Grain Focusers & Enlarger Alignment
Well hello - finally stopped lurking, and here's my first post!
Returning to the darkroom after a 15 year or so absence. Using a Beseler 67c, Single column. It's got some minor alignment issues.
I've got it fairly well dialed in using a black 35mm neg with a grid scratched into it. Used a Magna Sight to get this far.
Just got a 25x Microsight. Man - that thing's intense! I have to stop down to f8 or so to avoid frying my retinas. Nice! But... when I've got roughly a 16x20 area going, I can see grain even when the micro is placed several inches off center - eventually I'll have sort of a "quarter moon" of grain, which shimmers until the eye is aligned just right. But - I can see grain far enough from the center to notice I could still do some fine tuning.
My question is - if I can see grain, is it accurate for focus - or is only the center going to be correct for focus, and are the edge focus issues I'm seeing a product of the micro sight being off-center? Anyone know? I've emailed the manufacturer, so far just got a reply of "helping them with emails, I'll ask someone". I'd love to buy a top-of-the-line, full field focuser, but the Mrs. is wondering why all the huge eBay boxes every day (I'm working towards 3' x 5' emulsion on canvas prints...)
By the way, this forum's been a daily search for me - so much friendly knowledge here. If anyone needs to know how to dupe your color slides onto 8x10 velvia sheet film, just let me know (that was my last enlarger usage, for my commercial portfolio pre iPad and website days...) Thanks all.
Welcome to APUG.
I have a similar grain focuser, except mine is x15 or x20.... (I can't recall) With mine, like yours, if I get too far from center, there is nothing to see. I did see well enough to notice mine was off-alignment because grain wasn't sharp off center. Yes, I do believe, if you can see the grain SHARP, then it is good enough focus AT THAT LOCATION. But since we can't get far enough off center, it's no use.... What really matters is what happens around the four corners.
What's even worse, trying to align enlargers using grain focuser is pretty much impossible. So I ended up (after months of frustrating experiments with less than ideal methods), get a laser alignment tool. It was fairly easy with this tool but even with that, I had to deal with repeatability (or lack there of) of results.
Develop, stop, fix.... wait.... where's my film?
If the grain is in focus then the negative will be too. Bear in mind that the definition of the grain will deteriorate the further out from the centre you will go but I focus on the centre and then stop down to F8-11 with my Nikkor 50mm and it will be sharp all over. This all depends on the quality of your lens too. Get the best that you can afford and it won't let you down. Nikon, Rodenstock or Schneider are the ones to aim for.
The best focussing aid I have ever seen is one made or at least marketed by a company called 'Peak' There may be the same focussing aid sold under different names but this one has a rocking eyepiece which you can use to focus on the image/negative from the very corners to see how for it is 'out'. I have one that has seen better days but still does the job.
They do occasionally turn up for sale 2nd hand so expect to pay around £80 or $120 for one in tip top condition.
If your enlarger has a movable head it may well be worth checking that it is truly vertical and parallel with the baseboard, by using a small spirit level on all the vertical and horizontal surfaces.
If you see grain that far out, you will be fine.
Keep in mind that you actually increase the depth of field on the paper the further you stop down.
And of course... if you stop down to far you start to lose sharpness from diffraction.
But I would say you are now at the point where it will behoove you worry more about making a beautiful print as opposed to one which is in focus.
Thanks guys - my enlarger has an adjustable negative stage; the lens board is attached to that. Difficult to adjust and then tighten without it falling back off. I got things basically aligned with a spirit level (bubble level in the states!) and found I needed to shim the lens board. Using an El Nikkor 50mm 2.8. After using the Magna, I'm amazed at the magnifying power of the micro though.
I'm aware of the peak focuser, but will try to get by without one for now - they seem to get grabbed up quickly when they appear. I see a slight focus shift when I get about 4" from center (on a 16x20 so I'm fairly close to the edge). You can still tell that it's grain and see the structure - it's pretty minor. I'm sort of mentally designing something like a lensboard with tapped holes and small thumbscrews to fine tune the lens board angle - shimming's such a hit & miss process vs. "dialing it in".
I feel like I have the thing reasonably close and to a point that all this may be moot when stopped down, and I'll do some materials tests at 20x24 and see how everything goes. At some point I'll need to build a sort of level-adjustable combination easel & dev. tray of "rather large size" (I'd like to use materials up to 5'), and I'm curious to see what effect DOF has going very big. Anecdotally I've heard the focus tolerance increases for projected prints, so I may be fine. Thanks again!
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The quickest / easiest method of enlarger alignment IMO is the Versalab "Parallel" device, provided your enlarger has decent adjustment controls to make it possible.
Mfr's website: http://www.versalab.com/server/photo...s/parallel.htm
Also check out reviews here:
Thanks Silver... I've read a lot of love letters to the versalab; when I start running some large prints we'll see. If I have any frustrating issues, I'll likely talk myself into one. (I tend to compose and record the music for edits I do so I'm surrounded by electronic audio gear... my wife has pointed out how I seem to love "any gear with blinky lights on it". Anything with a red light on it has just upped its value by 90% in my eyes!)
I use one of those, but I have 7 enlargers to align. Well worth the gray hair it saves.
The Nikkor 50mm 2.8 that you have will give a quite non-flat field when used for 16x20 and larger. Assuming your enlarger is aligned, you can focus the center and far edge by moving the enlarger head up and down (don't touch the focus knob). Then set the enlarger head at the linear midpoint between the two points of focus and stop down to about f16. You should be able to make a reasonable print, but if you intend to do a lot of images that size you might want to look at the HM Schneider or the Rodagon-G.
Originally Posted by M Carter
Interesting - I tracked down the Nikkor because they seem universally well regarded and are plentiful. My heart is really set on prints around the 48" and up size though. Food for thought.
Originally Posted by ic-racer