International teamwork: Fixing Spotmatics

magkelly · Joined: 06 Jul 2010 Posts: 182

I had problems with this with my SP but I've never had any problems with using non-Weins with my SPII. I use that camera with the Energizer batteries all the time. Maybe a bit overexposed or under sometimes, but not by much. Usually it's just me doing it, not the camera. Nothing I can't attribute to user error and me being new to SLR's. It's nothing a quick trip through Camera Raw can't handle.

My only problem with using them is that no one seems to carry them locally so I have to special order them all the time from Amazon. Queenie, my SPII, seems to do just fine with the bunny batteries though. I like them better than the Wein cells myself. I kind of wish she used the LR44 clones though. They're all over the place, unlike the S387's.

I'd never try something like this. It is just way beyond me, but you guys, I am very impressed. I don't think that it's a problem with every Spottie. But for those who need an adjustment, why not? I say go for it if you can do it.

peterqd · Expire: 2014-01-04

rnbc · Joined: 29 Nov 2010 Posts: 4 Location: Lisboa

peterqd, as you said it's not possible to correctly calibrate the meter for 1.57V before the modification, but the difference at high and medium light levels is so low as to be meaningless. The real problem starts at low light levels, where it becomes oversensitive, and is compounded with the fact that film starts to have reciprocity failure at 1/4s or so... not a good prospect. You end up with underexposed negatives.

I find the meter is a lot more accurate than shutter speeds. BTW, my shutter is correctly calibrated, since you calibrate at 1s, 1/60 and 1/1000, with other speeds supposedly "falling in". Despite that some intermediate low speeds are shorter by almost 1/3 EV, as you can see in the table, and one of the high speeds is a bit lazy. Anyway, by factory specs the meter and shutter only have to match each other better than 1/2 EV over the whole range, so mine is officially approved, so to say Smile

We must not demand to much accuracy from these old beasts Wink

magkelly, the modification is easy, the real problem is disassembling/assembling the camera. Some tools are also not readily available: I used a modified (sharpened) needle-nose pliers and a caliper as tools... but I think if you study the manuals you won't have much trouble. Just don't try it before you understand exactly what you are doing!

Apart from the fact a LR44 has a sloping discharge curve I don't think a SR44 (silver oxide LR44) will fit the Spotmatic's compartment: it's 11.6 x 5.4 mm while the original battery is 9.5 x 3.6 mm (plus plastic gasket, but only around the top, not on the bottom). The closer you can get is, of course, the 387S, but I never saw them for sale over here. Otherwise a SR936 (AG9, Renata 394...) will do, since it's the same battery minus the gasket. To avoid a short circuit, which is what the gasket does, I recommend isolating the interior of the battery compartment (except for the + contact and the metallic lid) with a bit of tape. Also be careful when you start to screw in the lid to avoid short-circuiting the battery: check the battery is leveled, and put the lid leveled from the beginning.

A smaller cell will also work, albeit with some rubber ring to center it, and since the meter uses so little energy will probably last for the same time: cell self-discharge is probably more important than meter drain. For example, the cell I mentioned is 84mAh and will take 4 months to discharge (in the dark) even if you forget to shut down the meter, and 13 days under maximum the maximum consumption I could measure. If you don't forget the meter switched on, it would probably last >10 years, except it will self-discharge before.

magkelly · Joined: 06 Jul 2010 Posts: 182

I use the 387S from Energizer. Fits perfectly, no ring needed, and works just fine. LR44's are too big for Spotmatics.

peterqd · Expire: 2014-01-04

graffixjones · Joined: 14 Feb 2022 Posts: 1

I realize this is necro’ing an old thread, but I wanted to thank you guys if you happen to still be around. I found some Vishay resistors on eBay rated at 442ohm 1/8 watt 1%, and 23.2K 1/4 watt 1%. That was close enough for me. Mounting the resistors was a fun experience, and I ended up using their legs and soldered them in “ugly bug” style, with one bridging across the circuit board, and one branching off the board and then connecting to the red lead for the galvanometer.

I converted two Spotmatic SPs, and while I haven’t ran any film through them since the conversion, they’re responding to light just like they did prior to the conversion. I take that as a good sign. The meter seems to be more sensitive in the lower range, but I’ll know once I get a couple rolls of film through each of them.

I’m just getting back into B&W film after 20 years of shooting digital, so I’m getting all this old gear back into shape. Threads like this have been a godsend, even 10+ years after the last reply was posted.

Thanks again.