Recommend this product?
Objective Lens Diameter: 35 mm
Eye Relief: 12 mm
Field of view at 1000 yds: 578 ft
Prism Type: BK-7
Lens Coating: Fully Coated
Weight: 22.5 ounces
AUTOMATIC FOCUS? UNBELIEVABLE!
PermaFocus binoculars are described (by Bushnell) as auto-focus optics. This gives the impression that youll never have to adjust the focus. Well, this is true...sort of. You wont have to, or you wont be able to is probably a more direct and honest way to say it. Ill try to break down the pros and cons of auto-focus in general while specifically reviewing the Bushnell PermaFocus 7x35 binoculars.
7x35 porro prism binoculars are a pretty typical configuration, and physically, the 7x35 PermaFocus binoculars dont stray from the norm much. They weight 22.5 ounces and measure 6.5 wide x 4.75 long. (A typical paperback novel is 6.5 x 4.25)
The exterior is rubber coated and ribbed to enhance grip and soften bumps the binoculars incur. Also, the body of the binocular is ergonomically contoured for secure, comfortable grip. Since you dont adjust the focus on these binoculars, there isnt any sort of focusing wheel or knob.
The included neck strap is plastic and only 3/8 inch think. This can make them uncomfortable to wear after a rather short amount of time. I got bought a $5 replacement that works well.
FUNCTION AND USE
Since auto-focus is the big gimmick of the PermaFocus series, Ill start there. These binoculars dont magically focus themselves from objects right under your nose to objects miles away. They will allow you to view objects from about 35 feet away and beyond. So they arent good for close focus, but 35 feet to infinity without focusing is still good, yes? Well...truth is, you could do that with any similar binocular that does have focus knob. If you adjusted the focus until objects became clear around 35 feet away, then glued the focus knob in place, youd basically have the equivalent of auto-focus binoculars.
What PermaFocus binoculars really do is take advantage of the most lenient range of focus. The closer objects are, the more precise your focusing has to be. Greater adjustment is required when focusing from 1 to 5 feet than is needed when focusing from 100 to 500 feet. By eliminating the closer ranges, PermaFocus binoculars do all their work at more forgiving distances. Instead of fine tuning with a knob or lever, your eyes do the adjusting as you view objects at varying distances.
This leads to the next issue: since the focus is permanently set, PermaFocus binoculars cant adjust to visual impairments. If I look through most binoculars without my glasses or contacts, I can still adjust the focus to compensate for my prescription. Not so with PermaFocus. If you are nearsighted and need corrective lenses, you have to be wearing them. Otherwise, these binoculars will do no more than magnify blurriness.
The above paragraph is more important because of eye relief issues. Eye relief refers to the optimal distance your eyes should be from the eyepiece lenses. Sometimes glasses-wearers arent able to get as close to the lenses as is recommended. PermaFocus binoculars have an eye relief of 12 mm, which isnt too bad for glasses wearers. The problem however; is the eyecups. Eyecups are the rubber rims around the eyepieces that touch or nearly touch your face or glasses. These often help keep the lenses the proper distance from your eyes. Many binoculars have fold-down eyecups, which are pliable enough to be flipped up (for regular use) or down (for glasses) to allow any user to get the correct eye relief. Bushnell claims PermaFocus binoculars have fold-down eyecups, but the eyecups on mine are too thick and stiff to fold down at all, so when Im wearing glasses, my eyes are too far from the lenses. The resulting images are darker and fuzzier, and the field of view gets smaller.
Simply put, these binoculars are not a good choice if you wear glasses for nearsightedness.
The lack of variable focus hinders the level of detail you can hope for, but there are other factors to consider as well, and I will address those factors before giving my own opinions.
Binoculars use prisms to transfer the images from the objective lens to the eyepiece. The better the prism, the sharper and less distorted the transferred image. They are generally made of two kinds of glass, Bk7 or Bak4. PermaFocus binoculars use Bk7 glass, which is the lesser of the two. Prisms come in two main styles, roof or porro prism. Roof prisms tend to be more compact and durable but cost more, and porro prisms of equal value can provide slightly better depth and clarity. Porro prisms also tend to have a larger field of view. PermaFocus binoculars use porro prisms.
Objective lenses gather the light your eyes need to process an image. Dividing the size of the objective lens by the binocular magnification gives you the "exit pupil", which basically refers to the amount of light passed to your eye. More light means a brighter image. This is especially important in dim conditions. A higher number means more light. The PermaFocus binoculars exit pupil is 5.0 (35 divided by 7), which is about as high as youll find on general use optics and is good for fairly dim conditions.
Most binoculars have lens coatings on them. These are chemical coatings that generally enhance image brightness and contrast. Lens coatings are broken into 4 categories: coated, fully coated, multi-coated, and fully multi-coated. I have listed them in ascending order. They range from a single coating on some lenses to multiple coatings on all lenses. PermaFocus binoculars are fully coated.
A specification that has more to do with how much you see rather than how well you see is field of view (FOV). FOV is basically how much space you can view at a given distance (usually measured in terms of feet viewable from one edge of the frame to the other when viewed from 1000 yards away) This can indicate how large the viewing frame (circle) is, but FOV is affected by magnification as well, with higher power often resulting in smaller FOV. With this in mind, binoculars with porro prisms and modest magnifications have some of the widest fields of view. For the sake of comparison, Bushnell makes 10x42 roof prism binoculars that have a FOV of 315 feet at 1000 yards. Bushnell also makes an adjustable focus 7x35 porro prism binocular that has a FOV of 420 feet. The PermaFocus 7x35 binoculars have a FOV of 578 feet. This is VERY wide.
Speaking more subjectively now, these optics wont provide razor sharp edges or crystal clear detail. This is probably due not only to the permanent focus but also to value-priced materials and production (they cost $50 most places). Still, they arent terrible, and in terms of detail, these binoculars will outperform most of the binoculars youll find at discount department stores for $35, adjustable focus or no. As for brightness and color, my PermaFocus binoculars compare well to more expensive optics Ive used.
NOT designed to be waterproof
Included carrying case is made of a soft, black, vinyl-like material (possibly vinyl, I suppose). It fits the binoculars well, closes with Velcro, has adjustable shoulder strap
Lens caps and lens cloth included
Can be mounted on a tripod, but tripod is NOT included
No, auto-focus isnt as wonderful as it sounds, but these binoculars aren't a total loss. The exceptionally wide field of view and simple use make them a logical choice for viewing sports and or anything in motion (precise manual focus isn't especially helpful for this viewing anyway). And the binoculars are light enough not to wear your arms out, but solid enough to remain stable. The wide view also allows for general panoramic viewing. For these purposes, I'd give the PermaFocus binoculars 4 stars, and for $50, I'd recommend them.
However; if you're looking for close viewing capability, precision focusing, or super-high magnification, youd best look elsewhere. Also, glasses wearers should steer clear.