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Eyecup diameter, Zeiss pockets (1 Viewer)

Ignatius

Putting the Red back into Redneck
Palestine
The eyecups of my Curio 7x21s are exactly 30 mm in diameter.

Can anyone please help me out with the eyecup diameters of the Zeiss Terra ED 8x25 and the Zeiss VP 8x25?
And how long are they each, with the eyecups fully extended?

Thank you.
 
Thank you for that comprehensive and helpful answer.
Seems as though I was not being clear - I meant the total length of the bino with the eyecups extended all the way, not the length of the eyecups themselves.
Very interesting point about the 'eyeballing distance', what Mr Canip/Pinac calls 'Usable eye Relief': Zeiss themselves put it at 16.5 mm (and Mr. Canip at 13 mm)
 
The eyecups of my Curio 7x21s are exactly 30 mm in diameter.

Can anyone please help me out with the eyecup diameters of the Zeiss Terra ED 8x25 and the Zeiss VP 8x25?
And how long are they each, with the eyecups fully extended?

Thank you.
The (outer) diameter of the Terra eyecups is 30mm, total length is 120mm (total legth of VP is 119mm).
 
My answer of “eyeballing distance” was probably not clear enough. What I was saying is that I was estimating (eyeballing) the distance from the eyepiece glass to the top of the eyecup. I wear eyeglasses when I use binoculars, and to me the 16.5mm eye relief that Zeiss claims seems about right. The 12mm figure that I mentioned above is consistent with user reports of the eyecups being a bit short to allow a non-eyeglass user to get the eyecups seated in the eye socket without blackouts.

For the total length of the binocular with the eyecups extended, I get 4.68 inches or 119mm.
 
Ok. Maybe I have always misunderstood the concept of eye relief. I understood it to mean the distance from the outer surface of the last lens in the eye piece to where the light travelling through the binos converges to form a sharp image. As such that would mean on the surface of the pupil, the point from where the eye itself takes over (focussing, accommodation, etc) in relaying the visual information to the brain.
So with the eyecups down, the glasses would touch the surface of the last lens and ER would be the distance through the glass in the spex to the surface of the eyeball. When not wearing glasses and with the eyecups up, that distance would be bridged by the upturned eyecup.
So there would be 4 to 4.5 mm missing.
Using calipers, for my Curios I just now measured 13 mm, vs 16 specified by the manufacturer, and 14.5 by Mr. Canip.

I wonder whether the whole eye placement thing doesn't depend on a combination of usable ER and eyecup diameter, especially on these small instruments.
 
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And we measured an eyerelief of 16 mm using a Ramsden dynameter measured from front lens of the eyepiece to eye, see our test report on the WEB-site of House of Outdoor.
Gijs van Ginkel
 
Mr. van Ginkel, when you say from the front lens of the eye piece, of the lenses making up the eye piece, is that the lens closest to the eye, or the one furthest away from it? And would that be the side of the lens facing the eye or the one facing away?
(In your comparative test from Feb. 2019 you measured an EP of 17 mm for the VP 8x25)
 
I have measured the usable ER on those of my binos I have access to here and worked out the delta to the manufacturers' figures.

Brand​
Model​
Manufacturer ER (mm)​
Measured usable ER (mm)​
Δ (mm)
SwarovskiCL Curio 7x21
16​
13​
3​
ZeissVictory T*FL 7x42
16​
14​
2​
SteinerNavigator Pro C 7x50
20.2​
17.4​
2.8​
SwarovskiHabicht W O GA 8x30
12​
8​
4​
ZeissSFL 8x30
18​
13.4​
4.6​
ZeissSFL 8x40
18​
15​
3​
ZeissConquest HD 10x56
18​
14​
4​

This works out as an average delta of 3.3 mm with a standard deviation of 1.14.
Is there a scientific explanation, why across the board the measured figure should deviate by ca. 3.3. mm?
 
