infinity mark is off
I've notice that my EX lens (when I have it slipped into manual mode) seems to roll right through the real infinity focus point well before I reach the end of the focus barrel travel or even the infinity mark on the barrel.
Anyone else have the same experience? Is it normal. It would be a big problem except the color peaking is so good i can clearly see where I need to be. |
It's normal. The mechanical stop goes beyond infinity to allow for temperature changes in the environment...the focus shifts when the temperature changes.
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Sounds like a backfocus issue.
Though I don't have too much faith in those lens markings - they seem like an approximation to me. Otherwise they'd be more committal and have withness marks like a Panavision lens rather than nebulous numerals. |
Bill is correct. All true pro lenses go through infinity to allow for temperature changes and the use of adapter lenses. It is not a fault.
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Thanks, that's what was wondering.
I'm used to it a teeny bit but this seems more noticeable though. No back focus problem though as far as i have seen. |
Quote:
Leonard, Bill and Alister are correct that all pro lenses, including still camera lenses go a bit past infinity to allow for any slight mechanical variations - however the problem you descibe is that the lens is focused at infinity before reaching the mark - not that the lens can go past the mark. So that's why I think it's a (slight) backfocus issue. |
Well I've discovered what my problem is . My backfocus and my infinity mark are exactly where I would expect with no filter in plsce. As soon as I roll in an ND filter my back focus completely goes to hell and my infinity focus rolls in around 30'. Very very bad news. I don't think the back focus adjustment would fix it because its OK without filter.
. Didn't notice the back focus problem till I looked on a big monitor. Beware out there. It goes back to Sony on monday. Perhaps there is a software fix for this. Also I've discovered lots of CA when I am fully zoomed in. very distressing. Lenny |
Perhaps somebody could try doing the backfocus calibration procedure for each of the ND filter settings. It's possible the camera stores a different set of values for each position of the ND filter wheel.
I'd try this myself but I suspect I don't have enough light to light up a back focus chart with the NDs engaged. |
Bob,
You could use the back focus chart outdoors. Its pretty sunny today! |
Both of my EX1s are going back to UK with backfocus and slight vignetting problems.
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