What distance needed to enlarge to 30" x 40" with 135mm or 150mm lens for 4x5?

[David Wolf]

Looking for some info to help me design an adjustable enlarging table, please. Would anyone know ~ or have a formula for ~ what distance is needed between the negative stage and easel to make prints measuring 24" x 30" and 30" x 40" with a 135mm and 150mm lens for 4x5 format?

Also, anyone have experience regarding comparative sharpness/fall-off at these print sizes for Schneider's Componon S lenses, and their Rodagon counterparts? Haven't found specific magnification info for the Schneiders; Rodagon lists 2x min, 6x opt and 10max magnification. I'm unpracticed reading image fall-off charts, so any first-hand user experience would be helpful ; )

Many thanks in advance to all!

D

[Bob Salomon]

If you have limited space and want large prints the 120 Rodagon WA is a spectacular performer and will make a 20% larger print as the 135mm at the same head height.

[Drew Wiley]

In terms of falloff risk, I'd far rather use a lens of longer than normal focal length like the excellent 180 Rodagon, provided you design your setup with enough height. But if you don't have enough vertical distance, follow Bob's advice. It all depends on the specifics. What enlarger chassis, head, and mixing box options are you contemplating? Ceiling height?

[Jerry Bodine]

Some time ago I found the formula that explains all this in Way Beyond Monochrome Ed.2, so I created an Excel file that allowed me to calculate and plot the curves that result. I’ll attach an image of the plotted curves for the 135 and 150 focal lengths. The 24x30 would be a mag of 6; the 30x40 would be mag of 8 (40/5).

Regarding light falloff into the corners of an image, perhaps you’ve heard of the cosine fourth law; it’s worth looking into. It will explain why a longer focal length lens will have less falloff than a shorter one, given the same magnification.

[Emmanuel BIGLER]

Hi!

The requested distances are very easy to compute.

Knowing the focal length f, 120, 135 or 150 mm, and the enlarging magnification M, 6 or 8, the following formulae apply

lens to image distance = LID = f(1+M)
lens to film distance = LFD = f(1+ (1/M))

hence we eventually find
f = 120mm M=6 ; LID = 840mm M=8 ; LID = 1080mm
f = 120mm M=6 ; LFD = 140mm M=8 ; LFD = 135mm

f = 135mm M=6 ; LID = 945mm M=8 ; LID = 1215mm
f = 135mm M=6 ; LFD = 158mm M=8 ; LFD = 152mm

f = 150mm M=6 ; LID = 1050mm M=8 ; LID = 1350mm
f = 150mm M=6 ; LFD = 175mm M=8 ; LFD = 169mm

[Tin Can]

I draw with pencil and paper to make it visual

OP may easier think of the 2 cones of light

[ic-racer]

Also, anyone have experience regarding comparative sharpness/fall-off at these print sizes for Schneider's Componon S lenses, and their Rodagon counterparts?

D

The lenses all use the same optical physics. You are barking up the wrong tree here. The light falloff problem will be related to your enlarger's light source. This can be anything from a hot spot to 100% even coverage. You don't mention your enlarger's light source, so we can only guess the problems you might have. In general a mixing box one size larger will give the least headaches in terms of coverage at the corners.
If using condensers, you need the exact combination of condensers to match your lens focal length and the magnification. Your lamp has to be the correct diameter or larger to make it all work. This might be impossible due to shortage of appropriate lamps.

[Bernice Loui]

More than just the enlarge head distance to base board required to achieve the print size needed, lens focal length, enlarge alignment from head to base board, inherent light fall off of the lighting system_lens_ and all. Comes the need for enlarger light source power. Keep in mind the amount of light needed to project an enlarged image from film on to the base board of this size to keep the print paper exposure times reasonable.

Powerful light sources demands proper film cooling and means of keeping the film to be projected flat for as long as the film is being worked on in the enlarger.

This is where a GOOD enlarger, light system, lens and all makes a very real difference in print making.


Bernice

[Drew Wiley]

You always want a surplus of wiggle room if possible. And there are no hard parameters formula-wise. What constitutes a nominal 30X40 inch prints size is affected by how much you might crop the original negative as well as what size margins you desire around the image portion of the print paper.

I just checked my own tip sheet out in the lab, but can't give a hard answer. When I did frequently make 30X40's from 4x5 film, I was using a horizontal enlarger on sheave rails. Now, if color at least, I would more likely being using either 8x10 film or an 8x10 enlarged internegative from 4X5. If I were using the vertical Durst L184 with its full oversize 12X12 inch mixing box, I can actually get a fully even field of illumination with a 150 Apo Rodagon N stopped down to f/8, but not with the 5X7 enlargers, where I'd either need a convex diffuser or longer lens to achieve that. A 180 lens would probably need over 6 feet between the negative stage and baseboard - almost on the floor. I've never even printed 4X5 in my really big vertical 8x10 additive color enlarger; but it will easily handle 30X40 prints from 8x10 film with a 360 lens, with the vac easel at comfortable waist height. I obviously have a high ceiling there. The enlarger itself is nearly 14ft tall.

