Perceived depth of field (2 Viewers)

[ceasar]

Does anybody have a 9x40 or so porro bin?

The last I knew Steiner made one. Maybe 2. (inxpensive and expensive) They are armored, have a fov of 300', and are relatively lightweight but bulky. They are aimed for the hunting market. They both look very much alike. the inexpensive one goes for about 220.00 bucks, the other for around $350.00.
Bob

 

[Tero]

The only Steiner I found
http://www.opticsplanet.net/steiner-binoculars-9x40-big-horn.html
has individual eye focus, too slow for birding.

 

[Sout Fork]

Sout,

I don't know what the near focus of all the Nikon Actions are, but this one is 16.4 ft. http://www.shopping.com/xPO-Action_Nikon_Action_Binoculars. It's hard to believe that you could have seen things at 9 ft. "nearly in perfect focus," — also with them set at infinity.

Ed
PS. Sorry, Jules, and you have been talking about 10x35 E2, which have a short focus of 5 meters = 15+ ft. Basically, I'd make the same statement about them.

OK.

Went out on the porch and tried the same thing again.
NOTE: When I'm talking about netting I mean standard 24 gauge chicken wire that forms a 1 inch hexagon by winding one side of hexagon to the next one with 6 turns of wire. It was put up to keep my cats from running off. The maximum distance I can back away from netting on this porch is a little under 11 feet.

Results with a distance of 9 feet between the objective and netting (measured):

Nikon Action 7x35 non EX (Nikon part number 7215);
netting very obvious and distinct to the point where it is distracting to try and concentrate on something at infinity. Can clearly count the six small loops that form the netting.

Zeiss 7x42 Classics:
Netting is very vaque and soft the loops are a thick blob that can not be counted.

Leica 8x32 BA:
Just the slightest hint of netting if you really look for it. When concentrating on infinity not aware of netting at all.

With the diopter set for my eyes I checked the close focus of the three and came up with this:

Nikons:11 feet
Zeiss: 16 feet
Leica BA 14 feet

At these distances all were tack sharp.

SF

 

[FrankD]

If I remember correctly the actual close focus distance for any given binocular is going to vary somewhat depending on the individual's eyes. I believe my Nikon 7x35 Action EX has the same close focus distance as the Non-EX model and yet my actual close focus distance is about 7 feet (assuming you push the barrels together to get an overlapping image).

 

[elkcub]

OK.

Went out on the porch and tried the same thing again.
NOTE: When I'm talking about netting I mean standard 24 gauge chicken wire that forms a 1 inch hexagon by winding one side of hexagon to the next one with 6 turns of wire. It was put up to keep my cats from running off. The maximum distance I can back away from netting on this porch is a little under 11 feet.

Results with a distance of 9 feet between the objective and netting (measured):

Nikon Action 7x35 non EX (Nikon part number 7215);
netting very obvious and distinct to the point where it is distracting to try and concentrate on something at infinity. Can clearly count the six small loops that form the netting.

Zeiss 7x42 Classics:
Netting is very vaque and soft the loops are a thick blob that can not be counted.

Leica 8x32 BA:
Just the slightest hint of netting if you really look for it. When concentrating on infinity not aware of netting at all.

With the diopter set for my eyes I checked the close focus of the three and came up with this:

Nikons:11 feet
Zeiss: 16 feet
Leica BA 14 feet

At these distances all were tack sharp.

SF

Sout Fork (& Frank D),

I've looked at birds through cyclone fences once in a while, when I couldn't get around it. In truth, I never considered that one binocular would be any better or worse than another, but like you said, seeing the fence clearly would be more annoying.

I can't explain why you'd experience this effect with the Nikons, or why they have an 11' (or 7') short focus when advertised to have 16'. The short focus for the Zeiss 7x42 B/GAT is advertised at 12', and the Leica BA (Ultra) at 10'. Again, your numbers are considerably off, and in the wrong direction.

But, the old saying is "seeing is believing."

Ed
PS. Yes, the short focus does vary with the user's eyesight, but I would not have thought this much. Also, you'd think Sout's good eyesight would work with Zeiss and Leica optics too?

 

[Sout Fork]

Sout Fork (& Frank D),

I can't explain why you'd experience this effect with the Nikons, or why they have an 11' (or 7') short focus when advertised to have 16'. The short focus for the Zeiss 7x42 B/GAT is advertised at 12', and the Leica BA (Ultra) at 10'. Again, your numbers are considerably off, and in the wrong direction.

One possible explaination-you are putting too much faith in "advertised" specs?

Logically One could just as well conclude the advertised specs are in the "wrong direction" as well.

Don't trust everything you read by me nor the specs put out by someone in the mass marketing depts at Nikon or Zeiss.

What does your own experience tell you?

 

[FrankD]

elkclub,

I have no explanation other than it seems almost all the bins I own focus more closely than their advertised specs. My only conclusion would be that it is going to vary depending on the individual. Just in general, does anyone know how the manufacturers actually measure the close focus distance?

