Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-25-2016, 07:24 PM   #1
Pentaxian




Join Date: Jul 2013
Photos: Albums
Posts: 782
Pentax AF-540 FGZ Overexposure in bounce mode

I just got this flash, but in P-TTL it nearly always overexposes if I bounce the flash. Doesn't really seem to matter what mode I use. What's the deal? Is the flash defective?

12-25-2016, 08:08 PM   #2
pjv
Otis Memorial Pentaxian
Moderator
Loyal Site Supporter
pjv's Avatar

Join Date: Mar 2015
Location: Melbourne, Australia
Photos: Gallery
Posts: 7,384
Just a thought Wolfeye. Have you got any flash compensation set in the camera or the flash unit itself? Good luck.
12-25-2016, 08:55 PM   #3
Pentaxian




Join Date: Mar 2007
Location: Christchurch, New Zealand
Photos: Gallery
Posts: 947
QuoteOriginally posted by Wolfeye Quote
I just got this flash, but in P-TTL it nearly always overexposes if I bounce the flash. Doesn't really seem to matter what mode I use. What's the deal? Is the flash defective?
Wolfeye,

What camera are you using? From previous posts on this issue there is a hardware bug in Pentax digital cameras where bounce flash from an AF-540 FGZ or the AF-360 FGZ always over exposes the shot. I believe that this was finally fixed on the Pentax K-3.

Regard

Chris
12-25-2016, 09:09 PM - 1 Like   #4
Veteran Member
Sluggo's Avatar

Join Date: Sep 2006
Location: Ames, Iowa
Photos: Gallery | Albums
Posts: 768
QuoteOriginally posted by Wolfeye Quote
Is the flash defective
Best to avoid jumping to any conclusions too quickly - see how much information you can gather. Besides checking the compensation settings as pjv mentions, what metering mode is the camera in (spot, center weight, full matrix)? What shooting mode? Do you have AE/AF points linked in the custom menu? What happens if you change between P, Av, green mode? What zoom setting is the flash on? What shutter speed shows up in the EXIF data (because, at the risk of asking stupid questions, might there be overexposure from the *ambient* light?) Does the result vary if you have a longer or shorter distance to the bounce surface?

I'm thinking about these things today as well, because I just got an AF360FGZii as a gift from my wife and found dramatic differences among several bodies I tried it on. My K3ii exposes with it perfectly every time so far in p-ttl mode, which is great, since that's what I intend to mostly use it with. It does fine also on my Q7, even if it looks comical attached there. A K-01 seems to be hit or miss, and a K20D underexposes terribly regardless of what I do ... again, so far. I expect the latter two are because of camera settings I haven't tracked down yet. Seems like p-ttl ought to always "just work" but if something is throwing it off, I'd suspect something to do with the camera first, rather than the flash -- just because the camera has so damn many settings.

12-25-2016, 09:45 PM   #5
Pentaxian




Join Date: Jul 2013
Photos: Albums
Posts: 782
Original Poster
QuoteOriginally posted by seventhdr Quote
Wolfeye,

What camera are you using? From previous posts on this issue there is a hardware bug in Pentax digital cameras where bounce flash from an AF-540 FGZ or the AF-360 FGZ always over exposes the shot. I believe that this was finally fixed on the Pentax K-3.

Regard

Chris
My camera is the new K-70.

---------- Post added 12-25-16 at 10:51 PM ----------

QuoteOriginally posted by Sluggo Quote
Best to avoid jumping to any conclusions too quickly - see how much information you can gather. Besides checking the compensation settings as pjv mentions, what metering mode is the camera in (spot, center weight, full matrix)? What shooting mode? Do you have AE/AF points linked in the custom menu? What happens if you change between P, Av, green mode? What zoom setting is the flash on? What shutter speed shows up in the EXIF data (because, at the risk of asking stupid questions, might there be overexposure from the *ambient* light?) Does the result vary if you have a longer or shorter distance to the bounce surface?

I'm thinking about these things today as well, because I just got an AF360FGZii as a gift from my wife and found dramatic differences among several bodies I tried it on. My K3ii exposes with it perfectly every time so far in p-ttl mode, which is great, since that's what I intend to mostly use it with. It does fine also on my Q7, even if it looks comical attached there. A K-01 seems to be hit or miss, and a K20D underexposes terribly regardless of what I do ... again, so far. I expect the latter two are because of camera settings I haven't tracked down yet. Seems like p-ttl ought to always "just work" but if something is throwing it off, I'd suspect something to do with the camera first, rather than the flash -- just because the camera has so damn many settings.
Thanks for the advice. I haven't found any rhyme nor reason to it. I have tried changing several settings you mentioned, one at a time, and none seem to make a difference. I've seen the overexposure in green mode, P, SV, etc. The only constant is the flash is bounced, and the setting is P-TTL.

