Why is the 3m mark on an XA red?

I love my XA, but I've always wondered why the 3m mark is red.

Hyperfocal at some f-stop? Can't be an infra-red mark (can't get a

filter on). Your thoughts?

 

Thanks -- Mark

I pulled the family XA out of retirement a week or so ago, and noticed the red 3m mark too--I assumed it was the hyperfocal distance. The manual is silent about that, but the depth of field table tends to confirm that guess.

 

Set at 3m, "circle of least confusion 1/30mm" is between 1.31m and infinity at f16. Check the pic for the rest of the table.<div></div>

My manual has a section called "Snapshots", with instructions to set distance to 3M, and aperture to 5.6 (this is marked in orange on the camera). Then you fire away.

Prolly for prefocusing at snapshot distance for people pix.

 

My Agfa Isolette folders have the 3M and 10M distances marked in red. The 3M preset is for people pix. At 10M and a reasonable aperture, like f/8 or smaller, it's hyperfocal setting for generic scenic snapshooting. Since these are guess-focus cameras I actually rely on those red-marked settings. Works.

<p>I'll second Lex's comment. The 3 meter mark is for quick snap shots of people. At this distance your subject should fit from head to toe within the bright lines of the viewfinder. In short, you preset the focus and camera is ready to roll for shooting people in the tourist mode.</p>

 

<p>By the way, the least circle of confusion occurs when the camera is focused spot-on to your subject. Any object away from that point of focus will have a greater C.O.C and hence be by definition less accurately resolved on the film plane.</u>

 

<p>Again, back to Lex's comments, sometimes its advantageous to <u>zone</u> <u>focus</u> when shooting from the hip. Therefore, 3 meters is a nice distance to keep in mind. At 3 meters there is quite an <u>acceptable</u> <u>zone</u> <u>of</u> <u>focus</u> around a subject for a snap shot when the aperture is set to f/8 to f/11.</p>

 

<p>The <u>acceptable</u> <u>zone</u> <u>of</u> <u>focus</u>, (a.k.a depth-of-field), for a subject at the 3 meters is noticebly greater with a 35mm focal lens as fitted to the XA than with longer focal length lenses. Looking at the above table with regards to a focus setting of 3 meters at f/11, everything within 1.5 meter mark and 38 meter mark should appear to be in reasonable focus on a 4 by 6 inch print.</p>

 

<p>The item that has me perplexed on the XA is why the f/5.6 aperture is marked with gold lettering. Is this to let you know that it's imperative to use the miniscule range finder patch to set the focus?</p>

I'm liking the hyperfocal distance arguement. The snap shot thing may be correct, but my XA is not a "snapshot" camera so that can't be it <grin>. I am at a loss on the gold 5.6 too. Is it the sharpest aperture? I doubt it, but I don't have a better idea.

My XA4 Macro (28mm lens), which does not have a rangefinder but estimated focusing distances by means of a focusing lever/distance scale, also has the 10 foot distance marked in red. The owner's manual says with regard to this setting: "You can take sharp pictures in this range [one meter to infinity] without focusing." Well, that is at f16. At maximum aperture of f3.5, the depth of field is from about 7 to 18 feet. No matter at what distance the focusing lever is set when the camera's sliding dust barrier is opened, when the cover is closed, the lever returns to the 10 foot distance, so the camera is instantly ready for snapshot-type pictures. John Mitchell

My Super-Takumar (I know, Pentax, sorry) 35/3.5 has f8 in red and 5m in red. On the depth of field scale on the lens for f8, that's slightly over 2 meters to infinity when lined up.

I also noticed that my first Isolette came with the focus ring firmly glued to the 3M mark; the second firmly stuck at the 10M mark.

 

Evidently the previous owners adhered to Agfa's recommendations for usage.

 

For folks unfamiliar with Agfa folders and the stuck focus ring syndrome - and I'm kinda new to 'em myself - apparently the otherwise skillful Agfa technicians substituted a tenacious green adhesive for grease on the focus helicoids. After decades of disuse the green goo hardened, leaving the focus ring jammed at its last setting.

 

Kidding about the substitution of glue for adhesive. It was a commonly used lubricant. I've found it used in older Herman Weirauch precision airguns as well, hardened like bits of green plastic.

I second the remarks of 'the first John' after consulting my manual as well. The table indicates that the combination of the 2 red markings: f/5.6 and 3 meters, provides a depth-of-focus that ranges from 2 to 5.6 meters. f/5.6 will allow a short shutter speed provided you have a suitable film inserted.