1/180th - please help me understand!


Link Posted 13/06/2014 - 07:04
ears wrote:
Thanks Ken. Sorry to hijack my own thread with what's probably a simple question - but what is program mode? I've looked in the manual but it's not clear - 'sets exposure according to the program line' is about the best I can wring out of it. Not prone to over-elaboration in those manuals are they?

I get sensitivity priority, aperture, exposure priorities, auto, bulb but that seems to cover all the bases - in program mode, what preference do I set, and what does the camera do for me?


Program or 'P' is where the camera chooses the optimum settings for the situation you are in. In the party situation you describe, the camera might use 1/40 second so that the ambient light in the scenes has an effect whereas using 1/180 might wipe that out and give you a very 'flash' lit image.

P is very very good. I use P MTF where the camera sets the aperture where any particular DA lens works best
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -


Link Posted 13/06/2014 - 09:41
I use P MTF

Sorry Ken. What is MTF.. Maybe i'm just stupid
K-1Gripped K-1 ungripped K-5ii K7 Various lenses



Link Posted 13/06/2014 - 10:06
Modulation Transfer Function, is a method of measuring the quality of lenses. Very basically, it electronically replaces the concept of lines-per-millimetre.

Most lens tests use methods to measure MTF values. So, the MTF setting on a camera just selects what is known to be the best aperture of a lens in terms of quality. This will presumably only work with Pentax lenses that have electronic contacts.
Best regards, John


Link Posted 13/06/2014 - 10:31
Just to explain further...

The "P" mode on the Pentax cameras will use the currently selected "Program Line" to decide how to balance the aperture and shutter speed for a given light level.

Out of the box, the "P" mode will use the "Normal" program line, which will be fine for everyday use.

However, the Record Mode settings in the camera allow you to choose between four different program lines, depending on your shooting style. For example, "Hi-speed Priority" will aim for a higher shutter speed, at the expense of shallower depth of field due to a wider aperture.
"DOF Priority (deep)" will aim for a smaller aperture (larger f-number) to get as much depth of field as possible. Obviously the shutter speed will be slower.
"DOF Priority (shallow)" will aim for a larger aperture (smaller f-number) to get as narrow a depth of field as possible. So, focus accuracy becomes more important.
and "MTF Priority" will aim for the aperture that gives the sharpest result on the attached lens (only if the lens actually reports that MTF aperture value of course).

However, when it comes to flash exposure, there are other factors at play. The flash menu has a choice of how you want to balance the ambient (non-flash) exposure with the flash exposure.

Setting the "Slow" or the trailing curtain flash sync modes will aim to set the exposure for the ambient light level and then fill in with flash. So, you'll have slower shutter speeds, but well lit subjects from the flash.

(Technical tip: if you set the overall exposure to -1Ev, and the flash exposure to +1Ev in the slow shutter sync flash mode then the camera will aim for perfect flash exposure, but with the ambient flash lighting one stop underexposed - giving a sense of the atmosphere, but nicely lit).

Unfortunately there is no "correct" flash exposure or magic bullet - you have to use your photographic imagination to work out what you want to achieve and then set the camera+flash up appropriately. It's not that hard, but better results can be obtained from helping the flash system know what you want

(For gallery, tips and links)


Link Posted 13/06/2014 - 11:49
Thanks guys that explains it.. I've never ever selected "P" mode on my camera. But I can see it could have interesting connotations when using flash. I'm off to experiment...
K-1Gripped K-1 ungripped K-5ii K7 Various lenses



Link Posted 14/06/2014 - 11:05
Sadly it looks like there are no settings for a program line on the K30 - but some test photos taken in P mode have come out fairly well.

It seems to operate on a very low shutter speed, though, and when I try to speed it up, it switched to shutter speed priority mode.
K30; DA35 2.4; DA50 1.8; A35-105 3.5; Sigma 70-300 F4-5.6 APO DL; M 80-200 F4; 18-55 WR Kit; Sigma 24-70 2.8
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