How to check shutter accuracy in Hasselblad lenses?

<p>I have anther question please regarding of buying a used Hasselblad lens online.<br>

I live in a place that I can only buy a lens via the net.<br>

My question is- how do I check for shutter accuracy after receiving the lens?<br>

Thanks.</p>

 

<p>Expose a roll of slide film.<br>

Keep the EV constant while going through all speeds. You will need two subjects, one bright (to try the fast speeds), one dimmer (to test the slower speeds).<br>

The shutters have a slow time gear train that cuts in at 1/15 (if i remember correctly), so overlap the speeds, i.e. use one speed - 1/30 or 1/60 - in both series.</p>

<p>You will readily see whether the exposure is consistent, and whether it is anything near what you expected based on your meter reading.</p>

<p>Q.G de Bakker,<br>

Thanks for you help. But I didn't understand it deeply.<br>

Do you mean : 1. I should choose the subject for the whole shutter speeds.<br>

2. meter it ( I will use Sokonic L508) with Aperture priority or speed priority? <br>

3. shot with the matching aperture and speed throw out the whole speed range (i.e 1/1 to 1/500) or just 1/30?<br>

4. What happen at 1/15?</p>

<p>Thanks for your kind help. </p>

<p>First, you meter the scenes you're going to shoot in any way you like, as long as the readings you get are correct (so that any possible resulting bad exposure is not due to metering errors).</p>

<p>You should select two scenes, because you there aren't enough aperture settings to run through the entire shutterspeed range at a given, single EV-setting.<br>

So select a bright one to test the fast speeds, and a darker one to test the longer speeds.</p>

<p>At 1/15 (still not sure whether that is the fastest speed that makes use of it, but i think it is), an additional 'slow speed mechanism' is engaged, that slows the shutter down. A mechanism that is not used for all faster speeds.<br>

That slow speed mechanism itself is the thing that causes most problems with shutters. Problems that if and when they exist, you will of course not notice when that slow speed mechanism is not engaged.<br>

What can happen is that the slow speeds, with the mechanism engaged, are consistently too slow. When you only test these slow speeds, the exposure may appear uniform throughout that slow speed range, even though they all are too slow.<br>

So to see whether the slow speed mechanism is good, you need to include at least one speed that doesn't make use of the slow speed mechanism in that series of exposures.</p>

<p>If it is good, there is no difference in exposure between that faster speed and the slow speeds that do make use of the slow speed mechanism.<br>

If however it is not good, you will see a difference in exposure between the fast speed that doesn't, and the slow speeds that do make use of the slow speed mechanism. Even when there is no difference between all the slow speeds.</p>

<p>But if the slow speed mechanism is gummed up, the slow speeds will more likely than not not produce consistent exposure. So do try to include a faster speed, but do not worry about it too much.</p>

 

<p>I don't know what computer programs you have (you can get some free audio recording programs at download.com), but get one that shows you a timeline you can zoom in on. Fire the shutter and see the difference between the time the initial click starts, and when it ends. You'll need a microphone, of course.</p>

<p>There is a way to perform a shutter speed test that involves the use of a Digital camera. You will have to place the lens/camera to be tested front to front with the digital camera (like if they were kissing). You may use just black tape to avoid light leaks or use a combination of adapters and reverse mount adapters.<br /><br />The area on the back of the lens/camera to be tested should be lit by a constant and even light source <br /><br />This method assumes that a recent or new digital camera with an electronic controlled shutter will be accurate<br /><br />Here is the procedure:<br /><br />The lens in the digital camera should be on manual, constant aperture, constant ISO<br /><br />- First put the lens to be tested open and make an exposure with the digital camera at the speed or speeds you want to test<br /><br />- Look at the histogram, you should see a narrow band at some point. You can adjust where the band should be either with ISO or the digital camera lens aperture<br /><br />- Now, cock the shutter to be tested and open the shutter in the digital camera on B. Release the shutter to be tested<br /><br />- Check the histogram and compare with the previous histogram. You would be able to tell if the shutter is accurate or how much it is off.<br /><br />- You can also use this procedure to check the effect of high shutter speeds whit small apertures in central shutter or to check if the diaphragm is properly closing before the shutter.<br /><br />Regards</p>

<p>Any camera repair shop will have the means to measure shutter speed directly. They might even do it for free. If you have access to an oscilloscope, use a pinhole light source and a photodiode.</p>

<p>O.K. guys,<br>

Thanks for your help.<br>

Since I don't have a digital camera, or a pro repair shop where I live,<br>

I will try Q.G. de Bakker method.<br>

If any thing will pop out, I will post again.<br>

Again- Thanks for you willing to help.<br>

Nir.</p>

<p><a href="http://www.open.hr/~dpleic/photo/Shutter.html">http://www.open.hr/~dpleic/photo/Shutter.html</a></p>

<p>Edward is right, a good repair shop will do this for you for free or cheap. Any cheap way won't be accurate. I'd just shoot a roll of slide film and see how it turns out.</p>

Outrageous suggestion here but I'll make it anyway. How about using a DSLR's sensor to check Carl Zeiss lens speed.

Using a grey card and grey scale (Kodak) as a target, If you then make an exposure at say 1/125 at F/8 with a "normal lens" on the DSLR and compare the exposure using 1/125 @ F/8 on the CZ lens you'll see any difference, the grey scale will indicate 1/3 of a stop difference so a fairly accurate means of comparing speed accuracy I think.

