letus film plane/focus

PaPa

PaPa

Major Contributor
I am having trouble accurately measuring my focus distance with the slr lenses. I read that you are supposed to begin your read from the focal plane, which is ad the back end of the letus support/riser.

For example, i will set my slr nikon lens to 5feet. I place my camera infront of an object to get exactly 5 feet away, take out my measuring tape, measure 5 feet, and it doesnt even reach the object!!! Whats going on here, i tried with other lenses and same problem..

Anyone?


also, that letus riser that came with the extreme doesnt seem to hold in place very long before it lets the weight of the letus slip it down ever so slowly.
 
Replace the tightening screw on the riser or use a washer. The problem is it's the plastic cap of the screw thats actually putting the pressure on the riser. This makes for a slick connection once the bumpy paint wears down.
 
I'm about to use mine with some PL lenses, which are usually very accurate compared to SLR lenses. I'll let you know how it goes.
 
They just came out with the PL Mount a few weeks ago. Havn't tried it out yet but it seems pretty solid.
 
PaPa - Your question is not clear.
How far off are your measurements?

Focus on a few different objects at different distances, note where the lens markings say they focus, then measure those distances. Tell us how far off they are. If they are not close you probably have the lens back focus distance wrong.
The best way to tell is take it outside and check infinity focus on a distant object - preferably as far away as possible over 300 feet if you can. Longer for telephoto lenses. You should hit infinity focus on a distant object just as your lens barrell ends its movement. If it does, your footage markings should be pretty accurate on the barrel as well.

If you don't reach infinity or you go past it your back focus is wrong and you need to loosen the allen screws and move the lens until the infinity focus is correct. Be sure that you are keeping it straight in the adjustment tube as you will lose side to side focus if it is off. Its not really a good system yet but you can get it with some time.

Lenny Levy
 
hmmm, thats interesting. ill have to check the infiity focus thing, because i know when on infinity, it goes further and even the most distant objects are slightly out of focus.
 
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