Pentax Flash Questions

BBear · 01-06-2010, 09:14 AM

Hello guys,

I currently have a set of (6) 285 + Cybersyncs for manual-mode off-camera flashing and a kit with (1) 540 + (1) 360 Pentax flashes.

I wanted to test the P-TTL system and how it would perform in wireless mode, and maybe compare to manual-mode with radio Tx, and ideally selling the Vivitars and buying more Pentax flashes (which could be used in Manual & TTL).

I played with it for a while, and few questions came up:

- Under PTTL mode, what is the "1/1" "1/2" "2/3" "1/3" numbers that can be selected? I thought it was power output, but it is not and changing from lowest to 1/1 was not changing anything on the pictures. I could not tell any differences in the pictures.

- Under PTTL, if I go from f/4 to f/11, and kept the compensation zeroed, the exposure SHOULD be exactly the same (regarding flash output), no?? I tried this, and as I stop down, the exposure was getting DARKER, which would make sense in MANUAL mode, but NOT in TTL mode. Shouldn't the TTL system adjust flash output to keep exposure correct?

- What is the difference in SL1 & SL2 modes (it is called SLAVE under the manual, pages 52 and 63 or something like that)? I know SL2 only offers mode "A" and "MANUAL", but the confusion comes from the fact that under SL1 I also have these modes. If I am using the flash wirelessly in MANUAL, does it matter if I am under SL1 or SL2?

Thanks in advance for any inputs,

BB

Russell-Evans · 01-06-2010, 04:24 PM

Originally posted by BBear

- Under PTTL mode, what is the "1/1" "1/2" "2/3" "1/3" numbers that can be selected? I thought it was power output, but it is not and changing from lowest to 1/1 was not changing anything on the pictures. I could not tell any differences in the pictures.

Use both flashes off camera with the pop up as a controller, i.e. custom menu > flash in wireless > off. With the 540 on the left and the 360 one the right, setting the 540 to 1/3 and the 360 to 1/1, should have the 360 casting a shadow. Setting the 540 to 1/1 and the 360 to 1/2 should have the 540 casting a shadow.

I only did this with two 360 flashes and the pop up so the settings above might not work with the different Pentax flashes, but by using this setting with the two 360s, I could cast the shadows around the table top subject I was shooting. I'm not sure how this will work in a larger scene as I didn't test that.

Originally posted by BBear

- Under PTTL, if I go from f/4 to f/11, and kept the compensation zeroed, the exposure SHOULD be exactly the same (regarding flash output), no?? I tried this, and as I stop down, the exposure was getting DARKER, which would make sense in MANUAL mode, but NOT in TTL mode. Shouldn't the TTL system adjust flash output to keep exposure correct?

This depends on the camera mode setting, flash setting, and sync used. In some modes the flash is included in the exposure, and in others not.

This probably gives the best concise answer.
Flash Modes for Pentax Photo Gallery by Steve Jacob at pbase.com

Originally posted by BBear

- What is the difference in SL1 & SL2 modes (it is called SLAVE under the manual, pages 52 and 63 or something like that)? I know SL2 only offers mode "A" and "MANUAL", but the confusion comes from the fact that under SL1 I also have these modes. If I am using the flash wirelessly in MANUAL, does it matter if I am under SL1 or SL2?

SL2 mode is a simple optical trigger. The flashes will trigger on any flash. You could mount one of your 285 flashes on the camera and use the 540 and 360 as optical slaves. If you have any pre A lenses, the pop up flash will only fire a full power and a main flash of the Pentax DSLRs. Having the SL2 mode means you still can get the flash off the camera.

Manual or Auto under SL1 mode is still using the wireless channels to communicate so the camera and flash have to be set correctly. This is nice if you are working around other Pentax photographers where each can be shooting on their own channel. In SL2 mode, being a simple optical trigger, your flashes would go off on any flash, whether from your camera or not.

