Help needed with dark background portraits using multiple Pentax wireless flash units

dizzyfish · 02-22-2020, 04:57 PM

I'm hoping someone can give me some advice. I want to take some facial portrait images with dramatic lighting and dark backgrounds, without having to purchase a black background.

I watched a few Youtube videos, and it looked fairly simple, this one was one of the best...

You Tube

So I thought I would try myself. I have a Pentax K-70 and 3 flash units - Pentax AF540FGZ II, Pentax AF360FGZII and Pentax AF360FGZ. I put the camera into Manual, and took a picture (head and top of shoulders) without the flash so that the image was completely dark (F11 1/160s ISO100).

Next, I set up the on camera flash (I understand that the K70 internal flash cannot control external wireless flash units). I add the AF540FGZ II as a P-TTL Wireless Control on the camera, and another external off camera flash (AF360FGZ II) as a P-TTL Wireless Slave. The wireless slave is set up close to the subject's face (so that the light from the flash shines only on the subject's face, and does not illuminate the background. The flash is also zoomed in manually).

I have a couple of issues -

1) The on camera control flash seems to fire twice (I understand that it needs a pre-flash to communicate to the slave, but it appears to be firing a second time - when the photo is taken?)
2) I am struggling to adjust the front wireless slave's output (it is very difficult to reduce the amount of light and the subject's face is very bright). Also, the background is not very dark. I was adjusting the slave flash output using the EV adjustment on the slave, but even -3ev was not enough, I also used the flash output level, but its very course 1/1, 1/2, 1/3.
3) I did think about putting the slave in Manual wireless mode (as opposed to wireless P-TTL). In this mode, there was no ev level control on the slave, but alot more adjustment of the flash output levels than in P-TTL mode. Also, I was a bit confused as to what to do with the on camera controller, as the only wireless Control mode seemed to be P-TTL?

Hoping someone can help to advise me.

Many thanks - Ian

SharkyCA · 02-22-2020, 05:28 PM - **1 Like**

You may want to check out the posts from McGregni a lot of info available on flash photography!

https://www.pentaxforums.com/forums/125-flashes-lighting-studio/300073-compr...ml#post4924315

Read more at: Comprehensive Pentax Flash Guide - Page 4 - PentaxForums.com
Comprehensive Pentax Flash Guide - Page 4 - PentaxForums.com

stevebrot · 02-22-2020, 06:02 PM - **1 Like**

Originally posted by dizzyfish

1) The on camera control flash seems to fire twice (I understand that it needs a pre-flash to communicate to the slave, but it appears to be firing a second time - when the photo is taken?)

The controller needs to fire twice to instruct the slave. Conventional wisdom is that there is little contribution from the second flash. Truth is that contribution is minimal, but present. If you are concerned, orienting the head of the controller towards the slave and away from your subject might help as might crafting a long snoot for the controller and setting its zoom to maximum focal length for narrowest beam.

Originally posted by dizzyfish

2) I am struggling to adjust the front wireless slave's output (it is very difficult to reduce the amount of light and the subject's face is very bright). Also, the background is not very dark. I was adjusting the slave flash output using the EV adjustment on the slave, but even -3ev was not enough

There are limits to how much one can reduce the slave contribution. This is particularly true if P-TTL is attempted at close range where the pre-flash overwhelms the camera's meter. In that case, the flash may default to full output (my experience, but perhaps not with your gear). Move the slave away from the subject and see if that helps.

Originally posted by dizzyfish

I also used the flash output level, but its very course 1/1, 1/2, 1/3.

I am not sure what you mean here. If you are referring to the flash settings on the camera, those generally only apply to the built-in flash.

Originally posted by dizzyfish

3) I did think about putting the slave in Manual wireless mode (as opposed to wireless P-TTL). In this mode, there was no ev level control on the slave, but alot more adjustment of the flash output levels than in P-TTL mode. Also, I was a bit confused as to what to do with the on camera controller, as the only wireless Control mode seemed to be P-TTL?

As a general optical slave, the on-camera serves a simple relay with the slave firing when flash from the master is detected. Unfortunately, I don't have your setup, but my understanding of the manual is to set the master to manual (non-PTTL) mode and the slave also to manual in SL2 mode.

I hope this helps.

