Well-rounded pair of binoculars for wildlife/travel. Newbie here, help! (1 Viewer)

denco@comcast.n · Apr 23, 2015

jordn613 said:
They both came today, and here are my initial impressions, from a total newbie with binoculars.

The Sightronics are lighter and smaller. They feel more in line with what I was looking for when it comes to portability. Even with their size, I still would love something even more pocket-friendly, but then I realize I'd be sacrificing lens quality (within the choices in my price range, at least).

The Vanguard Endeavor are clearly a better made pair than the Sightronics. That said, they are heavier and a bit bulkier.

With just a few minutes of A/B testing in the backyard, the Vanguard appear to be a bit sharper and to have a better image all around. The Sightronics look ever so slightly "washed out" in comparison, and maybe this is a matter of adjusting but they seem to give my eyes a bit of strain.

Truly the difference in image is not enormous, and so I'm faced with a tough decision. The Sightronics win for travel-ability but the Vanguard are, to my eyes anyway, a superior pair of binoculars.

You will appreciate the 42mm objective of the Vanguard ED under the canopy in Costa Rica. In a lot of the rain forests very little sun filters thought the trees. Are you going to Monteverde Rain Forest? You can usually see Quetzal's by a group of trees off to the left at the entrance to the park if you get there early in the morning before 7am. Many, many varieties of Hummingbirds buzzing around there. The Costa Rican guides are very inexpensive and can be found at the entrance to the park. They are well worth the money. The road going to Monte Verde is the worst road I think I have ever seen in my life. On the way there there will be kids selling maps but don't buy them because you really don't need them. Also, make sure you take the night tour of the jungle at Monteverde. It is amazing how many weird creatures come out at night. Don't overlook the Arenal Volcano area for birding. There are a lot of interesting species to put on your life list there and a lot of things to do including sitting in hot pools. You can eat at the Sodas along the roads in Costa Rica for about $3.00 for chicken, black beans, rice and a salad. Don't worry if they LOOK dirty they are not and the seediest looking ones have the best food because grandma is cooking in the back. Your comparison of the Sightron and the Vanguard is right on and I agree with the "washed-out" view of the Sightron's compared to the Vanguards. The build quality of the Vanguards is way better than the Sightron's. The ED glass just gives the Vanguards the edge and is well worth $50 difference.

HighNorth · Apr 23, 2015

jordn613 said:
The Sightronics are lighter and smaller. They feel more in line with what I was looking for when it comes to portability. Even with their size, I still would love something even more pocket-friendly, but then I realize I'd be sacrificing lens quality (within the choices in my price range, at least).

A binocular with a 42mm objective will always be optically superior to a 32mm objective binocular given that the optics are otherwise equal. 42mm has better light gathering, resolution, exit pupil etc.

FrankD · Apr 23, 2015

I have a feeling that the more you use the Sightrons your opinion of their optical performance will change.

Just a hunch though.

Swedpat · Apr 23, 2015

HighNorth said:
A binocular with a 42mm objective will always be optically superior to a 32mm objective binocular given that the optics are otherwise equal. 42mm has better light gathering, resolution, exit pupil etc.

I agree about the advantage of larger exit pupil(more comfortable to use) and the brightness that provides(under dark conditions). But I have actually never experienced a relation between aperture and resolution. I know that the theoretical resolution is higher with larger objective lens but what I understand this gain of resolution requires far higher magnification than a normal binocular to be seen. Among the sharpest optics I have ever experienced are Zeiss 6x20B and Leica Ultravid 8x20.

It's possible that persons with extra ordinary eyesight can see a difference between small and large aperture, I don't know. But is really the best 8x56 sharper than even the best 8x20? I have yet to experience it.
Therefore I highly doubt that anyone can perceive an 8x42 to be sharper than an equal 8x32.

ads · Apr 23, 2015

You didn't mention the 8x36 Bushnell, but I found the Bushnell Legend Ultra HD 8x36 to have better center resolution and significantly larger field of view than the Sightron Blue Sky. I also like the focusing on the Bushnell better.

