Seven lenses checked out at camera repair shop

[jloen]

I had accumulated quite a few modern large format lenses over the last 6 months or so, from local sales and the web auction place. These ranged from 65mm to 210 mm, made by Fuji, Rodenstock, Nikon, and Caltar. They seemed to be in nice shape but I was uncertain about the precision of the shutter timing, so I took them to a camera repair shop for testing.

The story was the same on each lens!! All seven! : Fast times were overexposed. Biggest problems were with 125 to 500, which were slow by 100% or more. Shop owner said that the mainsprings weaken with age and need to be replaced (if they are still available; many are not). Obviously this is a chronic problem even with lenses made since the 1970's. Somehow I had expected them to be a bit better than this....

Slow times (1 sec to 1/60) were good to exact.

The shop kindly charted out the times for each lens, and offered to repair lenses that they could get parts for. Rather than opting for major surgery I simply made tiny P-type labels and stuck them over the old numbers on the lenses.
The tests cost me $160 for 7 lenses (which cost me about $1500 total).
Now I know what I have here.

They also tested my Pentax and Soligor spot meters, which each were one stop off, but were easily recalibrated for $10 or so each.

So if you have any question about your gear, you can get accurate answers fairly cheaply. If you are like me, your gear is not as good as you think it is.

[Sideshow Bob]

I don't think I have ever exposed a sheet of film at a shutter speed faster than 1/60 of a second so I wouldn't worry about it (YMMV).

Gale

[eddie]

jloen,

what kind of shutters were they? i have a shutter tester and most all my copal shutters run almost right on. some of the older shutters are slow just like you suggested. the 1/10 seems to be right on on most every old shutter i have tested....most

I don't think I have ever exposed a sheet of film at a shutter speed faster than 1/60 of a second so I wouldn't worry about it (YMMV).

Gale

i shoot many fast lenses wide open...even the not so fast ones i shoot wide open. i wish that some of the bigger ones did 1/500....most are only 1/50 and they are several stops slower than i would have liked. but i can get some good speed out of the little copal 0....now if i could just get some f3 lenses in a fast shutter....

eddie

[Struan Gray]

At working apertures fast times should be overexposed - it's an unavoidable consequence of the way leaf shutters work. 100% at f22 is about right.

The marked shutter speed is an effective speed at full aperture. Because the shutter blades take some time to open and close, at the fastest speed the aperture is only fully open in the middle of the exposure, the rest of the time it is partially obscured by the shutter blades. The marked speed is the equivalent speed that would give you the relevant exposure if the shutter blades could move infinitely fast. At smaller apertures the shutter blades clear the opening much more quickly, and so overexposure results.

If you use leaf shutter lenses at high speeds often you either need to make a table for your usual apertures, or do the math in your head at exposure time.

[GPS]

Struan, although I agree with you about the small apertures overexposure, the OP did not state that the repair shop checked the shutters using these small apertures. I suppose that being professionals, they know how to check lenses... Unless they know how to incline amateurs to give them shutters for a repair...;-)

[BarryS]

"Obviously this is a chronic problem even with lenses made since the 1970's. Somehow I had expected them to be a bit better than this...."

Not obvious at all--It may be a chronic problem is with your shop. I have a shutter tester and a good number of lenses of varying ages and consistently find better accuracy than you describe (in Copal shutters). The very top speeds tend to run a little slow, but more like 1/500 is actually 1/400. The diagnosis of seven mainspring replacements sounds misguided--I don't believe it.

[Sevo]

The notion that "mainsprings weaken with age" is widespread, but entirely wrong. Springs do not weaken unless overloaded, which they'll never be in such a contained, sparingly used low-power device as a shutter, unless some previous owner once forced the shutter when stuck.

Sevo

[ic-racer]

I used to futz with my escapements, but now that I have over 25 shutters, I just make a note of any speeds that are fast (B&W Negative film user only).

[jloen]

Thanks for the interesting comments. I should have said these were Copal (five 0, and one 1) shutters, and one Seiko (on the Fuji 65 mm).
The 1/500 generally rated 1/200-1/300. The work was done at a camera repair shop near Seattle, recommended to me by a professional photographer.
Personally I rarely shoot faster speeds than 1/60 and more often 1/2 to 1 sec in the murky northwest woods.

[Sevo]

The 1/500 generally rated 1/200-1/300.

That is what I'd expect even for a perfect shutter, if you meter time rather than light flow. Shutters are supposed to be calibrated so that they perform a exposition equivalent to their nominal value. At their shortest setting the total runtime and fully-open time diverge quite significantly from the nominal value, to either side respectively (for 1/500, expect e.g. 1/250 total and 1/1000 fully open).

Shutter time testers cannot properly test for that peculiarity unless you do multiple measurements with a laser spot across the shutter radius and calculate the real speed from that and the shutter's mechanical specs - metering continuous light shots with a flashmeter and TTL probe is the only easy way short of test exposures which will get you a direct test.

Sevo