View Full Version : Xpan/ TX-1 close up filters possible?

The Patient

10-14-2010, 11:49 AM

Hello

I own a Fuji TX 1 one, and wondered if anybody has any experience with close up filters on a Xpan or TX 1. The minimum focussing distances of the 45 and the 90mm are fine for most uses, but I would love to try some close up panorama's.

Cheers,

Daniel

Vincent Brady

10-14-2010, 04:26 PM

I have an Xpan, but I would have thought that as a rangefinder camera how would know that you were in focus? I'll be interested to see the replies you get.

Vincent

Stuart

10-19-2010, 04:53 PM

You will need some 49mm + 1,+2 or +3 and so on filters and a tape measure.

The film plane index is marked on the top of the camera next to the hot shoe

on the Xpan should be the same on the TX1.

Measure the distance between the subject and film plane and do the math.

Hope this helps.

Stuart.

The Patient

10-20-2010, 03:13 PM

Of course I understood I had to buy some close up filters, but as Vincent I was also wondering how focussing will work.

I am the proud owner of the technilogical marvel that is the Holga, and recently I bought their close up filters. They are wonderfully simpel to use, set focus to infinity and hold the camera at the distance indicated at the filter. Seems to deliver sharp focus at the desired point (sharp for a Holga of course!).

Since I never was really good at math, I don't understand Stuart's advice completely. How do I know how much a certain filter affects the focussing distance? Does a +1 half the distance?

Hopefully someone can offer some further insight

Daniel

holmburgers

10-20-2010, 03:20 PM

Daniel,

I too am curious as to how the math would work. I'm sure there are a plethora of old books that would explain, as many of the old folding cameras used scale focusing and yet supplied "portrait" lenses and the like for closeups. Maybe check old manuals for cameras like the Kodak Tourist, and similar.

The math is not too difficult, but rather boring.

The close up lens shortens the focal length, but the lens to film distance remains the same. That means a now shorter focal length lens is sitting relatively (but not absolutely) further away from the film = you are focused to something closer.

Now if you would simplify things and assume that the focussing distance is the lens to subject distance, you can approximate the lens to film distance using the classic lens formula 1/f = 1/lens to subject distance + 1/lens to film distance.

Next you calculate the focal length of the lens combined with the diopter (turn the focal length into diopters, add the diopter power of the close up lens, and turn the result into a focal length again).

The using the lens to film distance and the calculated combined focal length, the lens to subject distance is calculated using that classic formula again.

It's a simplification that only produces an approximation. But it gives an idea of how to go about it. If you are really going to do this, you probably have enough enthusiasm for it to figure out how to find out what the internodal distances of your lenses are, how to get from the subject to film (i.e. focussing) distance to lens to subject and to lens to film distances, and get results that are close enough to produce good enough resukts when you set up using a tape measure.