Depth Of Field better when diameter is larger? (1 Viewer)

[ReinierB]

I have a Swaro SLC 8x42 and a Zeiss Terra 8x25 and found the DOF of the 8x42 way better. Is that because of the larger diameter (42 vs 25) or is it just because the quality of the optics of the SLC is better?
Can I say, the larger the diameter the deeper the DOF? Or doesn't the lens diameter affect that? Is for example the DOF of the CL 8x25 or Victory 8x25 simular? Or better because the optics are better?

The DOF of my NL 10x32 is also quiet shallow, but I understand 8 power is better regarding this. Or is the DOF of the NL 10x42 bigger because the lens diameter is larger?
Just wonder what the correlation is.

 

[Hermann]

No. Unless the laws of physics don't apply to your binoculars.

Hermann.

 

[ReinierB]

I have a Swaro SLC 8x42 and a Zeiss Terra 8x25 and found the DOF of the 8x42 way better.

You are implying that this is not possible?

 

[ReinierB]

Edit: I meant DOF. Sorry, my poor English 🫣

 

[has530]

The only parameter that affects DOF is magnification. Binoculars with lower magnification have better DOF than higher magnification binoculars. Aperture size does not affect DOF in any way.

Unless I'm mistaken that is not entirely true. It is certainly the biggest factor but exit pupil size (and thus objective diameter) can also play a roll. If one binocular uses your full pupil and another "stops down" your eye you can get a little more perceived depth of field from your visual accommodation. I just tried this with my Leica 8x20 UV and meopta meostar 8x32 and found the UV to have more DOF. Of course this is the opposite of what OP found and might not qualify as depth of field of the binocular itself (which is an inherently afocal system) but still should generally hold true for the user experience.

 

[has530]

DOF is determined entirely by the magnification of the binocular. Here is a mathematical explanation of it.

Depth of Field ? - Binoculars - Cloudy Nights

Page 1 of 2 - Depth of Field ? - posted in Binoculars: What optical parameters determine a binoculars Depth of Field?It would seem to be factor(s) besides magnification, objective diameter and effective exit pupil. For example, there are several web comments on the remarkable DOF of the Fujinon...

www.cloudynights.com

Depth of Field Test - Method and Results

I wish I had some time to do some actual birding but instead I had to get my fix by doing a simple test. There have been a couple threads relating to depth of field lately so I thought I'd use something from photography. For those of you with several sets of binoculars, or just for fun, you...

www.birdforum.net

I have read both of those before and yes the depth of field of the binoculars is magnification dependant. However the image formed on your retina is a combination of the afocal optics in the bino and your eye. If the exit pupil acts as a limiting aperture for your eye it can increase your eyes ability to bring more of the field depth into acceptable focus.

 

[Dipperdapper]

nota bene:

Product Review: Opticron Adventurer T WP 6.5 x 32. | Neil English.net

 

[Canip]

Unless I'm mistaken that is not entirely true.

Unless I am mistaken you are not mistaken 👍

 

[Maljunulo]

I have read both of those before and yes the depth of field of the binoculars is magnification dependant. However the image formed on your retina is a combination of the afocal optics in the bino and your eye. If the exit pupil acts as a limiting aperture for your eye it can increase your eyes ability to bring more of the field depth into acceptable focus.

If the question involves a property of an instrument, which can be quantified and expressed as a number, the performance of an attached human eyeball is only relevant to the owner of that eyeball. It has nothing to do with the original question, and the answer remains “no”.

(see line three below)

 

[Hermann]

Unless I'm mistaken that is not entirely true. It is certainly the biggest factor but exit pupil size (and thus objective diameter) can also play a roll. If one binocular uses your full pupil and another "stops down" your eye you can get a little more perceived depth of field from your visual accommodation.

True: "Zusammenfassend halten wir fest, dass die Schärfentiefe, die ein Beobachter mit seinem Fernglas erzielt, maßgeblich von seiner Akkomodationsbreite bestimmt wird, ferner von der Vergrößerung des Fernglases, und, in geringerem Maße, von dem Durchmesser der effektiven Austrittspupille." (Merlitz ²2019:157).

Hermann

 

[Trinovid]

True: "Zusammenfassend halten wir fest, dass die Schärfentiefe, die ein Beobachter mit seinem Fernglas erzielt, maßgeblich…

さっぱり分からへん、最初の単語以外。さぁ。。。

 

[Tringa45]

True: "Zusammenfassend halten wir fest, dass die Schärfentiefe, die ein Beobachter mit seinem Fernglas erzielt, maßgeblich von seiner Akkomodationsbreite bestimmt wird, ferner von der Vergrößerung des Fernglases, und, in geringerem Maße, von dem Durchmesser der effektiven Austrittspupille." (Merlitz ²2019:157).

