Using a split field filter

I just bought an Hoya split field filter lens along with some other

gear so it has no instructions.

 

<P>When i tried it-on a canon EF 50/1.8- it simply made everything

blurry

<BR>I know the basic problem is that it should idealy be mounted at

the some lens nodal point/focal center/or-something-else-i-don't-

fully-understand but it's made to only fit the filter threads.

What is the solution,if any?

If it changed what the lens was showing ,It must be a split field close up lens?They do make these, so you can focus on something close, and still have something at infinity in focus.What is the intended use for the filter you bought? I use split filters to darken the skies in a photo without darkening the ground.

If you want to have it work where part of the photo that is close is sharp and the far away is sharp,put the lens on the camera with the thick part of the lens on the same side as the close item and set the lens at infinity.I hope you understand this..........

Lol :)

<BR>Yep,got that michael

<P>The thing is that it simply doesn't work right at all when used that way

<BR>What's got me wondering is how anything like this can ever work....lens theory dictates that a light ray can travel through any point of the lens and still end up where it should on the image plane (i also know that it's not quite like this in practice,but close enough)

<p>So- how can this filter work?! Light rays from the close object can go through the half close-up lens part of the filter *and* through the gap

<BR>Light rays from the distant part of the picture do the same

<P>And this is how it looks in the pictures,sort of an image but with really soft edges!

 

<P><P>There is obviously some way to use it so that it works right,but how?

<br>Am i using the wrong main lens (50/1.8)?

If it is a split close up lens, first thing I would do is find out how many diopters it has, so I can know at what distance to place the camera from the near objet.

 

 

If it is a +2 then the focus distance es 100cm/2=50cm

 

If it is a +4 then the focus distance es 100cm/4=25cm

 

and so on.

 

The other half can be pointing to a far away lanscape (infnity focus)

 

 

Regards

I tested the close up part of the lens and it is a 2 diopter.However,when used as you describe it simply doesn't work like it should.The problem is still all to do with where the filter is located "in the light cone of the main lens".

<BR>It's obviously not going to work properly with this lens-i was just hoping someone had an idea what it DOES work on

<BR>Thanks for the help so far