AF540FGZ P-TTL vs A on K-1

mcgregni · 07-01-2016, 12:20 AM

Originally posted by Flasher

One strange thing I have just had a play with my K3 and when in Av the minimum shutter is 1/125 at f2.8 even in a dark room. You mentioned 1/60.
Turn the flash off and see what the shutter is (should be slow in a darkened room), turn the flash on and see if the shutter changes up to the minimum. Point the camera out the window to daylight and the shutter should go to the max shutter (1/160 or 1/180 on K3 and perhaps 1/200 on K-1?)

Of course the K-1 may be lower min shutter and I am using 1/3 EV stops not 1/2 so that may be the difference.

You need to use Slow Speed Sync mode for that to happen when in an auto-exposure mode ....

take a look at my guide, it has a lot of details of all these modes, including A mode ....

Flasher · 07-01-2016, 12:37 AM

Originally posted by mcgregni

You need to use Slow Speed Sync mode for that to happen when in an auto-exposure mode ....

take a look at my guide, it has a lot of details of all these modes, including A mode ....

No it was because I had zoomed in with my 28-70 lens. Zooming out set the shutter to 1/60th. That was in leading curtain sync. I had forgotten that zooming changes min shutter when in Av.

**clackers** · 07-01-2016, 01:06 AM

Originally posted by Flasher

No it was because I had zoomed in with my 28-70 lens. Zooming out set the shutter to 1/60th. That was in leading curtain sync. I had forgotten that zooming changes min shutter when in Av.

But you only have a minimum speed because you're not in Slow Sync.

You're so stubborn. You should listen to McGregni.

Flasher · 07-01-2016, 01:10 AM

Originally posted by clackers

But you only have a minimum speed because you're not in Slow Sync.

You're so stubborn. You should listen to McGregni.

Oh ok sorry I didn't realise that's what he was saying, my apology.

---------- Post added 07-01-16 at 06:45 PM ----------

Originally posted by Flasher

Oh ok sorry I didn't realise that's what he was saying, my apology.

Yes that was a misunderstanding, my original comment was just to point out that my minimum shutter was different to Sinus. I realised slow sync will allow lower but that wasn't my point. Sorry about that McGregni.

Last edited by Flasher; 07-01-2016 at 01:43 AM.

**sinus007** · 07-01-2016, 05:31 AM

Thank you guys,
It was a great lesson. Now I have to practice.
First task is to figure the right settings for family pictures with fireworks as background...

mcgregni · 07-01-2016, 09:34 AM

Glad its cleared up

... just to be precise, the exposure time restriction (which is related to focal length, as Flasher was saying) only applies to P and Av modes in practice. In Tav, Tv and M modes its not a valid flash mode because the time value can be set directly. So Slow Speed Sync is really a kind of temporary override of the limitation for people carrying out all-auto flash photography, the sort of thing you might use for portraits in low light when you want to record a balance between a dark background and a flash-lit subject ..... the typical example of this is the twilight cityscape scene. But then, we're not going to be using automatic exposure modes for that sort of thing, are we, we're going to using manual plus P-TTL, right ?

beholder3 · 07-01-2016, 10:19 AM

Originally posted by sinus007

First task is to figure the right settings for family pictures with fireworks as background...

Last time the ambient light was calling for 1/80, F2.8, ISO 4000 = LV 4 for the fireworks.

Usually you want more trails in the fireworks itself, so you go for longer shutter speeds than what I wrote and can go down with ISO to balance.If you have people in the frame, so probably can not go too long with the shutter times.

But the main challange for your scenario is that the 540FGZ is so powerful that at the above settings it can not limit its own output enough, so that it shows a minimum subject distance of 8 meters.
Assuming that you would want to employ a wide angle lens that will create small people with an even smaller fireworks background.

So you would need some filter on the flash head to reduce its output beyond what it can do itself.

**UncleVanya** · 07-01-2016, 10:59 AM

Originally posted by beholder3

Last time the ambient light was calling for 1/80, F2.8, ISO 4000 = LV 4 for the fireworks.

