Enlarging on Azo and Platinum

[Donald Miller]

This is a "heads up" to those who might be interested. I spoke to Durst last week and they are coming to market with a new 5X7 enlarger that has a new lamp suitable for enlarging negatives onto Azo and Pt-pd. The light source is UV.

Their representative indicated that the heat problem that they experience with that 5000 watt lamp for their 8X10 enlarger has been solved to a great extent. Of course the 5000 watt will enlarge on Azo as well.

The cost for the 5X7 unit is going to be $5,500.00 and is not suitable for typical photographic enlarging emulsions. The 8X10 unit complete is $12,000.00 and if you have a spare 184 enlarger around and want to upgrade it to the higher wattage lamp source the cost will be $5,500.00 for the lamp house alone. I think that you can buy a Lincoln arc welder for a little bit less then that. My neighbors kid could be taught how to strike an arc just as I get the paper on the easel.

So if any of you are really flush and want to contribute to a non profit charitable institution, email me and I will get you my mailing address.

 

[Jorge]

This was discussed in the Bostick and Sullivan web site as well as pn. I think the consensus was people who do this would rather get a new ULF camera than the enlarging head. I tend to agree, $5000 would buy me a nice Lotus or Canham.

 

[Donald Miller]

I don't know Jorge...It would probably take a younger wife to carry one of those big cameras for me. And you know how darned expensive they can get to be...the wives that is.

 

[Joe Lipka]

Oh, dn. Wives are not expensive. I have several friends who told me than ex-wives are far more expensive.

 

[Aggie]

..

 

[Donald Miller]

Aggie, only present hubby could answer that, I assume. You must have a thing for those Swedish types...Sven????

Now as for me, I am more taken with camera porters named Stacey, Melody, Chrissy... all of them, I will take all of them. Time to go shopping for that 12X20... Stacey can handle the holders, Melody the tripod, and Chrissy that little physical fitness dynamo can handle the camera.

What about me, you ask...Why, I will carry that new spot meter that Aggie told me about.

Later,

 

[jd callow]

Wimps! I carry my camera all my lenses and accessories, stobes, power pack and my wife when I go shooting. Did I mention I shoot 4x5 star trails hand held using interneg print film rated at .032 iso and crossprossed in E6?

By the way I know of 4 very fine used dursts w/ lenses that are available:<ul>[*]L1200 w/ color head[*]AC800 Elite with all the bells and whistles[*]HL2500 mural camera with 20' track[/list]They have rodenstock lenses (the HL has 'G's)and mixing boxes for all formates, ps, control panels etc. Email me and if you want more info.

 

[David Hall]

Howdy all...

Yes, it would make a lot of sense to just spend the 5k on a new Canham.

On the other hand...

I have probaboy 25-thousand negatives in negatives from 4x5 smaller, and I would love to be able to print those on Azo, or platinum. Many of them, anyway. I salivate at the thought. I just don't salivate THAT much.

dgh

 

[Jim Chinn]

A couple of years ago I had read an article on the web about a photographer who was also an electrical hobbyist that made his own high output light source for enlarging Azo. He had used a couple of 8x10 Xenon (sp?) tube light banks similar to what is used for animated light displays such as in Las Vegas. Each light board contained something like 40 small xenon tubes. The boards put out over 5000 watts and were pulsed several hundred times a second by a capacitor and transformer setup. If I recall, the pulsing was required so the unit didn't blow itself up.

Anyway, the author said that the whole thing could be put together with off the shelf parts including the xenon light units for under $2000. He had some listings of vendors and wiring diagrams, but I can't recall his name or the url. I hope this post might jog someone elses memory who had maybe seen the site.

 

[Aggie]

..

 

[SteveGangi]

Aggie, that is the way most of us do Azo, when we do it. My "equipment" is 2 pieces of glass and a floodlamp. Very high tech. I bet pumping 5KW into an enlarger would create a serious heat problem. Y'all better have some sort of forced air cooling (fans) and heat sinks figured in the equation somewhere, or something is gonna cook.

 

[avandesande]

You probably would get little benifit from using azo with an enlarger. You would still have the highlight blocking Callier effect, which would be exacerbated by the short wavelengths that the AZO is sensative to.

 

[lee]

Back when there was a perponderance of darkroom cameras in the printing business, some of the higher-end cameras were either retrofitted or came with pulsed zexnon lamps. These were very high output lamps. They had fans that ran only when the lamps were on. I think l remember that correctly. I think the output on each side was about 2500 watts per side. I could be wrong about that but that is what comes to mind right now.

lee\c

 

[Donald Miller]

The problem in enlarging Azo is not the quantity of light but the spectrum of light, as Aaron mentioned. Azo exposes entirely in the 350-460 nm spectrum which is "near" or "A" band UV. The reason that the high wattage lamps such as metal halide and mercury vapor are used is that they do emit UV as well as visible and IR light. The same is true of pulsed Xenon as Lee mentioned. The problem is that in the case of the first two lamps mentioned is that the UV output is only on the order of 20% of the total output. So a 5KW lamp will only put out 1KW of the spectrum needed. As Aaron mentioned condensors such as the big 184 Durst with the big lamp do supposedly exhibit the Callier effect, although that is open to dispute at this time. Additionally, I don't know that I agree with his statement about the UV rays being more prone to the Callier effect. In fact recent information indicates that a diffusion light source suffers greatly in the area of print resolution when compared with a condensor light source. While Ansel Adams made wonderful prints, some of his statements should be open to question. I spoke with John Z who has one of the larger Durst units and he says that the enlargement does not measure up to a contact print. Although an enlargement on Azo is better then an enlargement on any other paper. I should have information from Durst on their new enlarger and light source for enlarging on Azo and Platinum this week and I will be interested in that because it only emits UV rays from what I was told.