Anyone with the AF-540FGZ and the K-70 wanna chime in? I'd hate to think that a top of the line flash couldn't be made to work properly. I was shooting my Nikon D800 today too, with a cheapo SB-600, and the flash exposure was perfect, all bounced.

Last edited by Wolfeye; 12-25-2016 at 09:51 PM.
12-26-2016, 03:14 AM - 3 Likes   #6
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 38,784
QuoteOriginally posted by Wolfeye Quote
My camera is the new K-70.
More importantly, what lens are you using? Do you see similar behavior on your K-S1 with the same lens, flash, aperture, and ISO?

The reason I ask is that there is a known deficiency for Pentax P-TTL when paired with non-AF lenses (e.g. Pentax-A series and similar with KA mount). Full and consistent functionality for Pentax P-TTL is only available with AF lenses (e.g. KAF and newer mounts).* Pentax-A series and similar lenses ("A" contacts on the mount, but lacking the data pin), will generally work well, but will tend to overexpose under some conditions where the flash requires distance information in order to properly attenuate the preflash. If distance information is lacking, the preflash is fired full strength. If metered exposure from the preflash is out of range, the fail-over is to fire the main flash at full-strength as well. A common case where this happens would be high ISO under fairly bright conditions or close distance shooting at maximum aperture. The problem is potentially present with the built-in flash, but more common with higher-powered units such as your AF-540 FGZ.


Steve

* This restriction is noted in the flash user manual(s) (p26 in the AF-540 FGZ manual), though is not called out in most (all?) of the camera body manuals.

Last edited by stevebrot; 12-26-2016 at 03:28 AM.
12-26-2016, 05:27 AM   #7
Pentaxian
wstruth's Avatar

Join Date: Nov 2010
Location: at my kitchen table
Photos: Gallery | Albums
Posts: 1,176
QuoteOriginally posted by Wolfeye Quote
I just got this flash, but in P-TTL it nearly always overexposes if I bounce the flash. Doesn't really seem to matter what mode I use. What's the deal? Is the flash defective?
My 2 cents: I find that P-TTL works best not using auto ISO on the bodies i have: K-5 (with latest firmware) and the the K-S2. I use a Metz though, but let us know how it goes, I've been eyeing that flash.
12-26-2016, 05:32 AM   #8
Pentaxian




Join Date: Jul 2013
Photos: Albums
Posts: 782
Original Poster
QuoteOriginally posted by stevebrot Quote
More importantly, what lens are you using? Do you see similar behavior on your K-S1 with the same lens, flash, aperture, and ISO?

The reason I ask is that there is a known deficiency for Pentax P-TTL when paired with non-AF lenses (e.g. Pentax-A series and similar with KA mount). Full and consistent functionality for Pentax P-TTL is only available with AF lenses (e.g. KAF and newer mounts).* Pentax-A series and similar lenses ("A" contacts on the mount, but lacking the data pin), will generally work well, but will tend to overexpose under some conditions where the flash requires distance information in order to properly attenuate the preflash. If distance information is lacking, the preflash is fired full strength. If metered exposure from the preflash is out of range, the fail-over is to fire the main flash at full-strength as well. A common case where this happens would be high ISO under fairly bright conditions or close distance shooting at maximum aperture. The problem is potentially present with the built-in flash, but more common with higher-powered units such as your AF-540 FGZ.


Steve

* This restriction is noted in the flash user manual(s) (p26 in the AF-540 FGZ manual), though is not called out in most (all?) of the camera body manuals.
I've only used one lens, the new DA18-135mm.

12-26-2016, 06:58 AM   #9
Veteran Member
Sluggo's Avatar

Join Date: Sep 2006
Location: Ames, Iowa
Photos: Gallery | Albums
Posts: 768
QuoteOriginally posted by stevebrot Quote
If distance information is lacking, the preflash is fired full strength.
Thanks for pointing this out. Even if it isn't part of Wolfeye's issue, it's great info I will keep tucked away.

