Big (for me) Fiber Base Prints - A lot of work.

[138S]

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First, thanks for your advice I'm new to big enlargers and I've a lot to learn.
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What I was getting at is that while it definitely flattens the paper very well, it doesn't do it as well as two bristol boards in a traditional dry mount press - which in its turn isn't as perfect as the drum-skin flat finish of a print dried taped under tension. The differences are, in the bigger picture, pretty small, but they are there & you have to pick & choose the compromises you are prepared to live with.

Yes... I found that 30x40cm and up the Drytec flattering is perfect with FB papers I tested, for smaller papers it is more challenging and I have to improve. Drying drums are the perfection but the vacuum press makes 1m2 of prints in a single 5min cycle, with little manpower. It makes 7000 kg force from vacuum at the temperature you want, but still as the fibers are dry they don't slide well between them, I guess the effect of water is great, it provides an internal lubrication to allow internal displacements of fibers that would be permanent after drying, for this reason for small prints I'm to experiment by spraying distilled watter, to get a bit the "vapour Iron" effect.

More of a headache is the willingness of the silicone film to pick up all sorts of marks & microscopic debris & deboss them into the face of the print - cutting a new piece of film for every print gets old (and expensive) fast, but if you want a perfect finish, it's often necessary.

We use a DIY low noise powerful HEPA class recirculation filter to remove all dust in the darkroom. Also we are to install and osmosis filter to also make always a last rinse with purified water.

silicone film, but if you want a perfect finish, it's often necessary.

Yeah, a superb print may deserve that finishing !

siliconed film lasts way more than siliconed paper, salesman says x10

I use the permanent bond, neutral pH tissue - mainly because the heat de-bondable stuff doesn't have the best reputation for staying stuck & if a conservator really needs to de-bond the print, it can be done with solvents. If extreme archival permanence is necessary, I don't dry mount, I much prefer to use properly archival, fully reversible methods like float mounting etc.

Drytec Flobond is "heat activated, but permanent and neutral, not cheap sadly but I guess that it not fails, still I'm starting in mounting and I know that many pitfalls can be there, even seasoned professionals have pitfalls in that so a novice is a perfect candidate for pitfalls

Float mounting would also be nice, but I guess that it requires a very refined job.

the LAPAL is intended to diffuse a projector bulb (e.g. something like this Philips 375E) to deliver about the same coverage

Well, LAPAL is intended for this and for other things, IMO. It is required for a projector lamp if the lens is not wide open and etc, but it also is used to easily modify the degree of diffusion. I agree, we can diffuse in other places in the optic path, in the condensers like you say, but also remakably when using a diffuser in the masking sandwich we get a perfect diffusion yet and any previous diffusion only decreases light power, as I'm to rely a lot in masking I would prefer a true condenser in what the diffusion can be adjustable in the filter drawer when needed.

Perhaps diffusing in the drawer or in the conderser delivers a different nature, to avoid Callier while retaining the condenser footprint perhaps doing it in the drawer would be interesting.

Essentially the system is a semi-focused beam using a diffused opal bulb & clear condensers - if I were to design an LED system to allow you to continue to use the condensers, I'd make a diffused flat panel that matches the aperture hole between lamp box & mirror box - more importantly it eliminates the compromise Durst had to adopt in the late 1940's/ early 1950's to get even illumination. You could probably fabricate something that could drop in to the same slot as the filter holder. If I were going to dedicate the head to mural work, I'd seriously consider getting 200w of LED into the head.

Yes... I made a flat panel that substitues a condenser... it works, we get a diffuser enlarger... but finally I epoxy glued a mast in a E27 cask with a 100W rgb LED, illuminating a 120mm dome salvaged form a LED bub, tilted 90º and pointing to the window, in that way it presents a perfect disc, and no modification in the 138 head was necessary, beyond a hole for the new cabling.

I like using a bulb because it allows to adjust fall-off, that can also be discentered off-axis, being condenser, 100w LEDs deliver an insane amount of light for potential murals, but 200w it would be also nice.

For projecting on the easel a regular 18W LED bulb is mostly enough with condensers, projecting to the wall is another thing.

Most current enlarging lenses (depending on max aperture) hit optimal performance at f4.7-8 - going below that in a sharpness critical environment (like mural printing) becomes unpleasantly obvious rather quickly. Rodagon-G's are great for 135 & 120 & aren't necessary for larger formats unless you are going to truly extreme scales - do you need to go bigger than 40x50" or 48x60" - or are you writing about hypotheticals?

You have good lenses !

Mine (old Rodagons 210/240 ) require stopping a bit more . F/8- or 11 . I've tested that by projecting an USAF 1951 glass slide on the dslr sensor.

One thing is optimal performance in the center and another thing in the corners, specially for big prints. Many prints have irrelevant things in the corners, but IMO those that require a good job in the corners perhaps require one click more.

Rodagon-G's are great for 135 & 120 & aren't necessary for larger formats unless you are going to truly extreme scales -

The N was only made until 150mm, for 5x7 and 8x10 the G is the single Rodenstock to get one or two stops more of light for big prints and still working great, but not cheap.

do you need to go bigger than 40x50" or 48x60" - or are you writing about hypotheticals?

