PTLens already includes data for the OMZ 24/2.8 and the 24 shift. PTLens
comes with instructions on how to submit photos to determine distortion
characteristics of individual lenses. Given that the 18 and 21mm lenses
are used on DSLRs, PTLens might be amenable to including them, if
someone provides the needed photo. I suppose that this doesn't address
the change in distortion with distance issue though. I was wondering
about doing the required photo using a 21/3.5 and 18mm once the weather
here warms up and I can find an appropriate subject.
Martin
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On
Behalf Of C.H.Ling
Sent: Friday, February 22, 2008 9:59 AM
To: olympus@xxxxxxxxxx
Subject: [OM] Re: lightroom vs lightzone vs olymaster vs olystudio vs ps
vs capture 1
PTLens looks interesting but I see some problem for shots at different
focus distance, like the Zuiko 18/3.5, it has very slight pincushion
distortion for distance object but high barrel distortion at close
distance.
Distortion may not be very critical for 4/3 system. Most 4/3 lenses have
very low distortion. The cheap 40-150 has distortion as low as 0.08,
0.16 and 0.15% at 40, 100, 150mm respectively; the 18-180 super zoom has
distortion of 0.51, 0.2 and 0.18% at 18, 100, 180mm respectively and the
Leica 14-50/2.8-3.5 has distortion of 0.38, 0.02 and 0.04% at 14, 25,
50mm respectively. I believe these distortions can be corrected with
tools built-in most photo editing software if necessary.
For my works, I use very little distortion correction tools, if needed
it will be PS Transform-Distort, a heavy correction for perspective. I
also add barrel distortion for group photos where wide angle lenses were
used, this correct the distorted heads on both sides.
I wonder if PTLens will accept the OM Zuiko wides, since sooner or later
I will get a 5D successor for my OM lenses ;-)
C.H.Ling
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxx>
> C.H.Ling wrote:
>> <big snip>
>> Distortion correction can be done by most photo editing software, as
>> mentioned above, I believe you will need one besides the RAW
converter.
>>
> Again I seem to be a shill for PTLens, although I have no connection
> other than as a very happy user.
>
> All the RAW converters and editors that have a distortion correction
> function require you to do it by eye. Many contemporary WAs,
especially
> zooms, have a complex form of distortion, not pure barrel.
>
> If you roll the mouse back and forth, you can clearly see the form of
> distortion on one lens.'Fraid I don't have any Olys to show. In any
> case, the correction was done using PTLens - in a second or two.
> <http://moosemystic.net/Gallery/MPhotos/Calif/Morro%20Bay/Oak01.htm>
>
> To correct this with PS, etc., would take some fussing and inevitably
be
> a compromise. PTLens has a database of lenses with distortion info at
> various focal lengths. If it can read your image EXIF and the lens is
in
> the database, it simply makes the correction. If not, you may choose
> from any camera/lens combo that's in the database.
>
> Any AF lens for a DSLR that isn't in the database he will add if you
> send sample shots fitting his criteria. Here are the lenses currently
> supported:
>
>
> 4/3 Lenses
>
> multiplier = 2.0
> Zuiko Digital 7-14mm f/4.0
> Zuiko Digital 11-22mm f/2.8-3.5
> Zuiko Digital 14-42mm f/3.5-5.6 ED
> Zuiko Digital 14-45mm f/3.5-5.6
> Leica D Vario-Elmarit 14-50mm f/2.8-3.5
> Zuiko Digital 14-54mm f/2.8-3.5
> Zuiko Digital 18-180mm f/3.5-6.3 ED
> Zuiko Digital 40-150mm f/4.0-5.6 ED
> Zuiko Digital 40-150mm f/3.5-4.5
> Zuiko Digital 50-200mm f/2.8-3.5
> Zuiko Digital 50mm f/2.0 Macro
>
> As $15 for lifetime use and upgrades for both stand-alone and plug-in
> versions, it's a steal. DXo does the same thing (as well as other
> things?) for fewer models and LOTs more money.
>
> Moose
>
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