Usually you want more trails in the fireworks itself, so you go for longer shutter speeds than what I wrote and can go down with ISO to balance.If you have people in the frame, so probably can not go too long with the shutter times.

But the main challange for your scenario is that the 540FGZ is so powerful that at the above settings it can not limit its own output enough, so that it shows a minimum subject distance of 8 meters.
Assuming that you would want to employ a wide angle lens that will create small people with an even smaller fireworks background.

So you would need some filter on the flash head to reduce its output beyond what it can do itself.

Or shoot multiple exposures - expose the people in one and the fireworks in another.

Flasher · 07-02-2016, 03:11 AM

Good thread on the K-3 area about fireworks.
Best answer on the first page is probably this one from WPRESTO....I will second or third recommendations above: 1) prefocus (turn focus to manual, off of AF)2l) low ISO and small f-stop (ISO 100, f11~16 - - fireworks are very bright, too high an ISO will burn out all the color); 3) tripod with remote release; 4) set on bulb and keep the shutter open as several skyrockets go up. The images generally look better with multiple overlapping explosions.

And as UncleVanya says do multiple shot composite. If you want it in one shot then set the flash to trailing curtain sync. I haven't tried but it should work with Bulb mode. McGregni might be able to confirm that.

Read more at: https://www.pentaxforums.com/forums/172-pentax-k-3/324640-shooting-fireworks-...#ixzz4DFDrbx8c

mcgregni · 07-02-2016, 04:46 AM - **1 Like**

I don't know about that

... Based on how this thread started out, its amazing that its morphed into one about shooting fireworks with a flash-lit subject ! Quite a sophisticated technique to get looking really good. I'd say that for practising and getting to grips with flash exposure modes and ambient light / flash balancing, that much simpler scenarios would be better to perfect first.

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07-01-2016, 12:20 AM	#31
mcgregni Veteran Member Join Date: Sep 2012 Location: Surrey, England Posts: 2,603	Originally posted by Flasher One strange thing I have just had a play with my K3 and when in Av the minimum shutter is 1/125 at f2.8 even in a dark room. You mentioned 1/60. Turn the flash off and see what the shutter is (should be slow in a darkened room), turn the flash on and see if the shutter changes up to the minimum. Point the camera out the window to daylight and the shutter should go to the max shutter (1/160 or 1/180 on K3 and perhaps 1/200 on K-1?) Of course the K-1 may be lower min shutter and I am using 1/3 EV stops not 1/2 so that may be the difference. You need to use Slow Speed Sync mode for that to happen when in an auto-exposure mode .... take a look at my guide, it has a lot of details of all these modes, including A mode ....

07-01-2016, 12:37 AM	#32
Flasher Forum Member Join Date: Jan 2014 Posts: 50	Originally posted by mcgregni You need to use Slow Speed Sync mode for that to happen when in an auto-exposure mode .... take a look at my guide, it has a lot of details of all these modes, including A mode .... No it was because I had zoomed in with my 28-70 lens. Zooming out set the shutter to 1/60th. That was in leading curtain sync. I had forgotten that zooming changes min shutter when in Av.

07-01-2016, 01:06 AM	#33
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by Flasher No it was because I had zoomed in with my 28-70 lens. Zooming out set the shutter to 1/60th. That was in leading curtain sync. I had forgotten that zooming changes min shutter when in Av. But you only have a minimum speed because you're not in Slow Sync. You're so stubborn. You should listen to McGregni.

07-01-2016, 01:10 AM	#34
Flasher Forum Member Join Date: Jan 2014 Posts: 50	Originally posted by clackers But you only have a minimum speed because you're not in Slow Sync. You're so stubborn. You should listen to McGregni. Oh ok sorry I didn't realise that's what he was saying, my apology. ---------- Post added 07-01-16 at 06:45 PM ---------- Originally posted by Flasher Oh ok sorry I didn't realise that's what he was saying, my apology. Yes that was a misunderstanding, my original comment was just to point out that my minimum shutter was different to Sinus. I realised slow sync will allow lower but that wasn't my point. Sorry about that McGregni. Last edited by Flasher; 07-01-2016 at 01:43 AM.