Thank you
Russell

BBear · 01-07-2010, 09:25 AM

Russell

Thanks for the reply. I guess most people don't have too much experience at this level with the PTTL, so not much feedback on the forum.

First of all, I missed this very important piece of information: the pop-up flash was CONTROL-ONLY in all my tests, and did not participate in the exposure. Yes, I went in the menu and changed the setting.

Question #1: Regarding the 1/1 setting, I am not sure what the technical name is, but you explained it very well. It basically only works if you are using two PTTL and want to control contrast between them, correct? I'll play with it later and confirm it.

Question #2: i need to further investiga this, because the off-camera flash should be compensating/adjusting according to f/ to match the same exposure... this is (should) be the idea behind TTL. I am still trying to figure out the link you sent. Thanks.

Question #3: Great explanation... i'll try SL1 with my cameras in different channels to make sure it works. I guess if it does works as you explained, I should always leave it on SL1.

Thanks a ton for the feedback, and if you do please have any more material or threads on how to fully use PTTL, please let me know.

BB

Russell-Evans · 01-07-2010, 10:08 AM

Originally posted by BBear

Question #1: Regarding the 1/1 setting, I am not sure what the technical name is, but you explained it very well. It basically only works if you are using two PTTL and want to control contrast between them, correct? I'll play with it later and confirm it.

I tried to talk with Pentax's support about this and could not get a decent answer. The manual says that contrast control is only avialable via a wired connection. Being able to move the shadows around makes me think it is wireless contrast control, but I can't tell for sure that the total amount of light provided by the two flash set up stays the same. It would take a flash meter to really tell and I don't have one.

The only other information I can add about P-TTL is that P-TTL always uses matrix metering, regardless of what is set on the camera. Add to that, that wireless P-TTL disables the shake reduction feature in the cameras and you have everything I know about P-TTL.

Thank you
Russell

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01-06-2010, 09:14 AM	#1
BBear Veteran Member Join Date: Mar 2008 Location: CT / NY Photos: Gallery Posts: 822	Pentax Flash Questions Hello guys, I currently have a set of (6) 285 + Cybersyncs for manual-mode off-camera flashing and a kit with (1) 540 + (1) 360 Pentax flashes. I wanted to test the P-TTL system and how it would perform in wireless mode, and maybe compare to manual-mode with radio Tx, and ideally selling the Vivitars and buying more Pentax flashes (which could be used in Manual & TTL). I played with it for a while, and few questions came up: - Under PTTL mode, what is the "1/1" "1/2" "2/3" "1/3" numbers that can be selected? I thought it was power output, but it is not and changing from lowest to 1/1 was not changing anything on the pictures. I could not tell any differences in the pictures. - Under PTTL, if I go from f/4 to f/11, and kept the compensation zeroed, the exposure SHOULD be exactly the same (regarding flash output), no?? I tried this, and as I stop down, the exposure was getting DARKER, which would make sense in MANUAL mode, but NOT in TTL mode. Shouldn't the TTL system adjust flash output to keep exposure correct? - What is the difference in SL1 & SL2 modes (it is called SLAVE under the manual, pages 52 and 63 or something like that)? I know SL2 only offers mode "A" and "MANUAL", but the confusion comes from the fact that under SL1 I also have these modes. If I am using the flash wirelessly in MANUAL, does it matter if I am under SL1 or SL2? Thanks in advance for any inputs, BB

