Do you know how to test? camera-test prep By Rozemarijn on 2/9/20, 5:01 PM • 325 views For me, a proper cameratest starts with the mirror and having the camera checked by the rental. Resetting it all and checking for dead pixels. I use the mirror to aligning the sensor to the test chart. Setting the crosshair in the middle of the lens, when you aim for the mirror. Testing the lenses one-by-one. Using the oldskool rule, 50 x the focal length = number of cm from chart to sensor. So a 50mm lens is to be tested at 250cm from the chart. And always checking if the lens reaches infinity. In terms of iris, I will check it wide open, and see what the minimum t-stop must be to get the most out of the lens. Im very curious, how do you start your test, what must-not-be-forgotten and which test chart do you prefer? Im obviously forgetting things, so feel free to add how YOU do a test. Last year at IBC ive seen one of the most fancy charts I’ve ever seen. Loved it. https://pat-acc.fr/spherical-lenses-charts/ E. Roni Beraha On 2/10/20, 12:01 PM For me, the camera test starts with Rental company checking the flange focus and putting all the lenses into the collimator. Of course this is for a feature film. Afterwards, my job becomes very easy. I check the lenses in the closest l distance, 3 meters, 7 meters and infinity. I shoot all the tests. Record all the cards at high speeds. Transfer them. Shoot all nd filters as they may have color casts and it is good to know before hand. Of there is vfx shoot a grid for each lens. Set up the horizontal, vertical bubble. Do all the black balance, black shading if necessary. Check connections with various devices. Color code each camera, each accessory. Check all cables, batteries, connections. Clean, puf, wd40 any parts that needs it. Lastly, I have never witnessed a Focuspuller doing a test from a mirror. Is it possible to send me a photo to show how exactly you set it up? email@example.com Regards.
Kar Wai Ng On 5/12/20, 9:38 PM I have to admit, the idea of using a mirror to me to line up the lens is completely new to me and I have never seen that done, but it does make quite a bit of sense. I just measure the height of the lens, make sure it is level, and raise/lower the chart to match. I don't look at lenses with the 50x focal length rule; that's something I find makes sense if you are shooting film tests and are looking at resolution charts with a loupe on the neg, but in the digital world I find no use for that. I'm checking for flange accuracy at a few common distances: 2', 3', 5', and then I have a second chart on another wall at some convenient distance like 20' that I just pan the camera to, to check for far distance matching. I check for field flatness and if I suspect an element is not centered I will ask to have that lens projected on a projector. Obviously lens coverage issues will be apparent but usually prior to prep I will know ahead of time what lenses/shooting format combinations might have an issue. On long format, which is the majority of what I work on, I will have at least a week or a week and a half of prep, so I will also be shooting VFX grids, rack leaders, and be much more critical with getting all camera bodies' flanges all lined up and matching correctly. If there are any zooms (rarely, but hey it happens) I check for zoom tracking. Anamorphics take longer than sphericals to check out. Usually I can get all the lenses and bodies pretty happy and lined up in the first few days, the rest of the prep is all the electronic bits, brackets, builds, etc. The fun stuff.
Brian Aichlmayr On 3/14/20, 3:11 PM I made this Digital Prep Checklist awhile back for my preps. I have never had the pleasure of putting a lens on a collimator but I've shot a few test grids in my day. Usually don't have the time to finish cause my preps are one day for commercial projects. Feel free to comment and let me know if i should add anything to this list. https://www.dropbox.com/s/aorym2ncgmm2g6n/Digital Prep Checklist.pdf?dl=0
Roeland Bentvelzen On 2/15/20, 10:38 AM A small mirror, 10x10 inch, is places in the middle of a focus chart. Usually a rental has these equipped with magnets to stick em to the chart. If you align your camera like Rozemarijn said, with the middle crosshair in the mirror reflexion of the lens circle, you know that you are aiming 90 degrees on your focus chart. This will give you a best image of how sharp the edges/sides/overall image is/are of each lens. You could spot lens errors or characteristics focus wise this way.