DIY 5x7" enlarger .. or not?

[radiant]

As I have been shooting 5x7" and 6x17 for salt prints I have started to want to enlarge these negatives. The problem is there isn't that many 5x7" enlargers floating freely in Finland.

So I was thinking of building my own next winter, maybe.

I have one Sinar-mounted shutterless Nikkor-W 210mm f5.6 which I could use for the enlarger. Do you know if using it is smart or not?

As light source I was thinking of using just a diffuser and RGB leds (WS2812). Of course condenser would be much preferred but pretty impossible in DIY I would guess.

Any thoughts? Stupid idea or not?

ps. if anyone has rough distances for film+lens and lens+baseboard (for 10-12" inch prints) I would appreciate. Just to estimate does this thing even fit vertically in my basement..

 

[koraks]

I think it's perfectly feasible, but I'd start out with a chassis of e.g. a medium format or if possible a 4x5" enlarger and modify it to accommodate larger sizes. It will save you the hassle of having to engineer a couple of basic things like head adjustment. Depending on what kit you start out with you may run into some limitations concerning e.g. print sizes, but I'm sure you could make it work in some way.
After all an enlarger in itself isn't an insanely complex piece of equipment.
Let me know how you fare with the ws2812's. I'm still working on my second generation rgb led source, but I'm using individual r, g and b smd leds on a diy aluminium core pcb. Net power dissipation around 250W or so.

 

[seall]

It is not a stupid idea and I would go with koraks suggestion regarding the use of an existing chassis.

Another thing to ponder may be any advantages of making it for 8x10 instead of 5x7.

 

[radiant]

I think it's perfectly feasible, but I'd start out with a chassis of e.g. a medium format or if possible a 4x5" enlarger

Yes this has been in my mind too. At least some chassis with the head movement would save from lot of work.

Let me know how you fare with the ws2812's. I'm still working on my second generation rgb led source, but I'm using individual r, g and b smd leds on a diy aluminium core pcb. Net power dissipation around 250W or so.

I'm actively using WS2812 as light source and I'm really satisfied. I have done contrast tests with Stouffer wedges and even compared to distributed's blue led (which he kindly sent me) with pretty similar results. So WS2812 provides enough contrast with blue light.

Another thing to ponder may be any advantages of making it for 8x10 instead of 5x7.

As it increases size quite a bit I think I will skip this. There is already possibility that 5x7" is too large for my space.

 

[revdoc]

Lens to film/print distances are pretty simple to work out.

Lens focal length is F. Lens to film is d1. Lens to print is d2.

d2 = 1/((1/F)-(1/d1))

d1 = 1/((1/F)-(1/d2))

magnification is m = d2 / d1

total sytem length = d1 + d2

The actual distances will be slightly different, but these will get you very close.

 

[radiant]

Lens to film/print distances are pretty simple to work out.

Lens focal length is F. Lens to film is d1. Lens to print is d2.

d2 = 1/((1/F)-(1/d1))

d1 = 1/((1/F)-(1/d2))

magnification is m = d2 / d1

total sytem length = d1 + d2

The actual distances will be slightly different, but these will get you very close.

edit: I calculated myself something, is this correct?

 

[Horatio]

Why not convert your camera into an enlarger? There's an app that lets you use an iPhone or iPad as a light source, with built-in filtration. I'll post links later.

 

[radiant]

Why not convert your camera into an enlarger? There's an app that lets you use an iPhone or iPad as a light source, with built-in filtration. I'll post links later.

I know this solution. I would need a good base for atleast camera-paper height adjustment..

 

[ic-racer]

All you would need to do is make a special back for your 5x7 camera that holds the negative and has the light source attached (assuming lightweight LED assembly). Mount this on a tripod and aim it at a wall. I'd tape the laser alignment jig to the wall and, with the lens off, get the dot to bounce off the glass carrier back to the bulls-eye by manipulating the tripod. If you are not sure the front standard is parallel to the rear, mount the lens with a filter on the front and make sure the dot still is on the bulls-eye.
Sure it is a little trouble to do that for each printing session, but not much more than what you would go through for every negative exposure out in the field.

 

[koraks]

I'm actively using WS2812 as light source and I'm really satisfied

Ah of course, you posted about it before. In fact I was talking to someone on YouTube some time ago and they reported good results with RA4 as well and a ready made WS2812 product. Sounds promising.

 

[gone]

You'll need to put together a mixing box and find the right sort of material for your diffuser. Probably will be some trial and error on this part. You want even illumination across the frame, and 5x7 is big. Most of the DIY efforts I've read about online encountered really long exposure times due to the diffuser eating up so much of the enlarger's light.

If it were me, I'd buy a 5x7 neg carrier, get an existing enlarger to modify as koraks suggested (one that is capable of being modified to take the 5x7 neg carrier), build or buy a mixing box, and at that point all you need to do is get or make a bellows for the larger size negatives.

Probably easier to mount it vertically, it will use up less space and the enlarger is going to be big and heavy. That would also make it easier to place the enlarger on blocks if needed for larger prints, and it would be easier to make and keep things aligned.

 

[radiant]

Ah of course, you posted about it before. In fact I was talking to someone on YouTube some time ago and they reported good results with RA4 as well and a ready made WS2812 product. Sounds promising.

I wouldn't be surprised if someone else has connected the dots too. However I couldn't find any info on WS2812 in enlarger before.

You'll need to put together a mixing box and find the right sort of material for your diffuser. Probably will be some trial and error on this part. You want even illumination across the frame, and 5x7 is big. Most of the DIY efforts I've read about online encountered really long exposure times due to the diffuser eating up so much of the enlarger's light.

I think one needs the mixing bowl if using single bulp? Who uses such things in 2021 I was thinking of just 8" x 8" box with led strip taped to the walls, "roof" covered in foil. Then add two diffuser plastic plates before film. I've built myself light table this way and it outputs pretty hefty amount of light.

As I haven't used diffuser enlargers I don't know how much power it reduces but in times of LED technology I think it is easy to increase to amount where exposure times aren't too long. Just add more leds ..

 

[Mark Crabtree]

I converted a 4x5 enlarger to 5x7 years ago, and that included a diffusion box to spread the light from the color head over the larger format. The conversion was fairly easy, just a wooden box with a slot for a negative carrier. Using LEDs would probably make it a lot easier to get even illumination than with my color head, but even that worked fine. I made the negative carrier as a simple sandwich of two pieces of glass in flat piece of wood, but you could also just corner tape to a single piece of glass.. It worked well. I eventually gave the 4x5 chassis to someone here when I got a full 5x7 enlarger. I probably still have the conversion pieces somewhere.

The biggest factors are figuring the maximum magnification you need; mine needed more than usual which made it harder. You need to make the negative height such that you can get the lensboard close enough for maximum enlargement and extended enough for minimum enlargement. And then the light path so as to not get cutoff from the original negative opening. All pretty easy from a 4x5 enlarger.

 

[revdoc]

edit: I calculated myself something, is this correct?/QUOTE]

Looks right to me!