Is a VC paper with no filter equal to No. 2 graded paper?

[oldtimermetoo]

I think that I know the answer to my question if the instructions for using VC papers are correct. The question: are VC papers printed without filters the same as No.2 graded papers? If so why not shoot and develop your film so it will print on No.2 graded paper and not use filters? Am I overlooking something? In olden times we always tried to make negatives to work on No. 2 and only used No.3 to print 35mm. Of course it was easy to buy graded papers in those days. If the negative required No. 1,4,5 papers, we had failed, trashed the negative and tried again. It seems to me that it would be fun to try to do this again instead of trying to salvage prints from negatives that were not very good to begin with. What do you folks think?.........Regards!

 

[silveror0]

Let me put it this way: It depends on the color temp of the enlarger light source. Ilford states that their filter system is designed to work BEST with an incandescent light source (that would be around 2800K). I recently modified my 5x7 Omega enlarger light source to LEDs that were 8500K, then tested the performance with MGIV in MG developer 1+9. Any color shift caused by the diffusers may have some influence as well. I found that the response with no filter was close to Grade 2, except in the mid-tones where it was more like Grade 2.5. I've attached my curve plots so you can see it better (I've slid the curves so they all meet at a common reflection density of .09 highlights so the slopes can be more easily compared). The funky behavior seen for the "softer" filters is explained very well in this link. However, I think if you're interested in making FINE prints requiring close control of LOCAL contrast, you'd be missing out on a lot by avoiding the use of filters, especially the use of split-grade printing techniques.

 

[silveror0]

Correction: The LEDs were 7500K.

 

[oldtimermetoo]

You have answered my question but left me with another. It is my understanding that North sky daylight is around 6000K. How are you able to use filters designed for a 2800K light source with a light source of 7500K and not have problems? Are all LEDs 7500K? I have been looking into an LED light source for my Omega Dii but I am afraid that would kill the deal....Regards!

 

[silveror0]

Just because the light source color isn't 2800K doesn't mean the 7500K won't work. It does mean that you will get some differences in its performance. The important thing to note is how much blue component and green component is emitted. Some time ago I wrote up a rather lengthy post in the LF forum, describing the details of my modification:

http://www.largeformatphotography.info/forum/showthread.php?111226-Omega-5x7-E6-LED-Mod

That post provides a link to a pdf (from Cree, the LED mfr) that shows the spectral power distribution of my chosen LEDs; it shows the amount of blue and green emitted, and virtually no other colors in the output. A different LED with a different blue/green balance could still work, just with differing response by the VC paper. My curves above simply show the response of MGIV paper with Ilford's multigrade developer. Now that Ilford has stopped making MGIV, I'll have to redo my tests with the Classic paper that has replaced it, but I now have confidence that my LEDs will work with Classic also. The speed points with the various filters will likely be affected somewhat, but that doesn't really bother me as my VC printing technique isn't reliant on speed points for control (long story that stems from information in Way Beyond Monochrome 2nd Ed.).

silveror0 (Jerry Bodine on LF forum)

 

[StephenSteinke]

Light source shows power of green