Steve

Aaron28 · 02-22-2020, 07:34 PM - **1 Like**

the 'wireless' control I believe is p-ttl only.....the 1/1, 1/2 & 1/3 would most likely be for 'contrast control' another p-ttl function.....

you may have better luck going all manual to achieve yer goal...(as steve describes)...having the main/control flash just strong enough to activate the slaves to 'do their thing'...….as p-ttl will strive to give 'proper' exposure and be like 'day light'

also it will matter how you have all the flashes 'snooted' or modified to project the light

Last edited by Aaron28; 02-23-2020 at 11:19 AM.

pschlute · 02-23-2020, 01:39 AM - **1 Like**

Manual control is going to give better results than P-TTL for what you want to achieve. You can put the flash units into wireless manual mode. Turn the on-camera unit down to the lowest output 1/256 and point it towards the slave. Select the power setting for the slave to give you your desired result.

I use radio triggers and they are the best solution long term for better control.

remember that the distance from your slave to the subject is important. Too close and it may be that even on minimum power the flash will overexpose the subject. Use a diffuser.

You are on the right track using Manual camera control also.

chrism888 · 02-23-2020, 02:03 AM - **1 Like**

To add to all of the above, fully manual is defiantly the right way to go, also pull the subject as far away from the background as you physically can, more light fall off, you may get very close to achieving your goal straight from the camera, but may also need to tweek the final image in post.

**BWG** · 02-23-2020, 10:22 AM - **1 Like**

Use snoots on your flashes to direct the light on, and only on, your subjects. I’ve made my own snoots with card stock , Velcro tape and black duct tape.

**BarryE** · 02-23-2020, 02:22 PM - **2 Likes**

As is being said: wireless & manual is the way to go - forget ttl.

The way light intensity dropping rapidly over distance is your friend (Inverse square law), however a strip of cheap velvet is very handy as a backdrop and makes things easier. Velvet absorbs light very efficiently and is easy to store and hang. Doesn't need ironing either. It's there to take an almost black background (using inverse square law) to full black and any creases are not noticed and easily cleaned up in post if they occur.

Without a backdrop, I've found there's always something that gets into the frame that's not quite black. Yes you can often clean it up, but why not use fabric or a paper roll and make life easier?

This shot used a velvet backdrop and three flashes.

pschlute · 02-23-2020, 03:53 PM - **1 Like**

I know it is expense, but I use this background from Lastolite. Won't crease and does the job perfectly. https://www.manfrotto.com/uk-en/lastolite/plain-collapsible-1-5-x-1-8m-black...lb56gb-config/

You can also have hours of fun watching your friends trying to collapse it so it fits into it's handy carry bag.

Aaron28 · 02-23-2020, 04:28 PM

Originally posted by pschlute

I know it is expense

just a bit but it looks really neat!!!

Originally posted by pschlute

You can also have hours of fun watching your friends trying to collapse it so it fits into it's handy carry bag.

hahaha! maybe worth the expense!!

dizzyfish · 02-23-2020, 05:23 PM

Thank you to everyone for your replies - this is helping me to understand more about the issues involved. Now I understand that P-TTL is trying to achieve a perfectly exposed picture - it makes alot of sense.

So, it sounds like I need to put my slave flash into manual mode and step down the flash output. The Pentax AF360/540 manual (p22) states that there is a flash mode WIRELESS (M) which can be supported by the Slave. But how do I wirelessly set off the slave from the controller? It looks from the same table on p.22 that the only Wireless Control mode is WIRELESS (P-TTL)....

So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode? I am hoping this is possible without having to switch the Slave flash into optical slave mode (SL2)? (because my slave flash is close to the subject, and the optical SL2 trigger from the camera I am guessing is going to also affect the subject?)

Aaron28 · 02-23-2020, 05:54 PM

Originally posted by dizzyfish

So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode?

not sure of the mode or if it matters for control flash on camera.......for control flash on camera...set the channel of the flash 1-4 (say 1).....have the power switch in the middle for wireless....have the lower switch on C

off camera......for manual set the flash to slave 2... (make sure the channel is on 1) ..power on in the middle for wireless....have the lower switch to S......then set the flash to manual via the mode button and adjust the power output 1/1, 1/2 1/4, 1/8 1/16 1/32 via the wheel........

i'm sure I am missing something......

**West Penn** · 02-24-2020, 10:08 AM

Originally posted by dizzyfish

Thank you to everyone for your replies - this is helping me to understand more about the issues involved. Now I understand that P-TTL is trying to achieve a perfectly exposed picture - it makes alot of sense.