 

[elkcub]

elkclub,

I have no explanation other than it seems almost all the bins I own focus more closely than their advertised specs. My only conclusion would be that it is going to vary depending on the individual. Just in general, does anyone know how the manufacturers actually measure the close focus distance?

Frank,

There is a major disconnect here. You report typically better performance than advertised specs. Good. Sout reports the opposite: inexpensive Nikons doing much better than advertised specs, and expensive Zeiss and Leica models doing much worse.

Nikons:11 feet
Zeiss: 16 feet
Leica BA 14 feet

At these distances all were tack sharp.

Your eyes can accommodate (focus) very well, probably due to being young? The lens of the young eye is elastic, but will ossify with age (along with a few other things) ||

As for Sout, I know what it's like being able to see unusual things. http://www.birdforum.net/showthread.php?p=601210#post601210. I feel his pain.

Ed

 

[FrankD]

Your eyes can accommodate (focus) very well, probably due to being young?

34 and hope to keep them elastic for some time to come.

 

[Tero]

Close focus may depend on how sunny. Perhaps they are rated in Ireland.

 

[Sout Fork]

Frank,

There is a major disconnect here. You report typically better performance than advertised specs. Good. Sout reports the opposite: inexpensive Nikons doing much better than advertised specs, and expensive Zeiss and Leica models doing much worse.

Your eyes can accommodate (focus) very well, probably due to being young? The lens of the young eye is elastic, but will ossify with age (along with a few other things) ||

As for Sout, I know what it's like being able to see unusual things. http://www.birdforum.net/showthread.php?p=601210#post601210. I feel his pain.

Ed

Been thinking about this issue of close focus so...

Recently had a gathering of family and friends at my place.
So I took four from the group plus my wife and did a little test.

Took them to the porch I have been talking about.
With the exception of my wife none of them has any particular experience using binos.

Binos used:
The Zeiss, Leica, Nikon and the recently bought Bushnell Excursion 8x28 (claimed close focus of 6 feet).

Because these folks were not bino savvy I just set the diopter to zero and cranked the focus in as close as it would go.

All these folks had to do was walk towards the screening and tell me when it was at sharpest focus.

Results:
guest 1
Zeiss 14
Leica 13
Nikon 12
Bushnell 9

guest 2
Zeiss 16
Leica 14
Nikon 12
Bushnell 8

guest 3
Zeiss 14
Leica 14
Nikon 12
Bushnell 8

guest 4
Zeiss 15
Leica 14
Nikon 11
Bushnell 8

guest 5
Zeiss 16
Leica 14
Nikon 14
Bushnell 9

NOTE:
My wife is a very experienced birder and is used to using high-end optics. Her favored binos are the Zeiss which she has used for years. She is in her mid 60s and uses glasses for reading only.

One of the guests was a 12 year old girl who does not wear glasses.

All the rest were, roughly, in late 50s.

Can you guess who was who?

SF

 

[elkcub]

Can you guess who was who?

SF

No, but you're winning me over. |=)|

I don't own any Leica or Zeiss binoculars, but my Swaros, Swifts, Nikons and Bushnells (15 in all) are consistent with the specs considering my far sightedness. What I mean is that I have to add a few feet to the specs and can't focus as close as advertised. My children, however, can focus to the advertised distances or better. The Swift 804ED (my favorite binocular) was advertised to focus closer than the standard 804 HR/5 — and it surely does.

Is a puzzlement.

Ed

 

[Sout Fork]

No, but you're winning me over. |=)|

I don't own any Leica or Zeiss binoculars, but my Swaros, Swifts, Nikons and Bushnells (15 in all) are consistent with the specs considering my far sightedness. What I mean is that I have to add a few feet to the specs and can't focus as close as advertised. My children, however, can focus to the advertised distances or better. The Swift 804ED (my favorite binocular) was advertised to focus closer than the standard 804 HR/5 — and it surely does.

Is a puzzlement.

Ed

ED,
"consistent with the specs"...
These results are, with the exception of the Nikons, consistent with
the specs you gave in that one would expect the Bushnells to focus
closest, next the Leicas and then the Zeiss.

Also I wonder if depth of field may become critical at close focus.
Notice the 7x bins seem to have more variation than the 8x bins.

BTW. When it came to just letting folks look out over the field at
their pleasure the WOW measurement was never in doubt. The Zeiss won
easily.

SF

 

[elkcub]

SF,

Forgive me, but weren't you the person who said this on post #26?

Don't trust everything you read by me nor the specs put out by someone in the mass marketing depts at Nikon or Zeiss.

What does your own experience tell you?

If there is a point here, I'm confused.

Looking at your data, Guest 5 seems to have slightly inferior short focus ability compared to the others, i.e., averaged over the four binoculars.

Other than that, you have some interesting Nikons and, given the consistency of your five observers, possibly a reason to get factory adjustments to some to-die-for Zeiss and Leica instruments. They should be able to do better. |:d|

Enjoy the view,
ED