Monocular - Bushnell Legend Ultra-HD 10x 42mm

General discussions of measurement techniques and the results of testing of techniques and equipment.

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dbhguru
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Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Sat Mar 31, 2018 1:27 pm

Hi Ents,

Yesterday a package was delivered to my door containing my new monocular with reticle. It is from Bushnell and carries the name Legend Ultra-HD. Its lens is 10x 42mm.

The optics of the Bushnell are absolutely superior, better than the Vortex Solo RT 8x36. However, the two units are not exactly equivalent in easy of use and maybe, performance. The width of the Bushnell reticle is 100 units - that of the Vortex, 110. A total of 70 of the 110 unit spread of the Vortex are marked at increments of 1. Only 20 units of the Bushnell's 100 spread are marked one unit apart. This places a not inconsiderable burden on the measurer. In-exact interpolations will have to be done much more frequently with the Bushnell. That's disappointing.

In my first series of measurements of the width of objects at distances of 19 to 33 feet, the accuracy of the Bushnell varied from 0.1 to 0.5 inches. It appeared that very narrow objects were spot on, but wider ones show a greater difference between actual and measured widths. The problem was not distance measurements. I use the BOSCH GLM 80 for distance which has an accuracy rating of +/- 1.5 millimeters. My GLR 825 has an accuracy rating of +/- 1.0 millimeters. So, with either unit, distances are spot on. However, my tripod was wobbly. I didn't have it adjusted right. So I just completed a series of 7 tests comparing the Bushnell and Vortex. The result follows.
Screen shot 2018-03-31 at 2.21.46 PM.png
More tests are planned, but I expect that the results won't vary much in terms of which unit is the more accurate. I named the Vortex unit the Oracle and the Bushnell is named Gizmo.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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dbhguru
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Tue Apr 03, 2018 3:51 pm

Ents,

The attachment includes the result of a second round of testing of the Bushnell Legend Ultra-HD 10x 44mm monocular with reticle. It continues to appear that this instrument is not quite as accurate as the Vortex Solo RT 8x36, but it has superior optics. I think there's a role for both instruments. One feature that I wanted to confirm is that it returns good results for the Trapezoid-Diagonal reticle formula as shown below. No reason why it shouldn't, but I wanted to do testing.
TrapezoidDiagonal2Formula copy.png
TrapezoidDiagonal2Formula copy.png (12.98 KiB) Viewed 818 times
This formula allows us to measure the width of a target line that we view at an acute or oblique angle - as opposed to 90 degrees. When looking at the diameter of a circular trunk, the diameter line is always 90 degrees to the line of sight, but when viewing the width of a non-circular object, we have to be exactly positioned to get the 90-degree line of sight. With the above formula, location doesn't matter.

Bob
Attachments
GIZMO-a.xlsx
(133.78 KiB) Downloaded 23 times
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Larry Tucei
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by Larry Tucei » Wed Apr 04, 2018 2:50 pm

Bob- You are Da Man when it comes to checking, comparing, calibrating, testing or developing methods for measuring devices. I will be putting my new toy the Vortex Solo RT to use down in Cajun Country in two more weeks. Larry

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dbhguru
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Wed Apr 04, 2018 3:39 pm

Thanks, Larry. I look forward to working with you to model some of those whopper live oaks. I especially look forward to us determining the ratio of limb to trunk volume.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Erik Danielsen
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by Erik Danielsen » Wed Apr 04, 2018 7:45 pm

I'm sure those excellent optics make for an easy experience on the eyes. It's unfortunate that the reticle doesn't have precise markings all the way through- always a pity when a company produces an excellent piece of equipment with just one arbitrary detail that reduces its utility. You see that a lot in cameras, actually, given how much more complex they are than something as wonderfully simple as a good monocular. Sometimes it's an irritating attempt at segmenting the market by crippling features via software in lower-end models that use the same hardware as their more expensive counterparts, but other times you know someone in the design team said "I think it will improve the user experience if we make this change," and it ends up doing the opposite.

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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Thu Apr 05, 2018 7:52 am

Erik,

How right you are. Marketing mavens are often given the nod on design features, and they seldom really understand the specialty uses from the standpoint of expert users.

