Aristo

[ic-racer]

I have been under the impression (wrongly?) that the cold light was more diffused than the other diffusion-type heads. I purchase one not long ago but am not set up so have not used it yet.

In the Aristo the diffuser is just a piece of translucent plastic, nothing special.

 

[David A. Goldfarb]

The tube is also frosted and I'd think that the layout of the tube and the close proximity of the tube to the neg with cold light could make it a softer light source than a dichro head, but I haven't tested that proposition.

 

[Curt]

The diffuser surface is in the same plane for my Beseler head and my Aristo cold light head.

 

[ic-racer]

Its pretty easy to test. Just projection print any left-over film control strip on to graded paper using each light source.

 

[Robert Hall]

So to those in the know what do I need to convert my omega 4x5 enlarger to a nifty 8x10 enlarger?

 

[David A. Goldfarb]

So to those in the know what do I need to convert my omega 4x5 enlarger to a nifty 8x10 enlarger?

While I suppose it can be done some way, that's a conversion more suited to Beselers, because of the way the column is designed, and Beseler offered a conversion kit.

 

[RalphLambrecht]

Its pretty easy to test. Just projection print any left-over film control strip on to graded paper using each light source.

John Sexton demonstrated this to me once in his darkroom, using grade-5 paper. We were able to see the curved tube of his cold-light head. Not very uniform, I tell you. My dichroic head has a definite light fall-off to the edges, but thsat doesn't hurt too much (automatic edge burn).

 

[Peter De Smidt]

The main reason for the popularity of cold light heads is that big dichroic heads used to be very expensive, heavy, moderately difficult to adapt to a non-matching enlarger, complicated, and as mentioned they throw less heat the a comparable output incandescent head. An Aristo was often about 1/10th of the cost, much lighter, simpler (less to go wrong. Easy to fix.), more efficient, and came in a wide variety of sizes. My first 8x10 enlarger was an Elwood. I bought an Aristo head for it with the V54 bulb and a metrolux timer. This setup worked very well. Given that the cost of big color heads has nose dived, the cold lights aren't as compelling an alternative, although they're still very good, especially with aV54 bulb, which gives a very good range of contrast adjustment with VC filters.

 

[ic-racer]

John Sexton demonstrated this to me once in his darkroom, using grade-5 paper. We were able to see the curved tube of his cold-light head. Not very uniform, I tell you. My dichroic head has a definite light fall-off to the edges, but thsat doesn't hurt too much (automatic edge burn).

Oh yes, I'm not surprised. But I was referring to checking for the Collier effect by projecting step wedges made of silver film (ie old control strips rather than the step wedge itself) and checking the contrast range to which they printed. There should be a small difference between condenser and diffuse ,but Aristo and dichro head would be the same. (I guess if they were not the same one could write it up in a technical journal )

 

[ic-racer]

So to those in the know what do I need to convert my omega 4x5 enlarger to a nifty 8x10 enlarger?

Sell it and buy an "F"

Anything is possible, but I can't say I have ever seen anyone post that they did that particular conversion.

 

[Sal Santamaura]

John Sexton demonstrated this to me once in his darkroom, using grade-5 paper. We were able to see the curved tube of his cold-light head. Not very uniform, I tell you...

I completely solved this by adding a second acrylic diffusion sheet spaced 1/4-inch from the first one. However, substantial edge fall off results; one then needs a cold light head at least one inch larger in each direction than the largest negative to be enlarged.

...My dichroic head has a definite light fall-off to the edges, but thsat doesn't hurt too much (automatic edge burn).

Unfortunately, the result of light source edge fall off is automatic "edge dodge," not burn.

Some dichroic heads, like the 4x5 LPLs John Sexton and I use, have diffusion materials that are thicker in their center than at their edges, thereby providing extremely even illumination to all parts of the negative.

 

[Curt]

Some Beseler light tubes have two diffusers in them also.