But the Blue Sky has a larger sweet spot, is brighter, and has better color rendition (The Bushnell has a warm, overly yellowish cast).

ads · Apr 23, 2015

Swedpat said:
It's possible that persons with extra ordinary eyesight can see a difference between small and large aperture, I don't know. But is really the best 8x56 sharper than even the best 8x20? I have yet to experience it.

I don't know either. An 8x56 built to the same level should be about ten times price of the 8x20, right?

Swedpat · Apr 23, 2015

ads said:
I don't know either. An 8x56 built to the same level should be about ten times price of the 8x20, right?

It sounds logical, but in reality the price difference isn't so big.

typo · Apr 23, 2015

Swedpat said:
I agree about the advantage of larger exit pupil(more comfortable to use) and the brightness that provides(under dark conditions). But I have actually never experienced a relation between aperture and resolution. I know that the theoretical resolution is higher with larger objective lens but what I understand this gain of resolution requires far higher magnification than a normal binocular to be seen. Among the sharpest optics I have ever experienced are Zeiss 6x20B and Leica Ultravid 8x20.

It's possible that persons with extra ordinary eyesight can see a difference between small and large aperture, I don't know. But is really the best 8x56 sharper than even the best 8x20? I have yet to experience it.
Therefore I highly doubt that anyone can perceive an 8x42 to be sharper than an equal 8x32.

The short answer is that a big objective binocular will not necessarily appear any sharper than one with a small objective. Now for the detailed explanation.

The potential resolution of a binocular increases with objective diameter. However the actual resolution is normally significantly worse than the theoretical limit even for the alpha models.

The effective objective diameter and hence resolution is dictated by the eye's pupil diameter multiplied by the magnification. Your visual acuity peaks in bright conditions when the pupil diameter is around 2.5mm so the corresponding effective objective diameter would be 20mm for an 8x. Both an 8x20 and an 8x56 would be effectively 8x20 to the eye and have the same potential effective resolution.

Many binocular will be functionally resolution limiting for those with excellent eyesight in bright conditions. For those with more typical eyesight relatively few will be limiting. As light levels decrease, the pupil of the eye dilates and acuity deteriorates at the same time as the effective binocular resolution improves and generally the eye will become limiting for everyone. All binoculars will deliver the same level of detail irrespective of quality in low light.

Hope that helps,

David

denco@comcast.n · Apr 24, 2015

Swedpat said:
I agree about the advantage of larger exit pupil(more comfortable to use) and the brightness that provides(under dark conditions). But I have actually never experienced a relation between aperture and resolution. I know that the theoretical resolution is higher with larger objective lens but what I understand this gain of resolution requires far higher magnification than a normal binocular to be seen. Among the sharpest optics I have ever experienced are Zeiss 6x20B and Leica Ultravid 8x20.

It's possible that persons with extra ordinary eyesight can see a difference between small and large aperture, I don't know. But is really the best 8x56 sharper than even the best 8x20? I have yet to experience it.
Therefore I highly doubt that anyone can perceive an 8x42 to be sharper than an equal 8x32.

Your right. The bigger aperture has a lot of other advantages but resolution isn't one of them. I think that is what High North meant. I do think ED glass can make a binocular appear sharper because it removes CA though. I think that is why the Vanguard is sharper than the Blue Sky. Also, the ED glass in the Vanguard could be one reason that the Blue Sky appears washed-out in comparison but better coatings on the Vanguard could also play a part but I really think one reason the Vanguard is so good optically for it's price point is that it has remakably high quality glass.

Swedpat · Apr 24, 2015

typo said:
The short answer is that a big objective binocular will not necessarily appear any sharper than one with a small objective. Now for the detailed explanation.

The potential resolution of a binocular increases with objective diameter. However the actual resolution is normally significantly worse than the theoretical limit even for the alpha models.

