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View Full Version : Can a Copal shutter be adjusted for accurate highest speed? 1/500, 1/400 ?



pchaplo
28-Dec-2017, 23:21
Can a Copal 0 be adjusted to have true 1/500 sec, even if it makes the other speeds inaccurate?

Likewise can a Copal 1 be made to perform accurate 1/400?

Can a Copal 1 be modified to force it to 1/500? Anyone want to try?

I do understand that as stock they are limited to 1/500 and 1/400, respectively, and that they typically are slow by 1/3 to 1/2 step at highest/shortest shutter speeds.

Have you tested yiur shutter speeds? What did you find? Does anyone have a lens 125-180mm with a tested near-accurate high shutter speed? Are you selling lol

What controls the shutter speed? A spring? Several springs? Could they be replaced or shortened for faster shutter movement?

What physically restricts upper limit of a Copal shutter speed?

Bob Salomon
28-Dec-2017, 23:38
Yes, and the mainspring will quickly break! If you need a 1 size shutter capable of shooting at its highest speed for a prolonged period of time then you will need the Rollei Linear Motor Shutter and its hand piece.

Pere Casals
29-Dec-2017, 07:47
Can a Copal 0 be adjusted to have true 1/500 sec, even if it makes the other speeds inaccurate?



Let me ask, why do you want 1/500 speed ?


You can measure actual shutter speed with a shutter tester. This would cost from $15 to $99 at ebay. The cheap ones are a bare photocell that see through the lens, and it is conected to a PC sound input, from the wave you calculate the time. I use that way, but instead comecting it to the sound input I use an USB oscilloscope.

For having a right exposure the important thing is measuring the actual speeds (and you do with that) and checking the shutter always repeats the same time. This is specially important to shot slides, negative film (IMHO) has more margin for errors than with slides.

http://www.kenrockwell.com/tech/exposure-large-format.htm

For studio shots you can use strobes, this would ensure the image is perfectly frozen as your exposure time in practice is ultra short (can be 1/30000 sometimes).

Chris7521
29-Dec-2017, 09:02
I highly doubt you would ever get anything close to top speed. The retarding clockwork isn’t doing anything at that speed. It’s the strength of the main spring that limits top speeds. They just were not meant to do what you’re asking.

pchaplo
29-Dec-2017, 11:24
Hi Bob,

Thanks. Just thinking outside the box. What is the highest actual tested shutter speed for a stock Copal 0, which is clearly my best bet? Can anything be done to slightly improve that to approach the labeled 1/500?


Yes, and the mainspring will quickly break! If you need a 1 size shutter capable of shooting at its highest speed for a prolonged period of time then you will need the Rollei Linear Motor Shutter and its hand piece.

pchaplo
29-Dec-2017, 11:25
For aerial photography.


Let me ask, why do you want 1/500 speed ?


You can measure actual shutter speed with a shutter tester. This would cost from $15 to $99 at ebay. The cheap ones are a bare photocell that see through the lens, and it is conected to a PC sound input, from the wave you calculate the time. I use that way, but instead comecting it to the sound input I use an USB oscilloscope.

For having a right exposure the important thing is measuring the actual speeds (and you do with that) and checking the shutter always repeats the same time. This is specially important to shot slides, negative film (IMHO) has more margin for errors than with slides.

http://www.kenrockwell.com/tech/exposure-large-format.htm

For studio shots you can use strobes, this would ensure the image is perfectly frozen as your exposure time in practice is ultra short (can be 1/30000 sometimes).

pchaplo
29-Dec-2017, 11:26
Hey Chris, I just wonder how close I can get to 1/500 sec with a Copal 0, and if anything can help that.


I highly doubt you would ever get anything close to top speed. The retarding clockwork isn’t doing anything at that speed. It’s the strength of the main spring that limits top speeds. They just were not meant to do what you’re asking.

pchaplo
29-Dec-2017, 11:28
If you are testing your shutter speeds in Copal -type shutters, what are you finding as actual speed at the highest shutter speed settings?
1. For Copal 0, how close to 1/500 sec?
2. For Copal 1, how close to 1/400 sec?

I need to stick with mechanical shutter bc well, I work in the sticks :)

pchaplo
29-Dec-2017, 11:34
I know that this is not standard practice, but there are undoubtably small somewhat lightly stronger springs that are durable. Not all alternative springs would break. Maybe a watchmaker would know. I dont think that a loaded shutter is a massive load.

Carsten Wolff
29-Dec-2017, 12:49
Have you asked Carol Flutot?

Dan Fromm
29-Dec-2017, 14:17
Not to be a complete idiot, but why don't you use faster film or dispense with the leaf shutter and use a camera with a focal plane shutter such as a Speed Graphic?

Pere Casals
29-Dec-2017, 14:29
For aerial photography.

OK, most of the shutters don't reach the marked top speed, at least none of those I have.

In fact manufacturers specified that speed accuracy is +/-30%, so if a new shutter had a mark that said 1/400 but actually it was 1/280 then it fulfilled specs, so in theory no warranty claim had force. A common situation is that the max speed uses that margin in the low speed side. At the end 1/500 speed usage is not very common for LF, then LF photographers IMHO never cared.

So best way can be measuring well what what actual speed it has, and if it is repetitive, and adjusting aperture for the real speed you have. Mechanical shutters are not as precise as electronic ones, still are precise enough for potography work.

The good news is that even there is a difference from marked speed the exposure time is very repetitive, it can change if it is stored long time and not doing regular CLAs.

LabRat
29-Dec-2017, 16:01
Not to be a complete idiot, but why don't you use faster film or dispense with the leaf shutter and use a camera with a focal plane shutter such as a Speed Graphic?