So, it sounds like I need to put my slave flash into manual mode and step down the flash output. The Pentax AF360/540 manual (p22) states that there is a flash mode WIRELESS (M) which can be supported by the Slave. But how do I wirelessly set off the slave from the controller? It looks from the same table on p.22 that the only Wireless Control mode is WIRELESS (P-TTL)....

So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode? I am hoping this is possible without having to switch the Slave flash into optical slave mode (SL2)? (because my slave flash is close to the subject, and the optical SL2 trigger from the camera I am guessing is going to also affect the subject?)

Dizzyfish, forget the Master or Controller terminology when using Manual Flash. What happens in Manual Flash is that when you press the shutter, the on-camera flash fires and the off-camera will fire when is sees the flash emitted by the on-camera flash. In essence the two flashes fire simultaneously. It does this optically, so if for instance you have your off-camera flash inside a softbox (or you're outside in really bright light) the off-camera flash may not be able to see the flash coming from the on-camera flash. In other words, the two flashes must be in line-of-sight of one another. This is really where radio triggers have the advantage.

If you don't want the on-camera flash contributing to the exposure, you can set it to a low power, zoom the head to a narrow beam, and aim it toward the off-camera flash.

The off-camera flash should be set to Slave 1 mode and set the power level to whatever strength necessary to obtain proper exposure.

If the on-camera flash is set to P-TTL mode, you can get the off-camera flash to fire in Manual mode if you set it to Slave 2 mode. In this mode, the off-camera flash ignores the pre-flash and fires when it sees the second flash. You'll likely struggle to get proper exposure, however.

pschlute · 02-24-2020, 10:43 AM

Originally posted by West Penn

If the on-camera flash is set to P-TTL mode, you can get the off-camera flash to fire in Manual mode if you set it to Slave 2 mode. In this mode, the off-camera flash ignores the pre-flash and fires when it sees the second flash. You'll likely struggle to get proper exposure, however.

I don't think that is correct. In Slave 2 mode the off camera flash becomes a "dumb slave". It will fire when it recognises another flash has fired in the vicinity. So if your triggering unit is in P-TTL mode the dumb slave will fire on the pre-flash, not the main flash.

stevebrot · 02-24-2020, 11:28 AM

Originally posted by pschlute

I don't think that is correct. In Slave 2 mode the off camera flash becomes a "dumb slave". It will fire when it recognises another flash has fired in the vicinity. So if your triggering unit is in P-TTL mode the dumb slave will fire on the pre-flash, not the main flash.

Thanks for the clarification here. It is much appreciated due to potential confusion over terms. There is a small and quite reasonable deviation here of Pentax terminology ("Slave 1" vs. "Slave 2") from the conventions used on fully manual speedlights; the speedlight convention being "S1" to fire from any flash with "S2" meaning to ignore preflash. Thanks for pointing this out.

Steve

02-22-2020, 05:28 PM - 1 Like	#2
SharkyCA Pentaxian Join Date: Sep 2017 Location: Carleton Place, Ontario, Canada Photos: Gallery Posts: 806	Resident Guru on Pentax Flash...IMHO You may want to check out the posts from McGregni a lot of info available on flash photography! https://www.pentaxforums.com/forums/125-flashes-lighting-studio/300073-compr...ml#post4924315 Read more at: Comprehensive Pentax Flash Guide - Page 4 - PentaxForums.com Comprehensive Pentax Flash Guide - Page 4 - PentaxForums.com Last edited by SharkyCA; 02-22-2020 at 05:32 PM. Reason: Clean up post

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Macro Flowers \| Vivid Colors - Dark Background	DimC	Post Your Photos!	15	07-17-2018 12:58 AM
Help needed with SHanny SN600FGZ flash exposure issues using K-70	dizzyfish	Flashes, Lighting, and Studio	13	03-20-2018 06:28 AM
OC flash w/ grip mounted, hardwired, Metz 48 af1 & stand mount wireless manual units	MD Optofonik	Flashes, Lighting, and Studio	11	04-21-2013 11:15 AM
For Sale - Sold: Cactus V5 wireless triggers/receivers (4 units)	TOUGEFC	Sold Items	4	09-11-2012 04:03 PM
technical obstacle using monitor as background - strange shadow. Help!	Nass	Troubleshooting and Beginner Help	3	04-12-2012 03:07 PM

