Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-28-2009, 08:43 AM   #1
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Just Got My AF540GZ Today

As the title says, i've read the manual, personally I think the manual could do with some improvements.

Some things I don't quite get:

1. I don't get the auto & manual modes. In auto you have control over ISO & apperture yet in manual you can only dial 1/1, 1/8...1/64 etc. I was taking shots using a fully manual 50mm and found the auto mode gave the best results.

2. Wireless P-TTL, I figured out how to use it, suprisingly works a treat however is the zoom when set auto supposed to adjust like it does when the flash is attached to the camera?

Any other help would be really appreciated, so far I'm loving this flash just trying to understand it.

GY

08-28-2009, 03:52 PM   #2
Loyal Site Supporter
Loyal Site Supporter
Canada_Rockies's Avatar

Join Date: Nov 2007
Location: Sparwood, BC, Canada
Photos: Gallery | Albums
Posts: 9,900
Manual mode for flash puts the photographer in charge of the exposure. In my experience, it is not usable with a variable aperture zoom lens. The exposure can change dramatically as the lens is zoomed out and in, destroying your careful calculations. In case you want to try it, you need to
  1. Determine the flash zoom to match the field of view of the lens you are using
  2. At that zoom setting, determine the guide number. It will change with each setting of the flash's zoom.
  3. Once you have the guide number, you need to determine the distance from the flash to the subject.
  4. Note that the distance is from flash to subject, not from camera to subject, when the flash is not on the camera.
  5. Once you have the distance number and the guide number, you divide the distance into the guide number to get the aperture you use on the lens for proper exposure.
Now you know why most of us prefer flash guns with some automatic exposure system. Each time you change the distance from the flash to the subject, you must calculate and reset the aperture on the lens.

Your AF 540 FGZ has two automatic modes of operation. The first is P-TTL, the second is Auto Flash.

The earlier system is the auto flash system that uses a sensor on the flash gun to determine the light returning to the flash, and shuts off the flash when adequate exposure is attained. As with all metering systems, a really dark or really light subject will throw the exposure off.

The P-TTL system was developed to use the more complex metering in modern cameras. The camera meter is used to determine when the exposure is correct, using the matrix metering system. The camera sets off a pre-exposure flash and measures the results at the sensor. If you are using wireless flash, the camera sends off another blink to tell the off camera flash what exposure to use, then yet a third signal to actually take the picture. I just finished using my AF 540 FGZ in my basement to create "before" pictures of the uninsulated area, in hopes of getting an eco grant after insulating it to specifications. I found that I needed +1.0 stops of exposure compensation to get the exposure I wanted with the DA* 16-50.. One determines the exposure by trial and error.

It is entirely your own choice which system to use. When I take "studio" images, I use a flash meter to set the exposure for each flash I use. This metering system is identical to an incident meter, but is fash enough to capture the flash.

If you are completely confused by now, welcome to the club!
08-28-2009, 03:58 PM   #3
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,715
Albert's just given you a very good summary of how this great flash works.
For starters, I would just get used to the P-TTL results, judging for yourself how much extra FEC you may need to get adequate exposures.

Don't worry about the zoom of the flash - it will adjust according to the focal length automatically.
When you've understood how light works and the aspects of studio lighting, you'll be ready to venture to manual mode, then you'll have total control of your results.

All the best for that.
08-28-2009, 06:41 PM   #4
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
QuoteOriginally posted by Ash Quote
Albert's just given you a very good summary of how this great flash works.
For starters, I would just get used to the P-TTL results, judging for yourself how much extra FEC you may need to get adequate exposures.

Don't worry about the zoom of the flash - it will adjust according to the focal length automatically.
When you've understood how light works and the aspects of studio lighting, you'll be ready to venture to manual mode, then you'll have total control of your results.

All the best for that.

Thanks for that

Is there any known definitive websites or guides on flash work for beginners?

08-28-2009, 09:44 PM   #5
Loyal Site Supporter
Loyal Site Supporter
Canada_Rockies's Avatar

Join Date: Nov 2007
Location: Sparwood, BC, Canada
Photos: Gallery | Albums
Posts: 9,900
QuoteOriginally posted by Ash Quote
Albert's just given you a very good summary of how this great flash works.
For starters, I would just get used to the P-TTL results, judging for yourself how much extra FEC you may need to get adequate exposures.

Don't worry about the zoom of the flash - it will adjust according to the focal length automatically.
Unless you are in wireless mode with the 540 off the camera.
QuoteQuote:
When you've understood how light works and the aspects of studio lighting, you'll be ready to venture to manual mode, then you'll have total control of your results.

