What I found out is that when I look through the grain focuser and hit the expose button, it starts out of focus and comes into focus gradually over 15 seconds.
Originally Posted by Ian Grant
Sometimes the head on enlargers slip, they usually have a counterweight or spring system. This happens with Durst's and some other makes because the pressure pads wear, these lock the head assembly and it's very simple adjustments to cure the problem. Ironiocally the head creeps up the column.
Originally Posted by mwdake
I have a D5 that does exactly that, the head does not move but the bellows lock is a bit loose and I have seen it creep down and watched the focus change.
The timer does not control bellows creep or column slip. Any relationship would be only coincidental; though absent more info from the OP, creep/slip is an outside possibility.
The negative could be moving, or the focusing gears could be slipping. The latter used to happen all the time on my Beseler B22 until I did a "CLA" on it. It's a cheesy enlarger, but the plus side is that it is extremely easy to take apart and adjust. So, I would check both possibilities, though I cannot say I have had the buckling issue with anything but an open 4x5 film carrier. Do you use tape to hold your film down flat?
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The negative probably was focused with the heat build up during focusing of an already popped neg. So as the negative cooled again it is out of focus on the start exposure n returns in focus as it warms up again.
1--Heat absorbing glass is what you need or maybe an extra like I did. I put another HAG in my 4x5 Besseler right in the filter drawer as well as using the standard one in the head. That huge bulb get things pretty hot in there.
2--Glass neg carrier
3--- Best solution of all.... Cold light, unless you are doing color work. I converted a long time ago and will never go back to tungstin again.
Anyone can make a Digital print, but only a photographer can make a photograph.
It couldn't be the column slipping. I tightened it so much that I could barely focus.
I'm using 35mm negatives. I never had a problem before. I've used glass negative holders before with the exact same results, so I went glassless for the last 2 years and never had an issue with unsharp corners or uneven focusing problems.
I've had the beseler 4x5 enlarger for 2 months and have been printing medium and 35mm negatives up to 20x24 with amazing results. This only happened last night on all 3 negatives I went in to print. I ended up just focusing, then starting the time 20 seconds before the exposure and all my prints were great after that. It made burning and dodging a huge pain, but I just rolled with the punches. My glass carrier won't fit my beseler, so I'll have to hunt for a new one or make my own. I'm not huge on the idea of spotting more than I need to, but I'm pretty good at it and I guess I'll just have to go that route. I've lowered the top bellows further from the light source so I'll see if I can go that route for a while.
The only reason I can imagine this issue occurring now is that I had a huge flood in my darkroom last night as well, spent 3 hours cleaning it up, but noticed it was extra humid. I'm wondering if the combination of the heat from the lamp and the humidity in the air had something to do with the negatives buckling? Maybe someone could elaborate on that theory?
More humidity makes negatives more flexible. Since it was just three negaives and none before the flood or since the flood, then humidity is surely the cause. It must have been just enough to go past the tipping point to allow popping.
Keep your darkroom dry and see if the problem never recurs.
The humidity from the flood could also affect the focus and elevation locks and the stiffness of the bellows on the enlarger.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2