Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-22-2010, 08:52 AM   #1
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
a few more af360 questions

1. it appears that i only have access to certain modes on the flash depending on what exposure mode i've selected on the camera. is this correct?

2. what mode do i need to be in to access ttl? i can access pttl but i can't seem to find anything that will bring me to ttl. i don't imagine that i'm at the point where i'd need it over the pttl but after following the manual, and getting to the part about ttl, i'd just like to know i'm doing this right.

3. can i only choose the power output in "m" mode? 1/1. 1/2, 1/4 etc....becasue to be in m mode, it seems like i have to be shooting in manual on the camera as well which in a lot of instances keeps the shutter open too long for my linking. what i like about pttl is that its a quick shutter and eliminates the motion blur. but sometimes i'd like to lessen the output.

thanks,
kevin

12-22-2010, 09:50 AM   #2
Site Supporter




Join Date: Nov 2008
Location: Minneapolis
Photos: Albums
Posts: 588
I'm unsure re: 1 &2. Pretty sure for #2, TTL applies to older cameras that do not support P-TTL.

Regarding the balance of flash vs. ambient light in your flash photos, with the flash mounted on the camera - it is really a trial and error sort of thing, you need to practice alot to understand it. Also, maximum flash sync speed is 1/160th, so you can't set a faster shutter than that with the flash mounted.

I like to keep things simple, and shoot with the flash in P-TTL mode and the camera in M.

1. Green button will suggest an exposure.
2. Adjust aperture, shutter speed and ISO to a hand-holdable speed and desired aperture for DOF control. Those adjustments are changing your in-camera exposure and show in the viewfinder as positive or negative EV.
3. In PTTL mode, the flash is going to make up the difference by adding light. You can control how much power the flash is putting out by adjusting your in-camera exposure closer to the metered exposure.

Here's an example from my living room, right now.

One correct exposure: ISO 800, F2.0, 1/10. No flash.

I wanted lower ISO, smaller aperture, faster shutter speed. Clearly I need the flash.

I set to ISO 200, F2.8, 1/60. That is an ISO setting two stops lower, aperture one stop lower, and 2.5 stops lower shutter speed for a full 5.5 stops (shows in viewfinder as a blinking -3.0). That means the flash needs to make up the difference.

There were some reflective surfaces blown out by the flash so I grudgingly raised the ISO to 400 and slowed the shutter to 1/20, reducing the required flash output.

All three of the above were 'correct' exposures, and all had differing quantities of flash added. P-TTL figured it out every time.

That was fairly long winded but goes to show the complexity of trying to control the amount of flash in your photos.
12-22-2010, 10:50 AM   #3
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
you're saying you lowered your ev compensation three full stops to control the flash? wouldn't the pttl option zero your meter regardless, which would then not allow you to control the power of the flash? maybe i misunderstood your post. i want an option that will allow me to control the output of the flash, which i'm assuming is only possible in manual mode. i'll play around with your suggestions though
12-22-2010, 12:23 PM   #4
Site Supporter




Join Date: Nov 2008
Location: Minneapolis
Photos: Albums
Posts: 588
QuoteOriginally posted by Deiberson Quote
you're saying you lowered your ev compensation three full stops to control the flash? wouldn't the pttl option zero your meter regardless, which would then not allow you to control the power of the flash? maybe i misunderstood your post. i want an option that will allow me to control the output of the flash, which i'm assuming is only possible in manual mode. i'll play around with your suggestions though
First - there is no EV compensation in Manual exposure mode. You set the exposure manually using ISO, Aperture, and Shutter speed, and the camera tells you via the EV readout how your selected exposure compares to what its meter says.

In P-TTL, the camera tells the flash what the exposure should be. It also tells the flash what your in-camera exposure is, so the flash can make up the difference. By changing your in-camera exposure, the flash will add more or less light to arrive at the metered exposure. In essence, I chose the amount of fill flash required by choosing how much ambient light to let in.

If you choose the flash output manually by setting your flash in M mode to 1/x, your camera won't consider this output when metering the scene and you will have to consider the changes made to flash power in your manual exposure. I find it more difficult to get the desired exposure that way.

