Hot answers tagged front-focus
Moire Fringe Method Use Bart van der Wolf's moire fringe method (also explained here and here, and archived here): It works by exploiting the interference patterns or moiré between the R/G/B LCD elements and the camera's LCD elements when directly viewed with Life View [sic]. With good optics and perfect focus, the moiré is maximized. ...
To check if your camera/lens is having front-focus or back-focus issues you can download a pdf (incl a focus chart) here: http://web.archive.org/web/20121205195820/http://focustestchart.com/focus21.pdf The first few pages describe how AF works and how it can be tested. The actual instructions for testing the AF start at page at page 13.
Front focus is when the lens and camera focus in front of your intended focus point. Your subject will look slightly out of focus and something in front of them will be razor sharp in focus. Back focus is correspondingly when something behind them is in focus, instead of your intended subject. As to why.. it could be mis-aligned, mis-calibrated equipment. ...
Contrast-Detect-vs.-Phase-Detect Adjustment Method I've been a huge fan of the moiré fringe method suggested by @Eruditass. But in playing with it, I discovered that there's an even better way, if your camera supports contrast-detect autofocus in live view mode. This is, in some ways, a combination of "method 1" and "method 2" of the moiré fringe approach, ...
These cameras have microadjustment capability, just not in a user-accessible way. The exact method varies by model. Some have a software feature in an advanced (and secret) "debug" menu — the Pentax K10D, for example, had this. Others have physical adjustment screws or similar (like earlier Canon Rebel models). Or, repair centers may simply use shims. To ...
No. Well, I've never seen it happen. If it does, I would suspect an imminent mechanical failure. What I did see once is front or back focusing change between focus-distances. In that case the lens focuses well at one distance but is off at another. Since I've only see it once, it may a defect rather than tolerance error.
Testing autofocus is hard to get right, so it's a good question. I have used this chart with success: http://pentaxdslrs.blogspot.com/2008/06/part-1-autofocus-adjustment-for-pentax.html (It's a Pentax blog, but the chart and directions are general except for the interactions with the actual camera.) Follow the directions - they're very fiddly, but ...
It can be any number of different things. It all comes down to the tolerences that consumer cameras are built to. Typical suspects would include: Lens Element locations Flange-to-film distance Sensor location Focus sensor It is all about the location of the focal plane as outlined here: What is back-focusing?
I wouldn't panic just yet. As noted in a comment to the other question, I don't think your results are quite final yet. Assuming there is an issue, there's one way: sent them together into Canon for service. They may do this for free (Pentax did with my K10D, before Pentax started including a micro-adjust feature on their cameras), but may charge some (I ...
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