- Created on Monday, 10 September 2007 04:17
- Last Updated on Friday, 14 December 2012 20:15
- Written by Administrator
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Now you can move onto the next step: Do your camera test inside with 100% controlled lighting (exteriors are nice, but clouds can mess you up), on a super steady tripod with the viewfinder closed off after you set it up (you don't want to be touching the camera when you are rolling film), against an immovable background, preferably a wall (chalkboards work great, btw!). You may want to get a chart with lines on it, possibly an Air Force lens chart or something like this chart will work, and film it all in a big room if possible. The bigger the room the better, because you'll need a big room for your longer lenses.
If you want to make your own chart, there are many different preferred designs - HW Stone supplied the following info:
Cheap way to get a large copy--
Have your local blueprint service print you a standard test grid. Black on white works, too, although white on black is easier for most people to work with. If it only needs to be small (twice the size of a sheet of typewriter paper) you can spray paint a sheet of glass with flat black paint, and after it has dried scribe the lines in the paint using an architect's T-square. Put the glass in front of a light, painted side toward the light, and use it.
You're after a rock-steady shot, so make sure that before you turn the camera on, you are on a concrete floor or equivalent - some wooden floors have bounce and someone walking on that floor, even in the next room, may affect the steadiness of your shot!
Okay, now you'll need a few hundred feet of film loaded in your mag. I would prefer using reversal film, for projecting later (for the steadiness factor). Make sure the takeup loop is not too tight.
Setup the camera on a solid tripod in front of a chalkboard or wall. Draw a "t" in the center of the chalkboard or paper. This is to line up your "crosshairs" in the viewfinder. Draw a rectangular area around the edge of the viewfinder's edgeline also. If you're on a wall, tape a big sheet of paper up and draw the lines that way. Test the drawn lines with a second lens to make sure everything is correct.
Break out TWO lights and set them up 2 meters from the chalkboard and 3 meters apart. Center them so they both shine on the "t". Get your light reading with your lightmeter directly on the "t" - be sure not to block the light in any way. You should have a decent light meter - if not, borrow one.
Get a pad of paper and a pencil. Also, you will need a friend to help out. Make sure you write down all of the exposures so you don't forget.
Now, you're ready to put on each lens and test - make sure you're testing in a very large room with all windows blocked off - and NOT OUTSIDE, since the Sun moves around and the clouds may come overhead and change your test results.
The tests go as follows:
1) Set your lens to the recommended exposure for your lighting and film.
2) Set the viewfinder to "0". If you have 20/20 vision - excellent. If not, then put in your contacts, get laser eye surgery, or figure something else out.
3) Put on your first lens. Measure your distance from the chalkboard to the film plane (where the film inside the camera gate is exposed). Do NOT measure to the front of the lens!
4) Focus in on the "t" and look at the focal distance on the side of the lens. It should be close to your tape measure's readings. If not, grab a second lens and try it again. If that one is not, then grab a third lens. If all three are wrong, then you may have a bad viewfinder or the lens mount could be on wrong (or if you are over 40, bad eyesight - go get your eyes checked at the local glasses shop and make sure your eyes are good!).
5) If you're close to the correct focal distance, then get the box squared up, keep the "t" centered. Remove your eye from the viewfinder and close it off so that no light can go through the viewfinder. This is because you can shake the camera with your breathing and/or heartbeat. Shoot 7-10 seconds of film - enough to bring the camera up to speed for at least a few seconds. You're also checking to make sure the camera picture is stable.
6) Now, set the lens to -1 exposure, run for 7-10 seconds (let the camera get to speed), then -2 exposure, run for 7-10, +1 exposure, run, then +2 exposure and run. The entire time you're writing this down on the paper - and keeping notes for when you'll be watching the film at the lab.
7) Now that you've run enough film thru - change the lens, get this one centered in the rectangle and centered on the "t".
8) Repeat steps 1-7 until you've tested all of your lenses.
--Update: To make sure your lens focus is initially close, without shooting film, you may want to look at this Konvas.org Quick Lens Focus Check How-to
Take the film to a decent lab, and explain that you are doing camera tests. Have them process it (and if it is a negative, transfer it to a positive print). Watch it on their projector to make sure there are no problems. You'll want to view the positive print over the negative, since you'll want to look at your lighting and make sure the exposure is correct on every shot.
* Bad viewfinder
* Takeup loop too tight in Konvas Magazine causing streaks (I'm not sure how Kinor's load)
* Make sure you are running the film thru at the correct speed
* Broken aperture
* badly scratched lens
* magazine too tight
HW Stone also adds this in another post:
[Focusing the viewfinder on the Ground Glass] is how you make sure the problem is not the lens or the lens mount.
If the ground glass is in focus at 0.0 but the lenses are not, then either the lenses are off or the lens mount is off. I have shipped lenses to be serviced and had them all come back "off" by exactly the same amount because a tech set them as if it was PL mount, and I have had two cameras that not only had the lens mount itself off distance, but one was upside down.
-3.0 is frequently seen when the ground glass is in backwards, so check that first.
Why the ground glass would be in backwards baffles me, but it happens frequently unless you have a ground glass in a holder that will only go into the camera one way.
If it is correct then there are two pathways from here on in. Set the finder to focus perfectly on the ground glass grain, and shoot a test to check actual focus with a short piece of film with twenty to thirty seconds at infinity, then another twenty to thirty seconds at five or six feet, then the final twenty to thirty seconds as close as the lens will allow you to focus.
If that comes out okay, the problem is inside the finder.
The next test is to try a different viewfinder on your body-- if it focuses, then you need to check actual focus with a short piece of film with the same twenty to thirty seconds at infinity, then twenty to thirty seconds at five or six feet, then the last twenty to thirty seconds as close as the lens will allow you to focus.
Because of the way the finders for the Konvas are made it is cheaper and easier to swap finders than to try and fix yours.
Want to do more registration tests to make sure your camera is rock-solid? Then read the How-to: How do I test the registration? (this would be more for compositors and such)