AF540 Flash Photography


Status
Not open for further replies.

P3ntx

Senior Member
Apr 14, 2007
1,176
0
36
44
West Coast Road
www.pentaxphotogallery.com
#1
There seem to be quite a number of pentaxian using this flash ...

Scenerio
In very low light background condition, with a protrait subject at front ...:(


Condition and Setting

1. K100D - Sync 1/180 ... Anything shutter speed above 1/180 would need HS mode. You use HS mode in daytime shots.

2. To light up the background you chose a aperture let say 4.5, you take test shot .. and reduce the shutter speed until you have sufficient light at the background of the protrait..to reach a correct exposure for both the backgroung and front protrait for night/dim background shots:embrass:

Is the above a best practise and would it cause the front subject protrait to be washout with deceasing shutter speed??? I am tlking above using AF 540 pentaxian.:embrass:
 

fengwei

Moderator
Staff member
Aug 25, 2004
14,462
12
0
Queenstown
www.pbase.com
#2
If you want to have some low light background in the photo, better use higher ISO (e.g. 400 to 800) too. Smaller aperture (bigger F number) would only give you more DOF but not much of the dim background.

When using P-TTL mode w/ the 540 flash, you only need to set either the aperture (Av) or the speed (Tv) but can't do both manually (unless you are using the flash in manual mode).

When using the flash indoor, better use ceiling/wall bounce flash if possible. This would give you the best results, better than any flash diffuser in my experience.
 

P3ntx

Senior Member
Apr 14, 2007
1,176
0
36
44
West Coast Road
www.pentaxphotogallery.com
#3
Thanks for the input...

For K100D I find the noise level unacceptable at ISO800.

Heard another method Rear-Sync actually let the camera expose natural background and flash at the last moment to light up subject in front, but I think it should be done in Manual mode..with the combination of slower shutter speed. Any suggestions?
 

fengwei

Moderator
Staff member
Aug 25, 2004
14,462
12
0
Queenstown
www.pbase.com
#4
Thanks for the input...

For K100D I find the noise level unacceptable at ISO800.

Heard another method Rear-Sync actually let the camera expose natural background and flash at the last moment to light up subject in front, but I think it should be done in Manual mode..with the combination of slower shutter speed. Any suggestions?
Yes, you can use rear sync to light up the foreground, while use slow shuttle speed to capture the background. But this only works when the target is still. For moving target, it's not easy. This works the best when you take some night scenery w/ people in the front :)
 

Sep 16, 2007
126
0
0
#5
What happens when the camera is in manual mode? Does the flash adjust? Im also bought a 540fgz and still can't figure out how it works.
 

zveron

New Member
Jul 30, 2007
39
0
0
#6
Page 25 of the AF540 manual

The four modes for AF540 is P-TTL, TTL-Auto, Auto and Manual. (SB is only for low light focusing)

P-TTL
A Pre-Flash is fired before the main flash. The Pre-Flash allow the camera exposure meter (seems only for multi-segment mode according to the manual) to adjust the main flash output based on the scene. Do not neet to set Aperture and ISO setting in flash unit.

TTL-Auto
No pre-flash. The camera will measure the exposure as soon as the flash fired and cut the flash output once the correct exposure is measure. Do not neet to set Aperture and ISO setting in flash unit.

Auto

No pre-flash. The flash unit will measure the exposure and cut the flash output once correct exposure is obtain. The exposure is measure thru the small hole infront of the flash. Neet to set Aperture and ISO setting in flash unit to be the same as camera. Only leading curtain sync is available.

Manual

you need to use the Guide Number Table on Page 82 to set Aperture. Find the guide number from the table by using ISO, zoom and power output (from 1 to 1/64). Next determine the distance you want the flash to reach (bounce flash will double the distance). Use Guide number obtain in step one to divide by distance in step two to get the Aperture setting. I think can use all sync mode. I never brave enough to try this mode.
 

Status
Not open for further replies.
Top Bottom