Am I right in thinking the distance info is also missing when autofocus is turned off by the user, even if the lens supports it?
12-26-2016, 09:55 AM   #10
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 38,784
QuoteOriginally posted by Sluggo Quote
Am I right in thinking the distance info is also missing when autofocus is turned off by the user, even if the lens supports it?
Good question! It is my understanding that the distance information is pretty "course" and on most lenses is determined by conductive patches inside the lens. That being said, I have never actually tested.


Steve
12-26-2016, 10:08 AM   #11
Veteran Member




Join Date: Sep 2013
Photos: Gallery
Posts: 1,743
QuoteOriginally posted by Sluggo Quote
Thanks for pointing this out. Even if it isn't part of Wolfeye's issue, it's great info I will keep tucked away.

Am I right in thinking the distance info is also missing when autofocus is turned off by the user, even if the lens supports it?
No, that shouldn't be right. I was shooting P-TTL flash with decent exposures with my FA Limited in manual focus at a wedding last week.

Last edited by lithedreamer; 12-26-2016 at 12:15 PM.
12-26-2016, 10:12 AM   #12
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 38,784
QuoteOriginally posted by Wolfeye Quote
I was shooting my Nikon D800 today too, with a cheapo SB-600, and the flash exposure was perfect, all bounced.
FWIW, while I am happy your FF Nikon works great for bounce P-TTL and it is probable you have similar good results from your Canon 7D II, that information is not helpful in trying to figure out what is happening here. After all, neither involves the gear you are having problems with. I know sharing that information seems to bolster your case, but doing so makes your post sound more like a rant.

QuoteOriginally posted by Wolfeye Quote
I've only used one lens, the new DA18-135mm.
What happens with your new flash on your K-S1?

Is it possible to share an example in-camera JPEG with full EXIF intact? Unfortunately, a forum upload strips most of the EXIF, so one must provide a link to cloud storage (e.g. DropBox, Google Drive), original upload on Flickr, or something similar. The EXIF will provide multiple clues that might be helpful as well as whether a detected fault occurred.


Steve
12-26-2016, 11:36 AM   #13
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 38,784
QuoteOriginally posted by stevebrot Quote
What happens with your new flash on your K-S1?
Also...do you get good bounce results in Auto (auto-thyristor) mode?


Steve
12-26-2016, 11:57 AM   #14
Otis Memorial Pentaxian
Loyal Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 38,784
QuoteOriginally posted by seventhdr Quote
Wolfeye,

What camera are you using? From previous posts on this issue there is a hardware bug in Pentax digital cameras where bounce flash from an AF-540 FGZ or the AF-360 FGZ always over exposes the shot. I believe that this was finally fixed on the Pentax K-3.

Regard

Chris
Do you have a reference on that? I have not owned either flash, but original P-TTL compatibility was with Pentax film bodies (e.g. *ist and certain MZ-series) and both have a fairly long history as flash units go. During my time on this forum, I can't recall any general issues with P-TTL overexposure except when using A-series lenses and even then only for specific corner cases. Reviews for the AF-540 FGZ and AF-360 FGZ on this site are critical of build and price, but not exposure accuracy.


Steve
12-26-2016, 07:00 PM   #15
Pentaxian




Join Date: Jul 2013
Photos: Albums
Posts: 782
Original Poster
Well, ya know what, never mind. I'm sorry if it seems like too much to expect a flash to just work right in auto, as it does on my other cameras. So far, none of the "helpful" replies even own a 540, so if you all want to argue amongst yourselves about theories and ancillary settings which don't mean anything, go right ahead. I'm done here. The flash is defective or Pentax' implementation of TTL is. I'm inclined to believe either of those possibilities are correct.
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!
af-540 fgz overexposure, bounce, camera, flash, k-70, k70, mode, overexposure, p-ttl, pentax, pentax af-540 fgz, pentax k-70, settings, time
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale - Sold: Pentax AF 540 FGZ manishved Sold Items 2 02-29-2016 05:45 PM
AF 540 FGZ in HSS mode what flash power? jackseh Flashes, Lighting, and Studio 7 06-20-2011 08:12 PM
AF-540 FGZ with drive mode/continuous shooting. MRBHV Pentax Camera and Field Accessories 2 02-26-2009 06:40 PM
AF 540 FGZ for wireless in concert with the AF 360 FGZ Ed in GA Pentax Camera and Field Accessories 10 05-08-2007 09:45 PM



All times are GMT -7. The time now is 03:14 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