UV Point light source options

[Colin Graham]

Would like to try point light for contact printing but am wary of the size and ramp up time of some of the industrial HID fixtures. Anyone try any of the smallish metal halide or mercury vapor bulbs with the built in reflectors? This would be for pt/pd and kallitype, possibly carbon later, no bigger than 11x14. Thanks for any advice.

 

[gr82bart]

You mean units like this? http://www.elationlighting.com/product.asp?ProductIDNumber=1206&cat=Special Effect

I have two of these that I bought used from a local nightclub. To me, as a beginner, they work fine and provided me with consistent light. In terms of ramp up time, both units turn on instantaneously. The Elation units are also the perfect size for an 8x10 contact printer - it can fit snugly against the unit. An 11x14 printer would require a bit of distance to get the coverage.

Regards, Art.

 

[Colin Graham]

That looks very promising, thanks. What sort of exposure times are you getting with it? And do you think the light is more collminated that a bank of tubes?

 

[9circles]

Just bought a philips facial tanning studio don't laugh. £20 off of the auction place. It has a built in timer and variable output. Done a Van Dyke in 3 minutes, the salt in my gallery in 3 and a half at a distance of 12 inches. Might not be what you were after, but its another option. ( can also get a nice tan if you're inclined that way )
All the best

 

[gr82bart]

What sort of exposure times are you getting with it?

Well, depends on the negative, but I recently did 200 cyanotypes a few weekends ago at about 12-15 minutes each.

And do you think the light is more collminated (sic) that (sic) a bank of tubes?

Don't know.

Regards, Art.

 

[Colin Graham]

Translation: Do you think that the light is more collimated than a bank of tubes? Sorry, been a bit short of sleep lately.

9circles, that sounds interesting, though I don't think I'd know one if I saw it. I'll do some research. Thanks for the suggestion.

 

[9circles]

No problem Colin, the one I have is the Philips HB171. Hope thats of use.

ian

 

[Donald Miller]

While I am not a alt process printer, I do know about point light and light sources in general having designed and built a point light source for my Durst 138 S enlarger...A true point light source will require a short filament or arc length in order to produce the capability for maximum collimation...notice that I said capability for collimation and not collimation. Collimation requires an optical system in the light path to produce collimation. This is accomplished with the condensers in a condenser enlarger system. In consideration of a well designed light source two things are required for the greatest resolution and accutence...those being a short filament or arc length and collimation...these are not one and the same.

Any lamp that is of the BL or BLB designation will not have the capability for maximum collimation since the point of light origination is a large envelope relative to illuminated area...this is true whether that is any of the T (linear) lamps or any of the other spiral or wrapped lamp designs.

While the results obtained with a true point and collimated light source will be quite noticeably different when one is enlarging a negative...the result will not be quite as noticeable when one is contact printing...this is because there is less space for light ray dispersion in the negative/print interface in contact printed negatives when printed with a diffuse lamp. Yes, there will be a difference but not as noticeable as one may initially think.

The optimal in sharpness and resolution could be obained if one were to install a short filament carbon arc lamp in a well designed condenser system...this would require that one would install a lens shutter since the lamp fires slowly...this carbon arc/condenser enlarger would then be used as the light source for exposing your contact prints. Carbon arc has a high UV output and would be especially suited for exposing alt process prints.

 

[Colin Graham]

Thanks a bunch Donald for the detailed answer. I'm new to alt printing so I'm not sure what I'm after exactly just yet, but did want to explore some options before I built a bank of tubes. It's good to know that sharpness need not be a deciding factor.

Ian, yes that's very helpful. Thanks

 

[gr82bart]

Translation: Do you think that the light is more collimated than a bank of tubes? Sorry, been a bit short of sleep lately.

Still don't know. Honestly, don't care either. By the looks of it, my entire contact printer is 'bathed' in UV light and I get decent, repeatable images (true - there are a dozen other contributing factors). That's all that matters to me.

If you do care about the parallelness (sic - will this pass the scrabble muster?) of the light, buy the bulbs and make your own unit. I think you'll need UVA bulbs - wavelength peaks around 300 nm. For example, buy a bunch of these - http://www.bulbman.com/index.php?main_page=product_bulb_info&products_id=13846, sockets, household purpose electrical wire, some plywood and other materials, and voila! UV lighting bank with collimated light. Though, your local authorities might think your growing certain 'herbs'. And it'll still cost you as much as the Elation units, plus your time and aggravation.

Good luck whatever you do. Oh and join a print exchange so we can see first hand the results of your work.

Regards, Art.

