View Full Version : Where to find a focusing aid!
Douglas P. Theall
Thanks to all the knowledgible responses to my previous messages. This is by fa r the best resource I've come across in a long time. My question since I just g ot my 4x5 in the mail yesterday is where do you find a focusing aid. I have a g rain focuser in the darkroom but I need a tube type focuser for the 4x5. I woul d think most of you have one you use, would you mind some info on what and where ? Thanks again for all the great info I knew will be coming. I'll try and repay it in the future when I can. Doug
Any dealer who has large format will have these.
On the net, Calumet, Adorama, B&H.
I got my first ones at my college bookstore ages ago. I got a 10x magnifier and a 3x. You can just use a decent magnifying glass, though these are hard to get today. Most are plastic & not very good.
Doug, Something to consider when purchasing a loupe is its enlarging power. If the loupe has a high magnification it will begin to focus on the grain of the ground glass and will interfere with the focusing the image.
I use a cheap 7x horseman and it does the trick.
Check out Calumet and get there catalogue if you haven't done so already. Its great for looking at different products. Their website is www.calumetphoto.com.
Magnifiers are really only color-corrected diopters. You may want to try a cheap pair of +2 or +3 diopter reading glasses first to see if you really want more magnification.
John H. Henderson
In similar questions asked here in the past, other posters recommended the Toyo 3.6x loupe, so I just got mine, and love it. It is probably the least expensive loupe intended for ground glass focussing at about $40, and as the others have said already, the 3.6 magnification is all you really need - any greater and you just magnifying the grain structure.
I've put off getting a loupe and darkcloth for a year - trying to pare back my initial investment and see how I like LF, but am regretting not getting them earlier. Also based on recommendations here, I ordered the BTZS dark cloth. It should arrive today. Hmm...lessee [click, click]...yep...arrived in Melbourne at 3:57AM. Using your jacket doesn't work here in Florida because you're rarely wearing one!
Doug: My favorite loupe is one I made from a cheap 50mm enlarging lens I had in my junk box. I cut a piece of PVC pipe that the lens would fit into with a little sanding of the inside and then adjusted the piece of pipe to length. It is sharp and I get no color fringing. Works great and the cost was nil. Avoid the temptation to get one with too much magnification. That is worse than none at all. Also, I often use a pair of +4 diopter reading glasses I bought at a discount store. The cost was $5 and the glasses work great. You have to get your head pretty close to the ground glass. Glad to have you on the forum and good luck with your journey into LF.
For several years I have been using the strongest reading glasses I can find and stand. Bought one of those little cords that let you just hang them around your neck. I won't go back to a loupe for routine use because the reading glasses leave both hands free. Nothing like trying to focus in a strong wind...one hand tokeep the dark cloth out of your face, one hand to hold the loupe, one hand to turn the focus knob....you get the picture.
I like the Toyo loupe mentioned above by Mr. Henderson. Do avoid over magnifying the image on the ground glass. Worse than no loupe at all.
I beg to differ with almost all the replies to this question. I use a relatively inexpensive but quite sharp 8x loupe--perhaps forty or fifty dollars-- marketed under the Nikon name. You learn to focus on the image, which is easier if you invert the loupe so it is not resting on the ground glass and you can move it as close or as far as necessary for good focus with your particular vision characteristics. I find when using wide angle lenses, 90mm, or even normal length lenses, 150mm, that the high magnification does reveal slight focussing errors and make it easy to find the exact point of focus, which is not easily found with lesser magnification. You also have to know where to look on the ground glass to focus: You essentially want to focus through the centre of the image circle, but the centre of the image circle can be significantly displaced depending on your lens focal lenth and camera movement. Typically when photographing architecture with a 90mm lens and employing a significant amount of front rise you would focus near the top of the vertically framed image on your groundglass. Focussing in the centre or at the bottom will not give an accurate result. Another situation where a high powered loupe is invaluable is when using wide angle lenses to focus on objects that are receded from a distance close to the camera. You should carry good depth of field tables, consult them, measure or estimate distances very carefully, and then use that high powered loupe to focus exactly on the correct point in your image necessary to achieve over all depth of field. In this situation again you want to be focussing through the centre of the image circle, wherever that happens to be. Sometimes that means undoing your movements temporarily to be able to focus easily through the image circle centre.
David, how do you undo the movements without changing the point of focus?
To Steve's question: When I say I sometimes have to "undo" movements temporarily to be able to focus through the centre of the image circle, I mean lowering a rise or raising a fall or reversing a shift, in other words, undoing temporarily movements that in cases where such action does not alter the plane of focus. Obviously this won't work with a tilt or swing. The point I was trying to make, perhaps poorly, is that it is not always abvious where one should look to adjust focus, and I have found that the best focus is almost always obtained by magnifying the image at the centre of the image circle no matter where that falls on your fresnel screen after displacements are made.
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