Synchro Compur Speeds..

[stephen_morgana]

<p>Hi,<br>

I'm new to the forum and new to large format.<br>

I recently bought a Graphic View II that came with a Kodak Ektar 203 f7.7 lens in a Synchro Compur shutter.<br>

The lens looks great... but when I tested the slow speeds of the shutter by ear... it sounded way slow...<br>

So I figured I'd start looking in to the shutter to see if I could clean and adjust it (I'm a do it yourselfer, and think its within my skill level)...<br>

What I did first was to actually measure the speeds as they are now to see how far off it is...<br>

I did this by simply sound recording the shutter in action at each speed, and then loaded that up into my sound editor and made measurements by between the peaks in the waveform.<br>

Surprisingly what I found is that for higher speeds 100th 200th 400th are fairly accurate, but all the lower speeds, 1, 1/2 1/10 1/25 1/50 are each very close to being off by a factor of 2 slower..<br>

So 1 is 2, 1/2 is 1, 1/10 is 1/5 etc... not exactly but darn close on each of them...<br>

It makes me wonder if someone intentionally adjusted the shutter to extend it to allow for a 2 second exposure. at the expense of 1/50th.<br>

I figure I can start making exposures knowing actual speeds, but Im looking for any advice or pointers anyone has on this shutter.... Also if anyone has any pointers to disassembly and adjusting...</p>

<p>Thanks<br>

Stephen</p>

 

[CoryAmmerman]

<p>This should come in handy.</p>

<p><a href="http://www.suaudeau.eu/memo/rep/Compur-shutter-repair-manual.html">http://www.suaudeau.eu/memo/rep/Compur-shutter-repair-manual.html</a></p>

<p>The site is in french, but the pages are written in English.</p>

<p>It's my understanding that the slower speeds use a different set of springs, which tend to be weaker and tend to fail first. I would think that it's just happenstance that the speeds are doubled. How many times did you test them, are they consistent?</p>

[john_shriver]

<p>The slow speeds are also affected easily by congealed lube or dust in the slow-speed gear-train.</p>

[stephen_morgana]

<p>I will go with happenstance... the speeds are in the ball park of 2x, <br>

To check for constancy I downloaded a shutter speed measure app so I could take lots of measurements easilly... I'd say its consistant from try to try.. in this sense...<br>

1/50th is around 1/26.6-1/27.3 and the meter says 3/3 stops but I did get one 1/30th in a run of measurements...</p>

 

 

[thirteenthumbs]

<p>Speeds from 1 second to 100 second are controlled by the delay gear train, speeds above 1/100 are controlled by the booster spring.<br>

The Synchro Compur is a difficult shutter to learn on. The delay is controlled by a coil torsion spring like a watch/clock. Removing the delay mechanism will likely release the spring requiring its initial tension to be reset to get the speeds correct.<br>

The 203 Ektar is not listed in the service manual referenced in the link above but a base shutter was adapted to many lens and applications. It may be a composite of two shutters in the manual, one for the top side of the main plate and up, and one for the lower portion of the shutter. CN-1307-000 is a possibility.</p>

<p>See http://www.photo.net/large-format-photography-forum/0044cW especially the last few posts.</p>

[greg_heath4]

This was the first shutter I worked on. It might have been slightly smaller than yours but It is basically the same.

 

ONLY proceed from the front of the lens (towards the film plane).

 

Don't start from the back on a shutter as you will be rebuilding the aperture. It's not for the faint of heart.

 

My Compur Rapid shutter was from a Rolliecord IIe I rebuilt.

 

Here is a link you can cruise thru my photos.

Shutters are not really that difficult. Although this first shutter drove me crazy. Lol. It was the first one I ever tried. The Compur Rapid

uses a timing gear with speeds to 1/250. At 1/500 the shutter uses a spring to speed the shutter at close to 1/500th.

 

 

You will have to page down a bunch and find the Rolliecord disassembly photos.

 

I have a bunch of shutter rebuilds.

 

Another guy to look up on Flickr is Hans Kerensky.

 

Let me know if I can help you with any questions.

 

Greg.

[stephen_morgana]

<p>Thanks for all the info... I will be getting into this shutter to see if I can improve it... but with the app I have.. I've been able to measure all the slow speeds so I know how many stops they are off by (1 stop or there abouts)..<br>

Since the aperture setting is continuous I should be able to compensate for the speeds being off by setting to fractional aperture settings. At least this way I can get a few exposures on the camera so I can test it for other factors before I take the shutter apart.<br>

Greg.. I took a look at your Flickr page... Thanks. What would be helpful is to know what the first step is in even opening the shutter... I took the front lens off -- easy--- but nothing jumped out at me as to how to take the top cover off the shutter... don't want to break it right off the bat...</p>

[nbg90455]

<p>On a side-note, once you get the shutter working properly, you have one of the finest lenses for 4x5 work. It was designed for 5x7, so you have an image circle only surpassed by the modern 210 Sironars. Here is one of my favorite images taken with this lens:

 

[stephen_morgana]

<p>Ok... Read up on disassembly...<br>

so all set to open it up.. I've read a bit now on how to clean it... many people say cleaning alone can fix the slow speeds... different people recommend different chemicals... the main one being lighter fluid... some say electrical contact cleaner...<br>

Also... it will need careful lubrication.. I'm assuming watch oil.. but the manual may specify the right oil...<br>

Since the camera is right now being treated for a slight mildew smell on the bellows...it needs to sit a couple days... I might dig in to the shutter before taking any exposures...</p>

 

[thirteenthumbs]

<p>Technicians that use Lighter Fluid are satisfied if it just works IMO. Lighter fluid leaves a light oily residue behind, those that say it doesn't are not able to detect it. My main reason for not using it is the Naphtha is toxic and may damage plastic used in some shutters and will damage rubber. Its probably fine for shutters made before the 1930's except for the ones that use paper aperture blades and paper seals. There are several other chemicals used in the paint and varnish industry that are excellent degreasers but they have a lower flash point than Naphtha, will strip bluing off shutter and aperture blades as well as damage other materials previously mentioned.</p>

<p>Isopropyl Alcohol can be used to clean the shutter but it works much slower. I use CRC Quick Dry Electrical cleaner as its the best. There are some contact cleaners that aren't very good such as http://www.lowes.com/pd_172753-12704-40-610_0__?Ntt=electrical+contact+cleaner&UserSearch=electrical+contact+cleaner&productId=3127949&rpp=32. The CRC can be found at hardware and Auto Parts stores. http://www.oreillyauto.com/site/c/detail/CRC9/05103/N0439.oap?ck=Search_N0439_-1_-1&pt=N0439&ppt=C0090</p>

<p>Watch oil will be fine for shutters. I use TriFlow with Teflon. Any light weight grease including teflon bike grease where grease is called for is fine, manufacture's grease is either a spec number or in house type and not readily available. Only trace amounts of oil and grease are called for. If you can just see a light sheen of oil then you have the correct amount, a dab of grease about the size of a straight pin head spread out over the movement area is good. I soak a round wooden tooth pick with oil and then wipe the inside of gears and bushings and put a drop about the size of a straight pin point on shafts. I also put a trace of grease on spring ends where they move against the case or other levers even if not called for. Too much grease or oil inhibits the movement of the shutter. Shutter blades and aperture blades must remain dry. A very light coat of Dry lubricants such as extra fine powdered graphite or teflon are acceptable.</p>

<p>Take pictures as you disassemble to aid in reassembly.</p>