Good Way to Test Focus and Viewfinder W/O Fancy Equipment?
I received my D800E last week and have not had the time to conduct a meaningful test to see if it has the focusing problem. I understand that the focus problem is best detected with a wide aperture, say 2.8. I will therefore probably test mine with either the 17-35mm or 28-70mm at 2.8. I plan to shoot, as others have, a brick wall. Is there any advantage to using one of the more sophisticated targets that one can download? I have tried (not very hard though) to read a couple of articles describing how to test for focus and they quickly get too technical for me...or perhaps I am just too lazy to make the effort to follow them. So, being a lazy person, I am asking for a lazy man's technique that will determine whether my camera has the problem. I do want to make sure about this so I am willing to expend whatever time and enery is required.
Now for a pretty dumb question. I have been advised that I also need to do a "viewfinder test". I was too embarrassed to ask "what is that", so I am asking my fellow Nikonians "what is that"? I assume that it is to see if the viewfinder is displaying what the sensor is actually capturing. Is that right? If so, I guess one takes a mental picture of what the viewfinder shows, take a photo and see if the photo shows what one remembers was shown by the viewfinder. However, that seems like a very imprecise and unreliable way to do the test. Is there a better way...or am I not understanding what a viewfinder test is. Please save me the embarrassement of telling the well known professional who advised me to conduct the test that I don't know what he is talking about.
I will appreciate any help you are able to provide with regard to these questions.
#1. "RE: Good Way to Test Focus and Viewfinder W/O Fancy Equipment?" | In response to Reply # 0
#2. "RE: Good Way to Test Focus and Viewfinder W/O Fancy Equipment?" | In response to Reply # 0AZBlue Registered since 09th Jun 2012Tue 03-Jul-12 10:42 PM | edited Tue 03-Jul-12 10:44 PM by AZBlue
Do you have an iPad or a flat screen monitor that you can use as a target? If so, I recommend trying the following procedure:
Display the 1000x1000 pixel GIF test pattern on your iPad and mount the iPad to a wall or prop it up on something where you can get it as flat as possible. Zoom in to the target at maximum focal length on your zoom and back at least 50x the focal length of your lens. For instance, a 100mm lens will require you to stand at least 5 meters from the target, or approximately 15 feet.
Focus and shoot the target using live view - this is your reference image, it should be pin sharp and you should see a ringing interference pattern, or moire. This is good and shows you have achieved perfect focus. Now switch to your AF/viewfinder, focus on the same target, and shoot at -5, 0 and +5 fine tune settings. Compare the images using your camera's monitor zoomed at 1:1 ratio. In my case, the +5 was sharper but still needed work. Once I knew in which direction to go, I then focused the remainder of my shots at +10, +15 and +20 fine tune values. In the case of my Sigma 150mm macro, I needed a -15 adjustment.
You can use this same target to test the performance of your left/right AF points. Select the AF point you wish to test, then slide your tripod either left or right until the center of the test pattern is under your selected AF point. This ensures that the camera's sensor plane remains as parallel as possible to your focus target. I realize that sliding your tripod left or right is not the most sophisticated method, but for someone with an iPad and without the ability to print a wall full of test charts, it works in a pinch. Perhaps a better method would be to simply slide the iPad instead of the camera/tripod.
Using this method I was able to fine tune my lenses. I also determined, quite to my dismay, that the D800 body I've had for about a month is not focusing properly at the left-most AF point. I swear it seemed to work fine on normal subjects in real-world shooting, but it simply could not acquire good left-point focus using this test pattern. My 2nd D800 body, received today, has no such issue and seems to perform better in this test scenario. The first D800 body is going back, I'm keeping the new one.
I used this method because it allowed me to quickly compare the image on the camera monitor against a reference image (live view shot) to quickly settle on an AF fine tune amount. No printing required, no taping of targets to the wall, etc. I guess this method is "quick and dirty" but it gets the job done. It also gives you an idea of how well your focus points are performing.
#3. "RE: Good Way to Test Focus and Viewfinder W/O Fancy Equipment?" | In response to Reply # 2
#4. "RE: Good Way to Test Focus and Viewfinder W/O Fancy Equipment?" | In response to Reply # 0
Thanks to both of you for your replies. Preliminary testing with a Nikon 50mm f/1.4 indicates the presence of the left area focus problem. I plan to do more extensive testing today.