One downside with a LF FP shutter would be that with fast low altitude firing, the slightly slow curtain movement might cause a speed distortion effect if flying fast and low...

FWIW, my take on it is if not using a dedicated aerial camera designed with a rugged, fast powerful leaf shutter, it might be better just to use a smaller format camera with a large film or chip load, with high speeds that are a true speed, and even smaller cameras with a top shutter speed of 1/2000, 1/4000, 1/8000 etc...

I suggest again, an aerial photographer probably has MANY old film cameras they won't use now due to digital imaging, and probably has one you can have for little or nothing, so seek this out first...

Steve K

Pere Casals
29-Dec-2017, 16:27
No noticeable speed distorsion with common (non military) aerial photography speeds, if 100 knots this is 185km/h this is 51m/s, so at 1/500 the ground will move 4 inches during exposure.

If 200 knots (!) then ground will move 8 inches. Nothing noticeable in an aerial scene.

Dan Fromm
29-Dec-2017, 16:34
One downside with a LF FP shutter would be that with fast low altitude firing, the slightly slow curtain movement might cause a speed distortion effect if flying fast and low...

FWIW, my take on it is if not using a dedicated aerial camera designed with a rugged, fast powerful leaf shutter, it might be better just to use a smaller format camera with a large film or chip load, with high speeds that are a true speed, and even smaller cameras with a top shutter speed of 1/2000, 1/4000, 1/8000 etc...

I suggest again, an aerial photographer probably has MANY old film cameras they won't use now due to digital imaging, and probably has one you can have for little or nothing, so seek this out first...

Steve KY'know, there are many aerial cameras with focal plane shutters.

LabRat
29-Dec-2017, 18:48
Y'know, there are many aerial cameras with focal plane shutters.

Sure, but our rubber cloth versions are much less tension... The leaf + FP military aerial cameras I have messed with have powerful, metal bladed leaf or FP shutters that can snip or slice off your finger, if that finger was in the wrong place at the right time... :-0

Hope the new year is great for you and yours!!!!

Steve K

Dan Fromm
29-Dec-2017, 19:13
Steve, Speed Graphics' faster shutter speeds are in the range of aerial cameras' focal plane shutters' speeds. The only aerial cameras with metal FP shutters that come to mind at the moment are the Williamson F.134 and its successors the AGI F.139 and Agiflite. These are essentially cine cameras, have rotating sector shutters. I'm sure I missed some, correct away. You might want to count OMERA and S.F.O.M. aerial cameras too, these beasts have bizarre metal venetian blind shutters, change speeds by changing the shutters.

What's more interesting is why the OP is so fixated on lenses in leaf shutters. He has a problem that seems to have a simple and relatively inexpensive solution, but he ignores it.

Bob Salomon
29-Dec-2017, 19:49
Steve, Speed Graphics' faster shutter speeds are in the range of aerial cameras' focal plane shutters' speeds. The only aerial cameras with metal FP shutters that come to mind at the moment are the Williamson F.134 and its successors the AGI F.139 and Agiflite. These are essentially cine cameras, have rotating sector shutters. I'm sure I missed some, correct away. You might want to count OMERA and S.F.O.M. aerial cameras too, these beasts have bizarre metal venetian blind shutters, change speeds by changing the shutters.

What's more interesting is why the OP is so fixated on lenses in leaf shutters. He has a problem that seems to have a simple and relatively inexpensive solution, but he ignores it.
Not a metal focal plane shutter but instead a metal rotating guilitine shutter with speeds to 1/6000. The Linhof Aerotronica. Uses 100 70mm rolls, so not a 45. But much larger then the 45 Linhof Aero Technika EL with the 5 roll vacuum back.

LabRat
29-Dec-2017, 19:51
Steve, Speed Graphics' faster shutter speeds are in the range of aerial cameras' focal plane shutters' speeds. The only aerial cameras with metal FP shutters that come to mind at the moment are the Williamson F.134 and its successors the AGI F.139 and Agiflite. These are essentially cine cameras, have rotating sector shutters. I'm sure I missed some, correct away. You might want to count OMERA and S.F.O.M. aerial cameras too, these beasts have bizarre metal venetian blind shutters, change speeds by changing the shutters.

What's more interesting is why the OP is so fixated on lenses in leaf shutters. He has a problem that seems to have a simple and relatively inexpensive solution, but he ignores it.

I can't remember which ones, but I did salvage titanium FP shutters from outdoor junkpile large cameras years ago (for parts + lenses)... Maybe they were capping shutters???

Maybe it was also a little Maurer 70MM with one...

Still plenty of old aerial cameras out there, but I'd prefer something with a roll film load or digi, maybe motor drive, auto exposure, easy to see through & handle, or to fulfill my William Garnett fantasy, war surplus... It would also be cool to have a with a B-25 or LearJet with a camera bay, but short of that (for a few shots), a wooden box with a graflok back on one side, and a lens on the other if I decided to shoot just one or a couple of sheets over a site...

I still say to hit up aerial photographers... They had awesome gear cabinets I have seen, and know they won't be used by them again...

HNY

Steve K

pchaplo
29-Dec-2017, 22:20
Good idea. I will ask Carol Flutot and I also found another shop S.K. Grimes.

To me, it seems that Copal shutters are optimized for the lower speeds. It reasonable that something could be done to optimize the shutter to consistently provide the marked high speed as in 1/500 sec for Copal 1. From what I understand, that would typically take a 1/3-1/2 stop increase in performance. That would be useful to me.


Have you asked Carol Flutot?