20x24 enlarger lens

[rbrigham]

hi. all

I’m considering building a 24x24” enlarger for a printing project shot by somebody else

it will be horizontal with a diffused led lightsource

what lens would be good for this
I assume a process lens maybe a 600 apiece ronar
3x enlargement onto 55” paper but potential to crop into 5x would be nice

project is black and white but potential for colour someday …

what do you think ?

best

robin

 

[koraks]

I assume a process lens maybe a 600 apiece ronar

Does a 600mm ronar actually cover 24"x24" at 1:3-1:5? I'd expect you'd be looking at longer lenses.

Sounds like a cool product; looking forward to hearing/seeing how this pans out.

it will be horizontal with a diffused led lightsource

Interesting; you've got that planned out already? I'd be curious to hear how you're going to approach this. Especially if it's also going to be aimed at color, potentially.

 

[Ian Grant]

Well the Image Circle is given as 496mm 19.5" at 1: infinity, so no chance. You nee the 1000mm or a lens with wider coverage.

Ian

 

[Ian Grant]

Some perspective, I have a B&L 25" f10 Process Anastigmat, it covers 20x24" at 1:1 but that drops to 16"x20" towards the 3x to 5x. I don't know what was the longest Hexanon GRII FL available, they are much wider angle lenses, I have 3 150mm, 210mm, and 300mm, and the 150mm covers 10x8, so if there was something longer than 300mm. But that's an example, I don't think the WA G-Clarons were long enough FL.

Wray & TT& H made some large process lenses. Wray made f10 Process Lustrar lenses 25", 30", 36", & 42" versions (and shorter) ideally you need a coated version. I think the TT&H lenses were sold as Xerox and something else.

You need a UK LF photographer who worked in litho printing, often they saved the lenses when the repro cameras were scrapped. I've had someone visit me who said he had a drawer full of process lenses.

Ian

 

[Ian C]

The diagonal of a 20” x 24” film or plate is about 31” or 787 mm. Depending on how large of a projection you require, one of the APO Nikkor Process lenses should work. They’re similar to an enlarging lens. They produce a flat field, are well corrected for color separation work at magnifications similar to those used in enlarging, and have excellent antireflection coatings. I’ve long used the 305 mm f/9 for 8” x 10” enlarging.

See page 13 in the APO Nikkor file (link after comments) for a table of specifications. You’ll have to count, as the pages are not numbered. It gives a table of original sizes of the subject at 1X. It also gives the coverage angle for each of the focal lengths from 180 mm to 1760 mm.

It appears that the 610 mm lens is the shortest focal length lens in this series that would work at 1:1. It has a 46º coverage angle. Its maximum magnification that covers the 793 mm diagonal of the original is 1.88X.

The 760 mm lens has a coverage angle of 42º. It covers a 793 mm original up to 2.78X.

The 890 mm lens has 42º coverage and covers a 793 mm original up to 6.2X.

https://www.savazzi.net/download/manuals/Apo-Nikkor.pdf

 

[FotoD]

The 16/1000 Apo-Ronar should get you to 5:1 with 20x24" according to Rodenstock. 14/890 Apo-Ronar takes you to 4:1, and the 9/600 not even to 2:1.

 

[rbrigham]

Thanks for all the replies everybody

All this effort is a bit of a vanity project for a artist friend with about 30 b/w negatives she shot of herself in the 80s
she also has some C41 but thats a long way off as large RA4 processing is a lot more complicated in trays for me
I could possibly find a lab that would process them for me but thats a long way off just now
hopefully it can be done optically for a reasonable cost ... and not just digitally scanned /photographed and inkjet printed

The enlarger will be very basic - probably solid ply box camera maybe with with a little bellows on the front to fine tune
I have loads of Sinar equipment i can use

The colour LED light source I'm looking at is the intrepid camera one but up scaled up by them or more likely me !

If that dose not work out then I have access to film lights in my day job that will easily do the b/w
probably the "Nanlux dyno 1200" - a 1200w RGBW light behind a 40x36" diffuser and some multigrade filters
I have the means to measure the filters colour and dial them into the light and have a controller that could do multigrade printing like my ilford mg500 multigrade head
but its probably not worth the effort for what will probably be 1 off prints



Am I right in thinking that a lens that just covers to shoot 20x24 at infinity if used on an enlarger will not project much larger than 20x24 to print
and that its not just a matter of longer bellows
i.e. its the opposite of being able to do macro on a largeformat camera just by adding bellows extension ?

from fotoD's chart above it seems that a 480 app ronar or above will work and is obviously a lot cheaper and easier to find than the longer ones but maybe im missing how this works on an enlarger ?


what fun ...

 

[FotoD]

Look at the bottom scale for enlargement. The 480mm lens only covers if you will print 1:1.

If you look at the 20x24" format (right hand scale) and 3:1 (bottom scale) you'll find that they intersect on the line of 9/800.

That means you can print up to 3x enlargement of a 20x24" negative with the 800mm lens, but no larger (in theory). To print larger you'll need one of the longer lenses.

 

[FotoD]

What size are the negatives by the way?

 

[rbrigham]

20x24 both portrait and landscape so I plan to build a 24x24 enlarger so I can keep them the right way up

thanks for posting and explain the chart

 

[ic-racer]

If a lens covers 20x24 in a camera at infinity, it will project to infinity too. And therefore, at any less projection than infinity, the coverage will be greater than 20x24.

 

[DREW WILEY]

Here on the US West Coast, 4-element Apo Nikkor barrel process lenses were considered standard in relation to high quality print shop applications. The longest one I own is a 760; but a 600 would easily cover 20X24 too. I use 240, 300, and 360 f/9 ones for enlarging 8x10 film; and they're better than any kind of official enlarging lens. Being symmetrical, they're superbly apo corrected all the way from 1:1 to infinity. I don't know if you'll find these in Europe of not; Apo Ronars CL's are probably more common. You might have some illumination falloff toward the corners with a lens as short as 480 unless an oversized diffusion box is utilized; and you'll also need to stop a 480 down to at least f/16 for good performance. Something longer would be preferable.