RF Contrast

[johncox]

<p>I just received a Fuji Rangefinder in the mail and the RF patch is a bit hard to see. Are there any tricks to improving the contrast of the RF patch? Cleaning the front windows helped, would cleaning with alcohol be better?</p>

<p>Any ideas would be wonderful,</p>

<p>Thanks,<br>

John.</p>

[SCL]

<p>One old trick is to put a small dot (like a small piece of plastic electrical tape) dead center of the main rangefinder window...in many cases it will significantly increase contrast. Some people do the same thing with a Sharpie pen and black ink.</p>

[woolly1]

<p>I had one that I sold and the buyer commented the patch was indistinct. I didn't have anything to compare it to so couldn't comment. She said it was an easy job to take off the top plate and clean it so no complaints.<br>

It was a Fuji GSW690 mark 1 btw<br>

I now have the GW690 with a vastly improved RF patch.</p>

<p>@ Steven<br>

How does the dot trick work then?</p>

[juan_bonet]

<p>Leica made am orange filter for the rangefinder window. This filter increase the constrast of the rangefinder's spectral image. The special names of this filters are Okaro and Orako (depending of the camera model).<br>

<a href="http://c.fixya.net/fixya20/products/l/leica/118x100/leitz_okaro_14058_rangefinder_q4903080.jpg">http://c.fixya.net/fixya20/products/l/leica/118x100/leitz_okaro_14058_rangefinder_q4903080.jpg</a> <br>

Pherhaps, you can do the same for your camera.</p>

[woolly1]

<p>I wonder if it is possible to place a 'contrast' filter over the patch window (front winder side) to improve visibilty of the moving image?</p>

[soeren_engelbrecht1]

<p>I'm looking for an ORAKO myself at the moment for my IIIa. As an alternative, I have seen it recommended by others to try fixing a piece of unxeposed, but developed, color negative film in front of the RF window. Worth a shot, maybe ??<br>

<br />Soeren</p>

[SCL]

<p>Clive - here is a link to Rick Olesson's site which I discovered several years ago explaining the process. http://rick_oleson.tripod.com/index-165.html</p>

[Gus Lazzari]

<p>The principle of obstructing the background interference does work !</p>

<p>But I find that many don't realize that the poor performance and "searching" back & forth with their rangefinder device, was vastly improved once the<strong> vertical adjustment</strong> was lined up <em>perfectly</em>. (Horizontal of course for the infinity stop etc.)<br /> I find that it provides the "snap to" wow factor of a good rangefinder experience.</p>

[steve_mareno1]

<p>Like Stephen said, the electrical tape works very well. You can also try holding a yellow filter up to the window and see if that is better. If so, go to a hobby shop and get a piece of colored cellophane and place that over the window. Chances are though that the electrical tape will work fine.</p>

[christopher_junker1]

<p>The lack of contrast in old LTM cameraviewfinders is often the result of rangefinder mirror silvering degradation. In addition to a thorough CLA of the rangefinder/viewfinder optical system when CLA ing an LTM body, making sure you have coating intact mirrors and prisms is critical to sharp contrast. GL is correct about the vertical alignment. It needs to be spot on. You'll see his point if you focus an LTM body with it held portrait vertical instead of landscape horizontal. The LTM viewfinder is none too bright anyway until you get to the IIIg body so starting with a perfect condition viewfinder/rangefinder in alignment before any of the other efforts may be all you need.</p>

[mukul_dube]

<p>My friend Al Kaplan used to say that the trick to focussing a RFDR camera was to watch for the moment when there was a sudden jump in contrast. For this to happen, vertical alignment must be correct and the beam splitter must do its job well. I have used exposed film, as Soeren suggests, but that (or an OKARO or ORAKO) only makes for apparent contrast by altering the colour of one of the two R/F images.</p>