Ignatius,
The Ramsden dynameter is developed especially for this type of measurements. It has an optical scale to read the diameter of the exit pupil with an uncertainty of +/- 0,1 mm and the sliding tube in the outer tube can be moved so the exit pupil is focussed as a perfect round cicle. The dynameter is constructed in such a way that one reads the diameter of the exit pupil as well as the distance from the surface of the exit lens to the entrance surface of the eye (eyerelief)..
The instrument I use was made especially for this purpose by Bleeker optical company when that company started to produce binoculars.
Gijs van Ginkel
 
Ok. I suppose that means we now have three measurements:
1) manufacturers' figures,
2) caliper measurements of the usable ER from the top of the ocular lens to the top of the eyecup rim (eyecups all the way up), and
3) your measurements with the Ramsden dynameter.

Maybe we ought to start a matrix accumulating all those for binos and try and work out where the obvious differences come from.
After all, for the VP 8x25 we now have 16.5 from Zeiss, 12.5 (Canip/Jeffbennett12) and 17 from Mr. van Ginkel. For the Curio we have 16 per Swarovski and 13 measured by me.
That is, if anyone actually apart from me gives a rat's sphincter about this 'phenomenon'.
 
Usable ER.

To measure simply take vernier callipers, turn the eyecups all the way up (as an unbespectacled person only THIS ER is usable for me - it is also closest to that given by manufacturers), and use the depth probe or rod to measure the distance from the ocular lens to the top of the eyecup. Using the nonius, or eponymous vernier scale you can get a measurement to one decimal point, ie. to 0.1 mm. Mine is made by Mauser and I trust it. Modern digital ones may be even more accurate and give you more decimals.
 
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use the depth probe or rod to measure the distance from the ocular lens to the top of the eyecup
But this cannot be the definition of ER because exactly how (or whether) the eyecup sits on the face varies with individual anatomy, and also because eyecups aren't equally well designed in every model. The relevant distance is to where the exit pupil comes into focus, as Gijs said.

These measurements of yours may exceed actual ER on average because (Western?) eye sockets are typically recessed by a few mm.
 
But this cannot be the definition of ER because exactly how (or whether) the eyecup sits on the face varies with individual anatomy, and also because eyecups aren't equally well designed in every model. The relevant distance is to where the exit pupil comes into focus, as Gijs said.

These measurements of yours may exceed actual ER on average because (Western?) eye sockets are typically recessed by a few mm.
Thanks for playing. Actually my measurements undercut the manufacturers'.
I am just trying to find out whether ease of view or Einblickverhalten can be measured in some way or whether some sort of relationship between variables can be found to quantify this. Of course it will be different for everyone but otoh a figure of xyz may be good for one person who will then look for that in a bino, while zxy is good for another. My FL 7x42 is perfect in this sense as I can just put it to my eyes and voila. The Curio is fiddly. The SFL 8x30 is sort of in between.
Your comment leads me to another question in this search. If manufacturers' definition of ER is where the EP comes into focus, how do they determine the length of the eyecups, or what Canip calls the usable ER? Some binos just work for me, others have to hover before my face making them useless to me.
I imagine most people try to get a 'tripodular' arrangement between both hand and some part of the fron of their face, preferbaly the eye sockets, going.
 
Further to Gijs' posts,

A couple of images showing a dynameter being used to measure the eye relief from the rear surface of the eye lens:

View attachment 1542181

From Canip/ Pinac at:
a) Zeiss Conquest 8x56 - Binoculars - Cloudy Nights
b) A new Swarovski NL Pure? - Page 4 - Binoculars - Cloudy Nights


John


p.s. For some information on the construction and use a of dynameter, see: Dynameter - Wikipedia
Since they are sitting on top of the rim of the eyecup, are they measuring it from there, or as you say from the rear surface (closest to the eye) of the eyepiece. In Zeiss Conquest HD 8x58 one can see that there would be a difference of several millimetres ( on my 10x56 it is 5.4 mm).
 

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