“Levelness” of a D-2v top condenser lens

[Heroique]

Often, I switch-out my D-2v’s condenser lenses, VC box & lamp house for my Omegalite head.

Recently, I noticed my top condenser lens (i.e., not the variable condenser) was slightly askew – probably from a slight knock during one of these switch-outs. One side of the lens appeared to be, say, 2mm or 3mm higher than the other side.

Not much difference, and an easy fix of course – but it raised a question: Would this sort of difference produce uneven illumination under certain circumstances? I’ve never noticed any in my prints, but maybe under high magnification, a perfectly level top condenser would deserve careful, periodic checks.

[Nathan Potter]

That top plano-convex element sits on a rather inexact perforated aluminum insert that separates it from the bottom element. The top unit can slip laterally out of planarity so I place a few matboard shims around the periphery to snug it into planarity. But I confess to never observing any detectable uneven illumination when out of alignment. Just check for uniformity on a white baseboard using your spot meter while the top condenser is out of alignment.

Nate Potter, Austin TX.

[Heroique]

The shims of mat board are a good idea, thanks.

Yes, the corrugated spacer is an inexactly crafted piece indeed; it's tempting to judge the levelness of the condenser by using the spacer's top edge as the benchmark. Much better to use the top of the condenser housing.

BTW, using a spot meter to evaluate the enlarger's illumination on the base board ... Now that's an idea worth its own thread!