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lbenac
6-Jun-2011, 14:15
Hello,

A newbie question. I am just starting LF. One of the lens I purchased (from eBay) seems a little bit slow at 1 second. Now I might be wrong in what I hear. I tried to time it with a chrono but it is difficult to be certain. So I have a few questions for the seasoned veterans around:
1) I do not think that it is easy to check without special equipment?
2) I am wondering if this is even an issue, as a slower 1s might compensate for some form of reciprocity failure
3) Is there a recommended technician to send LF lenses for CLA preferably in Canada?

Thank you very much.

Andrew
6-Jun-2011, 14:48
if you think it's slow, it probably is.... leaf shutters like copal, compur etc etc are prone to problems as they get older due to drying of lubricants and intrusion of dust. The slow speeds are typically the first to go because they run on lower tensions.

maybe half the lenses I've got off ebay have had this type of problem and if I've noticed any hint of a problem it just gets worse so I'd definitely suggest you just get your shutter serviced now.

I'm in Australia so I can't point you to a tech in Canada, but I'm sure someone else will and there's always the option of posting it to one of the bigger names in the US that you've probably spotted already

ic-racer
6-Jun-2011, 14:55
You can check one second with a stop watch. Do it ten times and find the average. You will be very close.

Eric Woodbury
6-Jun-2011, 15:03
The nice thing about it is that at one second, it doesn't matter much. Reciprocity is starting to kick in, so you probably need 2 seconds anyway. I have about a dozen lenses and they range from 0.86 to 1.19 seconds for the 1 second mark. Those are all modern lenses in copal shutters. Their accuracy, or lack thereof, is not reflected in their age. YMMV

Louie Powell
6-Jun-2011, 15:44
The nice thing about it is that at one second, it doesn't matter much. Reciprocity is starting to kick in, so you probably need 2 seconds anyway. I have about a dozen lenses and they range from 0.86 to 1.19 seconds for the 1 second mark. Those are all modern lenses in copal shutters. Their accuracy, or lack thereof, is not reflected in their age. YMMV

To add to Eric's thought - I tend to find myself in one of two situations - either outdoors where the light is such that I need exposures of 1/4 to 1/16 second, or indoors where I need exposures in minutes. Once the exposure goes over 1 second, I rely on the second hand on my watch, and I also factor in reciprocity failure. So a shutter error at 1 second is not the end of the world.

lbenac
6-Jun-2011, 17:04
Thank you all. That confirms my first impression - it does not matter that much anyway at this shutter speed. If I have the chance to find a good repairman in Canada at reasonable price, then I will send the lens. If not I will keep using it that way.

Cheers,

Luc

Jim Jones
6-Jun-2011, 17:10
Most digital clocks tick once a second. It is easy to compare the shutter with these ticks.

engl
6-Jun-2011, 17:32
If you have a microphone for your computer, you can record the sound of the shutter and easily measure speeds slower than 1/10s or so. I use a free program called Audacity, it is available for all operating systems I believe.

lbenac
6-Jun-2011, 19:22
If you have a microphone for your computer, you can record the sound of the shutter and easily measure speeds slower than 1/10s or so. I use a free program called Audacity, it is available for all operating systems I believe.

Thank you very much. This is a great app. I checked the shutter on all my lenses and low and behold this one is right on the money but two of my Nikon are actually shorter 0.9 second. SO my hearing was not wrong I was just comparing to the wrong reference.

Cheers,

Luc

grahamcase
6-Jun-2011, 21:18
Hey Luc,

Horst Wenzel is a good resource for fixing completely mechanical lenses and shutters in Vancouver. VanCam and CamTex are also options in Vancouver as well (I currently have a lens at VanCam).

Luckily, your lenses are pretty good, so you won't need to CLA for a while, probably :)

Cheers!

Arne Croell
6-Jun-2011, 22:00
If you have a microphone for your computer, you can record the sound of the shutter and easily measure speeds slower than 1/10s or so. I use a free program called Audacity, it is available for all operating systems I believe.
Fot the iphone/ipod/ipad there is an app named oscilloscope (http://www.oscilloscopeapp.com/ )that can do the same thing in trigger mode for the lower speeds up to 1/60th (if you know how oscilloscope settings work), in quiet surroundingd it works with the built-in microphone.

engl
7-Jun-2011, 09:28
Fot the iphone/ipod/ipad there is an app named oscilloscope (http://www.oscilloscopeapp.com/ )that can do the same thing in trigger mode for the lower speeds up to 1/60th (if you know how oscilloscope settings work), in quiet surroundingd it works with the built-in microphone.

Nice to see that there are other options, but I don't think I'd trust the result at such high speeds. There is no way to tell when the shutter opens and closes. With a tool like Audacity it is easy to see the rattle during opening/closing and the whirr in between, and already at 1/30 it is pretty much all a mess.

If you have any advice for working around this, please share, as sound based testing is all I have available.

Arne Croell
7-Jun-2011, 13:57
Nice to see that there are other options, but I don't think I'd trust the result at such high speeds. There is no way to tell when the shutter opens and closes. With a tool like Audacity it is easy to see the rattle during opening/closing and the whirr in between, and already at 1/30 it is pretty much all a mess.

If you have any advice for working around this, please share, as sound based testing is all I have available.
These are two screenshots of the oscilloscope app showing the sound of a Copal 1 at 1/30th and 1/60th, respectively. 1 block on the screen is five milliseconds. The large peak of the first burst on the left is the shutter blades opening, the second large peak is the shutter blades hitting fully open, the smaller 3rd burst is the shutter blades starting to move back and the 4th one is the closing, followed by a slight bounce. That means that the time from the 1st to the 4th peak is 33ms for the 1/30ths, pretty much right on the money, and the 1/60th is 20ms, about 25% too slow.

Addendum: The same speeds measured with the Calumet tester give a little less then a 1/6th of a stop too fast for the 1/30th, and 1/6th too slow for the 1/60th. Given that the sound tests counts from the very first opening to fully closed, this makes sense as the Calumet tester stops counting below a light threshold, giving slightly shorter (and more realistic) times.