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AF540 "how to use" assistance

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CoolHandLu

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I must admit I'm pretty confused with all of the bells and wistles of this new AF540 flash I purchased. I set it up to default to P-TTL mode, but taking indoor pics in my K10Ds P mode is about as far as I've gotten. I'm frankly quite happy with the result - I'm boucing my flash and using a defuser and the pics look pretty sweet. Mostly house parties with guests both young and old plus assorted pets.

Still, there's a ton of functionality I'm not using b/c I dont' really understand it: stuff like leading shutter curtain sync, trailing shutter curtain sync, contrast control sync, high speed sync - lordy be.

This forum for Pentax is great, but I'm afraid most of the users and their comments re: flash go over my head. I'm a beginner photographer when it comes to flash, mostly shooting outdoors with my old Pentax K1000 and, when indoors, I manually entered my ISO, F stop and shutter speed on my old Vivitar Thyristor 1500 (or 2500?). This was all before I recently picked up my K10D (LOVE it) and, just last week, my new flash.

I know using a modern flash properly and realizing its full potential can be pretty complicated stuff - is there any resource (other than the owners manual for this flash - I'm NOT stupid, and that document still has my head spinning) that you can point me to? I thought there's be an online "how to" specificically set up for this flash, but I can't find anything.
Thanks!
Brian
 
steephill said:
For great flash advice in general have a look at this site
http://strobist.blogspot.com/2006/03/lighting-101.html
Click to expand...
Yes, this is the most frequently recommended site. And it does have a lot of valuable information about lighting.

But one thing you should be aware of is that its main emphasis is on manual flash and not P-TTL. OTOH, it should not be difficult to adapt the techniques (actually using P-TTL should be easier than manual flash).
 
Hey, thanks for the site! I'll definately take a look see. And I think you are spot on re: advice of taking it one step at a time.
:-)
Brian
 
CoolHandLu said:
I must admit I'm pretty confused with all of the bells and wistles of
this new AF540 flash I purchased. I set it up to default to P-TTL
mode, but taking indoor pics in my K10Ds P mode is about as far as
I've gotten. I'm frankly quite happy with the result - I'm boucing
my flash and using a defuser and the pics look pretty sweet. Mostly
house parties with guests both young and old plus assorted pets.

Still, there's a ton of functionality I'm not using b/c I dont'
really understand it: stuff like leading shutter curtain sync,
trailing shutter curtain sync, contrast control sync, high speed sync
  • lordy be.
This forum for Pentax is great, but I'm afraid most of the users and
their comments re: flash go over my head. I'm a beginner
photographer when it comes to flash, mostly shooting outdoors with my
old Pentax K1000 and, when indoors, I manually entered my ISO, F stop
and shutter speed on my old Vivitar Thyristor 1500 (or 2500?). This
was all before I recently picked up my K10D (LOVE it) and, just last
week, my new flash.

I know using a modern flash properly and realizing its full potential
can be pretty complicated stuff - is there any resource (other than
the owners manual for this flash - I'm NOT stupid, and that document
still has my head spinning) that you can point me to? I thought
there's be an online "how to" specificically set up for this flash,
but I can't find anything.
Thanks!
Brian
Click to expand...
Its never a bad idea to buy a good book on a subject - sorry I cant recommend one but ask around.

Flash like most simple things can be used in a bewildering variety of creative ways, but these are all based on the same three basic techniques...

1. Primary illumination
2. Contrast control illumination in high ambient light ("fill flash")
3. Freezing action and contrast control in low ambient light ("slow sync flash")

The first is the most obvious. Flash is used as the primary light source, period. Usually this works best with multiple lights, bounce, reflectors or diffusers to make it more subtle because a single direct flash can be pretty harsh. This is more or less the "standard" mode. If you use the flash in P or Av mode using normal flash or redeye flash this is what it will do - it will assume the flash is providing the light and if the ambient light is low, the flash will be the main illumination because the camera will maintain a shutter speed consistent with the program line (ie 1/focal length at least). If the ambient light is high enough to illuminate the subject anyway, then this is effectively providing fill-in flash (see below).

The second is generally used when you want to emphasise a subject relative to a background or reduce shadows caused by the position of the subject relative to ambient backlight. This latter is also called fill flash but the same technique applies. You want to expose both for the background but illuminate the subject using the flash so it stands out relative to that background or removes shadows. It is VERY hard for a camera meter to do this in full auto because the meter does not really know what relative light levels you want to apply to the subject and background, but generally if you fire the flash in HSS mode (external flash only) using PTTL in M, or Tv mode it will meter for ambient light and do its best to get it right depending on the focus distance. (Note HSS mode will allow the camera to exceed 1/180 which if you are shooting outdoors is quite possible). With digital you can always check and adjust and you can perform EV compensation on both flash and camera to change the relative foreground and background balance. However purists will use M more on flash AND camera and take some test shots and meter readings to perfect the lighting.

