How do I test the timing on a lens?

[calamari]

Hello,

I have a lens I would like to see if its keeping time well. Of course, I could send it into repair, but lately I've been repairing my own lenses and really do enjoy doing it myself.

Thanks.

[Leigh]

You need a shutter tester.

I expect you could find one on evilpay, although they're not real common.

Or you could build one. They're relatively simple devices.
Search the archives. Somebody posted some notes about one he built.

- Leigh

[Richard Raymond]

My first recommendation is to get a free application called Audacity. I use it on my laptop. This is a sound recorder and analyzer. You can use this to get a very reasonable approximation of the speed of the shutter. You can also find out if the speeds are consistent. This will provide enough accuracy for you to get an idea of how you are doing.

[Bill_4606]

Audacity is surprisingly useful. Especially if you are only interested in the slower speeds.
I used it to create a table that I carry in my bag for different lenses. It tells me how much (or if) to compensate different settings on my LF lenses. I also discovered that one of lens was constantly off a half stop unless I tripped the shutter once just before I expose. Then it's right on. (that lens is on the todo list for a CLA.)

1/250 and up get a bit sketchy. I've compared audacity to a calibrated source and slower speeds are within 5%. But that's using my computer... yours could be different.

I even tried using Audacity with my Digital SLR for grins. It clearly indicates the mirror / aperture timing. Not very useful but interesting.
Bill

[Jerry Bodine]

I bought the book "Way Beyond Monochrome" 2nd Ed. when it first came out not long ago. A very useful (text) book for my library. It includes instructions + illustrations on building your own shutter speed checker (inexpensive), using Audacity software (free download). I did this and checked ALL my LF lenses, then taped all necessary corrections to each lensboard. A very worthwhile undertaking. If you decide to do this, you'll probably discover that use of a DC light source will give a steady trace; I used an AC lightbulb, which gave an oscillating (~120 Hz) trace that was still adequate for the purpose.

[kbrede]

There's a guy (vfmoto) on ebay that builds and sells a variety of shutter speed testers. I've never used one myself but it's something you might research.

http://www.ebay.com/sch/vfmoto/m.htm...&_trksid=p3686

[wombat2go]

The photo of my "jerry" rig should be fairly self explanatory.
The photo transistor is biased to be in its active region so it is fast enough to replicate the penumbra.
In use, the photo transistor collimator is pressed against the ground glass. ( it is shown pulled away in the photo)
I machined a collimator out of black acetal which has a 1.2 drilled hole 10.5 mm long so the rays hitting the transistor are almost at 90 degrees.
A future improvement is to make an M43 adaptor to the old oscilloscope to allow the shutter pulses to be archived.
This rig can measure both the FP and the lens shutter speeds on the Speed

[ghostcount]

The photo of my "jerry" rig should be fairly self explanatory.
The photo transistor is biased to be in its active region so it is fast enough to replicate the penumbra.
In use, the photo transistor collimator is pressed against the ground glass. ( it is shown pulled away in the photo)
I machined a collimator out of black acetal which has a 1.2 drilled hole 10.5 mm long so the rays hitting the transistor are almost at 90 degrees.
A future improvement is to make an M43 adaptor to the old oscilloscope to allow the shutter pulses to be archived.
This rig can measure both the FP and the lens shutter speeds on the Speed

Wow, old school scope. Single channel?

[wombat2go]

Ghost: Yes it is an Eico TR410 transistor type maybe from the same decade as my Speed Ggraphic.
It works rather well but I would like a second channel at times
I have a Tek 466 here needing a special concentric knob/shaft for restoration but the parts are $hundreds. -Not sure what to do.
( sorry to interrupt, calamari)

[Zaitz]

This is how I tested my Speed Graphics focal plane shutter. I'm not sure how it'd work through a lens but I thought this method worked quite well.

I used my D300s to test the shutter speed by shining a light through the speed graphics ground glass and out the front towards my D300s. I had a spare ground glass in front of the speed graphic to further blur the light so the d300s would get a good reading. With the Speeds shutter set to open I'd take a shot with my D300s at the desired shutter speed - say 1/1000. I then would set the Speed to the same shutter speed, change the D300s to a 1/4second shutter and trip the D300s just before the Speed (in a dark room - I just did it at night with no other lights on). Then I could compare the histogram between the two photos on the D300s.