Digital camera focus peaking as grain focuser?

Mrtony4x5 · Mar 24, 2018

Just thinking out loud. Im setting up a darkroom from scratch. Can I use a digital camera focus peaking feature with a macro lens as a grain focuser?

John51 · Mar 24, 2018

I'm attempting similar with a de-lensed webcam.

How are you planning to see the image? I'm using the I-Spy app to see the image on my laptop and can see it go in and out of focus as I adjust the enlarger.

Ko.Fe. · Mar 24, 2018

To find answer to the question, OP needs to understand first how regular grain focuser works.
Lets brainstorm together.

I think regular grain focuser is fixed focal length lens focused on the level where it stands.
It is fixed focus lens. And you are focusing enlarger to hit the focus on the grain focuser.
If so, digital camera with prime macro lens needs to be placed on some support and focused in manual mode once.
Then camera and lens could be removed, lens focus ring has to be taped, but camera could be still in use.
Same support (no moving parts), same lens (focus never changed) and digital camera will do it for next time under enlarger.

Now obvious question arise - isn't it cheaper and straight to get normal, clean and used grain focuser?

Mrtony4x5 · Mar 24, 2018

Just thinking out loud. Well I tried. Doesn’t work.

David Brown · Mar 24, 2018

Or, with a little patience, one can buy a perfectly usable grain focuser for $10-20.

https://www.ebay.com/itm/Minisight-...399477?hash=item2aa413fbb5:g:ydcAAOSwClxangv-

All they are is a mirror and a magnifying lens, so that you can see the image magnified 10-25 times. It’s not rocket science.

I am hardly against digital tools. High end timers have been “digital” for decades. Some enlarger heads are “computerized”. All I am saying here is that there is no need to re-invent the wheel. I would especially recommend this to anyone (as I do to my beginning darkroom students) just starting out with printing. Don’t add another variable. Just get a good, proven tool and learn to print.

My $.02! Cheers,

E. von Hoegh · Mar 24, 2018

What Mr. Brown said.
I've been using an optical grain focusser, Gralab timer for film, and a Time O Lite on the enlarger without change since the mid 80s. They're simple, reliable, and do the job. That's very important.
I cannot imagine mucking around with a camera as a focussing aid when a Magnasite optical focusser takes literally two seconds.

Mrtony4x5 · Mar 24, 2018

E. von Hoegh · Mar 24, 2018

jim10219 · Mar 24, 2018

I would rather use my naked eyes. Seriously. I only use a grain focuser to check my focus after I’ve set it with my eyes. 9 times out of 10, I nailed it without the need for any focusing aids. If you know how to focus a manual camera without a rangefinder or split prism, it’s not too hard.

Still, for the price of a used grain focuser, there’s no reason not to get one. I rarely need it, but I still use it every time just to make sure.

photog_ed · Mar 24, 2018

E. von Hoegh said:
What Mr. Brown said.
I've been using an optical grain focusser, Gralab timer for film, and a Time O Lite on the enlarger without change since the mid 80s. They're simple, reliable, and do the job. That's very important.
I cannot imagine mucking around with a camera as a focussing aid when a Magnasite optical focusser takes literally two seconds.

Ditto, but since the 60s. I am not opposed to using digital tools, but this seems like more trouble than the traditional way.

Old-N-Feeble · Mar 24, 2018

I was thinking of something similar to focus and align mural-sized enlargements... a camera aimed near each corner plus one aimed at the middle.

paul ron · Mar 24, 2018

adapting a camera to a regular grain focuser (like a microscope to camera adapter) is a great idea! i can see it on a tablet as I focus the enlarger. i wear glasses when i take my contacts out to do darkroom work. so besides having to bend slightly plus the exit pupil of tge focuser being so small... i hate using it anymore unless im wearing contacts... then the problem becomes dry eye by 3am.

but to see the grain on my tablet would be a blessing.

edit: using a microscope adapter also takes the calibration focusing out of the loop since all you need to focus on is that thin line, the thread in the grain focuser. simple!

M Carter · Mar 27, 2018

I've thought about this for very large prints - it would be nice to see the focus while up near the focusing knob. I've thought of aiming a DSLR at the baseboard and using an HDMI monitor (my day gig is digital video, I've got tons of that stuff) but I think with the dim-ness of the image, digital noise would far overtake the image clarity, unless maybe one of the new high-iso Sony cams were used.

ic-racer · Mar 27, 2018

Sure it will work but the sensor has to be at the same plane as the paper and no lens on the digicam, of course.

DREW WILEY · Mar 28, 2018

Easel grain magnifiers can differ in quality. I've seen cheap ones with cardboard shims on the base which inevitably swelled or shrunk with humidity variations, changing the plane of focus. I use the Peak Critical model with a tilting head which allows you to check precise focus in the corners of the image and not just near the center. Not cheap, but well worth the extra cost. But I also keep a strong pair of good reading glasses nearby, to quickly achieve general focus.

DREW WILEY · Mar 28, 2018

M Carter - for focus on very large prints at a distance, I bought a special scope from Edmund Optics and mounted it on the big enlarger. It was around a hundred bucks back then. Can't remember the model no. offhand.

Old-N-Feeble · Mar 28, 2018

Drew, are the magnification and sharpness of that scope sufficient to clearly see the grain of 4x5 Tmx 100 on mural-sized prints? It focuses to just a few feet?

DREW WILEY · Mar 30, 2018

That kind of application would be easy.

Digital camera focus peaking as grain focuser?

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