[Tin Can]

I suggest you follow this guy, he shows everything including distances

https://www.timlaytonfineart.com/blog

I also have an XL wall mounted and could do what you want, but I don't want to

[David Wolf]

Thank you all for your generous answers! Invaluable and much appreciated : )

When posting, I thought my chief constraint would be the low ceiling height of my darkroom-to-be, at 87" floor to ceiling. Thus my interest in learning about negative to easel distance ~ before I build the adjustable table top, and purchase a suitable lens(es).

Now I see from several replies the light source itself may be an issue, so thanks for that, IC and Bernice ; )

Here are some more specifics that some of you have requested. Hopefully this may further discussion and get me on the right track.

Enlarger: Omega D5 XL, well-cared for and under wraps since I moved from my previous, much larger (!) darkroom some years ago. Have done only B&W work with this Omega, with the largest prints being 20x24 from 6x7 film. Did larger color work (40x48) from 4x5 in a rental space subsequently, with a set-up perhaps along the lines of Drew's.

Light Source: Aristo Cold Light, 7" diameter. Also have the Condenser head with glass and "Hi-Intensity" bulb that came with the D5. Would this be adequate to evenly illuminate prints up to 30x40? If not, what are my alternatives with this enlarger?

The XL Chassis height is 53." With a ceiling height of 87," this means there would be 34" from the chassis base to the floor. I'd need to make a cut-out in the table-top for the enlarger chassis/base to accommodate the table-top when in its highest position. The distance info Jerry and Emmanuel have kindly provided as well as which lens I choose will help me decide at what intervals I should install shelf rails to drop down the enlarging surface.

Printing: I tend to crop minimally, and often print full-bleed, edge-to-edge, using glass carrier with heat-absorbing, Anti-Newton glass.

Many thanks again to all! Please consider adding suggestions given the new info I've added above.

All my best,

David

PS Here's my Omega D5 XL, which I imagine you're all acquainted with.

[Drew Wiley]

Yeah, you'll be somewhat cramped, ceiling height wise. I'm familiar with the chassis, but not with the specific cold light you have in mind. I do have an Aristo 12X12 inch V54 (blue-green) high-output cold ight and it has tons of surplus lumen output relative to black and white papers. But I doubt you'll get fully even illumination with anything you've described so far. Needing to burn in edges and corners is not really much of a headache in the overall scheme of things. The advantage of a cold light is that it requires less head room and is less of a potential fire hazard close to the ceiling than an intense condenser head. But I don't know if the specific one you have in mind will have enough poop or not. One advantage of the 150/f4 Apo Rodagon N is that it's faster than than the f/5.6 135 and 180, and can even be used at a somewhat wider aperture, letting more light through. But you'd still have to deal with falloff one way or another. It also depends on what kinds of paper you prefer. For example, Ilford's MGWT seems at least a full stop slower than their Classic and Cooltone VC's.

My own notes show a 55 inch starting point between negative plane and easel when using a 150 with respect to a 30X40 print, which in my case does factor a bit of handling or masked off display margin. So you might want to allow at least 60 inches (5 ft) for your purposes. Seems doable with a 150 and cold light, at least if you don't mind the easel being very close to the floor. Otherwise, you're going to have to look into one of those wider lenses Bob S. recommended. I once owned a 135 Rodagon for 4X5 use; it was high quality but needed more aggressive corner burning. I have no experience with the 120 WA he mentioned. But when it comes to Rodenstock, Bob really knows his stuff. There's currently a clean 120 on EBay from a seller who has given me good service.

[David Wolf]

Thanks, Drew! I've sent you a follow-up PM.

[ic-racer]

Thanks for posting a picture of your enlarger. D5XL is awesome, one of the best 4x5 enlargers made in the USA. I use the Omega D5500 system for 4x5. (I have two of them).

First, before designing anything I'd use your D5XL as-is to make 16x20 prints, that are within its operating range, to make sure those can be made flawlessly, before going outside of its operating range.

Bob Carine has posted pictures of his Omega D5 setup for big enlargements. From what I recall, he also uses the condenser head to get enough light. I think also the 250W lamp. There should be a picture of his D5 setup somewhere (like YouTube), maybe he will chime in here.
Anyway, I'd copy his drop-table setup as it is known to work, and he is a master of huge enlargements.

Personally, none of my 4x5 enlargers has a drop table. I use the 4x5 mixing box on my 8x10 enlarger when needing big enlargements from 4x5 negatives. That enlarger has a drop table built in and it gets me up to 40" across.

Here is Bob, explaining his drop-table 4x5 setup:
218978

[David Wolf]

Thanks IC for suggesting Bob C's darkroom video tour, nice!

The "Enlarger" segment does show the drop-down table he's made (two others are built into two massive enlargers), but the video framing largely cuts off the view of the design! I can see, though, it's similar to what I have in mind, based on a rental space I've worked in. I'll PM Bob C with a couple questions based on the video, so thx again for the suggestion.

With the D5XL I've made good-looking prints up to 20x24 with a 105 El Nikkor using 6x7 film, and the Aristo D-2 HI cold light I mentioned in the post. Haven't yet printed 4x5 with it. Are you thinking perhaps the light source may not have enough coverage for the larger negative (compared to 6x7) at the size I hope to print? Others have mentioned this, too. Any suggestions for an alternative light source to increase coverage that would still allow me to use the D5?

Thanks for your help!