12-22-2010, 12:39 PM   #5
Veteran Member
Deiberson's Avatar

Join Date: Dec 2009
Photos: Albums
Posts: 734
Original Poster
ok. so i noticed a few times that my camera was showing f/7.1 but my flash was showing f/4. using those numbers can you explain this to me in laymans terms? in other words...if i wanted to control the flash power in that situation, what would i do?
i always assumed that the aperture reading on the flash was the same as what the camera was showing. now i'm realizing that's not the case.
12-22-2010, 01:52 PM   #6
Site Supporter




Join Date: Nov 2008
Location: Minneapolis
Photos: Albums
Posts: 588
QuoteOriginally posted by Deiberson Quote
ok. so i noticed a few times that my camera was showing f/7.1 but my flash was showing f/4. using those numbers can you explain this to me in laymans terms? in other words...if i wanted to control the flash power in that situation, what would i do?
i always assumed that the aperture reading on the flash was the same as what the camera was showing. now i'm realizing that's not the case.
In 'A' mode you set the ISO and aperture on the flash to match the camera settings, using the 's' button and control wheel. There's no reason to use A mode on a camera that supports TTL or P-TTL flash.

Have you read the manual? This is all outlined in detail there.
12-23-2010, 12:32 PM   #7
Pentaxian
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
Photos: Gallery | Albums
Posts: 4,862
QuoteOriginally posted by Deiberson Quote
2. what mode do i need to be in to access ttl? i can access pttl but i can't seem to find anything that will bring me to ttl. i don't imagine that i'm at the point where i'd need it over the pttl but after following the manual, and getting to the part about ttl, i'd just like to know i'm doing this right.
I only know this answer - and this time I'm sure: neither of your cameras do TTL. The only Pentax DSLRs that have TTL are the *ist D, ist DS and ist DS2. After that, they stopped installing the TTL sensors in the cameras.
12-23-2010, 04:49 PM   #8
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,484
Your flash is behaving exactly as it should. The TTL vs P-TTL question has been answered already.

By M mode, I'm assuming you mean on the flash, not the camera. I don't remember about the 360 but the 540 will adjust output from 1/1 to 1/64. With M mode, you set the flash and it simply fires a burst of light based on your settings. It does not take into any account, distance, camera setting, light metering, it only does what you tell it to do.

With the different numbers in A mode (aperture readings), again, doing exactly what it should. In A mode, the flash is paying no attention to your camera's settings. It is a Manual mode that has auto-exposure (on the flash). That is, you set the aperture on the flash and the ISO and the flash will measure the output and make it appropriate for the numbers you've set. As long as you have set (manually) the same values on the camera and flash, you will have a good exposure (pending camera shutter speed). In many situations, this actually works better than P-TTL.

All the camera is doing in A or M modes (On the flash) is firing it. It is not taking any of the settings into account.

Both (flash) A and M modes are quite useful when you are using a Manual lens (that has no A setting on the Aperture ring) because it will allow you to control the flash output independent of any camera setting.



12-23-2010, 05:47 PM   #9
Pentaxian




Join Date: Oct 2006
Location: Chicago suburb, IL, USA
Posts: 1,535
Hi Deiberson,

I don't quite understand what you're trying to do, but if you want to lessen the flash exposure in P-TTL, you can do this with Flash Ev compensation either in the flash menu on the camera, on the AF 360 flash body, or both. If you're shooting in anything but M mode on the camera, you can use Ev comp in the camera also.

If you're trying to balance ambient light and flash ("dragging the shutter"), set the shutter speed (at anything equal to or slower than 1/180), aperture, and ISO for the level of ambient light that you want in the exposure in M mode on the camera. Set the AE to link to AF point, choose a focus point, focus and shoot with the flash in P-TTL mode. The M mode settings will capture the background ambient light as metered and P-TTL will meter the flash for the subject you focused on. Fine tune the flash output with Flash Ev compensation in the flash menu on the camera or on the 360.

IMO, the trouble that people have with P-TTL is that they don't understand how it works. . .

Scott
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!
access, camera, mode, output, pentax help, photography, pttl, shutter, ttl
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Questions about AF360 sinus007 Flashes, Lighting, and Studio 1 02-05-2009 11:51 AM
AF220 and AF360 flash questions skid2964 Flashes, Lighting, and Studio 2 09-14-2008 10:22 AM
Wireless flash questions (AF360) codiac2600 Flashes, Lighting, and Studio 2 06-06-2007 09:29 PM
Need help with AF360! photodad Flashes, Lighting, and Studio 9 01-15-2007 08:55 AM
AF360 questions olc Pentax DSLR Discussion 5 12-14-2006 09:35 PM



All times are GMT -7. The time now is 07:25 AM. | 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