. assuming an ISO of 3. Does that cover the "Silver Masked" comment or not?

Asher

[Drew Wiley]

Not even close, Asher. For Ciba you'll need a max aperture of the enlarging lens around f/8 or even less or you'll run into hopeless reciprocity issues on a big print. Masks typically need to be around .60 density for most LF transparencies, or even as high as .90 - that's two or three stops added to what is already a very slow paper.
Now if you're experimenting with in-camera Ciba, that's another story. But I'm a bit
confused by you referring to both large print sizes and flash exposure within the
same context.

[Asher Kelman]

Not even close, Asher. For Ciba you'll need a max aperture of the enlarging lens around f/8 or even less or you'll run into hopeless reciprocity issues on a big print. Masks typically need to be around .60 density for most LF transparencies, or even as high as .90 - that's two or three stops added to what is already a very slow paper.
Now if you're experimenting with in-camera Ciba, that's another story. But I'm a bit
confused by you referring to both large print sizes and flash exposure within the
same context.

Drew,

This is just in camera Ciba paper using the camera obscura I'm building. The model is in the next room lit by a strobes. The apertures and flash requirements are accurate. The lens is a 750mm Apo Germinar.

I'll be doing the Ciba work first with my PS945 at f 4.5 on 8x10 to get the same DOF approx and so will need much less light. Then I'll do it 20x24 as I can still process that in my Job drums. The larger paper I'll send out.

Asher

[bob carnie]

Sounds like an amazing project Asher.

Drew,

This is just in camera Ciba paper using the camera obscura I'm building. The model is in the next room lit by a strobes. The apertures and flash requirements are accurate. The lens is a 750mm Apo Germinar.

I'll be doing the Ciba work first with my PS945 at f 4.5 on 8x10 to get the same DOF approx and so will need much less light. Then I'll do it 20x24 as I can still process that in my Job drums. The larger paper I'll send out.

Asher

[Asher Kelman]

Sounds like an amazing project Asher.

But scary, Bob! The big thing is to get the vacuum board and then I have everything for the large prints. However, I have a lot of work to make sure that lighting distribution is perfect as nothing can be corrected in the print, as there is only one! Also the chemistry for the prints up to 20x24 are not the same as the ones used for the large prints so there will be, I am sure, a hard learning curve.

Asher

[Drew Wiley]

OK, I get it Asher. Just remember that you're going to have to compensate for the
density of the various cc filters needed for correct color balance per paper batch.
Controlling contrast without masks means you will have to have a more mellow lighting
ratio than with ordinary film photography, but you can test for this. Certain color corrections will simply not be possible without masking, so you'll just have to figure out
how to best use Ciba creatively. It is its own beast anyway, and the inherent flaws
can become part of the inherent beauty. Sounds like a nice lens too. Someday I'd
like to hook up the 760 Apo Nikkor I've got laying around.

[Drew Wiley]

Oh, but another question, Asher. Why do you refer to two different kinds of chemistry?
P-3 can be used for any size Ciba.

[Drew Wiley]

Your biggest problem in the long run will simply be handling the big sheets of Ciba. You
might need an assistant, but it's tricky at best without getting irremediable kinks in the
polyester base. What I do is suspend a bar of appropriate lengths overhead, itself
attached to an adjustable-tension pulley system or "tool-balancer". Attched to this
bar are a serious of those silly plastic cushioned potato-chip bag clips, which hold
the top edge of the film wonderfully and let you gently maneuver it into position. A
low-tech solution to a high-tech problem.

[Asher Kelman]

Your biggest problem in the long run will simply be handling the big sheets of Ciba. You
might need an assistant, but it's tricky at best without getting irremediable kinks in the
polyester base. What I do is suspend a bar of appropriate lengths overhead, itself
attached to an adjustable-tension pulley system or "tool-balancer". Attched to this
bar are a serious of those silly plastic cushioned potato-chip bag clips, which hold
the top edge of the film wonderfully and let you gently maneuver it into position. A
low-tech solution to a high-tech problem.

Drew,

So far its seems intuitive that the active surface of the vacuum table should be steel to hold magnets and painted black in case I want to also shoot transparencies and not have reflections. I might perhaps include fitting essential/helpful for contact printing although I am not sure what that might be!!! One can have guides and even some holes can be threaded so that one could support a sheet of glass in a small area than the whole table.