Hermann

Yes, and the effects of accommodation are often overestimated because the user's ability to accommodate through a binocular is reduced by the square of its magnification. See:- Focussing: Just Do It!

John

PS: AFAIK there was no English edition of Holger's first book.

 

[Trinovid]

😿

You’re okay with one language that many here can’t read, but not another?
Ideally posts should be readable by all. Ideally, that is.

 

[Binocollector]

"Zusammenfassend halten wir fest, dass die Schärfentiefe, die ein Beobachter mit seinem Fernglas erzielt, maßgeblich von seiner Akkomodationsbreite bestimmt wird, ferner von der Vergrößerung des Fernglases, und, in geringerem Maße, von dem Durchmesser der effektiven Austrittspupille." (Merlitz ²2019:157).

"In conclusion we can state that the depth of focus that an observer can achieve with his binocular, depends mainly on his ability to accomodate, the magnification of the binocular and to a lesser degree on the diameter of the effective exit pupil."

 

[has530]

If the question involves a property of an instrument, which can be quantified and expressed as a number, the performance of an attached human eyeball is only relevant to the owner of that eyeball. It has nothing to do with the original question, and the answer remains “no”.

(see line three below)

All users of binoculars have eyeballs and if said eyeballs are stopped down by a virtual aperture at the exit pupil it will increase the depth of field. The original question was if aperture affects the depth of field and while magnification is the most important factor, the exit pupil diameter is the way in which objective diameter impacts the depth of field so I would contend it does in fact have something to do with the original question.

to a lesser degree on the diameter of the effective exit pupil

Q.E.D.

 

[Binastro]

Is Latin allowed?

Regards,
B.

 

[Binocollector]

Is Latin allowed?

Regards,
B.

I only know a few remaining phrases, like "In principio erat verbum. Et verbum erat apud deum. Et deus erat verbum." That's about all that is still left from studying theology . My Greek is much better though.
Oh, you meant the q.e.d?

 

[Hermann]

Yes, and the effects of accommodation are often overestimated because the user's ability to accommodate through a binocular is reduced by the square of its magnification.

In the end what counts is the magnification. It determines the depth of focus. All the other effects are small and depend on the observer.

PS: AFAIK there was no English edition of Holger's first book.

Nope. There still isn't. So I just followed the normal procedure in academic writing: I quoted the relevant text in the original language.

Hermann

 

[Maljunulo]

All users of binoculars have eyeballs and if said eyeballs are stopped down by a virtual aperture at the exit pupil it will increase the depth of field. The original question was if aperture affects the depth of field and while magnification is the most important factor, the exit pupil diameter is the way in which objective diameter impacts the depth of field so I would contend it does in fact have something to do with the original question.


Q.E.D.

Of course, but the question addresses the optical properties of the instrument, not the observer, hence the observer is irrelevant to OP’s question.

The answer is still “no”.

 

[has530]

Of course, but the question addresses the optical properties of the instrument, not the observer, hence the observer is irrelevant to OP’s question.

The answer is still “no”.

This seems like a weird technical contrarian hill to try to die on but I'll give it one more go explaining why the question doesn't even make sense without considering the user (and thus the exit pupil).

What is depth of field? A simple definition would be something along the lines of "The range of distances for which objects can be brought into acceptable focus". The key here is "brought into acceptable focus". This begs two questions. Brought into focus where? And brought into focus how? Binoculars are inherently afocal instruments meaning they broduce no net convergence or divergence of the optical beam. This means binoculars don't actually bring anything into focus, the image is formed by the users eyeball. Brought into focus where? Or rather where is the focus measured? Well that would be the imaging plane, or in the case of visual optical instruments...the retina of the user!

The difference from user to user in perceived depth of field is accounted to their own visual accommodation (how much they can focus their eyeballs) but even without any visual accommodation (changing the focal length of the eye) depth of field will be different for different entrance pupil sizes which in the case of binoculars is controlled by the exit pupil/objective diameter (until your exit pupil exceeds the entrance pupil dilation). You can try this on your own by punching a bunch of small holes of different sizes in a peice of paper, looking at an object at infinity and holding some text much closer to your face then looking through. The smaller the hole the more in focus the two objects will appear simultaneously (that is until diffraction comes into play...).