A series lens and AF540 problem

activeflush · 02-17-2011, 10:31 PM

This might be a dumb question but when I attach a 50mm A series lens on to a K5 body and set to manual exposure (M mode) should:

any changes in the iso be compensated by the flash, if the flash is set to pttl? (so giving me a correct exposure)
any changes in the aperture be compensated by the flash, again on pttl?

Because I seem to be having this issue where the flash does not compensate for iso or aperture changes, not only in M but also in A and I am getting hedious over exposure when I up the iso or open up the lens. Where as I didnt seem to have that problem with the K10D.

Last edited by activeflush; 02-17-2011 at 10:38 PM.

Peter Zack · 02-18-2011, 03:53 AM

Quick and possibly stupid reply. Is the lens locked in the "A" position? If so, are the contacts clean?

activeflush · 02-18-2011, 04:49 PM

Yeh, cleaned the contacts on both lens and body and the aperture ring was set on "A" position when I tested it. Tried flash with fa100-300 in M and A modes and that was fine, a bit underexposed when stopped down, but nothing dramatic.

So not sure whats wrong with the lens, I'll try to upload some samples later to show the issue.

activeflush · 02-19-2011, 06:07 AM

Here are the samples, so basically:

Shot using A priority @ f1.7, iso 80. Flash on pttl, 40 degree ceiling bounce for both.

Shot 1: Used A.zoom which registered @ 16mm
Shot 2: Used M.zoom by pressing zoom button in pttl @ 48mm

Attached Images

View Picture EXIF

View Picture EXIF

activeflush · 02-19-2011, 06:09 AM

Again same settings as above, these were done in TAv instead.

1/40, f1.7 and auto iso

activeflush · 02-19-2011, 06:14 AM

Am i doing anything wrong here?
I already set the focal length in the body to 50mm, is the zoom of the flash meant to stay at 16mm?

Sometimes when the flash in on camera it only cycles between pttl and SB when I press the mode button, other times it lets me access A and M mode for flash not sure why.

Any help would be appreciated

Edit: here's one done using M mode on camera (1/40, f5, iso400) and same auto flash settings as above. So frustrating....

Peter Zack · 02-19-2011, 09:06 AM

The mode selection issue (SB-PTTL only) has happened to me many times with various lenses. It's some sort of glitch in the flash and happens on different bodies (I've used the K10, K20 and K-x).

So I can't offer anything there. All I would do is take the flash off the body, power off and restart the unit. I suspected it was the pins were not lined up perfectly straight on the shoe. But it happens witha cable attached as well. So it's a flash issue that I've never heard a solution for.

As for it seeing the lens as 16mm. I can only suggest that it's not seeing the lens in the "A" mode. In fact it sounds like it doesn't see any lens at all. It's setting itself to the default. Does this lens expose and work normally without flash? Are you always getting correct settings and exposures say in A or S modes?

It almost sounds as if the lensis defective or oneof the contacts is not working on the lens. This would explain everything that's not working correctly.

activeflush · 02-19-2011, 09:11 PM

Yeh it works fine with no flash, correct exposures. I managed to try it on a K-r with and without the same flash unit and again same results.

Maybe it is the lens, because the flash exposes and reads the focal length fine on the 18-55 and the 100-300, on both the K-r and K5.

Edit: ok it turns out it was the lens. Just tried using the on-board flash with both bodies. It just fired at full power as well, you were correct the lens is not communicating with the bodies even though I manually set focal length and it can read the aperture values

02-17-2011, 10:31 PM	#1
activeflush New Member Join Date: Oct 2006 Location: Sydney Posts: 22	A series lens and AF540 problem This might be a dumb question but when I attach a 50mm A series lens on to a K5 body and set to manual exposure (M mode) should: any changes in the iso be compensated by the flash, if the flash is set to pttl? (so giving me a correct exposure) any changes in the aperture be compensated by the flash, again on pttl? Because I seem to be having this issue where the flash does not compensate for iso or aperture changes, not only in M but also in A and I am getting hedious over exposure when I up the iso or open up the lens. Where as I didnt seem to have that problem with the K10D. Last edited by activeflush; 02-17-2011 at 10:38 PM.

02-19-2011, 09:11 PM	#8
activeflush New Member Join Date: Oct 2006 Location: Sydney Posts: 22 Original Poster	Yeh it works fine with no flash, correct exposures. I managed to try it on a K-r with and without the same flash unit and again same results. Maybe it is the lens, because the flash exposes and reads the focal length fine on the 18-55 and the 100-300, on both the K-r and K5. Edit: ok it turns out it was the lens. Just tried using the on-board flash with both bodies. It just fired at full power as well, you were correct the lens is not communicating with the bodies even though I manually set focal length and it can read the aperture values Last edited by activeflush; 02-20-2011 at 12:11 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
K7: Focus problem at infinity (Vivitar Series 1 70-210 F3.5)	peter.antonius	Pentax SLR Lens Discussion	3	05-27-2010 02:34 PM
Vivitar Series 1 105mm macro infinity focus problem	mjkwee	Pentax SLR Lens Discussion	1	05-12-2010 01:31 PM
K7 and AF540 flash deal at walmart...and is K7 purchase required for lens rebates?	pxpaulx	Pentax News and Rumors	9	08-09-2009 10:25 AM
Vivitar Series 1 70-210 f3.5 problem	MrA	Pentax SLR Lens Discussion	17	08-09-2008 10:49 AM
DA-series vs A-series lens .. does it make a diference on a dSLR?	dresden_phoenix	Pentax DSLR Discussion	16	05-03-2008 03:56 PM

02-18-2011, 03:53 AM	#2
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	Quick and possibly stupid reply. Is the lens locked in the "A" position? If so, are the contacts clean?

02-18-2011, 04:49 PM	#3
activeflush New Member Join Date: Oct 2006 Location: Sydney Posts: 22 Original Poster	Yeh, cleaned the contacts on both lens and body and the aperture ring was set on "A" position when I tested it. Tried flash with fa100-300 in M and A modes and that was fine, a bit underexposed when stopped down, but nothing dramatic. So not sure whats wrong with the lens, I'll try to upload some samples later to show the issue.

02-19-2011, 09:06 AM	#7
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	The mode selection issue (SB-PTTL only) has happened to me many times with various lenses. It's some sort of glitch in the flash and happens on different bodies (I've used the K10, K20 and K-x). So I can't offer anything there. All I would do is take the flash off the body, power off and restart the unit. I suspected it was the pins were not lined up perfectly straight on the shoe. But it happens witha cable attached as well. So it's a flash issue that I've never heard a solution for. As for it seeing the lens as 16mm. I can only suggest that it's not seeing the lens in the "A" mode. In fact it sounds like it doesn't see any lens at all. It's setting itself to the default. Does this lens expose and work normally without flash? Are you always getting correct settings and exposures say in A or S modes? It almost sounds as if the lensis defective or oneof the contacts is not working on the lens. This would explain everything that's not working correctly.