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10-03-2012, 09:03 AM   #1
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Couldn't get 1/180s

I was shooting a mountain bike race last weekend and had a remote flash and a Cactus v5 trigger on the camera. I was in a place where the riders would be going pretty fast and I want to get as fast a shutter speed as I could while still triggering the flash. It's my understanding that 1/180s is the maximum sync speed so in manual mode my plan was to shoot at 1/180 but when I tried to set the camera this way I could get 1/160 and then the next click of the dial would go straight to 1/200s. So I shot at 1/160 and the shot turned out fine but I'm wondering why I couldn't select 1/180.
Can anyone tell me for future reference?
The shot was 1/160s, f/10, ISO 80:



10-03-2012, 09:16 AM   #2
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There's not actually a way to select 1/180, when you step up to 1/200 with the flash enabled, it fires at 1/180 is all.
10-03-2012, 09:17 AM   #3
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Check whether you have EV steps set to 1/3 or 1/2 stops. This will affect the values of shutter speed/iso/aperture you will get when adjusting the exposure, whatever mode you are in.
Custom menu 1 item 1 EV steps
10-03-2012, 09:19 AM   #4
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Sounds like it's because you're set to 1/3 stops for your shutter speed/aperture changes. From https://www.pentaxforums.com/forums/newreply.php?do=newreply&p=1745610

QuoteOriginally posted by ablundon Quote
For most I use 1/3 stops. However, when I use my Cactus V5 triggers I have to switch to 1/2 stops in order to get the 1/180 shutter speed. My K-r doesn't pick up the Cactus as a flash and therefore when on 1/3 stops the shutter speed goes from 1/160 to 1/200. Sync speed is 1/180 (which is a 1/2 stop).


10-03-2012, 09:35 AM   #5
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Ah! I bet it's the 1/3 stops. I'll check that when I have a chance. Thanks!
10-03-2012, 09:41 AM   #6
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QuoteOriginally posted by mattb123 Quote
Ah! I bet it's the 1/3 stops. I'll check that when I have a chance. Thanks!
Please let us know what you find out ... just curious - J
10-03-2012, 09:55 AM   #7
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Nice shot.

If your mode dial has an "X" setting, you can use that to get 1/180.
10-03-2012, 11:01 AM   #8
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QuoteOriginally posted by mattb123 Quote

-------my plan was to shoot at 1/180 but when I tried to set the camera this way I could get 1/160 and then the next click of the dial would go straight to 1/200s. So I shot at 1/160 and the shot turned out fine but I'm wondering why I couldn't select 1/180.
Can anyone tell me for future reference?
The shot was 1/160s, f/10, ISO 80:
It really doesn't/shouldn't matter what your EV-stops are. I have my K-5 EV-steps set to 1/3 and it works like this: When I am in M-mode and my external flash is powered on or if my built-in flash is raised then I can dial my way to down to 1/180s and no faster.

On the other hand, if I have set my exposure time to 1/200s or faster and I thereafter power my external flash on or raise the built-in flash, then the shutter speed will automatically jump to 1/180s.

I would believe, that the K-5 interprets a trigger the same way, but it would be interesting to hear what you find out.

By the way: Fine picture with great colours!

10-03-2012, 11:17 AM   #9
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Thanks for the compliments! I was happy with the shot also.

I just checked the camera and it was indeed set to 1/3 EV steps. Changing it to 1/2 allows me to select 1/180 but of course not 160 anymore, the click below 1/180 is now 1/125 which makes sense.

It seems that the Cactus v5 is not recognized as being a flash by the camera as I can see in the EXIF for that image:

Camera Pentax K-5
Exposure 0.006 sec (1/160)
Aperture f/10.0
Focal Length 33 mm
ISO Speed 80
Exposure Bias 0 EV
Flash Off, Did not fire
10-03-2012, 11:29 AM   #10
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QuoteOriginally posted by johnyates Quote
Nice shot.

If your mode dial has an "X" setting, you can use that to get 1/180.
I see! I'll try that next time. Thanks for the info!
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