 

[David A. Goldfarb]

It must emit some visible rays or it will be pretty hard to focus.

 

[SteveGangi]

I don't know if this is true, but my intuition tells me that all wavelengths would be affected by the Callier effect to some degree, and that shorter wavelengths would be affected more. This is just a "gut feeling" and I have no proof or facts to back it up, so take it as a guess, not fact.

 

[avandesande]

The sky is blue because shorting wavelengths are more likely to suffer from diffusion.


I was reading the old 'Darkroom 2' book the other day, and I came across a guy who used a 'point source' enlarger. I haven't run into a mention of this anywhere else. Apparently a point source enlarger resolves even better than a condensor enlarger. A xenon arc lamp would be perfect for this application.

 

[Ed Sukach]

Different wavelengths of light *refract* - that is, bend at different rates - in a refractive media (air or water, - or glass). Dispersion is a different animal - oversimplifed, it is "scatter' due the lack of homogenity of the refractive media.

Point light sources - true "points" are useful in detecting minute impefections in optical systems. Seeds, dings, scratches - and like that - will *not* be camoflaged by the "area" of the source. The greater the "diffusion" of the source, the less noticeable will be dust, scratches, etc. That is why "Condenser" enlargers seem to be "sharper" than "Diffusion" enlargers ... but that is a double edged sword - at times, extreme sharpness in not a desirable quality.

A "Point" Light Source would seem to me to be far more trouble than it would be worth.

Are we on the brink of a "Callier Effect - Does It Actually Exist?" discussion?

 

[Donald Miller]

In visiting with John Z about his Durst 8X10 enlarger, he mentioned that a fellow at Durst (I believe his name is Jensen) is a very knowledgeable person on the subject of the physical properties of light and it's application to photographic enlarging. He apparently has done some writing on the matter and posted an excellent discourse on the matter of diffusion versus condenser light sources on their website. I am still digesting the material that is located there since it challenges many of the beliefs that I have accepted simply because Ansel Adams once indicated it. For those who are interested it is on the Durst Pro USA site.

 

[brYan]

What about using a strobe unit when making contact prints, instead of a continuous light source?

 

[Ed Sukach]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (dnmilikan @ Feb 7 2003, 07:35 AM)</td></tr><tr><td id='QUOTE'>... He apparently has done some writing on the matter and posted an excellent discourse on the matter of diffusion versus condenser light sources on their website.
... For those who are interested it is on the Durst Pro USA site.</td></tr></table><span class='postcolor'>
I tried getting there, through a Google search, but became lost.
I'm interested .... Do you have a specific web site address?

 

[JohnArs]

Hi all

Why you get an enlarger for 5 kilo if you can do it like me?
I use a wonderfull Jobo LPL with a 200 watt lamp for my 4x5 inch enlargemants on 8x10 AZO but I use my colorhead with 100 cyan because AZO is blue sensitiv is somewhere stated in the pack of AZO! If you have not a colorhead just but a blue filter in!!!!!
Works perfekt I get times from 1-5 minutes at f 8!
If AZO love blue just give him the blues!!!!!!!
And for thad you need not an expensiv new Durst!
Did you get thad now?
Just keep it simpel!

 

[Donald Miller]

You are the second person who has indicated that cyan filtration will work on Azo enlargements. I have tried dialing in cyan filtration to the maximum...have even added supplemental cyan filtration beyond that...exposed for five minutes...guess what??? Nothing, nadda, zilch. So then I went to checking out the spectrum sensitivity for Azo on the Kodak site....called the Kodak tech even...he told me that Azo exposes at 350-460nm. That is light in the ultraviolet spectrum, which is invisible until the 400 level when it becomes purple...not blue, nor cyan. So for those who are able to expose this stuff with visible light I applaud you. Maybe the matter is the density of my negatives. I develop a negative with a fair amount of contrast to utilize the scale that Azo possesses. But I won't sacrifice full tonality at the expense of being able to enlarge.

 

[Donald Miller]

Ed, the site is down the page and is listed with a URL of Durst Pro Usa. If you fail to locate it get back with me and I will get the actual URL for you. Good luck.

Regards,
Donald Miller

 

[Donald Miller]

brYan,
Thanks for your input. I had considered pulsed Xenon which is the source of photographic strobe equipment. While pulsed Xenon will emit some UV the problem is that most manufacturers of photographic strobe equipment coat the quartz tube to filter out UV light because is extraneous and undesirable for photographic lighting. I guess that a person could fashion a light source for this application from a pulsed Xenon tube which had not been "doped". This does open another "can of worms" though in that a power supply and capacitor network would need to be designed. Additonally a means of variable power output would need to be incorporated in order to have control over exposures. The old Bessler-Minolta 45a had three channels of filtered strobe lighting but that system was primarily targeted to color work. It also was not nearly powerful enough for this application. Azo paper has a photographic paper speed of 4 and Kodak Polycontrast, by comparison, has a paper speed of 250. So it requires a lot of light to expose it.

Regards,
Donald Miller