Q: Trifocals and Focusing a TLR

F5B&W · Sep 6, 2016

I used to use a TLR quite a lot in my younger days, when eyeglasses and contacts were simple affairs with only one lens.

My youth is gone, and two graduate degrees later I wear trifocals. I'm using a TLR again, but focusing ... I can obtain a different focus if using the waist viewfinder and then magnifyer, there are at least six possible combinations of focus points when wearing a pair of trifocals.

Which lens of my trifocal should I be using to focus the camera with? The long distance, the midrange, or the reading lens? Each one will provide a different focus for the negative and focal plane.

I'm trying to eliminate some cumbersome experimentation.

Thanks.

Jim Noel · Sep 6, 2016

I use the magnifier in the hood with my closeup (reading) lens.

Dali · Sep 6, 2016

Jim Noel said:
I use the magnifier in the hood with my closeup (reading) lens.

Same thing. Convenient as you don't need to stick your glasses against the magnifier, so no risk to scratch them.

wiltw · Sep 6, 2016

The focus plane should ALWAYS be the surface of the ground glass, and your eye should simply 'focus best at the ground glass'...if you have a grid on the ground glass or some in-viewfinder display text (e.g. shutter speed or aperture), the text should be sharp. Period.

In order to make the above happen, typical assumption for conventional viewfinders is vision focused at 30-36" distance. IOW, most likely use the MID lens... reading books assumes maybe 12-18" for the bottom lens, reading the computer monitor assumes about 20-30" away.

Thomas Bertilsson · Sep 6, 2016

I think the distance magnification. I wear reading glasses and distance glasses changeably, and am about to get my first pair of either bifocal or progressive lenses.

I notice that when I use my reading glasses I am unable to focus properly unless what I photograph is also in focus when I look at it outside the camera. Therefore I use my standard distance glasses, and with the Hasselblad I employ the little flip-up magnifying glass in the view finder, same as you would have in a TLR, and for the most part my focusing is working really well.

ic-racer · Sep 6, 2016

The Rolleiflex magnifier lens was interchangeable to adjust to the owner's eyes. No knowing what lens you have in there. Obviously you want to focus your eye on the ground glass; not above and not below.

Thomas Bertilsson · Sep 6, 2016

ic-racer said:
The Rolleiflex magnifier lens was interchangeable to adjust to the owner's eyes. No knowing what lens you have in there. Obviously you want to focus your eye on the ground glass; not above and not below.

Correct me if I'm wrong, but when looking through the viewfinder, it's like looking into the distance. If I wear my reading glasses and look through the viewfinder of any SLR, I cannot focus the camera unless the object I'm focusing on is also within 'reading glasses depth of field'. Farther away than that, and it's fuzzy no matter how I turn the focusing knob.

frank · Sep 6, 2016

I wear old fashioned bi-focal eyeglasses. I've tried several times to adjust to vari-focals but each time could/would not accept only a small area in focus at closer distance. When reading with vari-focals, I was seeing clearly just one word at a time, needing to move my head for each new word.

Sirius Glass · Sep 6, 2016

Do what I do ==> put a prism on the camera. That works with progress lens glasses and contact lenses, although it is much, much better with contact lenses.

StephenT · Sep 6, 2016

With all the flip up magnifiers in the different brand camera bodies, I use near distance. When looking at just the ground glass, I use far distance.

DWThomas · Sep 6, 2016

I wear progressives and I'm honestly not sure what part I'm using. But I believe wiltw is correct; we're not trying to focus on an "aerial" image here, we're looking at the plane defined by the ground surface of the glass. If you can see sharp focus there, it should be sharp. Some of the "grain focusers" used with enlargers are working with an aerial image, that is why they have a cross hair or wire in the field of view to force the eye to focus at a specified plane.

M Carter · Sep 6, 2016

I'd say you just need to fiddle with it until you find what works for you. Whichj should you use? Whichever gives you an in-focus image.

