How to scale focus if your lens will focus closer than .7m

[rpavich]

I'm a bit unclear on something.

I have two lenses that have different minimum focus distances; a CV 21mm f/4 and a Summarit 50/2.5.


The CV lens focus' to .5m and the summarit to .9m.


How do I focus down to .5m on the CV...do I just do it the same as if I were using a lens that focus' to .7m? (I just line up the vertical lines like normally) or is there something I'm missing.

Same question on the 50mm.

 

[Calzone]

All you really need to know is that the zone of focus in front of the distance that you set is only about 1/3rd of the of the zone of focus measured between the F-stops, and the zone of focus behind the distance you set is about 2/3rd's the zone of focus measured inbetween the F-stops.

With extream close focusing I often set the focus a bit closer to try and center my subject more towards the center of the zone of focus since DOF gets even more shallow the closer one focuses.

I hope I was clear and didn't confuse the hell out of you.

Cal

 

[rpavich]

Well...with some experimentation I figured out that if my lens is set to .5 then I have to use a measuring device and not the focus patch.

As luck would have it, my camera strap is exactly .5m in length when extended from the camera.

 

[Rob-F]

Use a D/SLR for macro?

 

[Pherdinand]

you shall notice that the patch doesnt even move when you turn the lens from 0.7 to 0.5m therefore it cannot indicate focus closer than 0.7
so indeed you need to zone focus by guessing the distance and setting it on the lens barrel, or use a measure tape.

 

[Monochrom]

Hi, i´ve modifyed my redscale elmar to focus until the thread is coming out, thats about 50cm, just estimate distances...it´s only a amtter of practice there no way to focus precisely.

 

[Ko.Fe.]

Take test shots with ruler to see what is in focus if you are using RF patch.

 

[Imagedowser]

close focus

close focus

Set up your strap so you can disconnect one end and mark the strap as a measuring device in what ever way matches your lens/photo style needs...

 

[rpavich]

Use a D/SLR for macro?

Well, I could but that would spoil the fun.

I ended up learning the distance to .5m and also getting a Canon Auto-up which h is a lot of fun.