07-01-2016, 05:31 AM	#35
sinus007 Site Supporter Join Date: Jul 2008 Location: Cleveland, OH, USA Photos: Gallery Posts: 292 Original Poster	Thank you guys, It was a great lesson. Now I have to practice. First task is to figure the right settings for family pictures with fireworks as background...

07-01-2016, 09:34 AM	#36
mcgregni Veteran Member Join Date: Sep 2012 Location: Surrey, England Posts: 2,603	Glad its cleared up ... just to be precise, the exposure time restriction (which is related to focal length, as Flasher was saying) only applies to P and Av modes in practice. In Tav, Tv and M modes its not a valid flash mode because the time value can be set directly. So Slow Speed Sync is really a kind of temporary override of the limitation for people carrying out all-auto flash photography, the sort of thing you might use for portraits in low light when you want to record a balance between a dark background and a flash-lit subject ..... the typical example of this is the twilight cityscape scene. But then, we're not going to be using automatic exposure modes for that sort of thing, are we, we're going to using manual plus P-TTL, right ?

07-01-2016, 10:19 AM	#37
beholder3 Pentaxian Join Date: Dec 2011 Posts: 3,112	Originally posted by sinus007 First task is to figure the right settings for family pictures with fireworks as background... Last time the ambient light was calling for 1/80, F2.8, ISO 4000 = LV 4 for the fireworks. Usually you want more trails in the fireworks itself, so you go for longer shutter speeds than what I wrote and can go down with ISO to balance.If you have people in the frame, so probably can not go too long with the shutter times. But the main challange for your scenario is that the 540FGZ is so powerful that at the above settings it can not limit its own output enough, so that it shows a minimum subject distance of 8 meters. Assuming that you would want to employ a wide angle lens that will create small people with an even smaller fireworks background. So you would need some filter on the flash head to reduce its output beyond what it can do itself.

07-01-2016, 10:59 AM	#38
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,402	Originally posted by beholder3 Last time the ambient light was calling for 1/80, F2.8, ISO 4000 = LV 4 for the fireworks. Usually you want more trails in the fireworks itself, so you go for longer shutter speeds than what I wrote and can go down with ISO to balance.If you have people in the frame, so probably can not go too long with the shutter times. But the main challange for your scenario is that the 540FGZ is so powerful that at the above settings it can not limit its own output enough, so that it shows a minimum subject distance of 8 meters. Assuming that you would want to employ a wide angle lens that will create small people with an even smaller fireworks background. So you would need some filter on the flash head to reduce its output beyond what it can do itself. Or shoot multiple exposures - expose the people in one and the fireworks in another.

07-02-2016, 03:11 AM	#39
Flasher Forum Member Join Date: Jan 2014 Posts: 50	Good thread on the K-3 area about fireworks. Best answer on the first page is probably this one from WPRESTO....I will second or third recommendations above: 1) prefocus (turn focus to manual, off of AF)2l) low ISO and small f-stop (ISO 100, f11~16 - - fireworks are very bright, too high an ISO will burn out all the color); 3) tripod with remote release; 4) set on bulb and keep the shutter open as several skyrockets go up. The images generally look better with multiple overlapping explosions. And as UncleVanya says do multiple shot composite. If you want it in one shot then set the flash to trailing curtain sync. I haven't tried but it should work with Bulb mode. McGregni might be able to confirm that. Read more at: https://www.pentaxforums.com/forums/172-pentax-k-3/324640-shooting-fireworks-...#ixzz4DFDrbx8c

07-02-2016, 04:46 AM - 1 Like	#40
mcgregni Veteran Member Join Date: Sep 2012 Location: Surrey, England Posts: 2,603	I don't know about that ... Based on how this thread started out, its amazing that its morphed into one about shooting fireworks with a flash-lit subject ! Quite a sophisticated technique to get looking really good. I'd say that for practising and getting to grips with flash exposure modes and ambient light / flash balancing, that much simpler scenarios would be better to perfect first.