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How to change infinity on Samyang 35/1.4
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PostPosted: Mon Jun 18, 2012 5:56 pm    Post subject: Reply with quote

pholler wrote:
I am glad you could adjust the infinity focus. I used the same page when i was doing it.

I recommend getting a Dandelion chip for this lens. Focusing with pure eye-sight is quite difficult at 14 mm.


with this lens, if the infinity stop is well calibrated, you don't need to focus
at F8 the dof is from 40cm to infinity
at F2.8 from 1.2m to infinity


PostPosted: Mon Jun 18, 2012 6:30 pm    Post subject: Reply with quote

poilu wrote:
with this lens, if the infinity stop is well calibrated, you don't need to focus
at F8 the dof is from 40cm to infinity
at F2.8 from 1.2m to infinity

Yes, but this lens makes also makes fun with focus distances nearer than infinity and focusing this is quite difficult.


PostPosted: Mon Jun 18, 2012 6:48 pm    Post subject: Reply with quote

pholler wrote:
Yes, but this lens makes also makes fun with focus distances nearer than infinity and focusing this is quite difficult

nice, I am waiting your samples in the galleries to get some idea Very Happy


PostPosted: Mon Jun 18, 2012 7:18 pm    Post subject: Reply with quote

poilu wrote:

nice, I am waiting your samples in the galleries to get some idea Very Happy

I just checked my LR-library and i did some shots of people indoors when there is not much space, like in the kitchen using a crop-camera. Especially cutting a cake or unpacking Christmas presents. On FF it is too wide for such an application. On FF it is too wide for nearly everything.


PostPosted: Thu Jun 21, 2012 8:02 am    Post subject: Reply with quote

Orio wrote:
...
I start to doubt seriously about the quality of the product though, if so many buyers report this problem.
One case may be bad luck, but so many cases means there's a poor production issue.


For me it seems that 10-30% have not a right adjusted focus scale.
I could live with that. On my Samyang 14mm lens the adjustment of the internal focus didnt worked - it was to limited. So I made the register distance approach http://www.4photos.de/camera-diy/Samyang-Walimex-Rokinon-Vivitar-Falcon-14mm-2.8-Focus-Correction.html
This helped and worked good.
But after some time infinity was deadjusted again (no drop), and the hole front part wobbles. With three outer screws I could "fix" that. And I took the shims away - infinity ok.
But the screws seem to influence the iris, it was stuck sometimes.
Again some time later the lens front wobbels again, outer screws did not help.

Opend the lens a bit more. There where three screws deeper inside the lens barrel loose. Those screws hold front and back part together. I pressed font and back togehter to get parallelism. But afterwards I saw that the lens is tilted even with those parts pressed togehter. For me it seems (not sure) that Samyang adjust with a special machine front and back part, and then close the screws in this machine. This would result in a nearly not serviceable lens.

Furthermore I only read from people that they have their lens with problems replaced with a new one. Never read from repaired lenses apart from DIY approaches (or some tinkering workshops).


PostPosted: Thu Jun 21, 2012 9:10 am    Post subject: Reply with quote

ZoneV wrote:
For me it seems that 10-30% have not a right adjusted focus scale

maybe they put the mount at the last minute, if they calibrate for Nikon then put a Canon mount that could explain this mess
anyway calibrating this lens is easy, don't use the washer method

use those instructions http://www.photo-worx.de/index.php?option=com_content&task=view&id=55&Itemid=
for those who don't understand German (like me), this is what I did on mine
- remove the rubber, it is elastic but take your time
- set lens at f2.8 and adjust infinity on borders (with liveview), you will be little more than 2m on the scale
- unscrew the 3 screw marked '1' by 2 or 3 turns
- with a screwdriver move the inside barrel '2' until the max (infinity stop) without moving the exterior so you stay at 2m on the scale
- screw back the 3 screws
- now the infinite is at max but the scale is at 2m instead of infinite, you have to remove the scotch '3', move the scale to infinite and put scotch back
- put the rubber back

I had problem to set the scale at infinite, even after removing the scotch it was like glued, but after playing up down, right left, it moved freely and I could put it to the right place


ZoneV wrote:
But after some time infinity was deadjusted again (no drop), and the hole front part wobbles

I hope mine keep in shape for longer, first time I see a lens assembled with scotch Laughing

ZoneV wrote:
I suppose that correction alter the IF - internal focussing
One can not know, which is "the right one"

it just change the infinity stop not the internal focusing so it is the right method, shimming would be good if no other method existed


PostPosted: Mon Jul 16, 2012 8:28 am    Post subject: Reply with quote

poilu wrote:
...I hope mine keep in shape for longer, first time I see a lens assembled with scotch Laughing
..

There are a lot of lenses with taped internals. This is used because it is easier to handel than screws on such elements.
First heard about this ~15 years ago, when my brothers Sigma zoom fell apart in hot enviroment and sun.
On newer lenses this is quite often used. But even on the Minolta Rokkor 28mm/2.0 the infinity stop and focus scale is hold with tape (when I remember correct).

poilu wrote:
...
ZoneV wrote:
I suppose that correction alter the IF - internal focussing
One can not know, which is "the right one"

it just change the infinity stop not the internal focusing so it is the right method, shimming would be good if no other method existed


I tested first the other method with correction of IF or infinity stop - but it did not work for my lens.
Afterwards I made the register distance correction. Waht worked well for a while.
But I realized that internal screws are loose. It seems the hole lens parallelity depends on three or four screws. When they open, it is very hard to adjust the lens without Samyang tools. Have to do this now.


PostPosted: Fri Sep 28, 2012 3:51 pm    Post subject: Reply with quote

There is in fact a set of screws under the focus rubber ring but in the case of the 35 the ring is coupled to the helicoid in one defined position. I tried to unscrew the lower ones and then adjust the ring to the new infinity but the helicoid itself has already defined holes for the screws to fit into so there's no way to adjust the reciprocate position between the ring and the helicoid.
I ended up fitting spacers between the lens barrel and the mount.
For the 85 a single layer of electricaltape gave me a pretty much correct infinity (i'm lucky), but for the 35 i have to find something a bit thinner.
Just keep in mind that the spacer has to lay on the outer rim of the mount, otherwise you can't change the aperture because it blocks it ring.