Spotmatic TTL Light Meters

I haven't managed to find the Spotmatic F of my dreams yet - to join my SP and SPII bodies. In reading whatever info I've been able to find on "F"s (and there's TONS!) it is clear that the TTL CDS meter is always ON, and battery drain is controlled by the lens cap ie: no light - no drain.

Is this also true for the other Spotmatic cameras ie: could the switch be left on with the lens cap in place with zero drain? (Replacement batteries are dear, I'm too cheap to try this for myself, and wondered if anyone knew the answer from past experience).

Thank's as always:

Hi Mac,
If you leave the normal Spots on, you will drain the battery regardless of the lens cap and they are quite small. The cheapest replacement is to use small Silver Oxides. I am not sure of the number but it is in the archives here or I will look it up when I get home. They should be less than a $.

As to the SPF, the meter cells are switched off with the cap in place but there is still a very small drain to the switch circuit. In time this wil also flatten the battery which is why you shouldn't leave a battery in if you do not intend to use the camera for a protracted period. It is also why Pentax changed the battery fron the small 400 to the much larger 625.

Regards
Kim

Kim,

That answers a couple of other questions I had re: why the battery changed, and why minty F's often have such scarred-up battery covers.

All in all, because us Spotmatic nuts automatically push that DOF/StopDown/Meter switch up anyway during composition (I usually leave it up while firing anyway), do you think Pentax's "Always On" meter in the "F" was a good idea?

My eyesight sucks except in hindsight.

Cheers

Hi Mac,
Two things. If you stopdown/meter lever stays up when you fire the shutter, the camera needs a service. It should reset when the shutter is released and is one of the first indications that the camera's lube is beginning to gum up.

As to the SPF, it may not be ideal but if you had to use the stop down lever to activate the meter, you would have ful aperture metering. Fuji went down a slightly different road. The meter was activated on a first push of the shutter release. This is one of the reasons I like the 801 body. Unfortunately, you have to keep the button pressed while metering and I can only use Super Taks with it rather than the SMC ones because the pin gets jammed. Pentax kaeep this meter switch on the K1000/KM but for the KX went for a shutter push. If the film wind is in the stand off position a half press will activate the meter and it will stay on until the wind is parked. This is probably the best compromise and why I would advise a KX over the other 2.

As to the SPF battery cover, I rather suspect that the reason many are chewed is not that people took the battery out a lot but rather they didn't and the mercury cells leaked a little as they are prone to do. As a result, the covers needed forcing to remove them. (This is the main reason I don't use wein cells which are even worse as well as costing far too much!)

Kim

I agree that my SPII needs Eric Hendrickson - badly. We're arranging a little trip to Tennessee son.
I'll go back to your site to get info on batteries - I'm using Wein's now but if they go and leak - shriek!

Betcha didn't think you'd be tutoring me THIS much did ya?

All the Best

Hi Mac,
No problem, glad to be of help. There was a thread discussing this problem earlier in the year ( https://www.pentaxuser.com/forum/viewtopic.php?t=1448 ) If you have a look at this you can see my views on it as well as some of the other menbers. It also has the battery numbers and some links to sites with more info.

If we generate a bit more traffic, we might even get a dedicated M42 Forum!!

Kim

Kim,
In the thread to which you refer, you said that you could get silver cells for 60p. You also posted a link to a site which sells these cells, but the price they charge is £5.50. How do you get them for 60p?

Regards

G

Kim,

No need to reply. I have just bought 10 on Ebay for £2.50, inc postage.

Lets's hope they work.

George

Hi George,
The batteries I use are the 394/SR936 silver cells. These can be used with or without a collar in the Spots. If you hunt around, you can typically get these for about 60p at best and most places sell them (including 7DayShop) for about £1 or slightly less. The small battery company charge a relatively high price because the post charge is included regardless of how many you order. I don't use the S400 because as you point out they are typically £5. The S400 come with a collar but in reality are nothing more than 394 with collar. So in that thread I posted that link to show where to get an S400 if you wanted to geta collar to reuse.

Kim

Thanks Kim.

G

Hi George,
If you need a collar, I should be able to find a spare. Drop me a PM if you do.

Kim

Kim,

Many thanks for the offer. I'll evaluate the situation when the batteries arrive.

G

Thank's for all this - and the link! Wow.

George, could you post your thoughts when you have tried out the silver's?

Best of luck with them.

Hi George,
Having done a search on eBay, I rather suspect you have bought a set of AG9 Alkaline batteries. Most of the batteries on eBay are the alkaline equivalent of Silvers and are imported from the Far East. Normally these are not very suitable for cameras and certainly not for watches for 3 reasons (despite what they say on the Bay)

1. Voltage. Alkaline have an unstable discharge line. They start at about 1.5v but drop to about 1.25 volts before they are exhausted. This is not very important in the Spots because of the bridged circuit but critical in most other non Pentax cameras.

2. Capacity. A good alkaline cell only has about 1/2 the capacity of a good silver cell such as Rayovac and the imports from the Far East about a 1/3. Not too much of a problem if they are cheap but remember to carry a spare.

3. Leakage. Alkaline are more prone to leak and vent gas especially if they get warm and are near the end of the discharge. http://www.qualitybatteries.co.uk/Unsuitable.html Again not too much of a problem if you are aware. I would check the battery on a regular basis and discard it when it gets down to 1.3-1.35v. Also don't leave the camera in a warm place and don't leave the battery in when the camera is out of use for some time ( As if you would )

On the other hand, despite the voltage problem, they are still better than Wein's. 10 batts for less than half the cost. Time wise under a light drain, they will last longer and despite the warning above are less likely to leak.

Kim

You're absolutely right, Kim, and thanks for the warnings. I've now looked up silver oxide batteries, and have seen some at 99p each, plus postage.

However, I'm just playing around with an old Spottie, so the AG9s should be fine. My first proper camera was an SPII, bought for a month's pay in 1973. I got the present one on Ebay for next to nothing just out of nostalgia. It'll be interesting to see how it performs.

G