I could load the sheet flat with the easel set has a table and then with the sheet fixed, swing the easel vertically. I also should look into your system. I have nightmare visions of an entire roll unwinding. Alternatively, Perhaps loading it vertically and pulling the paper up from the ground is the best way. I could first attach a magnetic lead bar clamped to the upper edge to keep it all straight. One would have to prevent air pockets from giving waves of crumpled paper!! I think that fixing the top and gradually bringing in the paper to the vacuum board might be best. I had better get some blank material to practice on! :)

Asher

[ROL]

FYI – Asher PM'ed me his questions, presumably because they had remained unanswered in this thread. For the record, it is not usual that I return to most threads, unless there is some specific reason to do so. I don't even check in on the forum every day. I am also reticent to respond to PM's, as I feel that there is nothing that could, or should be said, that cannot be said in proper civil discourse, and useful to others, in public forum – with the possible exception of someone seeking a "date". And I've seen a lot of you in this thread (http://www.largeformatphotography.info/forum/showthread.php?t=75204), and must be frank in saying that you are all too ugly and overwhelmingly of the wrong sex to make this even a passing consideration. My response then, is highly subjective, and only my opinion, aimed primarily and without guile to Asher's concerns, who I have alerted by PM. To paraphrase a famous American, Yosemite Sam, "I ain't looking for no trouble, varmints!"



ROL,

How do you calculate that? What assumptions lead to this difference that no vacuum board would be needed for prints of 40x60 or 76x50 etc? It seems intuitive the getting the paper as flat as possible would tend to give a sharper print. The larger the paper size, coming from a large roll, the more likely it's not lying flat.

My consideration is for photographic imaging directly on to Harmon or Ilfochrome paper with no negative.

Asher

Asher,

I have reviewed your thread again and have to say that there have been many fine and rational respondents on the employ of vacuum easels. Some, like me, either by choice or necessity, must keep techniques basic (K.I.S.S.). If I had the desire, skills, time, or money to make or acquire a vacuum easel of large dimension, I might invest in one. But I do fine with simple techniques based on my existing desires and needs. My paradigm is the fine print, not the equipment used to produce it.

I guess the "assumptions" are that large fine prints have been made for many decades by talented darkroom artists without the use of exotic (or even vacuum) measures. Many of these prints started out taped to table surfaces. The fact is that I have made many large prints myself on simple, imperfect, mural easels of my own design to 30x40, the largest size I can individually manage in a limited amount of lab space, on a vertical enlarger and drop table arrangement (seen here (http://www.rangeoflightphotography.com/pages/a-darkroom-portrait#enlarger)). I have had digital–chested, grain sniffers pressing noses right up to the glazing of my largest prints and exclaim, "Yes, this is what large format can do!" They were viewing prints enlarged from medium format – 120 film.

I recognize that you wish to go larger still. I find sharpness to be less of an issue with large prints than with smaller sheet sizes. They are forgiving in part because of increased normal viewing distance, in part because mural prints take on a life of their own with respect to their unusual size, and in part because depth of focus with normal enlarging lenses is physically greater. The calculations are different for every lens (check your lens manufacturer), but will grow as the distance from lens to paper increases (i.e., the enlargement). Flat field process lenses are the only exception, that I know of, to this rule. I often use a somewhat wider lens than normal, say 180mm vs. 210mm, for 5x7 negs. only because they will give me more DOF at the paper. Stopping down will also assist in loosening up focusing. This is one good reason to check focus with the lens wide open, besides offering a brighter image. Some of my murals require up to 40 minutes of exposure, including burning. Monochrome printers should be sure to check the "safety" of their safelights before engaging in long exposures. I would think the only way of checking focus on the paper, given the direct camera obscura technique, will be to visually check focus of the scene prior to exposure with eyeglasses or possibly bi/monoculars.

As far as lying flat, the larger the roll–cut paper (fiber), the more likely it will relax. I wouldn't think you'd have any problem with plastic/resin coated color papers.

Sharpness, IMO, has become the digital tail wagging the dog. Film enlargement, or even direct camera obscura as is your intention, need not necessarily seek the sharpness of digital, unless it desires to be digital. Conversely (perversely?), many digital manufacturers continue to seek the "film look" as their holy grail.

To the good, by the time reach the end of your project's journey, you may be the reigning authority on printing large, vacuum easel or not.