 

[Colin Graham]

Like I said I'm not sure what I'm after yet, so I'm researching a few options. If I didn't live in the Pacific northwest I'd probably just use the sun. There's a lot of info about bl units here but not so much about HID or short filament light sources, hence the initial questions. Thanks for your input.

 

[philldresser]

Colin

I'll 2nd 9circles suggestion of a Phillips facial solarium especially if you are just starting out. I have been using one for a few years for Cyanotypes, Kallitypes and Salt Prints with no problems. Exposures range from 5 to 30 mins. They are reasonably cheap off of ebay in UK (not sure about US) or you can pick them up from local boot sales/ yard sales.

I have mine in a homemade frame which holds the unit about 25cm off the table. The unit is fine for A4 or smaller prints

Cheers

Phill

 

[Vaughn]

Colin,

If print sharpness is one of your main considerations, one thing that can help when using a non-collimated light source (such as tubes or multiple light sources), is a vacumn frame. But it will also depend on the alt processes you are using.

I make carbon prints using a relatively thick layer of pigmented gelatin. Using a good contact printing frame, I can not get a razor sharp print using a bank of BL tubes. With the same contact printing frame, I get much sharper results from a set-up of two 175W merc lamps. I am planning on replacing this with a single 450W lamp eventually, as there are still some sharpness issues with using two bulbs if I move the print around under them to even out the exposure. This is the bulb I am thinking of:

http://www.bulbman.com/index.php?main_page=product_bulb_info&cPath=5387_8870&products_id=10939

Talking with others (such as Sandy King), it appears that a vacumn frame would increase my sharpness also. I have a vacumn easel that I might try to convert into a vacumn frame. I have a vacumn pump that I thought I could use, but appearently it is more for liquids rather than air.

Vaughn

 

[Colin Graham]

Thanks for the second on the facial solarium Phill, I very much enjoy the kallitypes you've been posting, so that speaks volumes. Ian, started looking through your gallery too, very nice.

Vaughn that's very interesting about the carbon prints being unsharp. Does it have something to do with the relief, if you use a thinner tissue does it help with sharpness? I really want to try carbon printing soon so that could be a factor. Although, it could very well be that I might not care so much about razor sharp prints when I actually get going, hard to say. So much to experiment with! Can't wait to start. Thanks again everyone for the great advice.

 

[Vaughn]

Vaughn that's very interesting about the carbon prints being unsharp. Does it have something to do with the relief, if you use a thinner tissue does it help with sharpness?

It has to do with the relief indirectly. To get relief, one must have a thick tissue and be able to expose a good way down through it. If one imagines a black speck of something on top of the tissue, and light hitting it from all directions (diffuse), then one can imagine that the speck would create a shadow below it, but because the light is diffuse, the shadow is not sharp.

The same thing happen when there is not good contact between the negative and the photopaper, or when one tries to contact print a negative upside down (emulsion up) with a diffuse light source. There is too much distance between the emulsion and the paper, and the shadows cast by the light gets diffused in that space. But in a thick carbon tissue, the spreading out of the light happens within the emulsion itself

Thinner tissues might give one sharper prints than thick tissue with a diffused light source. It should not make much difference with a point light source.

I feel that I am being as clear as mud...sorry. Just as I started this post, one of my boys arrived home with a (most likely) broken arm...they just left for the ER. So my brain is a bit scrambled.

For my carbon images, I prefer sharpness -- and the raised relief seems to greatly increase the appearent sharpness. Your results may differ.

Vaughn

 

[Colin Graham]

Vaughn, I hope your son is ok. Thanks for the explanation, it's quite clear in fact.

 

[Vaughn]

Hey Colin,

Here is a carbon image for ya!

From a 5x7 camera negative...

"Indian Rhubarb, Tamarack Creek, Yosemite Nat Park"

 

[Vaughn]

And what the heck, here is another.

From an 8x10 negative.

"Crowning Glory, Yosemite National Park"

Name comes from the interpretive sign you see on the left -- readable in the print (but backwards!)

Vaughn

 

[Colin Graham]

Great stuff, Vaughn. Would love to see them in person. Thanks for posting them.

 

[Jim Noel]

I have two UV sources - one is a bank of fluorescent tubes, the other is a 1000 watt metal halide bulb which is a point light source.
The fluorescent tubes are one stop slower than the sun in summer in southern California, the point light is about 1/2 stop faster than the same sun.

As far as sharpness,I detect little if any difference.