As an example, the feature that mystifies me on new products is the 2-power scope LTI is putting on its soon to be released TruPoint 200H. I asked a executive friend in LTI how that decision was made and he said that users of other LTI Laser products wanted the feature, presumably for a wider angle of view and he said they complained about the lack of clear focus for the current higher-powered laser measuring devices - I assume they mean up close. I have no problem with most targets I shoot.

I expressed my unrestrained opinion that whoever gave that advice couldn't be a competent tree-measurer. It helps to see the target and a higher power is essential for that. So, with the TruPoint 200H, we'll get a combination of infrared and class 2 lasers - the most accurate we'll see on the market for a product which is advertised to sell for under $2,000. But we won't be able to see what the beam is hitting on our distant, tall tree targets. Smart! BTW, the regular tangent-based tree measuring routine is included as a feature. LTI has to bow the the wishes of the big users.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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dbhguru
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Fri Apr 06, 2018 9:27 am

Ents,

The attachment brings us up to date as of April 8th on testing the Bushnell Legend Ultra-HD. It passes with room to spare. I added a feature to the attached, updated workbook. It is at the bottom of the sheet.

Bob
Attachments
GIZMO-a.xlsx
(198.73 KiB) Downloaded 25 times
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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dbhguru
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Sat Apr 07, 2018 3:07 pm

Ents,

After a successful tree walk for Forbes Library in Northampton attended by 27 eager people altogether this morning, on returning home, I had a tiny bit of energy left. What to do? What to do? Off I went into the woods with Gizmo (Bushnell Legend-HD monocular), Sparky (LTI TruPulse 200X), and my 36" calipers. A N. red oak trunk was the target. Putting an orange disk on the trunk of the oak, setting up Gizmo on my tripod (a past gift from Michel Taylor), I measured the distance from the centroid of Gizmo to the center of the orange disk at 136.08 feet. The reticle value was 15.8. Oy yes, the caliper measurement was 25.8 inches. So, what was Gizmo's result? The rest is math.
Screen shot 2018-04-07 at 3.57.53 PM.png
Screen shot 2018-04-07 at 3.57.53 PM.png (20.95 KiB) Viewed 751 times
So, there we have it. At, 136.08 feet away, the error is 0.204 inches - less than a quarter of an inch. The average error for 25 trials now stands at 0.281 inches, which includes a number of obliquely angled targets.

At 136 feet from the target, there is no way that the LTI RD1000 can come close to that level of accuracy, and RD is a $1500 instrument.

Bob
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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dbhguru
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by dbhguru » Mon Apr 09, 2018 3:14 pm

Ents,

At the risk of wearing out this topic, I present the latest version of the worksheet testing Gizmo. BTW, it was my good friend Don Bertolette who first alerted me to the Bushnell Legend Ultra-HD 10x44 monocular. So, I guess Don is Gizmo's uncle or perhaps its godfather. Take your pick, Don.

Anyway, Gizmo performed magnificently in Look Park on a white pine measured first at a distance of 137.5 feet and then at 160.58. In both cases the difference between the DBH tape wrap and the computed trunk width courtesy of Gizmo was only 0.27 inches. Think about it folks, you're standing 160 feet away from a target and you can measure its width to with roughly a quarter of an inch. That level of accuracy is what we need to model trunk and limb volumes.

So, armed with either the Vortex Solo RT 8/36 or the Bushnell Legend Ultra-HD 10x44 monocular and a TruPulse 200X, measuring trunk width from a distance is "elementary my dear Watson." Simply elementary.

Bob
Attachments
GIZMO-a.xlsx
(202.99 KiB) Downloaded 24 times
Robert T. Leverett
Co-founder, Native Native Tree Society
Co-founder and President
Friends of Mohawk Trail State Forest
Co-founder, National Cadre

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Don
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Re: Monocular - Bushnell Legend Ultra-HD 10x 42mm

Post by Don » Tue Apr 10, 2018 1:42 am

Bob-
Glad the Bushnell Reticled monocular lived up to my 'hype'...one feature I hadn't picked up on was it's "picatinny' mount which it appears to allow a 1/4 x 20 tripod attachment...certainly saves time modifying the Vortex's clip to accept a 1/4" x 20 tripod !
Is the advantage in optics dimension (10 x 42 vs. 8 x 36) significant? It has a lot of exotic metal coating which should support their claims for image brightness, even in low lighting conditions.
By the way, I don't know if a black one would be preferable, but it appears one is available...
-Don
Bushnell.png
Don Bertolette - President/Moderator, WNTS BBS
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