Mystery glass in Omega D-II DV condenser

[tkamiya]

I have an Omega D-II with variable condenser. In the FIXED condenser portion of the assembly, I have two HUGE (6/12 lens) lens. On top of it, there is a piece of flat round glass with a slight tint.

This is the piece that if you take the fixed assembly off, it will be sitting at the top of the top lens (that is facing concave side down) and in contact with this lens.

What is this flat glass for?? This flat glass does not show up on an instruction manual I found for D-2 with VC, but I am aware, Omega has produced similar models for years so there could be some changes to its design.

Thank you.

 

[David A. Goldfarb]

It could be a heat absorbing glass.

 

[fschifano]

That might be the heat absorbing glass. I've a smaller Omega condenser enlarger (B-600) with a similar piece of glass sitting on top of the condensers, and according to the diagram, that's what it is. I expect the same to be true for the D2, only larger. In any case, it does serve a useful purpose, and that is to prevent the negative from becoming excessively hot and "popping" in the negative carrier.

 

[Rick Jones]

If the glass is tinted it is undoubtedly heat absorbing glass which Omega offered in two configurations. Both were available as extra cost accessories. The circular HAG was installed in direct contact with the top fixed condenser just as you found it. A rectangular HAG was also available and fit in the variable condenser housing. I believe they were primarily meant to absorb the extra heat generated by the PH212 (150 watt) bulb. Heat generated in the head can cause negatives to buckle or pop out of focus in mid exposure when using glassless carriers. I experienced negative popping with 120 film even when using the PH211 (75 watt) bulb. Installation of HAG eliminated that problem.

 

[tkamiya]

Thank you, thank you, thank you! (to all who replied)

I thought it might be the heat absorbing glass but I wasn't aware it was offered in two varieties as Rick Jones said. I've only seen a type where it goes into the variable lens rack. I use 75 watts bulb but I will keep it in its place.

Thanks again.