Hasselblad C & CF lenses - Flash Sync w/Extension Tubes Problem

[eyecee_.]

<p>Hi All,</p>

<p>I'm a newbie to the medium format world and I'd love any advice from the more seasoned veterans here on Photo.net on an issue I've encountered trying to sync a flash from a CF lens with an extension tube attached.<br /> I recently took the plunge and bought a Hasselblad 500C/M with 4 C lenses (40mm, 50mm, 80mm, 150mm) and 1 CF lens (120mm Makro) as well as the 21mm and 10mm extension tubes. While testing out the camera and lenses in my studio, I connected a PC-to-PC cable between the PC post on the lenses and the PC socket on a Nikon SB-900 Speedlight. I connected all the C lenses and extension tubes in various combinations (lens only, +10mm, +21mm, +10+21mm) and with every set up, the flash synced to the shutter when triggered as expected and all is working well.</p>

<p>On the CF 120mm Makro lens, things went a little differently; attaching just the lens to the body, the PC-to-PC cable perfectly triggered the flash on firing the shutter, however, when attaching either or both of the extension tubes, the lens would NOT trigger the flash at all.</p>

<p>I'm totally confused as there isn't any electronic connections between the lens and 500C/M body which controls flash sync plus when using the C lenses, the flash syncs with all lenses and extension tube combinations so I think the extension tubes are working perfectly from a flash sync perspective. The CF 120mm triggers the flash sync perfectly when there's no extension tubes so I'm lost to why when using the CF 120mm lens with an extension tube, the flash sync does not fire at all.</p>

<p>Is there such as thing as a updated extension tube to allow flash sync on CF lenses? or am I missing something? Unlike the C lenses with the V-X-M switch for timer/flash sync options, my CF 120mm makro only has dials/switches for aperture, shutter speed, aperture preview and bulb mode. There isn't the X-M option for flash sync.</p>

<p>Any advice on how to trigger the flash sync on the CF 120mm f4 makro when using extension tubes would be greatly appreciated,</p>

<p>Thanks in advance!</p>

[brad_trostad]

<p>First things first, I am hoping some experts chime in with their wisdom as I am new to this as well.</p>

<p>Just one question / suggestion:<br>

- Remove the back and make sure the camera is cocked<br>

- Verify the slots are correct and mount the tube on the camera and then the lens on the tube (hope I got that order right?)<br>

- Take a picture while looking through the back and out the front of the lens - do you see the shutter open?</p>

<p>...from what you described above, unless you actually have photos (which are exposed but just under exposed) it sounds a lot like the shutter just isn't opening at all which would appear to be a PC sync problem. Perhaps there is an issue with the extension tube to your 120 lens (maybe the shaft does not turn enough for this combo?)</p>

<p> - Brad</p>

[Ed_Ingold]

<p>You should use cables with a long PC tip for best compatibility with C and CF lenses. Conventional short tips don't always make good contact, and tend to fall off for C and CF lenses. (CFi and CFe lenses have a PC clamp.) CF sockets have an O-ring which helps hold the PC tip in place, but the tip needs to be beveled to avoid damaging the rubber ring.</p>

<p>Cables are consumable items, so always have two good ones (or more) in your bag. It's possible that the extra strain on the cable when extensions are used affects a marginal contact. Older lenses may have a loose or defective socket.</p>

<p>You may be able to buy commercial cables with a suitable tip, but they can be hard to find. I pay a little more and get exactly the cables I need from Paramount. The Nikon SB-900 has a PC connection on the side, which is a good alternative to a hot shoe adapter. Paramount offers a PC tip with a threaded collar which fits the Nikon perfectly and locks in place.</p>

<p>Let's just hope it's the cable, not an expensive repair.</p>

[brad_trostad]

It was my understanding the PC synch and cable

fire the strobe via the lens in question - when no

extension tube in place.

 

Since the shutter actuation is purely mechanical, doesn't that mean

the cable and lens are fine? That's why I was

wondering if the shutter even opens in the lens - when fired via the extension tube.