01-06-2010, 04:24 PM	#2
Russell-Evans Veteran Member Join Date: Nov 2007 Posts: 1,553	Originally posted by BBear - Under PTTL mode, what is the "1/1" "1/2" "2/3" "1/3" numbers that can be selected? I thought it was power output, but it is not and changing from lowest to 1/1 was not changing anything on the pictures. I could not tell any differences in the pictures. Use both flashes off camera with the pop up as a controller, i.e. custom menu > flash in wireless > off. With the 540 on the left and the 360 one the right, setting the 540 to 1/3 and the 360 to 1/1, should have the 360 casting a shadow. Setting the 540 to 1/1 and the 360 to 1/2 should have the 540 casting a shadow. I only did this with two 360 flashes and the pop up so the settings above might not work with the different Pentax flashes, but by using this setting with the two 360s, I could cast the shadows around the table top subject I was shooting. I'm not sure how this will work in a larger scene as I didn't test that. Originally posted by BBear - Under PTTL, if I go from f/4 to f/11, and kept the compensation zeroed, the exposure SHOULD be exactly the same (regarding flash output), no?? I tried this, and as I stop down, the exposure was getting DARKER, which would make sense in MANUAL mode, but NOT in TTL mode. Shouldn't the TTL system adjust flash output to keep exposure correct? This depends on the camera mode setting, flash setting, and sync used. In some modes the flash is included in the exposure, and in others not. This probably gives the best concise answer. Flash Modes for Pentax Photo Gallery by Steve Jacob at pbase.com Originally posted by BBear - What is the difference in SL1 & SL2 modes (it is called SLAVE under the manual, pages 52 and 63 or something like that)? I know SL2 only offers mode "A" and "MANUAL", but the confusion comes from the fact that under SL1 I also have these modes. If I am using the flash wirelessly in MANUAL, does it matter if I am under SL1 or SL2? SL2 mode is a simple optical trigger. The flashes will trigger on any flash. You could mount one of your 285 flashes on the camera and use the 540 and 360 as optical slaves. If you have any pre A lenses, the pop up flash will only fire a full power and a main flash of the Pentax DSLRs. Having the SL2 mode means you still can get the flash off the camera. Manual or Auto under SL1 mode is still using the wireless channels to communicate so the camera and flash have to be set correctly. This is nice if you are working around other Pentax photographers where each can be shooting on their own channel. In SL2 mode, being a simple optical trigger, your flashes would go off on any flash, whether from your camera or not. Thank you Russell

01-07-2010, 09:25 AM	#3
BBear Veteran Member Join Date: Mar 2008 Location: CT / NY Photos: Gallery Posts: 822 Original Poster	Russell Thanks for the reply. I guess most people don't have too much experience at this level with the PTTL, so not much feedback on the forum. First of all, I missed this very important piece of information: the pop-up flash was CONTROL-ONLY in all my tests, and did not participate in the exposure. Yes, I went in the menu and changed the setting. Question #1: Regarding the 1/1 setting, I am not sure what the technical name is, but you explained it very well. It basically only works if you are using two PTTL and want to control contrast between them, correct? I'll play with it later and confirm it. Question #2: i need to further investiga this, because the off-camera flash should be compensating/adjusting according to f/ to match the same exposure... this is (should) be the idea behind TTL. I am still trying to figure out the link you sent. Thanks. Question #3: Great explanation... i'll try SL1 with my cameras in different channels to make sure it works. I guess if it does works as you explained, I should always leave it on SL1. Thanks a ton for the feedback, and if you do please have any more material or threads on how to fully use PTTL, please let me know. BB

01-07-2010, 10:08 AM	#4
Russell-Evans Veteran Member Join Date: Nov 2007 Posts: 1,553	Originally posted by BBear Question #1: Regarding the 1/1 setting, I am not sure what the technical name is, but you explained it very well. It basically only works if you are using two PTTL and want to control contrast between them, correct? I'll play with it later and confirm it. I tried to talk with Pentax's support about this and could not get a decent answer. The manual says that contrast control is only avialable via a wired connection. Being able to move the shadows around makes me think it is wireless contrast control, but I can't tell for sure that the total amount of light provided by the two flash set up stays the same. It would take a flash meter to really tell and I don't have one. The only other information I can add about P-TTL is that P-TTL always uses matrix metering, regardless of what is set on the camera. Add to that, that wireless P-TTL disables the shake reduction feature in the cameras and you have everything I know about P-TTL. Thank you Russell