Allowing for any lens extension etc. can be alleviated by using aperture priority with the CZ lens open at the desired aperture and adjusting film speed/lighting to give the required shutter speed - I probably haven't explained this very well and I'll probably be told its a stupid idea......

Old thread I know, but I have a handy little Calumet branded shutter speed tester that I use on all of my cameras.

 

Basically, you shine a bright light source through the lens(I use a slide projector with the projector lens removed and just use the condenser lens) and set the photodiode of the tester in front of the film gate.

 

It will work for focal plane shutters, although isn't ideal for higher speeds(anything faster than the X-sync speed) since with one diode you're only seeing a "snapshot" of the lens. It's great for leaf shutters, though, which of course applies to the common Hasselblad lenses.

 

With my Hasselblads, I just keep mental note of which speeds are "good" and which aren't. Many LF photographers consider a shutter speed tester essential, and regularly test their shutters(often with a device similar to mine-after all Calument is a name mostly associated with LF) before an outing. I've adopted the common practice of taping a table to the board of every lens with the marked vs. actual speed.

here ya go....

 

Filmomat Photoplug smartphone shutter speed tester ( free APP download required)

 

follow this thread n hear the many ways you can check speeds....

 

Concept for a Shutter Tester

here ya go....

 

Filmomat Photoplug smartphone shutter speed tester ( free APP download required)

 

follow this thread n hear the many ways you can check speeds....

 

Concept for a Shutter Tester

 

- 40 bucks for a photodiode in a cheap stereo jack? Wizard wheeze!

 

I hope there's a low value resistor in there as well, to shunt the diode's capacitance and increase its response time.

 

I've used a silicon photodiode with a 470 ohm resistor across it to measure flash output, connected to a digital storage 'scope. It outputs a few millivolts. Without the shunting resistor the photodiode output is non-linear and quite slow to respond.

 

You could easily make the sensor for under $5. And download the free app.

 

Oh BTW. No need for any power supply. A photodiode generates current in proportion to light. Expect a nanoamp or so for each incident lux.

Edited December 10, 2018 by rodeo_joe|1

some people arent very handy n want ready to use, so $40 is reasonable.

 

ive never needed the resistor but i am feeding into the MIC input of a sound card which has a preamp where line in doesnt.

 

back in the day i built a wave capture gizmo for my techtronics duel trace i got out of popular electronics or maybe radio electronics magazine. tube n wire wrap p-p, it was the best thing since slice bread. but the digital age came with digital scopes n even recording programs for the computers. cant get any simpler with a jack into a phone. besides, your calumet speed checker would cost you about $40 on flea bay anyway.

^ Paul do you know of an app that makes use of a photodiode device for an android phone ? The above

app only appears available with the purchase of their device . Audacity doesn't work on androids , and the

sound card on our home computer is toast :( . Regards,Peter

The app isn't free, but doesn't cost much.

 

Available here.

^ Thanks for the info , I've just installed it and I'll be testing my freshly cleaned and lubed Pentacon 6 TL .

Wish me luck :) , Regards,Peter

hi peter, i hope you will post your results? curious how well this phone giz works.

 

good luck peter. btw dont be surprised when testing every camera you own n find so many variations in speeds? its normal to be off a slight bit.... usually about 25% is considered good (mechanical shutters).

 

main thing is repeatability... consistancy.

Edited December 13, 2018 by paul ron

^ Thanks for the info , I've just installed it and I'll be testing my freshly cleaned and lubed Pentacon 6 TL .

Wish me luck :) , Regards,Peter

 

- A Pentacon 6, ouch! Good luck with that!

There are two main issues with adjusting a P6 shutter.

1. At the higher speeds the 1st and 2nd curtain tensions need to be carefully balance to get an even exposure across the frame.

2. There's no adjustment for the slow speeds apart from the degree of mesh of the slow-speed gear train with the main shutter. This requires that the separate slow-speed unit is carefully 'nipped up' in the exactly right position as the camera is re-assembled. You can't just screw the thing back together willy-nilly.

 

In short, you really need the optical gizmo to measure the higher speeds all across the frame. Just going by the sound of the shutter slap is useless.

 

FWIW, at 1/1000th, the best I could get from my P6 was a variation between 0.9 ms and 1.1ms across the frame. That was after about an hour spent tensioning and re-tensioning the shutter curtains.

Edited December 13, 2018 by rodeo_joe|1

Thanks for the responses , up until the time the negatives started banding I'd had good exposures at all the various speeds that were used .

Inspection later showed that the curtain wasn't completely closing on my favorite speed ( 125th) . The cleaning and lubing certainly cured

that problem . I sure hope to test and then post any "proof of the pudding" shots . Auto electrical repairs and washroom renos have put a

temporary halt to photography for the moment ( happy wife, happy life ! ). Peter

Shutter testers are now so cheap ($150 or so) most people can buy a set up (new) if they aren't capable of building their own. I picked up one over the summer because I was doing exactly what you are (resurrecting a P6). The tester worked great and I finally got the body dialed in.

 

As far as Rodeo Joe's encouragement, he's right. I started tensioning at 100 clicks on each curtain.