For FB I'm limited by the HPG260, this is 47x35"

When I mentioned the N/G I was quoting a post about big print crafting seen in youtube, saying that the high efficience of a condenser illumination would require less a fast/good enlarging lens for monster prints, I guess this is right.

I agree with you that a condenser would be nasty for big prints if negative has dirt/scratches etc, so a clean/flawless processing is required, but an intermediate solution is possible, a semi-diffusion may be the good compromise, while it removes most of the Callier it conserves most of the power. Fortunatey today we have LEDs allowing a diffuser a higher output for big projections, with lower reheating in the head and in the negative. At the end the G glasses were sold to people specialized in murals having a diffuser machine (many Aristo, I guess) to get more light, those were the firsts that moved to Lambdas...

I don't think that condenser is better or worse than diffusion, but they are a bit different... but nothing better that being able to adjust diffusion, at least to learn what one likes.

 

[Lachlan Young]

DIY low noise powerful HEPA class recirculation filter to remove all dust in the darkroom.

It's not the dust that's the problem - it's the silicone film that creases, gets dented, picks up the edges of previous prints & boards & then debosses all of that into the face of subsequent prints.

Regarding smaller prints, are you using a sheet of smooth board under the print when flattening in the press?

Drytac Flobond

How well does it bond to aluminium? I've been trying to find a specific grade that does this well.

Float mounting would also be nice, but I guess that it requires a very refined job.

Not very difficult to do, just mildly fiddly in terms of cutting slits in the board for the archival tape.

Well, LAPAL is intended for this and for other things, IMO. It is required for a projector lamp if the lens is not wide open and etc, but it also is used to easily modify the degree of diffusion. I agree, we can diffuse in other places in the optic path, in the condensers like you say, but also remakably when using a diffuser in the masking sandwich we get a perfect diffusion yet and any previous diffusion only decreases light power, as I'm to rely a lot in masking I would prefer a true condenser in what the diffusion can be adjustable in the filter drawer when needed.

Perhaps diffusing in the drawer or in the conderser delivers a different nature, to avoid Callier while retaining the condenser footprint perhaps doing it in the drawer would be interesting.





Yes... I made a flat panel that substitues a condenser... it works, we get a diffuser enlarger... but finally I epoxy glued a mast in a E27 cask with a 100W rgb LED, illuminating a 120mm dome salvaged form a LED bub, tilted 90º and pointing to the window, in that way it presents a perfect disc, and no modification in the 138 head was necessary, beyond a hole for the new cabling.

I like using a bulb because it allows to adjust fall-off, that can also be discentered off-axis, being condenser, 100w LEDs deliver an insane amount of light for potential murals, but 200w it would be also nice.

For projecting on the easel a regular 18W LED bulb is mostly enough with condensers, projecting to the wall is another thing.

Essentially all you're doing by putting diffusion in the drawer is delivering something close to or better than the original bulb in coverage - the 110mm bulb was the best compromise for the era the 138 was designed in (1947 I recall from Durst's literature), but we now have better solutions with no fall-off problems that can properly illuminate the optical system if you must use condensers. If you're using diffusion between masks, then the condensers are rendered fairly pointless. I'd also point out that European enlargers tend to use clear condensers & some American models have slightly diffused ones (at least from what I've encountered), which can make Dursts etc seemingly fussier about bulb shape and placement.

Mine (old Rodagons 210/240 ) require stopping a bit more . F/8- or 11 . I've tested that by projecting an USAF 1951 glass slide on the dslr sensor.

One thing is optimal performance in the center and another thing in the corners, specially for big prints. Many prints have irrelevant things in the corners, but IMO those that require a good job in the corners perhaps require one click more.




The N was only made until 150mm, for 5x7 and 8x10 the G is the single Rodenstock to get one or two stops more of light for big prints and still working great, but not cheap.





For FB I'm limited by the HPG260, this is 47x35"

When I mentioned the N/G I was quoting a post about big print crafting seen in youtube, saying that the high efficience of a condenser illumination would require less a fast/good enlarging lens for monster prints, I guess this is right.

Getting an enlarger locked down in truly excellent alignment (which De Veres excel at) and the neg properly flat often improves the seeming performance of a lens more than significant stopping down - and the big problem is that culturally speaking we are still stuck with the received wisdom applied to 1950's/ 60's enlarging lenses - and/ or 50mm/2.8's. An effective 2 stop boost in contrast will help improve perceived 'sharpness' but a better performing lens in the first place will 'improve' even more. Unless you absolutely must go above 10-15x off 4x5 or 8x off 5x7 and up, don't bother with the G series Rodagons - besides which you would be deep into complex multi-strip printing territory etc with attendant issues. Getting a Peak focus finder with the moveable mirror (or the new Kienzle equivalent) is a good way to check focus across your image & how well aligned everything really is. I have a fair old variety of Schneider, Rodenstock, Nikkor, Leitz, Minolta lenses etc & generally I've found they perform much in line with Ctein's characterisations of them in 'Post-Exposure'.

At the end the G glasses were sold to people specialized in murals having a diffuser machine (many Aristo, I guess) to get more light, those were the firsts that moved to Lambdas...

