Focusing Handle Loose or Negative Heating Up?

[DF]

While doing prints, I check - re-check image with the grain focuser and notice the image starts to blur abit.
It can be after 5 or so minutes, maybe longer, maybe shorter during the whole test strip-then-actual print routine. The focusing knob feels firm, in fact sticky/sqeekey. So, is something happening to the negative because of the light or heat perhaps?
I wish the Omega's I use were looser, yet with some sort of lock-in-place mechanism.

 

[John Wiegerink]

Which model Omega do you

 

[ic-racer]

Get a glass carrier, or pre-heat the negative with the lenscap on.

 

[mike c]

I have a Omega D2-V and had the same problems until I started using the glass neg carrier, I'm using a 150 watt bulb, 120 film.Preheating the neg (so it pops) before making a print was a PITA with the regular carrier's.

 

[Sirius Glass]

I have not had problems like that with my Super Chromega Dichroic II 5D-XL.

 

[Jim Jones]

My Omega B22 popped negatives in long intensive enlarging sessions. Leaving the lamp on and controlling exposure with cardboard taped to the enlarger's red filter caused the negative to pop quickly, before starting the exposure. Using enlarger lamps continuously may cause early lamp failure unless the voltage is reduced slightly.

 

[bence8810]

I had this issue with Medium format negatives when I was using my old condenser enlarger - there was a lot of heat.
Small format didn't change much to be noticed - at least I didn't. Medium format once popped - was totally out of focus in the middle. If I waited until it popped it was in focus in the middle as I used that to set the focus and the 4 corners were out of focus.

I got a glass carrier and realized I just tripled the surfaces I needed to clean and worry about keeping clean. I had a lot of garbage showing up on my prints.

I then swapped to a diffusion enlarger with a halogen bulb where no noticeable heat is projected towards the negative and I am happily printing away with a glass-less carrier and no focusing issues. I did have to put up with longer printing times and slightly less contrast when using graded paper.

Ben

 

[Ronald Moravec]

preheating will cause the neg center to pop into focus, however the edges do not move.

glass carrier is only solution

 

[DF]

Wouldn't there be some image degradation from a glass carrier - from that extra layer of glass?

 

[Bob Carnie]

Wouldn't there be some image degradation from a glass carrier - from that extra layer of glass?

No there is not. I recommend glass carriers for all enlarger printing, soon the negative stretcher folks will come on board but a good cleaning sequence for glass carriers in a humid room is what I suggest.

 

[ic-racer]

No there is not. I recommend glass carriers for all enlarger printing, soon the negative stretcher folks will come on board but a good cleaning sequence for glass carriers in a humid room is what I suggest.

This ^^

Also, every one post of Bob's carries the weight of about 20 posts from us hobby-printers.

 

[mike c]

Thats a lot of weight for one man to carry, but Bobs the guy to do it. I have been to one of his work shops and he knows his stuff.