The effective objective diameter and hence resolution is dictated by the eye's pupil diameter multiplied by the magnification. Your visual acuity peaks in bright conditions when the pupil diameter is around 2.5mm so the corresponding effective objective diameter would be 20mm for an 8x. Both an 8x20 and an 8x56 would be effectively 8x20 to the eye and have the same potential effective resolution.

Many binocular will be functionally resolution limiting for those with excellent eyesight in bright conditions. For those with more typical eyesight relatively few will be limiting. As light levels decrease, the pupil of the eye dilates and acuity deteriorates at the same time as the effective binocular resolution improves and generally the eye will become limiting for everyone. All binoculars will deliver the same level of detail irrespective of quality in low light.

Hope that helps,

David

David,

Thanks for another careful and detailed explanation, which confirms my experience. Larger aperture has theoretically higher resolution but it demands that the eye can make use of that aperture.
In the comparison between 8x20 and 8x56 both will be perceived to have the same brightness and resolution a sunny day because the eye pupil will be 2-2,5mm. At dim conditions, for example when the eye pupil dilates to for example 5mm the 56mm optics will work like 40mm and the perceived brightness will be 4 times of the 8x20.
Well; I know there are more detailed aspects to take in consider here, like that the outer part of the aperture is not as effective as the center. Ed Zarenski wrote about that.

Anyway I think we can state that for normal practical use(especially at daytime) there is hardly no reason to get a 8x42 instead of a 8x32(or 10x50 instead of 10x42) in the order to get higher perceived resolution. There are other reasons like eye relief and a slightly brighter image under low light conditions.

But I have to comment about when you say: "All binoculars will deliver the same level of detail irrespective of quality in low light". It can't be really correct.
I know that the eyes resolution drops under low light and consequently an increase of magnification is better than a higher optical resolution at a given magnification.
But if we compare, for example an 8x20 to an 8x40: 8x40 is 4 times brighter than an 8x20 at low light when the eye pupil dilates to at least 5mm(for most people).
If the image is 4 times brighter it in some cases results in a better perceived resolution, simply because of the less dim image when the eyes resolution increases. And if it's very dark you will see just darkness in the 8x20 while the 8x40 will reveal some detail.

typo · Apr 24, 2015

You got it! :t:

David

typo · Apr 24, 2015

You are right I should have qualified that by saying providing the aperture isn't limiting. I was simply suggesting the eye is limiting in low light. The complicating factor is that your eyesight may technically be sharper when aperture is limiting but the dimmer light is triggering fewer receptors and producing a lower definition image. With bright sources such as brighter stars smaller apertures produce a tighter point, whereas big aperture will reveal dimmer objects at lower definition.

HighNorth · Apr 25, 2015

Well, it seems my somewhat flippant comment resulted in quite a discussion!

I guess I was thinking of astro scopes when I wrote that bit about resolution.

jordn613 · Apr 27, 2015

Quick update:

I'm still feeling like the Vanguards are the ones for me. I just put them up to my eyes and bam, I'm focused and comfortable. I'm not having that same experience with the Sightronics.

I also headed over to REI this weekend and bought the Nikon Trailblazers, just to further compare. The size of them is what I was after when I made this post, but of course I've now come to understand that they can't compare even slightly with bigger binoculars.

The Vanguards are now back up over $100 more than I paid for them on amazon, so I feel like I got a good deal (at $240). I'm now wondering if I'd be better off with the Spirit model, at 8x32 instead?

longboat · Apr 29, 2015

typo said:
...
The effective objective diameter and hence resolution is dictated by the eye's pupil diameter multiplied by the magnification. Your visual acuity peaks in bright conditions when the pupil diameter is around 2.5mm so the corresponding effective objective diameter would be 20mm for an 8x. Both an 8x20 and an 8x56 would be effectively 8x20 to the eye and have the same potential effective resolution.
...
David

I've wondered about limiting aperture to increase acuity. In photography, a lens is typically stopped down to increase sharpness. For example, if a lens is f/2.8 wide open, then its sharpness typically increases when stopped down a few stops (where the lens is letting in less light). Stop it down too far and diffraction begins to set in.

