[photo-3d] Re: XA or XA2

[Michael Watters <michael.watters@xxxxxxxxx>]

>    From: "Ray Moxom" <raymoxom@xxxxxxxxxx>

> Jim Norman asked:
> > Can anyone summarize the relative pros and cons of the
> > Olympus XA and XA2 for twinning?
> 
> Very briefly - the XA has very high quality f2.8 35mm lenses and aperture
> priority auto exposure. The later being a big advantage in 3D work as it
> gives some control over depth of field.  Also the well proven method of
> joining these cameras to operate in master slave mode ensures matched
> exposures and near perfect sync.
> 
> The XA2s and XA3s on the other hand have slightly lower quality f3.5 35mm
> lenses and there is no control over the aperture. The twinning circuit that
> I have seen for XA2s still has the cameras operating with independent
> exposure control so that exposures may not always be perfectly matched -
> this may be acceptable with print film but is likely to result in less than
> perfect stereo pairs with slides.  Perhaps someone could advise if the
> method of coupling being discussed for XA2s/XA3s does or does not use master
> slave mode.

Regarding the lenses in XA vs XA2 (I haven't worked with 
XA3's).  The XA has a (by memory) 7 element lens and the 
XA2 has a 4 element lens.  Short of doing tightly 
controlled resolution tests, I haven't seen any difference 
in the performance of these two lenses.  The XA2's image 
quality is very high.  I suspect the primary reason for the 
extra glass in the XA was to squeak out that extra f-stop.

The apeture-priority exposure system on the XA is handy of 
course, but when you twin cameras at the shutter release 
level (much much simpler to pull off than a solanoid-level 
twinning) it behaves more erratically.  ie. XA's are less 
likely to give you consistant exposures between cameras.  
The XA2's simpler exposure system is more consistant.

Of course you can be sure of consistancy with a solanoid 
level linkage, but, as mentioned, that's harder to do.

Mike

-----------------------------------------
Dr. Michael Watters
Email: Michael.Watters@xxxxxxxxx
Valparaiso University