Re: [PanoToolsNG] Samyang 8mm
I get for some reason a sharper image and DOF with setting at F6.7-8 and prefocus at .7m.
Why, I don't know.
I read a longtime ago on this forum about optimal settings for this lens, but forgot what they were. Maybe other owners would remind me.
Cincinnati, Ohio, U.S.A.
--- On Mon, 11/1/10, Roger D. Williams <roger@...> wrote:
From: Roger D. Williams <roger@...>
Subject: Re: [PanoToolsNG] Samyang 8mm
Date: Monday, November 1, 2010, 11:03 AM
On Mon, 01 Nov 2010 22:00:36 +0900, A Kielcz <roblee007@...> wrote:
> Thank you Roger.
> It was shot in RAW at 5.6 and focus was set to 1.5m.. I could not u/l
> original NEF, because it wouldn't accept it.
> Is it possible that CA wasn't even on both sides, because it wasn't
> Tests are good, but I want be able to correct anything anyway.
You're welcome. Hmmm. Looks a bit soft for F/5.6. Try it at F/8 and 11
and see if you get noticeable improvements. Also try 2.0m or even 3.0m.
As I said, I had to focus further out than dictated by the hyperfocal
rule in order to get the best sharpness from my Peleng.
If CA is not the same on both sides the cause will be in the internal
geometry of the lens, not any orientation of the camera. I suggested
"decentering" which simply means that the optical axis of the lens
isn't precisely aligned with the lens barrel. But the effect is very
slight, so I wouldn't worry about it.
You must have used a RAW file processor to get your JPEGs, and it
can introduce softness in the resulting images. The RAW processor is
where you should remove the CA. CA looks bad and seems serious, and
if left uncorrected plays havoc with control point location (think
about having fringes on the opposite sides of the same feature when
it appears on the extreme left of one shot and the extreme right of
the next, overlapping, shot! You don't want that. All RAW processors
I've played with have sliders to eliminate CA. Play with them until
you can't see coloured fringes at full x1 screen magnification!
[Non-text portions of this message have been removed]
- I had found by myself the same way to mechanically set the focus scale ring at the correct position. I can confirm that it made me a happy user of the Samyang 14 mm for more than three years now.I was inspired by Jeffrey R. Charles who had kindly taught us in 2009 how to solve the problem that similarly affects the Samyang 8 mm f3.5 fisheye lens. It is a simpler fix than for the rectilinear WA though:Best regards,Michel Thoby