Groundglass stacking

[daniel_fj_ll]

<p>Howdy photogs!<br>

First time poster - long time reader. Couldn't find anything on this matter but I figured I knew where to ask. I'm currently getting used to my Rolleiflex 3.5 mx-evs and yes, the ground-glass is a little dim at low light conditions. I've got a fresnel ground glass which is much brighter (I tried it) but a nightmare to focus with.<br>

Would stacking the two make it both brighter and easier to focus you think? I could try but I don't want break either of the two. Better safe than sorry!</p>

<p>Thanks a bunch!</p>

[ellis_vener_photography]

That is an interesting idea but probably not workable.

[Ed_Ingold]

<p>There are third party sources for Rollei screens which are much brighter than the originals. There are several options for focusing, including a plain center, split-prism, microprism, or combination thereof. Fresnel lenses are needed to brighten the edges of the screen, even if they interfere with critical focusing.</p>

<p>Most small cameras put the Fresnel lens on the back side of the screen. View cameras, including Graphlex, put it on the viewing side where it does not affect the image plane. You can buy plastic Fresnel lenses from various sources and cut them to size.</p>

[jens_g.r._benthien]

<p>This is the way to assemble a fresnel with a ground glass with view cameras - it should be identical to the Rollei ground glass:</p>

<p><img src="https://dl.dropboxusercontent.com/u/108865744/forum/groundglass_fresnel_assembly_2013-12-27.png" alt="" /></p>

[daniel_fj_ll]

<p>I got the whole thing dissembled and I couldn't fit both of the glasses in there when I tried to assemble it again. I could use only the fresnel when only using larger apertures but I probably wouldn't because I would need it for low light.<br>

I'm a milimeter short of fitting both of them in there!</p>

[daniel_fj_ll]

<p>I exercised the same principal by focusing the bulb in my lamp with a lens on to the stacked glass in my hand. It didn't make any significant difference except that the corner got a little distorted but also a little brighter.<br>

I got my ground glass out and cleaned anyway. :)</p>

<p>Thanks guys!</p>

[fwstutterheim]

<p>Hello Daniel,</p>

<p>From 1953 until 1961 the Rollei factory marketed a Rolleigrid Fresnel lens that could be dropped into the finder hood. The Rolleigrid was seated under two notches in the finder (front and back) on top of the ground-glass. It was meant for cameras with a real glass ground-glass, not the later plastic bright-screen. That one already had a built-in Fresnel.<br>

Your plan to stack is not new. See if your camera has the notches. Then the Fresnel has to have the right size and thickness to fit: 54 x 58.5 x 1.1 mm. The grid side should be turned to the ground-glass. </p>

<p>Ferdi.</p>

 

[richard_fateman]

<p>The Rolleigrid was not very effective, being a rather crude arrangement. And yes, the Fresnel lens makes it harder to focus, which is why the screens often have a focus aid e.g. microprism in the center.<br>

An alternative is to use the "sports finder" in dim light, or the weird Rollei range-finder attachment in conjunction with the sports finder. Or the binocular attachment (can't be used with a fresnel ground glass).</p>

<p> </p>