All the best for that.
08-29-2009, 07:15 PM   #6
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
I should note that I am really impressed with the wireless flash functionality, only complaint I can give is that it can't shot wirelessly over 1/180 (unless you use a RF trigger)

I was testing the flash in different angles and positions in a room, even without direct line of site the flash still fired.
08-29-2009, 08:10 PM   #7
DAZ
Veteran Member
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 715
QuoteOriginally posted by C.W Tsorotes Quote
I should note that I am really impressed with the wireless flash functionality, only complaint I can give is that it can't shot wirelessly over 1/180 (unless you use a RF trigger)
“scratch head” Ha? 1/180 is a camera limit not a flash unit limit. If you have 2 P-TTL flash units and at lest 1 can be a command in P-TTL you can use HSS in optical wirerless P-TTL mode. AFAIK there is know no RF tigers that can do P-TTL so there is no way other then P-TTL to get faster then 1/180 on a Pentax camera.

DAZ
08-29-2009, 08:12 PM   #8
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
QuoteOriginally posted by DAZ Quote
“scratch head” Ha? 1/180 is a camera limit not a flash unit limit. If you have 2 P-TTL flash units and at lest 1 can be a command in P-TTL you can use HSS in optical wirerless P-TTL mode. AFAIK there is know no RF tigers that can do P-TTL so there is no way other then P-TTL to get faster then 1/180 on a Pentax camera.

DAZ
Sorry I meant to say with the built in flash it's limited to 1/180.

08-29-2009, 08:16 PM   #9
DAZ
Veteran Member
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 715
QuoteOriginally posted by C.W Tsorotes Quote
Sorry I meant to say with the built in flash it's limited to 1/180.

Shucks, I thought I was going to learn something new. Oh well there is always tomorrow.

DAZ
08-29-2009, 08:36 PM   #10
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
It this right I can only use HSS when the flash is in P-TTL mode?

I can't seem to make it work in manual or auto mode.
08-29-2009, 08:50 PM   #11
DAZ
Veteran Member
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 715
QuoteOriginally posted by C.W Tsorotes Quote
It this right I can only use HSS when the flash is in P-TTL mode?

I can't seem to make it work in manual or auto mode.
This is correct. It is tied into P-TTL. AFAIK all camera systems that have a high speed mode (except some Nikon cameras with electronic shutters) are tied into there X-TTL modes. When you think about what HSS is doing it kind of makes sense.

The reason you can’t use HSS with the on camera flash is it takes a lot of power to do HSS (even just to command it in wireless mode) and the on camera flash just doesn’t have the poop.

DAZ
08-29-2009, 08:52 PM   #12
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
Just for arguments sake lets say you had a wireless trigger on your camera hooked to the flash, set the flash on manual and set the shutter speed on the camera past 1/180. Would it work or not?
08-29-2009, 09:11 PM   #13
DAZ
Veteran Member
DAZ's Avatar

Join Date: Sep 2006
Location: Everett, WA USA
Photos: Gallery
Posts: 715
QuoteOriginally posted by C.W Tsorotes Quote
Just for arguments sake lets say you had a wireless trigger on your camera hooked to the flash, set the flash on manual and set the shutter speed on the camera past 1/180. Would it work or not?
Sounds good but no. I have tried thou. Some camera makes will send a flash sync at any speed but Pentax will not provide a flash trigger closer (try to trigger the flash) on either the hot shoe or the PC connector if the speed is not 1/180 or less. If the flash is in P-TTL mode on the hot shoe it talks to the camera. No RF trigger system sends the information from the flash to the camera and back so no HSS. This is why if you are going to use HSS wireless you have to have a P-TTL flash on the hot shoe even if it is only going to command the other flash units. By the way this is the also true for trailing curtain flash needs to use P-TTL but you can use the on camera flash.

DAZ
08-29-2009, 10:01 PM   #14
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
Well here's a quick test of the wireless flash, I really love it. So cool, so many new creative avenues.
Attached Images
 
08-30-2009, 12:46 AM   #15
Veteran Member




Join Date: Jun 2009
Posts: 1,689
Original Poster
Also whats the difference between Flash compensation & flash output setting?
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
auto, flash, lighting, photo studio, strobist
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Has my AF540GZ Flash Lost It's Mind? Christopher M.W.T Pentax DSLR Discussion 16 07-07-2010 11:59 PM
645 TTL and AF540GZ GeneV Pentax Medium Format 0 09-14-2009 06:21 AM
Just Got My AF540GZ Today Christopher M.W.T Flashes, Lighting, and Studio 2 08-28-2009 11:52 AM
How to fix some chips and cracks on an AF540GZ? jaebles Flashes, Lighting, and Studio 1 02-20-2009 11:25 AM



All times are GMT -7. The time now is 03:25 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top