Lens Shutter Problems

[richard_hart]

Just recently purchased a used 500C with standard 80mm Lens via

ebay. Although the shutter speeds (sound) correct, I'm thinking that

they are not. Images taken without a flash are consistantly way

under exposed. My lab seems to think it's a shutter speed problem.

About a 40 density reading. Is there any way other than sending it

in to camera repair to check if the problem is actually the shutter

speed or something else is wrong with the camera itself.

As a side note, I've used various light meters and they all give the

same readings which I've used to set the lens to.

Any help would be greatly appreciated :)

[stephen hazelton]

I'm thinking shutter speed checkers are fairly commonplace- have you got a local camera repair shop that can test it?

[q.g._de_bakker]

Richard,

 

A computer, sound card, microphone and .WAV editing program can help.

 

Set the camera on a tripod, put the microphone on or near the lens, prerelease the camera, and record (highest possible sampling rate) the sound of the lens shutter opening and closing. Then have a look at the wavefile recorded. It will not be hard to spot the beginning and end of the shutter cycle, select the entire cycle, and the editor will show you how long it is (if not, most editors have a time bar beneath that can be used).

Remember that shutterspeeds are seperated by a factor 2, so the real sequence should not be the one on the shutterspeed ring, but the reciprocal values of the sequence wellknown to "computerists", i.e. 1/1, 1/2, 1/4, 1/8, 1/6, 1/32, 1/64, 1/128, 1/256, and 1/512.

[skipd]

The sound duration might be OK for the slowest shutter speeds, but in my opinion won't be worth a darn for the highest speeds. What is important is how long any particular spot on the film has been exposed to light through the shutter. The shutter movement starts before the light gets through the opening and stops after the light has been blocked.

[harry_akiyoshi]

Checking shutter speeds with a sound card and a microphone seems to work all right up to about 1/250 or so. It seems to work better with leaf-shuttered lenses, which generally emit simpler sound patterns than focal-plane shutters. That's my experience, anyway.

[peter_rosenthal]

Richard-

 

Underexposure, or in your case way underexposure, is pretty rare in leaf shutters. It's very easy to explain overexposure but it takes some kind of catastophic failure to underexpose. This would also show up primarily in the slowest speeds if the slow-speed escapement were broken. If the slow speeds sound OK, the escapement is probably OK. After all, a lens shutter can only go so fast.

 

It's also possible that the aperture, the only other variable here, is bad. Exceedingly rare that the aperture control stops working. Here, again, overexposure is easy to explain but underexposure implies that the ap is closing down farther than the simple and virtually foolproof control wants to let it. I'd look through the back of the camera and shutter at various aps with a single speed to see how it's doing. This is a good simple test.

 

All this is assuming that your exposures are correct. Just to rule out everything else I'd shoot transparency film (WYSIWYG) at the sunny 16 rule at different aps during the sunny 16 rule time of day and conditions. OR, you could just take it to a local repair shop and have the shutter and ap tested for nothing. Then you'll know what's going on.

 

My money is on the aperture.

 

As far as using a computer to test speeds... Leaf shutters are not open and close like a focal plane shutter. They are start open, finish open, open duration, start close and finish close. No sound card can quantify the efficiency of a leaf shutter. It might be fun, but in my opinion, useless. Can a sound card identify where on the opening and closing of a leaf shutter the light curve hits mean open? Nope. Blah blah blah. Sorry, just defending my expensive test equipment from "pretenders".

 

Let us know what you find. I'm dying to know.

 

Peter / PR Camera Repair, Flagstaff, AZ

[charles barcellona www.bl]

I'm suprised QL didn't add this, so I will.

 

The test is simple. Take off the magazine. Open the aperture fully. Attach the flash to the camera via cord to the lens. Point the flash and camera at a white wall about 2 meters away. Advance the camera and set the speed to 1/500. While looking through the back of the camera, release the shutter. You should observe a perfectly round, and fully opened aperture. Test other speeds. Thats it!

[z_z1]

Take a series of chromes using only your flash. Use all the shutter speeds you can, and vary the distance to the subject if that gives you more range. If all the chromes are ok then it's not your shutter or aperture at fault. If you are using older light meters that were designed for the mercury batteries and you are using the newer 1.5 volt batteries you will experience at least a 2 stop error leading to under exposure.

 

Blad shutters get slower, not faster when they go out of adjustment in most cases. I wouldn't be very surprised if your meters are not the problem. Double check them against a newer SLR.

[edward_burlew]

This seems to be a constant problem with buying from ebay. You go and buy something for a good price but the vendor relied on dumping his or her proble on you and we ae constantly pretending to bid on good working items when in fact most of the items are really just junk and need repair. the best approach is to realise that whatever you buy will need serious repairs and to treat all items as just scrap and pay appropriately. Then when you have to take the item to an authorized Hasselblad repair center you can afford to do so without being worried about the cost. This is no help to the poster but it has been bothering me because I do buy from ebay and I am amazed by people who bid items up to ordinary retail when you could just be bidding on scrap and the vendor may not even be aware of the problem. My 2cents.

[harry_akiyoshi]

Just as a side note, none of us think that we can analyze a sound clip and get accurate results for shutter speed tests. It's certainly not going to be dead on, it's just a simple way to see whether you're in the ballpark. I was playing with an old Yashica-mat the other day, and my exposure tests (metered meticulously and shot on Provia) confirmed that the audio analysis method can be accurate to within 1/3 of a stop or so even at the higher speeds--which, frankly, is really all I needed. I just wanted to know whether those top speeds were dragging by more than say, a stop. Then I was unsure of my results and shot a test roll, and it corresponded remarkably well with the audio data. So I think the method is practical for rough estimation and troubleshooting.

[q.g._de_bakker]

Andrew,

 

My thoughts exactly.

It's easy to do, cheap, and perfectly good enough to let you know whether or not there are serious problems, even when times can't be measured to the closest microsecond. That's why i suggested the method, and why Richard should try it, despite protestations to the contrary.