Good luck in your efforts. The more I think about the project, the more I become envious of it and wish I were involved. Please post back your results and give museum location of showing. And then PM me so I don't miss it. ;)

[Asher Kelman]

FYI I am also reticent to respond to PM's, as I feel that there is nothing that could, or should be said, that cannot be said in proper civil discourse, and useful to others, in public forum – with the possible exception of someone seeking a "date".

ROL,

The only date I'd want is for Per Volquartz to work with me as he promised just weeks before his tragic passing. There's someone who's company was so special. He was to help me set up and guide me in my processing of 8x10 before I work with the large materials. More than the help, I miss his person. I wish I'd have met him earlier! What a treasure, now lost!




Asher,

I have reviewed your thread again and have to say that there have been many fine and rational respondents on the employ of vacuum easels. Some, like me, either by choice or necessity, must keep techniques basic (K.I.S.S.). If I had the desire, skills, time, or money to make or acquire a vacuum easel of large dimension, I might invest in one. But I do fine with simple techniques based on my existing desires and needs. My paradigm is the fine print, not the equipment used to produce it.

I'm anti-gear. Just the gestalt of exporting my ideas into the giant, immersive physical form; nothing else. Sometimes though, one has to change when one's gear limits one's work. Although I must have one of the largest collections of Lumedyne lights, new and ancient, these are insufficient for UULF work with 3 ISO media. So either cost or complexity increases, KISS, notwithstanding!


I have had digital–chested, grain sniffers pressing noses right up to the glazing of my largest prints and exclaim, "Yes, this is what large format can do!" They were viewing prints enlarged from medium format – 120 film.

12X enlargements that are perceived to be LF testify to your technic at every stage.


I find sharpness to be less of an issue with large prints than with smaller sheet sizes. They are forgiving in part because of increased normal viewing distance, in part because mural prints take on a life of their own with respect to their unusual size, and in part because depth of focus with normal enlarging lenses is physically greater. Good point.


The calculations are different for every lens (check your lens manufacturer), but will grow as the distance from lens to paper increases (i.e., the enlargement).

I'll be at ~ x2 focal length at 1:1. So for 760mm Apo Germinar, lens to paper distance is 5ft. For the Red dot Artar, 47.5" the distance is ~8ft. With your 120 film enlarged to 30"x40" your magnification is x12 so, your DOF will be better. If I'm in error, let me know.


Flat field process lenses are the only exception, that I know of, to this rule. I often use a somewhat wider lens than normal, say 180mm vs. 210mm, for 5x7 negs. only because they will give me more DOF at the paper. Stopping down will also assist in loosening up focusing.
That's why I have the 760 mm which is rather wide for portraits. I also have the 600mm Apo Germinar but am not sure how it will look. It may be too much close lens-to-subject perspective-distortion of features.


Some of my murals require up to 40 minutes of exposure, including burning. That's hardly possible with live models, although one could first partially expose background and then use the strobe for just the model. For still life, of course, there's no issue. I plan to test the papers at 4x5 or 8x10 simple areas over the large image field to sample and make sure that the exposure, UV filtering and color correction is perfect before committing to the giant print.


Monochrome printers should be sure to check the "safety" of their safelights before engaging in long exposures.Good point; I'll talk to the Ciba pro lab folk!


I would think the only way of checking focus on the paper, given the direct camera obscura technique, will be to visually check focus of the scene prior to exposure with eyeglasses or possibly bi/monoculars.
I can calibrate the system for each set up and have lateral laser lines to reproduce, as close to what's possible and then also check the focus at the easel.


As far as lying flat, the larger the roll–cut paper (fiber), the more likely it will relax. I wouldn't think you'd have any problem with plastic/resin coated color papers. Before I buy the easel, I'm going to visit some pro labs to get their feedback. From what I've heard, the curl in the paper is significant. Perhaps, magnetic bards on each side would be sufficient.


Sharpness, IMO, has become the digital tail wagging the dog.Well, that's an interesting idea. For most of my work, digital or film, I use wide apertures as I love soft focus. I'm just concerned with esthetics and the ability to image skin, flaws and all without any post processing. So this is the most anti-digital one can get. Everything has to be in the lit subject's projected image at the instant of exposure. There's no possibility of corrections in most cases. Obviously, if technique does not match the ambitious size, I'll run out of funds fast. The biggest challenge is not sharpness, but lighting design and distribution adequate to purpose of the image with no excuses. Nevertheless, I want skin to look real at 16-30" or closer if possible.


