What VC LED Heads for LF B&W Are You Aware Of?

[Rafal Lukawiecki]

There is a thread, started just a few days ago, about a new VC head being designed by some folks. There is another thread, on APUG, also about an experimental design, plus a few more threads, describing issues and failures in using some green and blue LEDs to make a working head. I am only aware of one commercially available LED VC head, the relatively (for me) pricey, Heiland one.

What have I missed? Do you know of any commercially available, or experimental VC light sources?

Just to avoid confusion, I am not asking for an LED white lamp that I could use with filters. I am looking for a light source that mixes blue and green (or magenta and yellow) light by itself, like the venerable dichroic Ilford 500 Multigrade system, or similar, filter-based heads, like Ilford 400 and 600, or the Saunders/LPL VCCE.

And if anyone is looking for a feature spec, I'd be happy to provide a long list. The short one is:

• speed-matched, so a given esposure time that prints a midtone of ISO paper speed point of 0.60 above base, prints the same midtone at every contrast setting

• evenly spaced, and finely controlled contrast settings, ideally at no less than ISO-R steps of R10; ideally, this would be configurable to calibrate for different characteristics of various VC papers

• easy to use controller, that is simple, offers time-based exposure, focus, and burn, with a foot switch option, and, if possible, ability to use a 3rd party timer

• exposure must be made in one cycle, at the determined contrast, and not in two cycles, that is not a soft then hard exposure; however, an option of making split-grade exposures should be possible for those who use that method—ideally, both modes are selectable

• I only care that I can use it on my De Vere 504, but the head ought to be modular enough to work with different enlargers—Ilford 500H had been designed that way, perhaps that idea could be replicated

I realise that some of those points were raised here and there, and I apologise for any repetition. My only goal is to find out what is available, and to hopefully inspire someone to make this possible, if they can.

[Sal Santamaura]

http://heilandelectronic.de/led_kaltlicht/lang:en

[Leigh]

...like the venerable dichroic Ilford 500 Multigrade system...

The Ilford 500 is not a dichroic system. It uses two 300-watt halogen lamps, one with a blue filter and one with a green filter.

- Leigh

[Bob Farr]

Kienzle Optics

They make an LED head for split printing with B&A papers.

[Rafal Lukawiecki]

http://heilandelectronic.de/led_kaltlicht/lang:en

Sal, that is the very Heiland device I was referring to in my post. Unfortunately, at £1750, that is $2800, for the light source in 4x5 format and the controller, it is rather outside of my price range... Perhaps it will become more affordable in due course.

The Ilford 500 is not a dichroic system. It uses two 300-watt halogen lamps, one with a blue filter and one with a green filter.

Thank you, Leigh, for your comment. I have this head, and it contains two dichroic (one blue and one green) filters, and four heat filters, in front of two 300W ELH bulbs, whose intensity is varied by frequency modulation, not dissimilar from PWM. Filtered light is subsequently mixed in a box, that contains an additional diffuser. May I ask you, Leigh, please, how does this use of dichroic filters make this system not a dichroic one—or, what makes a dichroic system?

Bob, thanks for the Kienzle tip, I'll research and post back here.

[Pavel+]

I too have the Ilford 500 head and have a similar interest in finding a LED replacement, that is affordable, but works the same way. The age of the 500 makes me worry about the looming, sad day of a component failure. The dichroic filters that come with the 500 seem impossible to find nowadays, and I thought I'd mention that when one of mine fell out and chipped, I took apart a Saunders Dicro 6x7 enlarger and used its dicroic filters instead, to replace the original filters. The Saunders filters look different but seem to work just fine. To optimize the system I am going to send swatches to RHDesigns soon (when I finaly settle on papers) to get it calibrated by them.
The way the RHDesigns Analyzer 500 works is brilliant, btw, on the 500. Rather than mix the two lights, it exposes through first the soft, and then the hard filter and so you have a defacto split grade system. Marvelous! The only thing I really dislike about it besides the ticking life span, is the heat which, makes exposure too short and which necessitates the use of a fan. That fan ruins it for me! An LED source would be, for me, like the calvary coming over the hill at the last second.
So..... where's the calvary?

[Arne Croell]

In the US, Calumet made a 4x5" LED head (blue and green) for a short while, around 2004, but they are pretty rare used.

[Robbie Bedell]

Rafal, There is a guy in North Carolina who has been making a constant LED head for filters beneath the lens. He is selling them on E-bay I got an email from the company the other day saying they are working on a multigrade head, but I do not know if the design is finished. I deleted the mail (spent too much lately!) I will do some research and see if I can dig up the name of the company, Robbie

http://robbiebedell.photoshelter.com

[Robbie Bedell]

OK, I found it. It is Modern Enlarger Lamps in Hickory, N.C. at www.modernenlargerlamps.com I think they are working on a multigrade head but I am NOT sure...

http://robbiebedell.photoshelter.com

[Robbie Bedell]

Boy am i dumb. I just read the earlier thread! Sorry about that...Robbie

http://robbiebedell.photoshelter.com