Pentax 645N aperture display

[ath]

Hello,

I have a small problem with my Pentax 645N. While it works flawlessly there is often a discrepancy between the aperture I set at the lens and the aperture displayed in the viewfinder and subsequently imprinted on the negative (which is the annoying part). Usually the displayed value is half a stop less.

Since this happens with four different lenses I assume this part of the body is out of calibration.

Has anybody experienced the same? Had it repaired? Was it expensive?

And, just for curiosity, is the aperture value transferred via the lever or the electrical contacts on the 645(N)?

Thanks,

 

[clogz]

Hello Andreas,
As long as the negatives are OK...why bother?

Hans

 

[ath]

Hello Hans,

because the data imprinting is a useful feature when it imprints the correct data.

 

[winger]

Is it consistently off by the same amount (which would make me think adjustment)? Or is it off by different amounts in different situations? To figure it out without spending $ on sending it somewhere, knowing exactly when it happens would help. Especially if it only happens with a zoom and not with primes.

 

[ath]

Hello Bethe,

I'm talking primes here. Yes, it is more or less consistently off which led me to the calibration assumption.

 

[Phillip P. Dimor]

I recall reading something about this a long while ago.. Are you using original P645 lenses? Something about certain older-style 645 lenses (the 50mm?) on the N bodies where the display gives the wrong aperture and it's off consistently at the maximum aperture. I think it was a design error and is normal. I tried finding a link but didn't have much luck. I do remember it was on photo.net though..

 

[telkwa]

This is a well known problem when using the Pentax 645N with SMC Pentax-A 645 lenses. The aperture will sometimes be 1/2 stop off, but which direction it will show up isn't consistent, and not only that - it can even flicker back and forth in the viewfinder while you look at it. I've never noticed an exposure problem from it though, so I wouldn't worry about it too much. The problem doesn't happen with FA lenses. I own a 645 and 645N.

Sending it in to get 'fixed' won't help. It's kinda funny watching the aperture change between 8 and 9.5 four times a second, but it hasn't bothered me beyond that.

 

[ath]

Thanks, Phillip and telkwa. Seems I have to live with it.

 

[katphood]

Yep. I have a 645N and a 55mm A lens. Mine flickers back and forth sometimes and imprints the wrong aperture setting occasionally, but not consistently up or down. I have noticed that the in-finder display seems consistent with the data imprinting in that if the display is wrong, so is the imprinting.

I tried cleaning the contacts on the lens but it did not help a bit. I think of it as a bug. I just treat the data imprinting as being close, not exact.

It's OK. It's funny how I'm so accustomed to taking the camera from my eye to look at the lens barrel when I adjust the aperture. i do this even on my Nikon bodies that let you look through a small window at the aperture on the lens (can't get that wrong). Here the manufacturer gives me something to make life easier and out of habit, I don't use it.

 

[stradibarrius]

Read Ken Rockwell's review of the 645N. This is a know problem and if I recall it only happens like at f/16 or higher???

 

[katphood]

Read Ken Rockwell's review of the 645N. This is a know problem and if I recall it only happens like at f/16 or higher???

Just used my 645N yesterday. It did the aperture flicker thing at both f8 and f5.6 (55mm A lens).