Which 10x has the greatest DOF? (1 Viewer)

[gandytron]

I’ve been using 7x and 8x binoculars for the last decade but a year ago bought a pair of Leica 10x32 Trinovid HDs and I find the DOF annoyingly shallow and I continually need to refocus when birding in urban green spaces (where I do 95% of my birding). This is not helped by the Trinnie HD having some play in the focus wheel.

I’m planning to replace them with another 10x later this year and to help me narrow my search for an alternative model I’d be interested to know how much DOF is offered by the various top-tier models, and whether a 10x42 might offer more DOF than a 10x32.

Any thoughts?

 

[qwerty5]

DOF is determined by magnification alone. See this thread: Is binocular depth of field in focus variable?

 

[BKoh]

Depth of field varies with magnification, so all else equal a 10x will have less depth of field than a 8x.

However, at the same magnification, depth of field is also related to focal ratio. We see this in camera lenses, where closing down the aperture increases depth of field. Unless you mask or stop down your binoculars, the only way to get better depth of field at the same power is to find binoculars with a longer focal ratio.

Most binoculars are around f/4 but abnormally short or long units may fall outside this range. Leica Ultravid binoculars tend to be short for their objective size. The opposite is true for Zeiss SF and Swarovski EL. This is especially obvious in the 32mm size for all 3 brands.

Most likely the Leicas have shorter focal ratio, while the Zeiss and Swaros have longer focal ratios, so depth of field in the Zeiss SF and Swarovski EL should be correspondingly greater than in the Leica Ultravid. As for the Trinovid, its length should give appropriate hints about its focal ratio.

EDIT: After further reading I believe that for binoculars only magnification affects DOF. My apologies to anyone who was misled.

 

[gandytron]

Thanks for these replies.

I think the slack in the focus wheel on the Trinnie HD might be a contributing factor to the feeling of especially shallow DOF, so when I look for a new 10x I will pay particular attention to the precision of the focus, as well as the length of the body.

 

[MiddleRiver]

Thanks for these replies.

I think the slack in the focus wheel on the Trinnie HD might be a contributing factor to the feeling of especially shallow DOF, so when I look for a new 10x I will pay particular attention to the precision of the focus, as well as the length of the body.

You should have the binos looked at by Leica service. I own a half-doz Leica including 8x and 10x Trins and NONE of them has slack in focus wheel.

 

[MiddleRiver]

@BKoh I hope you don't mind but I cross-posted (and quoted you) on the other DOF thread mentioned above. I'm really interested in the comment that DOF is affected by focal-length of bino (and thus physical size?). I was under the impression that it is not, but will admit it's been hard for me to get a grip on DOF in binos and I'm genuinely curious!

 

[Tringa45]

However, at the same magnification, depth of field is also related to focal ratio. We see this in camera lenses, where closing down the aperture increases depth of field. Unless you mask or stop down your binoculars, the only way to get better depth of field at the same power is to find binoculars with a longer focal ratio.

This is not the case. See Canip's post #31 on the other DoF thread.
Disregarding factors such as accommodation, field curvature and reduced exit pupil, DoF is prportional to the inverse square of the magnification, i.e. a 7x binocular has double the DoF of a 10x binocular.

John

 

[BKoh]

@BKoh I hope you don't mind but I cross-posted (and quoted you) on the other DOF thread mentioned above. I'm really interested in the comment that DOF is affected by focal-length of bino (and thus physical size?). I was under the impression that it is not, but will admit it's been hard for me to get a grip on DOF in binos and I'm genuinely curious!

My apologies. After fully reading this thread:

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

I stand corrected. In the above discussion, careful experiments by experienced members agreed with mathematical calculations that for binoculars, only magnification affects DOF.

 

[MiddleRiver]

Coming from a photography old-school background, I've had to rethink a lot There's no question that different binoculars present a different picture to the eye/brain, but quantifying it and discussing it, is often harder than you would expect!
To the original poster, I would simply say: try as many binos as you can! Everyone's ergonomics and perceptions are different (and pocketbook of course).