02-22-2020, 06:02 PM - 1 Like	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by dizzyfish 1) The on camera control flash seems to fire twice (I understand that it needs a pre-flash to communicate to the slave, but it appears to be firing a second time - when the photo is taken?) The controller needs to fire twice to instruct the slave. Conventional wisdom is that there is little contribution from the second flash. Truth is that contribution is minimal, but present. If you are concerned, orienting the head of the controller towards the slave and away from your subject might help as might crafting a long snoot for the controller and setting its zoom to maximum focal length for narrowest beam. Originally posted by dizzyfish 2) I am struggling to adjust the front wireless slave's output (it is very difficult to reduce the amount of light and the subject's face is very bright). Also, the background is not very dark. I was adjusting the slave flash output using the EV adjustment on the slave, but even -3ev was not enough There are limits to how much one can reduce the slave contribution. This is particularly true if P-TTL is attempted at close range where the pre-flash overwhelms the camera's meter. In that case, the flash may default to full output (my experience, but perhaps not with your gear). Move the slave away from the subject and see if that helps. Originally posted by dizzyfish I also used the flash output level, but its very course 1/1, 1/2, 1/3. I am not sure what you mean here. If you are referring to the flash settings on the camera, those generally only apply to the built-in flash. Originally posted by dizzyfish 3) I did think about putting the slave in Manual wireless mode (as opposed to wireless P-TTL). In this mode, there was no ev level control on the slave, but alot more adjustment of the flash output levels than in P-TTL mode. Also, I was a bit confused as to what to do with the on camera controller, as the only wireless Control mode seemed to be P-TTL? As a general optical slave, the on-camera serves a simple relay with the slave firing when flash from the master is detected. Unfortunately, I don't have your setup, but my understanding of the manual is to set the master to manual (non-PTTL) mode and the slave also to manual in SL2 mode. I hope this helps. Steve

02-22-2020, 07:34 PM - 1 Like	#4
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	the 'wireless' control I believe is p-ttl only.....the 1/1, 1/2 & 1/3 would most likely be for 'contrast control' another p-ttl function..... you may have better luck going all manual to achieve yer goal...(as steve describes)...having the main/control flash just strong enough to activate the slaves to 'do their thing'...….as p-ttl will strive to give 'proper' exposure and be like 'day light' also it will matter how you have all the flashes 'snooted' or modified to project the light Last edited by Aaron28; 02-23-2020 at 11:19 AM.

02-23-2020, 01:39 AM - 1 Like	#5
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,212	Manual control is going to give better results than P-TTL for what you want to achieve. You can put the flash units into wireless manual mode. Turn the on-camera unit down to the lowest output 1/256 and point it towards the slave. Select the power setting for the slave to give you your desired result. I use radio triggers and they are the best solution long term for better control. remember that the distance from your slave to the subject is important. Too close and it may be that even on minimum power the flash will overexpose the subject. Use a diffuser. You are on the right track using Manual camera control also.

02-23-2020, 02:03 AM - 1 Like	#6
chrism888 Senior Member Join Date: Feb 2012 Posts: 178	To add to all of the above, fully manual is defiantly the right way to go, also pull the subject as far away from the background as you physically can, more light fall off, you may get very close to achieving your goal straight from the camera, but may also need to tweek the final image in post.

02-23-2020, 10:22 AM - 1 Like	#7
BWG Loyal Site Supporter Join Date: Feb 2007 Location: Monterey County, California Posts: 165	Use snoots on your flashes to direct the light on, and only on, your subjects. I’ve made my own snoots with card stock , Velcro tape and black duct tape.

02-23-2020, 03:53 PM - 1 Like	#9
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,212	I know it is expense, but I use this background from Lastolite. Won't crease and does the job perfectly. https://www.manfrotto.com/uk-en/lastolite/plain-collapsible-1-5-x-1-8m-black...lb56gb-config/ You can also have hours of fun watching your friends trying to collapse it so it fits into it's handy carry bag.

02-23-2020, 04:28 PM	#10
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	Originally posted by pschlute I know it is expense just a bit but it looks really neat!!! Originally posted by pschlute You can also have hours of fun watching your friends trying to collapse it so it fits into it's handy carry bag. hahaha! maybe worth the expense!!

