Constructing an enlarger

[Ash]

Well I'm in a bit of a funny frame of mind. I think severe tiredness is affecting my judgement so I'd like some help please!

Basically I pulled out the half-plate camera that I bought a while back with the idea of FINALLY building masks for the darkslides to accomodate 4x5 film (and I just spotted Era film on ebay - 25 sheets at £5 wow!). Instead of sorting measurements for a basic mask, I was playing with a torch to see extension needed to project the light from the ground glass to the floor. THEN I placed the bellows camera on the tripod, removed the filter sheet from my archaic safelight and placed that on the ground glass, sandwiching
a 10x8 neg (the only 4x5 neg I had has gone walkies).



I'm pretty certain when I've had a good nights sleep and sat down to think about this I should be able to construct it before xmas (as long as I don't get a call to work, or go out taking more photo's). My questions if you'd be so kind to answer:


I shoot 35mm regularly, and 120 less regularly. The 35mm enlarger is still in one piece, the 120 enlarger is a little worse for wear (see post about broken enlarger). I'll be making a habit of shooting 4x5 once I have this whole process sorted. I also have access to a 10x8 camera (my mother's).

so...

• do I build it for:

-full 10x8 enlargements,
-5x7 (currently can't shoot - but maybe shooting half-plate at some point so I'll need the extra space?)
OR
-4x5 - the most sensible option maybe?

• for enlargements what are the 'normal' lens lengths for 4x5/half-plate/5x7/10x8 enlargements?

I take that 50mm is for 135, 75-80mm is for 120, so what are the larger film size lenses? I think I remember something about 4,5inch for half-plate?




My thoughts are to use a projection lamp (12V?) as I think I read someone on pnet was recommended that.

• What do I do about this diffuser/condensor/reflector business??

• Any idea the typical height I'll need for enlarging 4x5/half-plate/etc onto 10x8 paper and larger?

• Metal or wood? I want light-weight and inexpensive, and I don't want splinters or nasty cuts!

• I'm considering using my spare metal (cylinder) column that I had from the other 2 cheap enlargers (the 35mm and 120 enlargers together cost me £40, which is just under my budget for this project!!) á la MPP monorail enlarger/copier/camera, so I need only clamp front and rear standards and mount the column somewhere (it mounts to a base board I alread have). Sound good?

I probably forgot a few things but I think that'll do for now, back to doodling the designs!


Unless someone fancies buying me a DeVere enlarger then any help with this project is much appreciated!!

[Ash]

oh another question, can I use a typical sheet of glass to lay the flat neg on? or do I need anti-newtonian or anything?

[markinlondon]

Have you considered that a horizontal enlarger would be easier to build? I've got some instruction in one of my old photo manuals. Give me a day or two to dig it out and I'll scan and mail the pages. You build it out of wood, sounds like you're halfway there already.

[lmd91343]

How do you intend to make the light source even across the entire negative surface? I recall the condenser ( between the light and neg) on my omega enlarger had twice the diameter of the 35mm diagonal, so that neg was immediately below the "sweet spot" of the condenser lens?

Where would you put a filter holder for PC papers?

[Ash]

Hey Mark, it's an option, but managing to stand up the photo paper and everything may become a bit of a pain. At least with an upright I know for the most part things are helped by gravity to stay flat
I'd be really grateful for the pages if you could send them to me. I expect the first attempt to fall a little short of acceptible!
I got the Kowa 50mm by the way, many thanks!



Hi Lance, yep I'd like the light source to be even, but with large negs I'd need a HUGE condensor lens, I thought possibly a projection lamp and something like foil or reflective material and/or a diffuser would help to avoid a vignetting effect.

I was going to build a filter holder either between the light source and neg, or either side of the lens, but not sure on that yet...

[markinlondon]

It might be handy anyway 'cos it'll give you ideas for diffusion screens and the like. As for holding the paper, you pin it to the wall and move the enlarger back and forth.

[FrankS]

It may be easier to build a diffusion type enlarger light source. You could use the 8x10 camera, building a light source above it.

