Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Apparently no prisms, but with that wide view not Galilean "field glasses"--and eyepieces offset from objectives. Anyone understand the optics?
Document: I'm sure this is a result of the optics required to generate the incredibly wide field of view. I own several binoculars from image stabilizing to 100mm astronomical binos. I consider these 4x30 Utra Wides to be a valuable addition to my group. My one bone to pick with Bushnell, which prevents my giving them 5 stars, is the neck strap. It does not fit the strap attachment points. Kind of funny for the Bushnell labeled strap to be so wide, one cannot force it through the strap loops.
I wear glasses. The autofocus feature does not work well for me. I can see clearly things that are 100 yards away, but things that are 10 yards away are not in focus. That said, the 4X feature is what I want, the field of view is wide and the image is bright so I am keeping these. If I could purchase one of these with the ability to set the focus myself I would give it 5 stars.
I use these glasses to view performing musicians on stage when I am running sound from over a hundred feet away from the stage. They work just fine, although I would like some focal adjustment, it isn't really much of an issue.Nice wide field of view and a good power to make viewing any sporting event, concert, etc. easy. A bit bulky but very well made and quite useful.
It might help everyone better understand these reviews of optical devices if reviewers would mention whether they wear eyeglasses or contact lenses. Evaluation of optical devices depends on whether the reviewer is looking through another set of lenses. If you wear glasses, please share the strength in diopters, and whether there is an astigmatic or cylindrical correction. Please mention if you wear bifocals or trifocals, and the strength of the reading areas.Overall, I found these Bushnell Xtra-Wide 4x30 Binoculars to be a good value.
This was also true for ballet, since you can see the field of view with your eyes, and you mainly want opera glasses to see one person or thing. Elsewhere on Amazon you can buy a Bushnell binocular for around $15 that gives you a great image at the opera or ballet of one person, with the 8X power magnification.
But they are light enough to carry easily, along with an umbrella and water bottle. (This was a long, HOT, summer road trip.) The 4X magnification is a bit stronger than the traditional 3X of opera glasses. However, the field of view IS significantly wider than the smaller, traditional opera glasses. The extra magnification did not make the image more unstable, that is, shaky or jittery.
To get the great field of view, I needed to take off my glasses and put my eyes directly into the eye pieces. However, the eye pieces do not adjust for different vision in each eye. As a result, it seems to me that the scene being viewed is inevitably blurry. Without being able to adjust the eye piece to the differences in visual acuity between each eye, you inevitably end up with some blur depending upon the differences between your two eyes.
You will not regret the simplicity of use. Wide view. Magnification fantastic, don't need to wear glasses to see. Perfect for boating
Very wide view&#8230;.great. I wear glasses but had no problem using the Bushnell with the caps down. Really looking forward to using them for theatre this Fall.
These binoculars are truly remarkable in their clear picture and wide range.They do not need focusing for someone with normal vision, but I wish it were possible to focus so I could take my glasses off to enjoy the complete view.They are a bit bulky in width, but their short length is nice.
Answer: only thing i understand is that they are very good.  i have so enjoyed watching ballet with them.