[pure-silver] Re: focusing loupe
- From: Georges Giralt <georges.giralt@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 17 Apr 2007 16:34:19 +0200
Selon Bogdan Karasek <bkarasek@xxxxxxxxxxxx>:
> Hello,
>
> What would be a practical way of focusing such a loupe. You can't do it
> on the GG as the image on the GG has to be in focus first, hence the
> need for a loupe, so where do you focus your loupe first before using
> it? I was thinking of placing a sharp negative on a light table then
> calibrating the focus using that and then locking it in (gaffer's tape)
> for use on the ground glass.
Hi !
when making my own lupe, I used this method to get the correct tube lenght :
I took a very good tranny, and put it on my light table, emulsion side up.
On top of it I put the GG of my camera, the ground face in contact of the tranny
emulsion, as it is the image surface.
Then I moved the lens to get an in focus image. I measured the lens to GG
distance and cut a cardboard tube at this dimension plus a little extra, put the
lens in it and "screwed" it until the image was in focus. I then carefully
measured the lens distance and cut the PVC tube to this one.
Once the lesn was fitted, I double checked on the light table before putting the
GG back on the camera.
I then make a couple of shots at high magnification with lens wide open to check
for proper focus, without deep of field/focus.
I assume you can use this method to adjust your loupe.
--
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