[Ash]

Thanks Mark

Hey ManGo, thanks - now I know which lengths I need to add to my growin collection of 'useless' enlarger lenses

Greyhoundman - Awesome! I'd lost that link months ago, forgotten all about it, thanks!!


Frank - I'm thinking diffusion too, but the idea is that it's a permanent solution for a temporary problem (until I can afford to buy a DeVere or the like), and I'd hate to put the old 10x8 in my soon-to-be darkroom, as it will definitely suffer abuse. I'd prefer to build something



Oh I was thinking, can I grind myself a ground-glass screen to use as a diffuser?

[FrankS]

Use opal glass, or white plexi-glass for a diffuser.

[Bryce]

A diffusion enlarger would be much easier, and just fine for larger format film. Grinding the glass for the condenser is extremely simple- rub two pieces of glass together with an extremely fine, loose abrasive and water between them. Abrasives like this are commonly available through amateur telescope making circles, quite a popular hobby in the U.K. as I think I've gathered.
Coming up with condenser lenses could be more difficult and expensive; making them yourself is probably out of the question.
Of course with used enlargers being as cheap and readily available as they are it doesn't seem like a good excuse for a project to me. Unless of course you're bent on having made it with your own hands, that is. Maybe if you started withh an old view camera....

[Ash]

greyhoundman, I think it was the old blog that inspired me months ago - it's taken this long to get my act together

Bryce, large format enlargers (all the ones I've seen) are still WAY out of my price bracket. I think a lifetime on my hands, and a small overdraft is a good enough reason to get practical even if enlargers are dropping in price. I'm poor remember?

[Bryce]

Ash-
Fair enough. I've just noticed that in making things like that you often end up spending more than if you just bought a useable unit. Also, the less complete of a workshop you've got access to, the craftier you have to be to make the project a success. Kind of a catch 22 if you're broke- access to a capable shop is usually expensive in and of itself.

Greyhoundman-
Nice work! I hadn't looked at your blog before, I'm impressed!

[Ash]

Well I don't really plan on spending much over £100 in the long run. Much less if I can help it. The timber will hopefully not be too expensive but will be the most costly I think.


Far as I can work out here's my list of materials so far:

-Timber for framework - I'm not gonna go cheap, but ply or something 'value for money' will do
-Bolts and wingnuts for clamping on lensboard focusing mech/up-down extension - odds and sods, hopefully won't cost too much for the handful of bits
-Stand - free if my current spare one will suit
-Opal glass/plexi-glass diffuser - no idea how much it'll set me back yet
-Projector bulb, bulb mounting stuff, wire, switch, plug
-lenses - already got a couple
-lens mount - M39 mount maybe? I'll make lensboards and use flanges from my vintage camera shop (M39 flange I'll nab off the Fed-4 in rough condition)
-leather for bellows - already got it from that jacket

I think that's it so far.

[mjflory]

Hi Ash --
Don't forget the old tradition of enlarging with the lens used to take the picture. In the olden days this was a good way of compensating for the vignetting introduced by a not-entirely-adequate large-format lens, since the vignetting would lighten the corners of the print. (It couldn't correct coma or other distortions, of course!)
Have you got some bellows plans? James Vail's excellent plans for an 8x10 camera are still here in the Wayback Machine, though his original site is gone. The links to the all-important sketches in the document are all OK except for one: the bellows! But I did a little rummaging around in their archive and found the bellows sketch, which I've attached. (Mr Vail gave permission to copy for personal use, so I trust I'm within bounds posting it here.)

You're re-sparking my interest in building a view camera from his plans -- I've had scraps of wood sitting in the corner for years.

-- Michael

[Ash]

Thanks Michael, I found a couple links that I think have borrowed from those plans. I'm first of all going to sew all my leather sheets together to the correct size, and see how I get on with a 'floppy' bag style. The enlarger being upright I might get away with it, or else get away with minimal folds. I'm thinking a few large folds versus a lot of little ones.

[mjflory]

Hmmm... An enlarger with a bag bellows! I'd guess that even one with a few big folds would be easier to deal with, though.

