Focussing problems only on far distances with 1.33x lens adapter

[Emin Henri Mahrt]

Maybe this is normal.

 

I have an 1.33x anamorphic lens adapter (widescreen center). Its not very sharp at all but especially on far distances its nearly impossible to focus.

 

Close objects (1-2m) are in focus, everything over 2m is nearly impossible to focus.

 

Maybe it has something to do with the lens build? It has a front and a rear glass, i im able to remove these glasses. Also, i can "turn" them around. Only, when both glasses are in an exact same position, the image gets sharp. I tryed to find the exact right position by hand buts thats very difficult...

 

 

So or so, nothing helps with the "far distance" focus, i just dont get a focussed image. Will post some pictures here later - or is this normal with anamorphic adapters?

 

I think this is my lens: https://docs.google.com/open?id=0Bxircl2ROioAX2ZxenZzMUFOcXM

 

[tony wilson]

think of an iscorama think of german perfection think mercedes sl500.
the lens was sold by widescreen centre london in the 70s-90s.

later came century optex both sold by widescreen think skoda.

optex uk costs where 600 sterling new for a so so lens.

you have a lens that was made to undercut the optex.
that is your lens
made to be cheaper than an expensive bad lens.
i cannot think of a car that is below a skoda but anyway with continual adjustment it should be possible to get a good focus unless it is reject glass.

find something 12 feet away and try to lock everything down as secure as possible this can take many hours or 120 secs depending on luck.
it is a fixed optic that will need a good f stop and maybe a diopter for close work.
depending on sensor size you will have lots of ca softness at the sides or not very much.
do not expectn this to be a low light monster for your crummy chinese 0.95 lens : )

[brucker]

a Lada perhaps?

[Emin Henri Mahrt]

Thank you for your answer but that basically does not explain why the lens has a "ok" focus on near distance and a bad focus on far distance objects.

[tony wilson]

are you using a sony pd100.

check out the sensor size of a sony vx1000.

the item you have was not even designed it was cobbled together quick.

it is not an executed concept it is prototype project that was made and sold quick.

sometimes even with good anamorphics one optic is higher quality than the other.

sometimes optics are just not good

 

are you playing with the glass out of the mount..

what is happening when you do that?

[Emin Henri Mahrt]

Wenn i turn around the glass insite the optic i can adjust the focus (the two glasses, rear and front have to be in the exact same position in order to get a focus picture).

 

The focus is good enough when i check close distance shots, but very bad for everything more far away than 2.5 meters...

[tony wilson]

take the glass out..

find a way to change the space distance between the 2 optics.

that is called astigmatic focus adjustment.

what camera are you testing this with

[Emin Henri Mahrt]

Thank you Tony! Im testing with gh2

 

see my work here www.deremin.de its on the front page

 

or here https://vimeo.com/56705511

 

I will try to play around with the lens. You think it is possible to order "better glasses" somewhere?

[tony wilson]

a lot of these issues are to do with metal work engineering.

nothing wrong with the glass.

x and y axis is super critical.

 

you need to find a way to lock off everything so it is as sharp as it can be 8-12 feet.

 

12 feet is better if you cannot get 12 feet the glass needs to be further away concave fr4ont convex back optic.

i think it looks better than some i have seen good for bigger sensor camera.

stopping iris down is good.

fixing focus at 12 feet then using a cheap + 1 diopter would be a good start and do critical focus with camera taking lens