 

[resummerfield]

......given the simplicity of other diffusion-type heads, why do you prefer a cold-light head, and what are the reasons to buy one in your opinion? What can they do, another diffusion head cannot?

I have a 2000w dichro head for my 8x10 enlarger, yet I normally use an Aristo cold-light. The cold-light is MUCH quieter and MUCH cooler.

 

[RalphLambrecht]

Oh yes, I'm not surprised. But I was referring to checking for the Collier effect by projecting step wedges made of silver film (ie old control strips rather than the step wedge itself) and checking the contrast range to which they printed. There should be a small difference between condenser and diffuse ,but Aristo and dichro head would be the same. (I guess if they were not the same one could write it up in a technical journal )

I assume, your talking about the Callier effect? I doubt that it is measurable within reasonable precision to compare cold-light and dichroic heads. They should be both having a coefficient of around 1.1.

 

[RalphLambrecht]

The main reason for the popularity of cold light heads is that big dichroic heads used to be very expensive, heavy, moderately difficult to adapt to a non-matching enlarger, complicated, and as mentioned they throw less heat the a comparable output incandescent head. An Aristo was often about 1/10th of the cost, much lighter, simpler (less to go wrong. Easy to fix.), more efficient, and came in a wide variety of sizes. My first 8x10 enlarger was an Elwood. I bought an Aristo head for it with the V54 bulb and a metrolux timer. This setup worked very well. Given that the cost of big color heads has nose dived, the cold lights aren't as compelling an alternative, although they're still very good, especially with aV54 bulb, which gives a very good range of contrast adjustment with VC filters.

I did not know that, but it makes a lot of sense, and explains their popularity!

 

[RalphLambrecht]

I completely solved this by adding a second acrylic diffusion sheet spaced 1/4-inch from the first one. However, substantial edge fall off results; one then needs a cold light head at least one inch larger in each direction than the largest negative to be enlarged.

Unfortunately, the result of light source edge fall off is automatic "edge dodge," not burn.

Some dichroic heads, like the 4x5 LPLs John Sexton and I use, have diffusion materials that are thicker in their center than at their edges, thereby providing extremely even illumination to all parts of the negative.

I'm glad somebody is paying attention. Almost got away with it. LOL

 

[ic-racer]

I assume, your talking about the Callier effect?.

I'm glad someone is paying attention...

Based on my experience I'd sum up differences as follows:

Dichro head:
-Hotter
-Noisier
-More prone to vibration
+More even illumination
+Less expensive bulb (usually)
+Nothing extra to buy for contrast control

Single Coil Cold Light:
+Cooler (but not 'cold')
+Smaller
+No fan needed
-More expensive bulb (usually)
-Lamp intensity changes with time
-Need to buy extra filters for contrast control
-Less even illumination

Similarities:
Diffuse light

A thread discussing the two might make a good 'sticky' as this question seems to come up all the time.

 

[David A. Goldfarb]

Before making it a sticky, we should probably split the thread so the posts about Aristo, the company, are separate from the posts about diffuse light sources. When I've got a few minutes...(or one of the newer moderators can try, if you want to figure out how to split a thread. This one should be relatively easy).

 

[jeroldharter]

This is the reply I received:

Dear Jerold,

You may not have heard, but As of August 6, 2009 LSI announced the execution and closing of the asset purchase transaction of Voltarc Technologies, Inc.

Light Sources, Inc., LCD Lighting, Inc. ( LightTech Lamp Technology, Kft., and Masonlite Ltd.) of Orange Connecticut announce the
Acquisition of Voltarc Technologies Inc & Aristo Lighting Technologies to its family of affiliated lighting companies.

Right now we are in the midst of the transition and will be able to answer you better in a week or so when the Aristo product line is sorted out.


Best Regards,


Louise M. Kessler

Light Sources, Inc.
LCD Lighting, Inc.
37 Robinson Blvd.
Orange, CT 06477
Tel 1-203-799-7877 ext 3163
Fax 1-203-795-5267
email: louise.kessler@voltarc.com

email: LKessler@LCDL.com