Topic: Contact printing light source

[Urban Hafner]

We recently moved into our own house and now that almost everything is unpacked I can start thinking about the darkroom.

I don't have an enlarger right now, also because I don't see myself having the time to go fully "analog" (I hate that word). So I was thinking of at least doing real contact sheets so that I can spend less time on scanning.

The plan is to use the room lights as the light source for now. And I wonder which light source would work best (as there's no light source installed in the room, yet). I have a big neon tube I could use, but I thought I'd ask if there's any reason why that wouldn't work.

[Pete_R]

What paper are you printing on?

[Francois]

The best thing is a refrigerator bulb on a cord that hangs from the ceiling.
The frosted bulb gives even enough light and once you've dialed in the optimal bulb height, your exposure times will be fairly even.

If it proves to be too powerful, a small indicator bulb can also be considered.

Bug fluorescent tubes are way too powerful for that.

[gsgary]

http://www.ebay.co.uk/itm/Vintage-Johnson-Exactum-Contact-Printer-/261669148995?pt=UK_Photography_VintagePhotography_VintagePhotoAccessories&hash=item3cecb25943

http://www.ebay.co.uk/itm/VINTAGE-BAKELITE-DARKROOM-CONTACT-PRINTER-/231403918810?pt=UK_Photography_DarkroomSupplies_SM&hash=item35e0bf95da

http://www.ebay.co.uk/itm/Vintage-Paterson-contact-printer-and-safelight-/251737283862?pt=UK_Photography_VintagePhotography_VintagePhotoAccessories&hash=item3a9cb61d16

http://www.ebay.co.uk/itm/Vintage-Paterson-contact-printer-and-safelight-/251737283862?pt=UK_Photography_VintagePhotography_VintagePhotoAccessories&hash=item3a9cb61d16

[Urban Hafner]

I have some Ilford MGIV RC paper Peter.

You mention fridge lamps François because they're low wattage, right? I've found 15W or 25W (and the 3W LED replacement) during a quick search. Is that the approximate range? Obviously it depends on the distance and how reflective the walls are.

Thanks for the help guys. And I guess an anti reflective glass (from a picture frame) wouldn't hurt. Although, for contact sheets it probably doesn't matter.

[Francois]

Well, the AR glass would be a better option since you can still get newton's rings in a contact print... but most people just use regular glass.
As for the bulb, having too much power will just get the exposures to be too fast to be able to do anything. I think that the 15 watt will be more than enough!
You might even end-up putting a dimmer on it. Just make sure it's high enough over the table to avoid creating a hot spot yet low enough to get a good exposure time. You can always use an exposure meter in incident mode at 3 ISO to get a rough idea of how much light falls on the table.

Also, light falls off to the rate of the inverse square law so you can always use this to adjust exposure.

[mcduff]

I have done a fair bit of contact printing but it only has been for contact prints. Nonetheless never seen any Newtonian disturbances, so I would just give it a try with regular glass.

While I am generally a fan of led lights for home use I would suggest an old school incandescent bulb. Some of those led lights have a more concentrated light source than an incandescent bulb. Perhaps the bulb will be far enough away that it will not matter but that is my $0.02.

[Pete_R]

I have some Ilford MGIV RC paper Peter.

I was asking because if you were going to use MG paper (which you are) then the type of light will affect the contrast you get. Will probably be OK if you use a domestic incandescent lamp but you mentioned a neon tube and I'm not sure what that would give you. Also, if it's the same in Germany as here, 'normal' lamps are getting hard to come by and you can only get low energy types. Again, not sure what effect this would have with MG paper. Just something else to consider.


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[Urban Hafner]

Thanks Peter, yes that's of course true! But as I only plan to do contact sheets so that I don't have to scan every frame it's not too much of a concern, I think.

As far as normal light bulbs, I think there's an exception for the small low wattage ones for fridges and ovens. I found 15W fridge light bulbs. Unfortunately they're not frosted.

[gsgary]

Urban i'm going to have a play tonight, instead of using my enlarger to make contact i'm going to try making them with my light box and contact printer

[Francois]

I found 15W fridge light bulbs. Unfortunately they're not frosted.

Maybe just put one in some sort of plastic container or something...
But in reality, I don't think it matters much that it's frosted or not. The only difference is that it will act as a point light source and show off the dust more easily... maybe.

[gsgary]

Lightbox didn't work even 1 second of light was too much

[Francois]

I'm not surprised. When you look at it, even enlargers don't produce that much light.

My Durst uses a 60 watt bulb. This gets projected on a curved styrofoam light diffuser in the light head, possibly eating-up a full stop. So now we're at 30 watts equivalent maybe?
Then, it goes through the lens. No lens would be equal to f/1.0 but I almost always print at f/8... that makes it a 6 stop difference. So, now the about 30 watt I have become... 15... 7... 3.5... 1.25... 0.75... 0.375 watts. And that's not considering the negative density. So, considering that my enlarger's head is about 1 foot above the easel for exposure... I think it gives an idea of how much light we're talking about here.

That's why an indicator bulb would be probably enough for most jobs... these are the smaller than golf ball sized ones that are rated at around 4 watt.

[gsgary]

My Focomat has a 75 watt bulb, I contact printed the same negs for 8 seconds at f8 and they came out lovely

[Adam Doe]

I tried bare bulb contact printing with 7.5 watt bulb about a year and a half ago. I found that with ample distance, 5 feet or so, from the paper I could control the time well enough to get a reasonable exposure. I never did get around to honing the process as I had intended, but others here had some interesting suggestions when I posted about it:

http://www.filmwasters.com/forum/index.php?topic=6378.msg79089#msg79089

[Urban Hafner]

I've searched abut more and I've found a 55 lumen LED bulb. That's less light than the 15W bulb and should give nice long exposure times.

[Francois]

That should do the trick. If it's still too bright, you can always make a "bulb sleeve" of some kind. Since LED's don't produce much heat, it can be a fairly enclosed box.