To the good, by the time reach the end of your project's journey, you may be the reigning authority on printing large, vacuum easel or not. If I am competent enough to express my ideas the way I hope to, that will be more than sufficient reward. For me this is a great challenge and there are many steps to climb. After all, photography is already set with fine standards. Just the ordinary work shown here, for example, is hard to match in technical quality and artistic talent.


Good luck in your efforts. The more I think about the project, the more I become envious of it and wish I were involved. I wish you were here to help out!


Please post back your results and give museum location of showing. And then PM me so I don't miss it. ;)

For sure and we'll have a great party! By that time there will be a 4x5 back with 320 MP for just $25,000 and even cars will float in the sky!

Asher :)

[Asher Kelman]

I'd love to hear about hole size and spacing in your vacuum boards.

Thanks,

Asher

[Drew Wiley]

A detail where I'd disagree with ROL - Ciba can buckle on long exposures and leave you with not only a "less sharp than ideal" image, but an obnoxious offset double image in certain places. True, LF onto Ciba is the gold standard of print sharpness,
and not anything printed digitally; but doubled-lines here and there will be out of place
even in deliberately soft work, just like "bad bokeh". Another problem is heat. It's best
to put the cc gels over the lights instead of the lens (multiple stacked lens filters will
degrade the film image). I assume you already know this and how to ventilate for it, but just in case. ... Rolling up the exposed images for transport will be tricky. You'll want to have on hand an absolutely clean smooth inner core which you can tape the print width to and roll it around prior to placing it in the light-tight tube to take to the processor. When you get down to the dress rehearsal, I'd practice with either some voided Ciba stock or drafting mylar and not just paper, just to get the hang of it.

[Asher Kelman]

A detail where I'd disagree with ROL - Ciba can buckle on long exposures and leave you with not only a "less sharp than ideal" image, but an obnoxious offset double image in certain places. True, LF onto Ciba is the gold standard of print sharpness,
and not anything printed digitally; but doubled-lines here and there will be out of place
even in deliberately soft work, just like "bad bokeh". Another problem is heat. It's best
to put the cc gels over the lights instead of the lens (multiple stacked lens filters will
degrade the film image). I assume you already know this and how to ventilate for it, but just in case. ... Rolling up the exposed images for transport will be tricky. You'll want to have on hand an absolutely clean smooth inner core which you can tape the print width to and roll it around prior to placing it in the light-tight tube to take to the processor. When you get down to the dress rehearsal, I'd practice with either some voided Ciba stock or drafting mylar and not just paper, just to get the hang of it.
Drew,

It could be that the Cibachrome pro lab has already designed tubes for this purpose. I was thinking of making some myself. My first ideas was to clamp a split solid rod to the leading edge and then have that be the spool. however, it's going to be better to have a larger diameter. So I may use a fat aluminum of plastic tube for this.

If I swing the table to horizontal position, rolling the Ciba might be much easier.

I just got an offer of a table 66"x127" but I wouldn't have a lens to cover that width unless I was doing a 2 X mag of still life! Still, I could make the largest contact prints ever! I think I'll stick to 52"x 76"; that's more conservative!

Asher

[Drew Wiley]

The idea of a tiltup table is excellent if it is accurately built. I once saw a very well
machined one of these that came with a gigantic copy camera, but didn't have any place to store it for some nonexistent future project. With any vac easel itself, even a small amt of vacuum draw over a large surface will significant affect the flatness of even a steel surface, so you either have to have internal struts to reinforce this, or have to back it with a much thicker and stiffer material.

[Asher Kelman]

The idea of a tiltup table is excellent if it is accurately built. I once saw a very well
machined one of these that came with a gigantic copy camera, but didn't have any place to store it for some nonexistent future project. With any vac easel itself, even a small amt of vacuum draw over a large surface will significant affect the flatness of even a steel surface, so you either have to have internal struts to reinforce this, or have to back it with a much thicker and stiffer material.

This one is built with an inner aluminum honeycomb core of aluminum sheet with slot in the base to allow the vacuum to spread evenly. So the honeycomb walls are the struts. I'm going to ask about deviation from flatness with the vacuum. What extras should I ask about for contact printing? I can have registration pins for the edges of the paper.

Asher