richard van hoesel

Hi John, yes I went through this episode a while ago too. From memory, the better batteries claim to give you something like 150mAH. I've measured the drain on the batteries when holding the mirror up & shutter open on one 6x7 body (not the p67 II) and found it was somewhere around 25mA (if I remember right most of that goes towards holding the mirror up). In other words, a single battery SHOULD be enough to give you about 5-6 hours of mirror-up ( /shutter open ) time. If you were to average even something like 15 sec per shot of mirror up time, you'd think you ought to get at at least 100 rolls.

 

However, I've found pretty variable results myself - but then I do use the TTL prism a lot and although it uses quite a bit less power (about 7mA comes to mind) than holding the mirror up, it's often on for 30sec at a time) and I also do a lot of 1 to 10 min exposures, so I usually don't complain if I get only a dozen rolls out of a battery. Maybe part of the variation is the specific battery type, so trying some others is probably worthwhile for you. How fresh the batteries are when yo buy them will also influnce the battery life. The lithiums will operate just fine too btw, no need to stick with the silver. Another thing to remember is that the battery indicator light is not a good way to determine whether the battery has had it - I've often shot quite a few rolls well past the point where the light stopped coming on.

 

Although you can make up a plate to use a standard release chord to hold the 'emergency shutter release button' to take very long exposures without batteries or use the battery extension accessory, I wouldn't bother unless you're doing really long exposures - probably easier to just find a good deal on batteries unless you're living somewhere remote like Tasmania ;)

I forgot to add that you might need to have your TTL meter calibraterd to get its simple sensor bahaving more or less linearly - if I remember right there are about 3 or 4 trim-pots in it that cover the available metering range. I found that when I first got my (used) prism, the difference for metering stopped down was at least a stop out compared to what you would expect from the wide open meter readings.

One situation in which you will not be able to meter with the TTL is in very low light. Even opened up all the way, the 4 second limit (with your shutter-speed dial on X) sometimes doesn't get me there with slow film I tend to use, but then again I often can't see the needle by then and have to guess anyway :) In general though, I think you can get to know these meters in a reasonable amount of time.

Brian, thanks for the explanation. I wonder however if one side effect of this rather heavy skewing of the number of ratings towards even less images might be yet another unreconcilable change as far as comparing ratings for previous posts with future posts? Maybe it's a wrong impression but from casual observation of today's top images there seemed to be a curious effect of migrating many of the VERY-frequently-rated images we're seeing with this system towards rather similar scores. If that is the effect we'll be seeing, it's surely not helpful? (yes I know seasoned patrons already warn that the ratings are meaningless but that message shouldn't be broadcast on your 'top images' pages if you want to attract subscribers and participants). Also, while of course subsribers should have certain priveleges over non-subscribers, I'm a bit doubtful that handicapping high quality submissions from non-subscribers is going to get you more subscribers - possibly less in fact because the overall standards in the most visible pages will probably fall. I wonder weather there aren't better ways to encourage subscriptions such as for example a more restrictive number of allowed submissions for non-subscribers (say just 25 images).

 

Anyway, those are clearly far more words that as a non-subscriber I'm presently entitled too :) No doubt you've been through all this many times before and thought long and hard about your decisions and I certainy appreciate the hard work that goes into keeping the site running as smoothly as it does.

 

best regards, Richard.

 

ps. on a different note, is there a thread somewhere explaining why the notion of including compulsory comments for very high or low ratings was eliminated - I thought the idea seemed quite helpful?

Having only really participated in the critique form since early this

year, I was wondering why there seem to be so many more ratings for

recent posts (although unfortunately not a proportional increase in

comments). Seems particularly evident on the on the 'top images'. Is

this a seasonal effect, i.e. are we seeing 'holiday raters'? Just

curious... thanks.

I agree the prism foam is likely to be the problem. I experienced exactly the same when I bought my used p6x7. I replaced the prism foam with the proper pentax replacement gaskets (less than $10.- for the front/back pair) and never had the trouble again. There shouldn't be any foam on the body itself (under the prism).

My recent intermittent metering problem was related to the prism not sitting quite flush with the body. It went away when I replaced the foam under the prism (the replacement 'gaskets' are only a few dollars each and should be available form you local pentax spare parts supplier). Might be worth a try if your foam is worn down.

thanks Allan, I actually played around with placing an extra strip of self-adhesive foam on the body under the front of the prism last night (taking care not to obscure the aperture link gap). The seems to have done the trick as far as stability goes - it forces the back of the prism to push down a little harder on the electrical contacts so it doesn't rock anymore. It still sits pretty level with the camera base as far as I can tell so I'm hoping I haven't changed the view through the finder by doing this, but time will tell. I guess this may indicate that the foam on the prism may have flattened out over time and needs replacing after all even though it looked in ok condition.

Having recently purchased my first pentax 6x7 MLU with a ttl prism

(both quite old but in well looked after condition) I have found that

the prsim actually seems to fit quite loosely on the body even though

there are no real signs of wear on the retaining clips. This seems to

cause power to the metering system to be very intermittent because

the spring loaded electrical contact pins at the back of the prism

loose connection with the body so easily (eg. tilting the camera

forward at say 45 degrees is enough to break the contact). This is

particularly bad when doing verticals and I find myself having to

press down on the prism to ensure getting meter readings (where's

that third hand when you need it). I'm a little surprised since I

haven't seen comments about this in the archives. Everything looks

straight and shows few signs of wear and as far as I can see the foam

under the prism looks ok. I'm looking for feedback on other users'

experiences regarding this - is it common to see this rather loose

fit between the two? Is there a fix? Is it also another reason for

dumping a beanbag on top of the prism (for horizontals at least) to

reduce image blur due to additional vibrations?