 

[chrobry]

This is the bulb I am thinking of:

http://www.bulbman.com/index.php?main_page=product_bulb_info&cPath=5387_8870&products_id=10939

Vaughn,
looks very interesting to me too. Thanks for posting this link. Do you think this bulb has a standard thread size? I bought recently a 400W mercury bulb on e-bay and it turned our it has wider threads so I just do not know where to get fixture to screw it in.
Do you have any estimation what kind of exposure times to expect with this bulb printintg with carbon from a distance enough to cover 8x10?
Also, as I have not used mercury bulbs so far, do they produce a lot of heat? If so, how do you deal with that?

regards,

Jan

 

[sanking]

Vaughn,
looks very interesting to me too. Thanks for posting this link. Do you think this bulb has a standard thread size? I bought recently a 400W mercury bulb on e-bay and it turned our it has wider threads so I just do not know where to get fixture to screw it in.
Do you have any estimation what kind of exposure times to expect with this bulb printintg with carbon from a distance enough to cover 8x10?
Also, as I have not used mercury bulbs so far, do they produce a lot of heat? If so, how do you deal with that?

regards,

Jan

Printing speed is going to vary a lot depending on how far you need to place the bulb from the sensitized material. If you limit print size to 8X10 or smaller you could probably place the bulb at around 12" from the paper and get fairly fast prnting times, say 3-5 minutes for pt./pd. If you double the distance, as you would need to do for 11X14 or 16X20 prints, you times will increase by 4X, or 12-20 minutes.

HID bulbs do indeed put out a lot of heat so consider this when deciding on location.

I have two UV printing lights, a bank of twelve 48" BL tubes, and a ULF-28 continuous wave xenon. Both units have vacuum easels and I would have to say there is no difference in sharpness between the two lights when used with the vacuum frame. I tend to use the BL bank for carbon printing and the ULF for pt/pd. The reason is that due to the fact that I make very thick carbon tissue my exposures are very long, upwards of 15-20 minutes and the BL does not heat up very much with very long exposures. Pt./Pd. exposures with the ULF-28 are in the 2-3 minute range.

Sandy King

 

[Vaughn]

Jan,

It has an E39 base -- which I believe is the Mogul base...much larger than the standard light bulb base. One should be able to pick up a fixure for it at a good hardware store...or worse comes to worse, at a electrical supply company.

I haven't got one of those self-ballested merc lamps yet, so I don't have any exposure experience with it -- and with homemade carbon tissue, and one's individual negatives, exposure times are all over the map.

I have been using two 175W merc vapor lamps -- 350W total, within 10" of the printing frame. My times are in the range of 30 minutes to an hour. My negs tend to be a bit heafty and with high contrast (very solid highlights). I also use a bit more sensitizer than Sandy, so I am fighting thru more of the yellow of the dichromate also. My record exposure for a single 175W lamp was 6 hours -- made a most beautiful print (I could not see into the highlights of the negative on a light table, yet had almost clear areas in the deepest blacks!) I unfortunately ruined the negative trying to make a second print with a 10 hour exposure. I wasn't using a fan back then and I think I baked the tissue against the negative.

I now use a table fan that blows air across the surface of the printing frame and that seems to be enough to keep things cool.

Sandy, On the print you sent me, I noticed you used a bank of BL bulbs for the exposure. Relative to the print I sent you and the sharpness I can usually get, I would not call it a sharp print, but I do not know if the is due to the exposure method or the negative (it appears to be from an inkjet neg). Have you been able to achieve the sharpness of a camera negative with an inkjet negative?

I ask because "sharpness" is a subjective term and I am not sure of your definition of sharpness relative to mine.

Vaughn

 

[sanking]

Vaughn,

As you suggest, sharpness is a fairly subjective issue and depends on a lot of things, including the subject, the lighting, and of course how the negative is exposed and developed.

In this case we have a subject which has no sharp contours as the entire scene has been rounded by natural erosion. Also, the scene was in very flat lighting which also limits the appearance of sharpness. Finally, the negative is an inkjet negative printed on Pictorico so the maximum potential detail is on the order of 6-7 lppm, in contrast to the in-camera original which probably has upwards of 50 lppm. I have made this print up tpo 12X17" in size with a digital negative and it actually looks a lot sharper than in 5X7" size because the magnification brings out detail which is hidden in the smaller negative.

In any case I have not found any difference in sharpness between the BL bank and the collimated light source, so long as a vacuum frame is being used.

Sandy

 

[Vaughn]

I understand your point about sharpness. A lot of it has to do with viewing distance, also. I have seen many large digital prints that look great from 4 or 5 feet away, but which "fall apart" up close -- similar to oil paintings. Up close one starts to see digital artifacts that are invisible at a short distance away.

I can see how a large carbon print made with an inkjet negative would hold up very nicely with a viewing distance that allows one to see the whole print at once, even with a low lppm.

Vaughn

PS...thanks for the print!