In my constant search for high-performing 7x binoculars I have started to explore some of the porro prism models from yesteryear. This was based on my experiences with the venerable Nikon 7×35 E series of which I now own three. In my “travels” I started looking at some extreme wide angle models and purchased two Tasco units circa 1970s. They provided the ultrawide field of view that I was looking for (11 degrees) but lacked a bit in the apparent brightness and apparent sharpness categories.
Further exploration led me to the Swift Sport King 7×35. Same field of view as the Tasco and approximately the same size and weight. The fact that it was a Swift model did sway my decision to purchase them. I received them about a week ago and after determining how to remove the metal eyecups I have to say that I am thoroughly pleased with this purchase.
I may now be beginning to understand why Swift porro prism binoculars have such a following.
What I found appealing about them is….
- Huge field of view
- Large sweet spot for such a huge field of view. Initial impressions lead to me to estimate something in the 70-75% range though I am sure actual measurements would be a bit less. Still, 75% of 578 feet is still 430+ feet!
- Great apparent sharpness. I have good eyesight but these are one of those binoculars that actually make me feel as if my eyes are the limiting factor in the amount of detail I can see.
- Well controlled CA. I have to look for some extreme conditions to see it and then it typically is only noticeable outside the sweetspot.
Of course, there are some disappointing optical performance characteristics as well. For one it is only a single-coated binocular so the light transmission levels are most likely lower which subsequently leads to lower levels of apparent brightness. Contrast is also affected.
They are big, heavy binoculars because of the oversized prisms.
Speaking of prisms, these must utilize Bk-7 prism as the exit pupils clearly are square inside of the circle.
Still, I have to admit that I am having a hard time pulling these binoculars away from my eyes. They are such a joy to look through. Furthermore they are addicting!