02-23-2020, 05:23 PM	#11
dizzyfish New Member Join Date: Mar 2018 Posts: 15 Original Poster	Thank you to everyone for your replies - this is helping me to understand more about the issues involved. Now I understand that P-TTL is trying to achieve a perfectly exposed picture - it makes alot of sense. So, it sounds like I need to put my slave flash into manual mode and step down the flash output. The Pentax AF360/540 manual (p22) states that there is a flash mode WIRELESS (M) which can be supported by the Slave. But how do I wirelessly set off the slave from the controller? It looks from the same table on p.22 that the only Wireless Control mode is WIRELESS (P-TTL).... So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode? I am hoping this is possible without having to switch the Slave flash into optical slave mode (SL2)? (because my slave flash is close to the subject, and the optical SL2 trigger from the camera I am guessing is going to also affect the subject?)

02-23-2020, 05:54 PM	#12
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	Originally posted by dizzyfish So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode? not sure of the mode or if it matters for control flash on camera.......for control flash on camera...set the channel of the flash 1-4 (say 1).....have the power switch in the middle for wireless....have the lower switch on C off camera......for manual set the flash to slave 2... (make sure the channel is on 1) ..power on in the middle for wireless....have the lower switch to S......then set the flash to manual via the mode button and adjust the power output 1/1, 1/2 1/4, 1/8 1/16 1/32 via the wheel........ i'm sure I am missing something......

02-24-2020, 10:08 AM	#13
West Penn Site Supporter Join Date: Apr 2012 Posts: 251	Originally posted by dizzyfish Thank you to everyone for your replies - this is helping me to understand more about the issues involved. Now I understand that P-TTL is trying to achieve a perfectly exposed picture - it makes alot of sense. So, it sounds like I need to put my slave flash into manual mode and step down the flash output. The Pentax AF360/540 manual (p22) states that there is a flash mode WIRELESS (M) which can be supported by the Slave. But how do I wirelessly set off the slave from the controller? It looks from the same table on p.22 that the only Wireless Control mode is WIRELESS (P-TTL).... So is an on camera CONTROL flash (360/540) in WIRELESS P-TTL mode able to set off a Slave flash in WIRELESS (M) mode? I am hoping this is possible without having to switch the Slave flash into optical slave mode (SL2)? (because my slave flash is close to the subject, and the optical SL2 trigger from the camera I am guessing is going to also affect the subject?) Dizzyfish, forget the Master or Controller terminology when using Manual Flash. What happens in Manual Flash is that when you press the shutter, the on-camera flash fires and the off-camera will fire when is sees the flash emitted by the on-camera flash. In essence the two flashes fire simultaneously. It does this optically, so if for instance you have your off-camera flash inside a softbox (or you're outside in really bright light) the off-camera flash may not be able to see the flash coming from the on-camera flash. In other words, the two flashes must be in line-of-sight of one another. This is really where radio triggers have the advantage. If you don't want the on-camera flash contributing to the exposure, you can set it to a low power, zoom the head to a narrow beam, and aim it toward the off-camera flash. The off-camera flash should be set to Slave 1 mode and set the power level to whatever strength necessary to obtain proper exposure. If the on-camera flash is set to P-TTL mode, you can get the off-camera flash to fire in Manual mode if you set it to Slave 2 mode. In this mode, the off-camera flash ignores the pre-flash and fires when it sees the second flash. You'll likely struggle to get proper exposure, however.

02-24-2020, 10:43 AM	#14
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,212	Originally posted by West Penn If the on-camera flash is set to P-TTL mode, you can get the off-camera flash to fire in Manual mode if you set it to Slave 2 mode. In this mode, the off-camera flash ignores the pre-flash and fires when it sees the second flash. You'll likely struggle to get proper exposure, however. I don't think that is correct. In Slave 2 mode the off camera flash becomes a "dumb slave". It will fire when it recognises another flash has fired in the vicinity. So if your triggering unit is in P-TTL mode the dumb slave will fire on the pre-flash, not the main flash.

02-24-2020, 11:28 AM	#15
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by pschlute I don't think that is correct. In Slave 2 mode the off camera flash becomes a "dumb slave". It will fire when it recognises another flash has fired in the vicinity. So if your triggering unit is in P-TTL mode the dumb slave will fire on the pre-flash, not the main flash. Thanks for the clarification here. It is much appreciated due to potential confusion over terms. There is a small and quite reasonable deviation here of Pentax terminology ("Slave 1" vs. "Slave 2") from the conventions used on fully manual speedlights; the speedlight convention being "S1" to fire from any flash with "S2" meaning to ignore preflash. Thanks for pointing this out. Steve