Focus of the Brownie Hawkeye Flash

[heqm]

<p><strong>Dave G</strong> noted (on the thread http://www.photo.net/classic-cameras-forum/00dEgD) that fixed-focus box cameras were generally not set at the hyperfocal distance, but something closer. That is, you could get too far away to be in focus as well as too close. I ran an experiment the other day to try to find out where the limits were. The camera I used was my Brownie Hawkeye Flash, on the right in the photo below.</p><div></div>

[heqm]

<p>I took the picture below, looking for a subject that had objects at various distances not too far from the center. I developed the film and had a commercial place make a 10x10" print. Of course they did it digitally, and I suspect they used sharpening software (I should have told them not to) which confuses the issue somewhat. But I find things start to be in focus at a distance of about 2 1/2 paces; are in good focus at 13 paces; and start to fall off about 18 paces. Of course my pace, while very useful for me, is not terribly informative for the studio audience. Last I checked it was just under three feet, maybe 90% of that distance--call it 80-85cm. So the in-focus range for the Hawkeye is roughly 7-45 feet, or 2-14m, which agrees with what <strong>Dave</strong> said. </p><div></div>

[lex_jenkins]

<p>I've noticed that as well, looking at the photos I took with my Hawkeye as a kid. Focus appeared to be optimized for the distance that would fit a head-to-toe adult in frame, with plenty of room for maw and the kids squinting in front of the Eiffel Tower or Lincoln Monument.</p>

<p>But in the contact print or, at most, 4"x4" prints typical of that era, everything appeared to be in reasonably sharp focus. I didn't notice any focus issues until I recently scanned those old negatives and looked at 'em magnified on screen.</p>

<p>Anyway, it's all part of the flavor, along with the light falloff, edge and corner softness, and inevitable rightward motion blur from mashing that awkward shutter release.</p>

[winfried_buechsenschuetz1]

<p>You should not confuse the simple lenses (meniscus or two-element achromat) of these cameras with highly-corrected 3- or more element lenses. <br>

Even if set to proper film-lens distance these lenses will always show some softness due to spherical abberrations and other lens faults that can not be corrected using one or two lens elements. So even the proper focus will always be somewhat soft, and objects out of focus will show similar softness (or sharpness) as the ones in focus. So the depth (or rather "softness") of field may be greater than with a highly-corrected lens. <br>

A similar approach was taken in the 1930s by Meyer-Goerlitz. They claimed to have designed a multi-element lens which would show an extended depth of field due to proper balancing lens faults in and out focus. </p>

[Mark Z]

<p>Alan, thank you for performing the experiment. If the circle of confusion is the same at both 7 and 45 feet, this suggests that the best focus was around 12 feet - with a fair amount of plus/minus.</p>

[heqm]

<p><strong>Winfried</strong>, you have a good point: if the sharpness of this kind of lens is never quite as good at its best as a more highly-corrected system, the range of distances at which it's almost as good could be larger.<br>

I would think that chromatic aberration would be important, which could be minimized by using a color filter (that would also make it easier to use fast film in bright situations). And one could add a weak negative lens, like eyeglasses for a near-sighted person, if one were really interested in landscapes.<br>

Or you could just use a different camera.</p>