Sometimes auto bracketing sets not recognized?

[kieranmullen]

Does anyone else have this issue? Sometimes the auto bracketed sets
are not recognized by ptgui. I have verified all the EXIF data is
intact and all the exposures were bracketed properly.

Any ideas? Here is a sample of 2 bracketed sets 7 each. The metadata
shows in Nikon ViewNX properly
in auto bracket exposure compensation as 0,-3,-2,-1,+1,+2,+3


http://www.mediafire.com/?zy24df1mzby 7.6 mb zip

Thanks!

[John Houghton]

No problems here on Windows XP (after the images were correctly sorted
on the Source Images tab). The "Link HDR" button on the Image
Parameters tab reported 2 sets of 7 bracketed exposures.

John

[PTGui Support]

Also when I press Align Images, PTGui will ask you what to do with the
bracketed sets.

My guess is that the problem occurred when the images were not ordered
correctly. PTGui expects the bracket sequence to be exactly the same
order for each of your bracketed sets.

Joost

[AceRimmer]

I just started messing around with the trial version of PTGui. I
noticed that the program seems to ignore the exposure compensation and
instead uses the shutter speed to bracket. I guess shooting in manual
mode is a must.

[PTGui Support]

PTGui calculates the exposure from the combined values of exposure time,
aperture and ISO. Then the images are grouped into values with the same
(combined) exposure value. This value is displayed in the 'EV' column in
the Image Parameters tab.

You should always use the M mode of your camera when shooting bracketed
images for PTGui. If you don't, the +1 shot of one bracketed set may
have the same exposure as the +2 shot of another bracketed set, because
your camera has adjusted the exposure time inbetween the two shots.

See 9.3:
http://www.ptgui.com/support.html#9_3

And the HDR tutorial (section 'Photographing HDR panoramas'):
http://www.ptgui.com/hdrtutorial.html

Joost

[AceRimmer]

It seems like there should be a way to "force" a shot to have a
particular exposure value in PTGui.

Part of the problem is my Pentax K10D. Exposure bracketing in M mode
seems to cause BOTH the shutter speed and aperture to change. Any
K10D users know if there is a way to change this?

[Erik Krause]

AceRimmer wrote:

> It seems like there should be a way to "force" a shot to have a
> particular exposure value in PTGui.

You can change exposure values manually on Image Parameters tab. Or you
can use exiftool (eventually with an appropriate GUI for your OS) to
change EXIF data.

> Part of the problem is my Pentax K10D. Exposure bracketing in M mode
> seems to cause BOTH the shutter speed and aperture to change. Any
> K10D users know if there is a way to change this?

This should be no problem, since PTGui uses both values (and ISO
additionally) to calculate the effective exposure value.

best regards
--
Erik Krause
http://www.erik-krause.de

[AceRimmer]

Isn't changing the aperture while doing HDR a bad thing? Because the
depth of field changes?

I messed around a little trying to change the exposure values manually
but couldn't figure out how to do it. I will try looking in the Image
Parameters tab more.

Thanks much for the reply.

[PTGui Support]

It's the Exposure, Aperture and ISO column in the Image Parameters tab.
The EV column is calculated from these three, and this is what PTGui
uses to distinguishes the blend planes.

Keep in mind that changing these values may not give perfect results; if
you don't want brightness variations across your panorama you should
really be shooting in M mode.

Joost

[Erik Krause]

AceRimmer wrote:

> Isn't changing the aperture while doing HDR a bad thing? Because the
> depth of field changes?

In theory, yes. In practice it doesn't change much and you probably
won't recognize it if you use fisheye or very wide angle lenses.

Moreover some (better) cameras know a feature called "safety shift".
This means that if an exposure can't be achieved using the exposure time
it shifts the aperture instead (or vice versa, depending whether you use
aperture lock or exposure lock).