Cameras and Lenses

Experiencing image size in scopes and binoculars

Hello birders,

I'm rather new to this forum and so I don't know if this item has been discussed before, for instance in the scope-section. Anyway, I feel it belongs here. The problem is: I don't like scopes. I also know why: I'm addicted to binoculars, I don't like to look with one eye, and most importantly, I find the view through scopes very disappointing. Even the best telescopes don't come close to what I see (and feel) through my binoculars. Problem? Yes, for a whole bunch of people seem to like their scopes very much. They feel close to the bird, feel they can almost touch them, they love the view. This is what I hear and read all the time: scopes are tops. As I usually don't like to feel things alone, the first question is: are there maybe more people like me?
For the second question, let me explain a little better why I don't like the view through a scope. Yes. it's disappointing. Most and for all because the image feels small to me, at least smaller than what I see, feel, experience through binoculars. And that's strange. Because through a telescope the bird should be 30x or more larger, it is filling the whole field of view isn't it? Well, my experience is quite the opposite. Question: how to explain this?

Renze de Vries

Renze, you are not alone. I have a rough time with scopes myself. I can always see better with two eyes vs one. I wish someone would develop a high quality 35 or 40x80, center focus bino. I would love to see someone like Minox do this.

ranburr

Renze,

Your question really gives me a kick, or I should say your questions, since there are several mixed together it seems to me. I don't believe they've been discussed comprehensively, but they are certainly discussion-worthy. I'll just make a few observations of my own and run for the hills:

1. Being two-eyed beings our brains are wired to create an internal "spatial field" that allows us to operate in a three-dimensional world. This remarkable biological capability is so unconscious that we take it for granted. However, when normal visual cues are denied, enhanced, or distorted, the effects become conscious — and along with that come feelings and judgments (and optinions).

2. It is a rare person who prefers a monocular view to a binocular one. No doubt this is because the binocular view is closer to normal, where at low magnifications it is still possible to perceive a "spatial field," depending in part on the depth of focus, field of view, and binocular disparity afforded by the optics. The brain also adds it's own interactive dynamics which we refer to as "attention." I've proposed in other threads (now lost), therefore, that properties of the spatial field are not exactly the same as what can be surmised from the optics. In particular the sense of spatial extent and depth, as well as the ability to switch attention from object to object, are primarily properties of one's internal perceptual field.

3. The hyperstereo property of porro prism binoculars compensates, to some extent, for the raw effect of magnification. If the images are presented with normal retinal disparity (roof binoculars), objects are interpreted as being much larger and closer, within a relatively flat spatial field. Hyperstereo images (porro prism binoculars) add compensating distance cues (retinal disparity). The perceptual mechanism of size constancy is then able to produce a more "natural" percept, with less apparent magnification and closeness, and greater spatial depth. When it comes to perceptual tradeoffs, many birders favor the more natural percepts produced by porros. Some, like yourself, apparently prefer the "right there" magnification effect. I like each at different times, and a broad spatial field can give me quite a "wow."

4. Now consider telescopes that have no retinal disparity being monocular, huge magnification, narrow field of view, and shallow depth of focus. There are virtually no visual cues to construct a spatial field. The observer falls back on a flat image with minimum context and loses a sense of even how far away the subject is. Hence, in my opinion, it is not meaningful to talk about perceived size in the same way, or judge the "view" in the same terms. Telescopes are the domain of rendering detail in spite of the distance. Packing a telescope and tripod is the price one pays to get it.

Thanks for opening up this interesting subject. I hope there are more opinions expressed.

Elkcub

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