I just found the other bellows link people seem to recommend: Doug Bardell's page here.

[Ash]

I'm going to oversimplify those bellows links. I needn't many intricate pleats, only a few to keep it from collapsing on itself. Alternating chunky card blocks. It needs to be functional, not pretty

[mjflory]

That sounds very practical. Just enough to keep the leather out of the light path.

[Ash]

Yep! I just had a play with drawing the basic alternating pattern on a piece of thick sketchbook paper and folding it. Surprisingly it was a lot easier than all those lines on the diagrams! I may just succeed with this project


Right time to sleep, any help you wonderful RFF members would like to leave until I return would be very much appreciated.

[Ash]

right, a bump in the morning (well... nearly 2pm here) for anyone who might have more help to give

[FrankS]

I don't want to put a damper on the building project because that can be fun and rewarding in and of itself, but consider just for a moment an alternative plan: use the money meant for the project materials to buy a used enlarger. With just a bit of time, patience and searching, surely one of the vast multitudes of unused enlargers will present itself to you at a give-away price. Just offering an alternative thought.

[Ash]

Hey Frank, I know that would be a 'sensible' option, but I've been keeping my eye out for a 5x4 enlarger with no joy. The costs for that size are too steep for me. Also as I said, my 120-film enlarger had managed to break on me, so I'm worried about buying another used enlarger at a giveaway price right now!!

I thought 'so I may as well go 'the whole hog' and build as big an enlarger as I can'.


So far:
I've nearly sewn all the bellows leather together. That's taken an hour.

Tomorrow:
I'll get the timber (probs ply)

[mjflory]

An afterthought, not about the bellows, but about the light source, which I suspect could be a big headache. Plan A, a diffuser: light bulb, plexiglas or frosted or (pricey) "opal" white glass. Smooth, not too contrasty, makes scratches disappear... Plan B, a condenser: light source plus monster lenses (or fresnels?). Hard to put together, but extra-contrasty and sharp. Consideration with Plan A or Plan B: heat generated by light bulb, not only radiating from around bulb but transmitted as infrared through condenser lenses or diffuser to film, perhaps necessitating an IR cutoff filter (big bluish piece of glass) above film. Plan C: an array of white light-emitting diodes (LEDs) and a diffuser, making an enlarger head with the character of a traditional diffuser but without the heat, and with effectively unlimited bulb life. The Nikon film scanners use LEDs, so it seems any problems with the light color are not insoluble, though color correction might be built into their firmware.

In the lab where I work we used this method to develop a featureless, instantly switchable visual "target" to which infants' gaze was directed in psychological tests. White LEDs are available for a dollar or two (a pound sterling or less in the UK, I imagine). The wiring is very simple: feed them DC, observe polarity, put a resistor in the circuit to limit current draw (variable resistor will control brightness), make a series-parallel array (several series in parallel) with proper number of LEDs to conform to whatever DC power supply you have sitting around.

I'd be surprised if this hasn't been tried already, it seems so obvious, but my knowledge of enlarger heads is as out of date as most of my other knowledge.

-- Michael

[Ash]

When I think LED's I think TINY. Maybe that's because the electronics I did ended when I hit about 15.

I'll go to a local-ish auto parts store as that's the only place that sells anything electronic these days. Problem is how many LED's I'd need for a suitable amount of light (I'm thinking loads), then as you said resistors and mapping out the circuit.

I'm always a little scared to plug anything into the mains that I've wired myself, so a whole untested circuit will be a little scary!

It's a really good idea, but it may be easier to wire (and design the light box to facilitate) a fan or two, rather than work out where to get the correct LED's and get a bright enough result without blowing something up!

[Screwy]

Probably of no help at all but my Devere 54 is a diffuser and has a plastic water filled flask between the lens and the rather Sci-Fi looking cathode tube , Leds are workable Heres a link with some info and I'm pretty sure there's plenty of links out there for building LED light arrays as there used on a lot of custom motorcycles these days .





Paul