Since binoculars don't have mechanisms to stop down the objectives, apparently we are relying on our eyes to do all of the stopping down that is necessary. But will our eyes "stop down" (or limit aperture) enough? Are some people able to decrease pupil diameter better than others? Do we typically lose that ability as we age, much like ability to dilate the pupil?

Would there be any benefit to mechanically reducing aperture on binoculars when using, say, mid-day at the sunny beach or in sunny snow-covered conditions?

OPTIC_NUT · Apr 30, 2015

Night sky buffs even mask down the aperture sometimes for more detail,
if there is enuogh light from the target. So...you're not far off.
At the least, you should experiment. I suspect there is an extra effect
in stepping down a large pair....the increased contrast from all the
extra dark space going through. A masked large pair seems richer and
sharper than the same lower aperture as the max...

typo · Apr 30, 2015

longboat said:
I've wondered about limiting aperture to increase acuity. In photography, a lens is typically stopped down to increase sharpness. For example, if a lens is f/2.8 wide open, then its sharpness typically increases when stopped down a few stops (where the lens is letting in less light). Stop it down too far and diffraction begins to set in.

Since binoculars don't have mechanisms to stop down the objectives, apparently we are relying on our eyes to do all of the stopping down that is necessary. But will our eyes "stop down" (or limit aperture) enough? Are some people able to decrease pupil diameter better than others? Do we typically lose that ability as we age, much like ability to dilate the pupil?

Would there be any benefit to mechanically reducing aperture on binoculars when using, say, mid-day at the sunny beach or in sunny snow-covered conditions?

There are parallels between a camera and the eye to a certain extent. The aberrations in the cornea and lens means there is an optimum pupil diameter for acuity which it typically around 2.5mm but there are individual differences. Below that, acuity tends towards diffraction limited but wider than that it drops off dramatically and may be 2 to 5 times worse at 5mm or more. The maximum pupil diameter, and to a lesser extent minimum, does change with age. Children may achieve up to 9mm but at 60 5mm would be more typical but there is quite a bit of individual variation.

The pupil's role is to try to keep the retinal light levels as constant as possible, and it's pretty effective over about a 30 fold range in light levels, what we might call normal daylight, but that is only a tiny part of the trillion fold range of sensitivity for the eye. The retinal receptors do make a number of adjustments to sensitivity to extent the working range but it alters the retinal resolution and of course at the extremes our sight becomes very indistinct. In fact out our eyes work best at a very narrow range of light levels, and only a tiny part of our waking hours.

It's not only astronomers than can benefit from artificially stopping down an objective. Effectively putting in an extra baffle reduces stray light and increases contrast and apparent sharpness. The benefit for some binocular can be quite dramatic at high light and/or high glare conditions. Obviously the benefit is smaller with better designs, but I've yet to find a binocular that didn't show an improvement at all, even under 'normal' viewing conditions.

David

longboat · Apr 30, 2015

Thank you both Optic_Nut and typo, for your explanations. Interesting topic, indeed. Perhaps aperture controls could possibly be a path forward for improving optics in a niche field? Imagine 10x70 astro bins with aperture levers on the objectives! Or perhaps a ByfieldOptics hybrid with polarization and aperture control for high-resolution work in high-glare situations...

typo · Apr 30, 2015

I suspect to build-in the variable aperture and switchable filter would be fairly prohibitive on cost and weight. There are some binoculars that have screw threads for filters but not many. A more generic answer might follow the lines of push on, flip-up objective covers but have a filter holder instead. Besides the reduced aperture and polarised filters there is a good argument for coloured filters for different light conditions as well.

David

Well-rounded pair of binoculars for wildlife/travel. Newbie here, help! (1 Viewer)

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