K5iis - flash speed bands - 160/125/100 shutter w/ Cactus Rf60 + V6

loji · 01-30-2017, 06:46 PM

I'm using a K5iis and Cactus RF60 + V6.

shooting in manual with only 1 group, no delay set on the flash or V6 trigger.

sometimes when shooting at 160 shutter speed I get banding .. (strip of flash exposure on the top 1/3rd, the rest is black)

once when shooting at 125 I has a black underexposed area at the bottom of the frame.

The flash speed is fine always once I get to 100 shutter.

I thought the flash sync speed limit on Pentax was 180? .. why is even 125 showing banding from a lack of sync speed?

This is my first foray into off camera flash, so is there a setting somewhere I missed ? ... it's also strange that it doesn't always happen. What gives?

Thanks!

Lake · 01-30-2017, 08:26 PM

I have occasionally experienced the same banding. I use cheap radio triggers and was using a fully manual lens on my K5. Maybe it's not caused by the radio triggers. What lens were you using? Hopefully more experienced people add their knowledge.
Lee

MarkJerling · 01-30-2017, 08:34 PM

I've just aquired a RF60x and a V6II. Have not had a chance to play yet - these only arrived yesterday. But, I have been reading the manual for the RF60x. There's a whole section in the manual about this. (Banding)

**UncleVanya** · 01-30-2017, 09:50 PM

I have a k-3 and the Rf-60 and v6 can you post some pics and describe the setup so I can test my k-3 in similar way?

mcgregni · 01-31-2017, 02:31 AM

As the Max sync speed on your camera is 1/180th sec then you are right to expect full flash coverage of the frame at that time value and longer. I have the same Cactus equipment as you and the K7, and shoot most of my flash images at 1/180th with no problems.

Apart from some kind of flash timing fault it could be a problem with the shutter or lens diaphragm, things you may simply not notice with natural light shots. I'd check the RF60 on the hotshoe(local mode) ... That should tell you if it's anything to do with the radio signal timing or not. Also carry out any firmware updates needed and do the factory resets on the Cactus units.

loji · 02-01-2017, 09:29 PM

Thanks for the info :

I tried with multiple lenses, all DA or FA limited .. one A50 1.7 but that worked fine.

the V6i and RF60x have more robust HSS features where banding occurs more often, so it makes sense the manual explains it more deeply.

I tried your suggestion of moving the flash on-camera, and the banding went away. So I did a factory reset on the trigger, and that seems to have solved the problem for now (it was intermittent before, so I'll have to see if it comes back in a few days).

One thing I noticed is in M mode on my K5, the shutter speed jumps from 160 to 200 directly. I looked at the menu settings .. EV is set to 1/3rd of a stop, ISO set to follow EV sensitivity.... is there a shutter range menu item I missed? ... I can't seem to get it to hit 180 ( i have f-stop on the rear dial, shutter speed on the front dial ... does each dial have finer/coarser gains?)

Always much to learn. Thank you guys!

01-30-2017, 06:46 PM	#1
loji Forum Member Join Date: Oct 2016 Posts: 73	K5iis - flash speed bands - 160/125/100 shutter w/ Cactus Rf60 + V6 I'm using a K5iis and Cactus RF60 + V6. shooting in manual with only 1 group, no delay set on the flash or V6 trigger. sometimes when shooting at 160 shutter speed I get banding .. (strip of flash exposure on the top 1/3rd, the rest is black) once when shooting at 125 I has a black underexposed area at the bottom of the frame. The flash speed is fine always once I get to 100 shutter. I thought the flash sync speed limit on Pentax was 180? .. why is even 125 showing banding from a lack of sync speed? This is my first foray into off camera flash, so is there a setting somewhere I missed ? ... it's also strange that it doesn't always happen. What gives? Thanks!

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01-30-2017, 08:26 PM	#2
Lake Senior Member Join Date: Jun 2015 Location: Minnesota Posts: 104	I have occasionally experienced the same banding. I use cheap radio triggers and was using a fully manual lens on my K5. Maybe it's not caused by the radio triggers. What lens were you using? Hopefully more experienced people add their knowledge. Lee

01-30-2017, 08:34 PM	#3
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	I've just aquired a RF60x and a V6II. Have not had a chance to play yet - these only arrived yesterday. But, I have been reading the manual for the RF60x. There's a whole section in the manual about this. (Banding)

01-30-2017, 09:50 PM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,401	I have a k-3 and the Rf-60 and v6 can you post some pics and describe the setup so I can test my k-3 in similar way?

01-31-2017, 02:31 AM	#5
mcgregni Veteran Member Join Date: Sep 2012 Location: Surrey, England Posts: 2,603	As the Max sync speed on your camera is 1/180th sec then you are right to expect full flash coverage of the frame at that time value and longer. I have the same Cactus equipment as you and the K7, and shoot most of my flash images at 1/180th with no problems. Apart from some kind of flash timing fault it could be a problem with the shutter or lens diaphragm, things you may simply not notice with natural light shots. I'd check the RF60 on the hotshoe(local mode) ... That should tell you if it's anything to do with the radio signal timing or not. Also carry out any firmware updates needed and do the factory resets on the Cactus units.

02-01-2017, 09:29 PM	#6
loji Forum Member Join Date: Oct 2016 Posts: 73 Original Poster	Thanks for the info : I tried with multiple lenses, all DA or FA limited .. one A50 1.7 but that worked fine. the V6i and RF60x have more robust HSS features where banding occurs more often, so it makes sense the manual explains it more deeply. I tried your suggestion of moving the flash on-camera, and the banding went away. So I did a factory reset on the trigger, and that seems to have solved the problem for now (it was intermittent before, so I'll have to see if it comes back in a few days). One thing I noticed is in M mode on my K5, the shutter speed jumps from 160 to 200 directly. I looked at the menu settings .. EV is set to 1/3rd of a stop, ISO set to follow EV sensitivity.... is there a shutter range menu item I missed? ... I can't seem to get it to hit 180 ( i have f-stop on the rear dial, shutter speed on the front dial ... does each dial have finer/coarser gains?) Always much to learn. Thank you guys!