[Ed_Ingold]

<p>If the camera, lens or any of the extension tubes are not cocked, you cannot assemble them together. If any do not fire, you get a jam which must be cleared through the back of the camera.</p>

[douglas_fairbank]

<p>You are correct to assume that the extension tubes can have no effect on the synchronisation of the flash. However the synchronisation of the shutter release may not be correct with this combination. Look through the back of the camera with the magazine off to see if the shutter of the CF120 is working when it should, it is possible that it fires before the body shutter opens or later than the body shutter opens. In both cases the flash should still fire, after all it is just a switch, but there may be no exposure on the film.<br>

Trial and error may be able to help you find what item(s) is/are the cause of this.</p>

[Ed_Ingold]

<p>Per the OP, the flash does not fire at all when the extension tubes are used. It's still a good idea to check the synchronization with the back removed. The most common problem is sluggish or sticking action of the auxiliary shutter (barn doors), which results in part or all of the film blocked during exposure.</p>

[Ed_Ingold]

<p>Just yesterday I encountered a fussy cable, used to connect the lens with a CFV digital back. The PC connector looks normal, but works only if you apply lateral force, or turn it just so.</p>

<p>A trick that works (and is recommended by Paramount Cables), is to bend the center conductor slightly off-axis. Of course, the cable can break internally, usually near the connector, and give intermittent contact. That's why you always need a spare.</p>

[scott_murphy5]

<p>You might want to think about going with a wireless set up.</p>

[leicaglow]

Is wiress going to help if the flash itself doesnt fire? It seems like that would be adding complexity to

the problem.

[eyecee_.]

<p>Hi All,<br /> <br />Firstly, Thank you all for your comments and advice on my situation; it's greatly appreciated.</p>

<p>Over the weekend I managed to get some time to try the suggestions as detailed above and I think it's now a shutter sync issue with the CF 120mm/f4 Makro lens and the extension tubes. I took the back off the camera and looked down the barrel of the lens and when the shutter is triggered, I can see the shutter open when only the CF lens mounted on the body. This is in line with the flash sync working when just the CF+Body combination.</p>

<p>When I add an extension tube (the lens, tube and body are properly mated and can fire and wind on all occasions), when I repeat the same tests (back off, looking down the barrel of the lens from the front that a light source behind the camera, once the trigger is fired, I can not see any light come through the set up but can see that the lens-shutter blades have been triggered and closed.</p>

<p>Based on this testing, it would appear that the CF lens shutter is not triggered in sync when the extension tube is in place, hence why no light can be seen during the shutter duration plus why the flash sync isn't triggered.</p>

<p>What's odd is that without the extension tubes in place, the CF 120mm/f4 Makro works perfectly (lens shutter opens and the flash sync is fired) and when I use the extension tubes on the my other C lenses, the shutters fire fine and the flash sync works okay. It's only when I have the combination of CF lens + extension tube does the in-lens shutter mis-syncs and I can't see any light come through the camera nor have the flash sync happen.</p>

<p>All the equipment are original Hasselblad items and, while old, are in very good condition and all are perfectly functioning except for the CF lens + extension tube issue. I'm thinking I may need to send the lens in for service but what keeps annoying me is that without the extension tubes in place, the CF lens works perfectly plus the extension tubes on the other lenses work perfectly too. Has anyone heard of the CF lens shutter mis-syncing when using extension tubes?</p>

<p>Thanks again!</p>

[brad_trostad]

<p>Sounds like we can rule out anything related to cables (although I found all that information very useful!)</p>

<p>I too would think you have narrowed it down to the lens (which you really had done prior to your original question). I sounds like the lens is out of tolerance when it comes to that shaft rotating. Perhaps w/o the extension tube it is allowed to rotate fast enough and far enough to fully handle all the required mechanical actuations. And with at least one tube attached it does rotate (completing some actions) but not with enough force, speed or rotational distance.</p>

<p>Perhaps the spring (or tensioning device) in the lens is now out of tolerance. It would appear to have enough force to operate the lens without a tube. But once you add the drag / play of the other shaft(s) in the extension tubes its just not enough to properly cycling everything.</p>

<p>Dumb question - are those tubes the older tubes or the newer tubes (or maybe one of each)? Probably shouldn't matter but maybe if they are older they won't work as well with a newer CF lens?</p>

<p>Maybe the 120 CF was sitting cocked for about 20 years with out being cycled and now the spring is out of tolerance?</p>

<p> </p>

[eyecee_.]

<p>@Brad - I think both my Hasselblad extension tubes (10mm and 21mm) are the older type as there are no electronic contacts whatsoever and everything is mechanical. Mind you, I don't know the difference between 'new' and 'old' tubes so I'm completely guessing here!</p>

<p>As for my next steps, I'll try to get the lens serviced to see if it is the lens shutter that is out of tolerance and I'll loop back to this thread just to give an update and hopefully close this issue.</p>

[brad_trostad]

<p>By old and new, I believe there were an older series of all mechanical extension tubes and then a newer series of all mechanical extension tubes. I think the newer series are 8, 16, 32 and 56 and perhaps have a different finish and better flocking (or whatever it is) on the inside. Probably doesn't matter as I would think they are all probably compatible if working to spec. </p>