Three 7x50 cleanings / repairs (1 Viewer)

All three from auction binocs were from the 1948-1956 period, approximately.

Patrician Deluxe:
Independent focus, stiff grease...cleaned up easily. Nice threads..light galling
but worked it out, mopped off the filings, paraffin made it happy. Gun/choke
grease for focuser...a bit loose feeling afterwards. Lenses cleaned easily,
body dinged a bit, eyepiece/eyecup OK.
Resolution: 10-font at 25 ft
Contrast: good
Brightness: not as high as expected
Color: yellowy, though prisms were white.
Depth of field: excellent FOV: plain

Stellar:
Independent focus, moderate grease, just loosened w/WD40.
Easy threads. Just a little paraffin to add. Mixed in Gun/choke
grease for focuser...went well (remove some, layer some on).
Lenses cleaned easily, body perfect, eyepiece/eyecup super.
Resolution: 8-font at 25 ft ... this is unusual for 7x .. very sharp
Contrast: very good
Brightness: not as high as expected
Color: yellowy, though prisms were white.
Depth of field: excellent FOV: plain

Daylite:
This was cleaned already, and very nicely.
However, the collimation was awful. After 2 minutes
swiveling the cell on one side, it was perfect again.
Easy. Someone knew the tools and the cleaning but
did not know to mark the objective alignments.
Has a center focuser but it works well and is solid.
Resolution at 25 feet: 10-font
Contrast: excellent
Brightness: not as high as expected
Color: yellowy, though prisms were white.
Depth of field: excellent FOV: plain

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So the Stellars are my 'keep 'em' pair,
and all three "brands" are a bit yellowy.
Looking at ivory-colored paper, they don't look so
dim compared to others. They just have a severe
loss of both violet and blue, much moreso than
the 7x35s of that era. I am guessing they had
strong haze-rejection in the coating because of
possible marine use and haze (?). I really wish there were some
older binocs with better color. Maybe in the 80s, if I can
dodge the rapid-focus. I'm hoping to really see the brightness
you should get from 7x50. Most 7x35s of the same era are
a little brighter and have truer color.

ADDL: A practicing optical engineer friend had this tidbit to toss in:
the 7mm exit pupil would rarely be met with an actual 7mm eye pupil,
unless it was very dark out. Thus, in daylight, the advantage of
easy eye placement when moving is what you get,
but so much any brightness gain. You would get the extra
brightness in an application like looking at the night sky.
Otherwise, it would be similar to a 7x35 in brightness.
That fits my overall impression. The color thing...that's
still there, but a different issue.
.

Add one pair of "Scope" 7x50s.

They seem like burly cousins of the Bushnell Custom at first glance,
with heavy-duty focuser, UV coatings on the front, nice case.
Claim for FOV: 525 ft at 100 yds. Unusual.
They clean up easily.

They are brighter than the others, but there is a very steep
rolloff in brightness at the outer image.

I was about to write them off as a hodgepodge of parts
that didn't add up, but for fun I took off the rubber
eye cups. Everything got better, with and without glasses.
They still have some edge-f-fov issues, but the brightness
and color are very good overall.

OPTIC_NUT said:

ADDL: A practicing optical engineer friend had this tidbit to toss in:
the 7mm exit pupil would rarely be met with an actual 7mm eye pupil,
unless it was very dark out. Thus, in daylight, the advantage of
easy eye placement when moving is what you get,
but so much any brightness gain. You would get the extra
brightness in an application like looking at the night sky.
Otherwise, it would be similar to a 7x35 in brightness.
That fits my overall impression. The color thing...that's
still there, but a different issue.
.

Click to expand...

So right, the easy eye placement of 7x makes them so comfortable to use, I have some top notch 8x porro bins but if I don't get the eye placement spot on I always get little black outs at the edge, not so with my 7x bins.

Exit pupil does seem to rope a bunch of related issues into one:
brightness, shake-resistance(via lower power), and easy placement.
Easy placement is nice because of the way birds are frequently found
by sound -> bare-eye -> binoculars targeting. So...your obsession is gaining on me.
This is in the Cognitive Psych. of bird acquisition.

A 5mm pupil (ie, in a 7x35) makes me fairly happy, too, and the FOV
of the 7x35 ultrawides helps acquisition in cluttered backgrounds.
Having an extra-wide 7x50 is nice for finding.
I suspect the dimming edge in the Scope's is actually deliberate, to perk up
the center field brightness. "Noticing" at the edges is still possible if things are bright.

The 8x30, meanwhile, is 3.75 mm. That does usually add time to my acquisition.
That's a tough target sometimes.

I have had a few 525 foot FOV vintage 7x50s. Some of them can be truly impressive. Keep an eye out for that Sears Discoverer 7x50. It impressed me more than a variety of other ones.

Now that I've been able to brighten a Discoverer 7x35, the 7x50 Discoverer does
sound very interesting.

One thing I have learned: there are not as many bright, sharp, wide 7x50s as
7x35s floating around out there. Much more rare.
The total quantity and variety of 7x35s from the past is staggering.