[OT?] Updated Samyand 8mm fisheye comes with removable lens hood. "Shaving" not necessary on full-frame.

[l_d_allan]

I've noticed various posts about "shaving" a fisheye lens for use on full-frame cameras. I believe the issue is that the lens hood is visible in the borders of the image without shaving.

 

FWIW: I recently purchased a Samyang 8mm fisheye, intending to use it with my Canon T3i (1.6 crop factor). Just to see what happened, I tried it on my Canon 5dm2 full-frame. So far, I'm pleasantly surprised by how well it seems to work.

 

Compared to the previous generation of the Samyang 8mm, the lens hood is removable. According to Samyang, the optics are also different. The review by the photozone.de website of the previous generation of the lens is very positive.

 

In use on the 5dm2 full-frame without hood, the image cicle is definitely larger than 24mm x 24mm on the 36mm x 24mm sensor. Rather than a circle, the "image light cone" is more like a rounded rectangle, perhaps 26mm x 26mm or perhaps even 30mm x 30mm or  larger.  IIRC, a website mentioned it may be a 10mm fisheye rather than a 8mm fisheye.

 

It goes horizon to horizon when pointed straight up, so this fisheye newbie interprets that to mean the lens has at least 180 degrees FOV. However, the opposite side horizons are very curved, so this fisheye newbie isn't sure if the Samyang provides a "real" 180 FOV.

 

I'm getting ready to stitch the first 300 degree FOV panos, and I'm curious how they turn out wrt avg/max CP distance errors, as well as stitching errors.

 

Note that the Samyang is marketed with several different brand names, including Rokinon, Bell-Howell, Samyang, and others.

[capedoryus]

Thanks for posting Allen, I just finished a run of focus test on a
8mm. I did a pano shot at f8 and entire pano was soft. I will post my
focus test results on Picassa later today. I cant figure out this
lens. It gets great write ups but I cant shoot sharp photos under f11.
When I shoot under f11 the background lacks detail. There are
tutorials on how to calibrate the focus but I dont think that is the
problem in that there is no difference between the infinity mark and
1.5 meters. All focus point are soft under f11. I did a 100%
enlargement on a section of the photo. Can the lens really be useless
under f11. I must be missing something. My last panos are in focus at
f11. I realize that this is not really the nature of your post. I am
looking to see if others are having the same issues. Thanks
John

[John Houghton]

On Oct 24, 5:21 pm, capedoryus <capedor...@gmail.com> wrote:

> When I shoot under f11 the background lacks detail.

What was the focus distance set to - the actual distance, not the not
the setting on the distance scale, which should be ignored in your
tests.

John

[Erik Krause]

Am 24.10.2012 18:21, schrieb capedoryus:
> I cant figure out this lens. It gets great write ups but I cant shoot
> sharp photos under f11.

This is a very cheap lens and one of the points where they saved money
is end control, it seems. There are few, but there are reports of
Samyang lenses being completely unsharp.

However, if you have, use live view zoom to focus. Try to find the best
focus (wide open of course) for very near things. If there is no such
point or if at best focus it still isn't sharp it is defective. If there
is a sharp spot compare the focus scale to the actual distance (from
sensor plane). If the scale indicates a larger distance focus needs to
be calibrated. If it shows a shorter distance mark the focus for far
away subjects and use it such.

If you don't have live view shoot images at various settings to find the
sharp spot.

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

[Roger D Williams]

I bought one of these lenses and there was nowhere on the focus scale that it gave a sharp image. I took it back to the shop but they insisted on giving me my money back. They said that they had no confidence that the importer (I am in Japan) would be able to either adjust the lens or provide a better substitute. They said the polite Japanese phrase for "It's a crap shoot." Of course that may also reflect widespread Japanese disdain for Korean optics (in my opinion usually unjustified but not in this case).

Very disappointing!

Roger W.

[capedoryus]

John I shot three shots. My lens stops at the infinity mark. I backed
off the infinity stop by about 2mm and then went back( towards close
focus) by about 4/6 mm. There is no difference in focus with the three
focus stops on the lens. The subject was houses and docks across the
harbor. What made the difference was the iris and it had to be 11, 16
or 22 to get detail. I did do a shot with a Nikon prime just to see
the difference. At 100% there was a major difference. At least I can
shoot at f11+ to get detail. I hope to have panos up tomorrow on
360cities to see if the f11 worked. Wifi was very slow today. Thanks
JOhn