Yes and no. The longer Rodagon-G's seem to have sold to specialists doing multiple strip large scale commercial displays like backlit adverts which were repro'd on Duratrans (these folk went to Lambda etc, then flatbed etc), aerial mapping etc - they were all using kit much more expensive and complex and powerful than an Aristo cold light. Think 4kW+ of tungsten in a dichroic head - or xenon arc etc. Durst, De Vere and a whole host of other names catered to this market with highly automated (often wall projecting) machines in the 5-6 figure price category. The 50mm's seem to have sold more generally to those making moderately big prints from 35mm (they do make a difference at 20x24"), but the 105mm is rarer because there wasn't as much demand - in professional printing terms, there were far more doing up to approx 20x24" prints than there were specialists offering bigger sizes. It's only in the last 20 years that there's been a growing culture of XXL exhibition prints for every show at every career stage. Most of the G series Rodagons (105 and up) I think are tweaked Apo-Sironar N lenses optimised for wide aperture diffraction limited performance - Rodenstock's own data hints rather loudly at this by stating that they correct perfectly for certain Apo-Sironar N aberrations when the Sironar N is used as a taking lens and a Rodagon G to print.

 

[138S]

Regarding smaller prints, are you using a sheet of smooth board under the print when flattening in the press?

For the moment I use mat board under the print in contact with emulsion, with moderate temperatures of around 85ºC, with the back of the print directly in contact with the heated glass, I'll experiment with siliconed film and high temperatures when we receive the siliconed film.

How well does it bond to aluminium? I've been trying to find a specific grade that does this well.

Still not tried, Drytac representative lives at 1 km from me and soon we'll get extensive advice from him, for the moment we have been told that they have proven solutions for a lot of situations, like mounting on glass. We also have been told that there are some situation we have to avoid to prevent yellowing in the print: There are several ways to place acidity on the print.

We feel service will be nice, our used machine had scratches on the paint, we asked the paint RAL code and they e-mailed it inmediately, this is a good start.

How well does it bond to aluminium? I've been trying to find a specific grade that does this well.

you're using diffusion between masks, then the condensers are rendered fairly pointless.

Well, in that case we have a diffusion type enlarger, still thanks to leds we can still place a lot of light on the mask, like if it was diffusion enlarger. In the past a condenser enlarger resulted underpowered when a diffuser sheet is used, while a diffuser elarger had an insane wattage, but today with LEDs we may easily overpower a condenser enlarger without reheating the head.

which can make Dursts etc seemingly fussier about bulb shape and placement.

To cover well 5x7 the 138 requires a 110mm size opal bulb, regarding position the 138 has three convenient knobs to modify XYZ position of the bulb. We have serviced and lubricated well the two 138S we have and both the head and the table move up and down by pushing with a single finger, and thanks to LED now we have two overpowered VC head machines, probably sure there are better enlargers, but I feel those 138S are bit like a Sinar Norma, no trouble.

Unless you absolutely must go above 10-15x off 4x5 or 8x off 5x7 and up, don't bother with the G series Rodagons

I agree, still a G can make sense if having not enough light in a big print, as it can deliver good performance perhaps with one stop faster aperture.

Ctein's characterisations of them in 'Post-Exposure'

Yes...

Getting a Peak focus finder with the moveable mirror (or the new Kienzle equivalent) is a good way to check focus across your image & how well aligned everything really is

Your advice is good... As I've not a moveable mirror focuser I place a mirror on the Nega 138 glass carrier (and in the Tripla) and I check alignment with a laser. The Nega 138 is very convenient to focus, with the carrier half inserted you find a hard point, then a focusing target in the frame is projected in the middle of the easel making it very easy to focus, the you totally insert the carrier, so it's about ensuring alignment with the laser. The focus target can be micro adjusted to match the film plane. The Nega 138 is great !!!

Most of the G series Rodagons (105 and up) I think are tweaked Apo-Sironar N lenses optimised for wide aperture diffraction limited performance - Rodenstock's own data hints rather loudly at this by stating that they correct perfectly for certain Apo-Sironar N aberrations when the Sironar N is used as a taking lens and a Rodagon G to print.

Yes... in fact APO Sironar N and bare (non APO) Sironar N MC are the same, with only perhaps the APO version having somewhat improved tolerances from manufacturing incremental improvements. If you see the cross-sections of the desings of the Rodagons and the Sironars N...

Of course Rodagons are tweaked for enlarging, with a way narrower coverage angle to obtain a better perofomance in the reduced circle, with also probable better field flatness which is the key in enlarging, beyond optimization for close work, possibly reducing inter-cell distance.

 

[scheimfluger_77]

Just remembered, I glued and screwed the 4x4's to a 5/4 (actual 1 inch thick) Oak board the screwed that to the 2x12 and the studs. This isn't going anywhere.

That’s what I thought but I wanted to make sure. The glue didn’t occur to me so good idea.

 

[138S]

That’s what I thought but I wanted to make sure. The glue didn’t occur to me so good idea.

Ok, but it has to be photo grade neutral glue, acidity may end yellowing the print.