The last is for creative folk - its basically called slow speed sync flash and is used when you wish to freeze and illuminate a near subject relative to a dark background that requires a slow shutter speed. If you use M or Tv mode it will work exactly as above (except you wont need HSS because the shutter speed is unlikely to exceed 1/180) except the shutter speed will be lower and the background will blur if its moving or you dont use a tripod - which can look cool. If you use Av or P mode you need to tell the camera to use slow speed sync and switch the CAMERA to slow sync mode. There are two slow synch modes, trailing and leading. This merely tells you when to fire the flash, at the beginning of the exposure or at the end. M and Tv default to leading curtain sync.

And dont forget, if your flash is not producing enough power, you can always increase ISO or open up the aperture.

Now all this sounds easy and it is in theory, but the number of ways you can exploit it is bewildering and thats where a books helps.
--
Steve
Pixel peepers miss the big picture.
http://www.pbase.com/steve_jacob
 
Steve - I must say, your explanation of the three fundamental purposes of Flash was just terrific, to say the least! While, to you, what you wrote may seem very basic, only points 1 (primary illumination) and most of point 2 (fill flash) seemed very familliar. No. 3, regarding HSS (High Speed Sync?) mode, was a bit over my head - but again, keep in mind I'm a rote begginer here.

Thanks for the illucidation (ha! get it? Good play on words, there!) Steve - very helpful!
Brian
 
No problem -

High Speed Sync (HSS) is needed whenever the shutter speed exceeds the "max sync speed". You see, the shutter on an SLR is effectively two curtains that move across the light path - curtain initially 1 blocks the light path, and curtain 2 is off to one side. When you trip the shutter, curtain 1 moves out of the way leaving the sensor exposed. Then the second curtain follows it, closing the light off again.

However the curtain takes a certain time to cross the frame. In the case of Pentax, 1/180 of a second. To get faster shutter speeds than that, the second curtain starts to close the light path BEFORE the first curtain has fully opened it. Effectively you pass a "slot" across the frame. If you use normal flash, only that part of the frame exposed by the slot at the time will be illuminated.

HSS gets round this by firing a rapid burst of short flashes (stobe) instead of one big one. The power is less but the curtain problem does not occur.

If you set your AF 540 to HSS, and the shutter speed is slower than 1/180 it will simply reset to normal mode, but its worth keeping it in HSS mode outdoors because the shutter speed may need to be higher to keep the background correctly exposed.
CoolHandLu said:
Steve - I must say, your explanation of the three fundamental
purposes of Flash was just terrific, to say the least! While, to
you, what you wrote may seem very basic, only points 1 (primary
illumination) and most of point 2 (fill flash) seemed very familliar.
No. 3, regarding HSS (High Speed Sync?) mode, was a bit over my head
  • but again, keep in mind I'm a rote begginer here.
Thanks for the illucidation (ha! get it? Good play on words,
there!) Steve - very helpful!
Brian
Click to expand...
--
Steve
Pixel peepers miss the big picture.
http://www.pbase.com/steve_jacob
 
Brian, I think that the Magic Lantern k10d book is a great reference for using an external flash, along with a lot of information on the k10d that you won't find in the manual. I've bought two books specific for the k10d and the Magic Lantern one is my favorite.

With that said, I am currently reading the AF540 flash manual for the third time. Not sure if that will get me further or not. ;-)

I've found Steve's contributions about flash extremely helpful. Here are a couple links to his past posts:
http://forums.dpreview.com/forums/read.asp?forum=1036&message=23744061
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=24181394&page=1

--
LaRee
http://www.laree.smugmug.com/
http://laree.zenfolio.com/
 
Thanks again Steve! Re: magic lantern guide, can you believe I JUST got mine in the mail earlier this week for the K10D. I haven't even cracked it, but looking at the table of contents, I see its all here! 32 pages devoted to flash! NICE!

Between Steve's posts, the web site that has been suggested and my Magic Lantern Guide, in no time I'll be giving out advice on all manner of Flash questions (NOT!).
Thanks again - this forum rocks!
Brian
 
depending on the subject matter, hss is what makes the 540 worth every penny that you spent on it.

--
dan
 
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