I wear bifocal contacts morning til bed, and would be blind without them, but even with bifocal contacts I need readers to see anything from a foot to 6"; With my RB, I wear the contacts but use the popup magnifier (the one built into the hood) and it's fine - readers without the magnifier; same with my SLRs, but I need to use the VF focus knob on the modern ones. With a 4x5, readers and a loupe; with my rangefinder (35) just contacts are fine. Shooting video with a 5" or 7" monitor, it's the readers again. And I need readers to check shots on a DSLR screen. So my camera bags are stuffed with 'em and I buy them by the pound from Amazon. The Prism on my RB is fine but in the studio, I usually put up a focus light, like a 750 open face. Gotten where I don't have to really think about grabbing the readers or not. When I'm shooting for myself or paid gigs, I have readers in my shirt pocket and in the camera cases. I always lose or break a pair on a hectic shoot.

Vaughn · Sep 6, 2016

I take my glasses off (near-sighted) and just get close enough to focus on the GG of the TLR -- about 4 or 5 inches.

frank · Sep 6, 2016

Vaughn said:
I take my glasses off (near-sighted) and just get close enough to focus on the GG of the TLR -- about 4 or 5 inches.

That's useful!

John Koehrer · Sep 6, 2016

Vaughn said:
I take my glasses off (near-sighted) and just get close enough to focus on the GG of the TLR -- about 4 or 5 inches.

Me too.

ic-racer · Sep 6, 2016

Thomas Bertilsson said:
Correct me if I'm wrong, but when looking through the viewfinder, it's like looking into the distance.

It depends on the optical strength of the viewfinder. For a 35mm camera and a TLR focus hood, obviously the ground glass or plastic, is only inches away from your eye, so a negative lens is used to make it appear to be farther away. The strength of that negative lens may not be comfortable for some, and the apparent ground glass (plastic) distance is adjustable in many (most?) cameras.

Kirks518 · Sep 6, 2016

ic-racer said:
and the apparent ground glass (plastic) distance is adjustable in many (most?) cameras.

But you never want to adjust the GG to accommodate your vision. If you do, you'll never have in focus images.

Vaughn · Sep 6, 2016

frank said:
That's useful!

Comes very close to my experience with the GG of view cameras, especially the 4x5 and 5x7. With larger formats (I also use 8x10 and 11x14) reading glasses are better as I can see the whole frame at one time from a little farther away (actually, instead of reading glasses I pull my normal glasses a little farther down my nose and farther away from my eyes.)

Blindly going where everyone else can see...

Paul in Arizona · Sep 6, 2016

Thomas Bertilsson said:
looking through the viewfinder, it's like looking into the distance

You may be using a mirror that does look into the distance but the image on the focusing ground glass is at the distance of eyeball to ground glass and not at infinity. That is in the area of two feet and not infinity.
I have superb distance vision but have to use glasses to be able to accurately focus a TLR.

ic-racer · Sep 7, 2016

Kirks518 said:
But you never want to adjust the GG to accommodate your vision. If you do, you'll never have in focus images.

I'm not sure how one would do that. The GG position affects the focus on the film plane, not the retina.

MattKing · Sep 7, 2016

ic-racer said:
It depends on the optical strength of the viewfinder. For a 35mm camera and a TLR focus hood, obviously the ground glass or plastic, is only inches away from your eye, so a negative lens is used to make it appear to be farther away. The strength of that negative lens may not be comfortable for some, and the apparent ground glass (plastic) distance is adjustable in many (most?) cameras.

Kirks518 said:
But you never want to adjust the GG to accommodate your vision. If you do, you'll never have in focus images.

I think ic-racer is referring to the adjustment of apparent distance one achieves by changing the diopter in the eyepiece of a prism finder or in the magnifying lens in a waist level finder.

btaylor · Sep 7, 2016

I wear trifocals. I have a Rollei TLR. I don't know how it can be so confusing. You can only use the surface of the groundglass to determine exact focus. I use my reading lenses to see it clearly. I can strain and mostly make it out with midrange, distance only gives me a blur and a headache. Doesn't matter if I use the Rollei built in magnifier or not, reading lenses are the only ones I can use to make out the grid lines and focus on my subject. If that doesn't work for you perhaps you need your prescription checked.

benjiboy · Sep 7, 2016

It depends on which camera, because focusing screens are either set at an apparent distance of one meter or infinity. The best way is to take your camera to your optometrist, optician or whatever they call them in your country and ask them to check them and advise you of your best option.

btaylor · Sep 19, 2016

To be specific, on a Rollei TLR used without a prism, the plane one focuses upon is the surface of the ground glass, just like a view camera. The "apparent distance" is the distance from your eye to the gg surface.

Q: Trifocals and Focusing a TLR

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