Blurred images unless stopped 90+with AP Ronar 480 on10x8greenspun.com : LUSENET : Large format photography : One Thread
Kind troubleshooters>>I have to stopdown my Rodenstock APo Ronar 480 totally in order to get any clear image. However this is so dim that its very difficult to see anything at all!! Is there something wrong with the lens ? (Ive just bought it second hand). I can't see any
focussing knob on the lens.
Everything I read regarding focussing seems so fine tuned (tilting etc) that Im thinking the problem is either me or the lens/shutter mounting (copal 3).
Am I being stupid or are you able to see clear images on the ground glass screen at f32 or less?
P.s. my camera is an old Eastman 2D 10x8. Also I have two lens boards stuck togeather.. as the hole diameter is right in one, whilst the square's size is right on the other. I dont think this makes any difference since it does not appear to effect the distance between the lenses.
-- kevin long (email@example.com), February 17, 2001
Hi Kevin, You may have any number of problems affecting your focus. First of all, the 480mm Ronar is a 19 inch lens. How long is your bellows draw? If you have an older Kodak D2, the bellows might have been replaced. If you are just a tad on the short side of 19 inches, this might well be what is happening to you. Wide open focusing will be blurred, yet close enough to your focal length to render an image at a smaller f-stop like f32 and beyond. I have an APO 480 f9 also, in barrel. I have no problem with focusing at f9. There are some of the best lens experts in this forum, I am sure one of them will detail your problem better than I. So Kevin, first check your bellows draw. Hope I helped a little, Dan.
-- Dan Kowalsky (firstname.lastname@example.org), February 17, 2001.
Do you have enough bellows extension? 480mm is around 19 inches--if your camera's bellows extend only to, say, 16 inches, then you won't be able to focus the lens.---Ca
-- Carl Weese (email@example.com), February 17, 2001.
I tried a 450mm Artar on my 8X10 2D the other days. Not enough bellows to focus at infinity, unless I installed the extra rear focusing track, and ran the rear standard back onto it. Do you have one of these? If not, you should probably start looking for one. You can possibly make an extension lens board to stick you lens far enough forward to get infinity focus. However, you need to extend it quite a little bit, and the weight of the lens that far out becomes a problem unless you can brace it back to the bed somehow. Finally, if you have a lens you suspect isn't focusing because you don't have enough bellows, just watch the focusing screen and hold the lens out in front of the camera. Drape a black cloth over the top of the front standard and hold it around the lens. Move the lens back and forth until you get a sharp image. This gives you an idea how much more extension you will need. If the lens focal length is longer than your arm, have another person do the holding for you.
-- Leonard Robertson (firstname.lastname@example.org), February 17, 2001.
I totally agree with everyone else. I own a 480 mm lens, plus 600 mm and 800 mm. I had to get rid of the bed camera when I became interested in these longer lenses becasue as you know, the focus at infinity at the lens draw in inches. So for example, the 19 inch lens focus is infinity when at 19 inches and for anyting closer the bellows draw must be even longer. I ended up getting a Sinar F with enough bellows to handle 30 inches. Good luck. Kevin
-- Kevin Kolosky (email@example.com), February 17, 2001.
A big thanks to all of you !!
I have tried Leonards suggestion of holding out the lens a few inches more than what my bellows can extend (@17") and I got a clear image at f 22 - a hundred-fold improvement. I have taken a sturdy cardbboard box and made an extention to the lens board (adding 2 inches) which brings the total extention to about 19 inches, enough to focus at f9 / infinity. Not sure about light leaks until I develop a photo ..but by eye,I cant see any. I have removed the catch at the back of the rail so now i can get another 1/2 inch...I'll try using a little clamp to see if i can extend beyong the rail and keep some rigidity. Despite these temporary efforts I guess I'll have to start looking for a back extention. Thanks once again for your help !! :o)
-- kevin long (firstname.lastname@example.org), February 19, 2001.