First of all thank you for the kind words. I am far from being a businessman. This has started as a fun thing that mixed my 2 hobbies for cameras and electronics. Now, I do it to fund my camera purchases. This way I don't get raised eyebrows from my family when I buy somewhat expensive photo items.

I will be the first one to admit that shipping is the Achilles heel of the deal and most of the time the postal services from both countries are at fault. The only countries that did a top job every time were Japan and UK. Also, I've checked the postal services form other European countries and their rates are just as high. (except UK)

Quote Originally Posted by benjiboy View Post
How do you know what tolerance in percentage of the marked speeds + or - is within tolerance ?, what is the acceptable margin of error, because unless you know this my training as a test engineer tells me that the digital readout is just numbers, so if the the marked speed is 1/500sec and the tester reads 1/410 sec is it within tolerance ?
I don't think I understood your question right so if my answer is different please ask again.

If the tolerance you are talking about is the shutter tolerance than this depends on the shutter type and manufacturer. Some old Compur shutters have a tolerance of 30% (given by the manufacturer). This means that if you take a photo with an exposure of 1 second, everything between 0.7 and 1.3 seconds is within spec. To find the tolerance you need a service manual for the shutter.

The LCD tester in the photo displays only a number. That's the time in seconds the shutter is open. In that photo a 1 second test was done.

So in the 0.997472 test the shutter is 0.002528 seconds faster than the 1 second desired time.

Now let's say you do a test at 1/1000th of a second and you get a reading of 0.001173. This means your tester is running at a speed of 1/852. Now depending on your shutter you might have to fix it or not. If you get a reading of 0.000972 your shutter is running at a speed of 1/1028. If you get a reading of 0.001 than your shutter is running at 1/1000th of a second.

The tester in the photo does not display the 1/852 speed but I plan to change this and have the time on the first row and the camera time in the 1/value format on the second row.

A display of "+17%" or "-17%" that displays the error in percentage is a tricky thing to do because the tester does not know you want to do a test at a speed of 1/125 and after that you want to do a test at 1/500. To do this you have to tell the tester the theoretical speed you are testing your camera at so the tester can calculate an error with your theoretical speed as a reference point. This would require major changes in the code and circuit board of the tester. It would also require multiple buttons that would allow the user to insert the theoretical value.

An easier way would be to have a rotating dial with speeds like 1/60, 1/90, 1/125, 1/250, 1/500 or whatever values you desire but in this case your error display in percentage would be limited to those values.

I could do this but I don't have the time to do it and I doubt many people would be willing to pay the extra price.

Quote Originally Posted by akaa View Post
Are any of these suitable for 35mm?
Yes, all of them. Most of my cameras are 35mm. I also have TLR cameras and I had customers with Speed Graphic cameras and Calumet shutters from large format cameras.