Kronos 26x70 Binoculars by Mike McIsaac, 60*N 150*W
(http://www.cloudynights.com/breviews/Kronos.htm).

I recently obtained a pair of these binoculars and have evaluated them during daylight and night time conditions. I am very impressed by their performance. Read on.

Specifications

26x magnification, 70mm objective lenses.
Multicoated lenses.
Individual eyepiece focus.
Dioptric correction: +5.
Porro-prism design with Bak-4 prisms.
Exit pupil: 2.7mm. Eye Relief: 9.1mm.
Interpupillary distance: 56-74mm.
Field of view 2*30', 22meters @ 1000meters / 66 feet @ 1000 yards.
Close focus: approximately 25 yards.
Weight 1.7kg. / 3.75 lbs. 11" H x 9" W x 3.5" D.
Temperature range: -22*F to +113*F

First Impressions

The body is very nicely finished in black paint and leatherette. Lens coatings have a purplish tint to them. Looking through the objectives I see no internal baffling. Eyepieces rotate smoothly and easily. We'll see how they perform in cold conditions. They feel very solid yet seem light for their size. There is no threaded socket for a tripod adapter. I will tripod mount them using a variety of binocular mounts.

Binocular Mounts

The Bogen #2893 binocular clamp attaches securely to the prism housing and then to the 1/4"x20 screw in the tripod head. I used a Bogen 3130 video tripod head. There is very little image vibration using this combination. The only disadvantage to this clamp is that the eyepieces are not held level if they are spread apart to accommodate a wide interpupillary distance when used on a 2-way video-type pan head like the 3130. The observer must match the angle of presentation by "cocking" his head at that angle.

The Webster Sure-Loc binocular mount is a piece of machined plastic with a 1/4"x20 threaded socket at midpoint. A pair or Velcro straps wrap around the barrels and attach back on themselves. This mount holds the binoculars level and balances well but does not hold them firmly enough to prevent vibration while observing, especially while focusing. I think it is better suited to porro prism binoculars with a magnification of 10x or less.

I think the best type of tripod mount for these binoculars would be one that clamps to the center hinge tube. I tried one made by Hama of Germany. This mount works well with lighter weight 7x50 binoculars but they wiggle a lot with these 3.75 lb. Russian giants. I may order another center hinge clamping model made by Nikon that appears to be very sturdy as it is made for their own giant "Astroluxe" series.

Daylight Performance

Observing conditions: clear and sunny, temperature +25*F, humidity 50%, winds calm.

The images are very sharp and in focus out to about 90% of the field of view. One must move one's head around to see all the way to the edge of the field so in normal use, the observed image is a flat field that is all in focus. Contrast is excellent. I was able to pick out subtle details on the snow covered mountains 25 miles across the valley to the east of my house.

Since these are individual eyepiece focusing they are not well-suited to close range bird watching due to the slowness of this focusing method. For long range wildlife observation they are great instruments. I observed a cow moose at a range of about one mile and while I couldn't quite count her nose hairs, I could pick out a lot of detail and the subtle color shading on the big ungulate.

Night Performance

Observing conditions: temperature +28*F, humidity 60%, SW winds 3-8 mph, air clear, no clouds, seeing relatively steady.

The first thing I noticed is that the 2.7mm exit pupil is small enough that the astigmatism in my right eye is not noticeable at all. The Moon was full and Saturn is about 7* to the left of it. The view of the moon is spectacular! The image is needle sharp with excellent contrast between the Mare and the surrounding lighter areas. The full Moon nearly fills the entire observable field of view. There is a slight green color fringe around the entire limb of the Moon. Moving over to Saturn there is a great deal of flare from the moon in the right barrel (now I see the effects of the lack of baffling!). I blocked the moon with my hand and the flare disappeared resulting in excellent contrast and a lovely view of Saturn with clear separation between the planet and her rings. Moving over to Jupiter and the results were equally impressive. I could see cloud bands and all 4 moons were distinct pinpoints. This night the moon is so bright that any observation of star clusters and DSO's will have to wait for a darker night. I did not experience any problems with the eyepieces fogging up.

The individual eyepiece focusing proved to be very convenient for astronomical observation. The eyepieces continued to rotate smoothly and easily when exposed to cold conditions (although +28*F hardly counts as "cold" by Alaskan or Russian standards). As smooth as these focus I expect that they would continue to perform well into temperatures that would send most observers indoors.

Summary

The Kronos 26x70 porro prisms are excellent astronomy and long-range "spotting" binoculars. However, they are seriously compromised by the lack of a suitable tripod socket or mount. If I had to choose between the three tripod mounts I evaluated, the Webster Sur-Loc is the one I would use in spite of the vibrations while focusing. The optics are excellent and would be superb if there was some internal baffling to ward off reflections. In actual use this is a minor point. How often is the Full Moon 7* from Saturn? The 9.1mm eye relief may be a concern for observers who must wear glasses while observing. The 2.7mm exit pupil is of benefit to those who suffer from astigmatism. Their cold weather performance so far has been superb. I like these just as much as the Pentax 20x60's I evaluated in October 2000. If I can get the tripod mounting problem solved, I believe I will probably use the Kronos' more than the Pentax. They're pretty darn good binoculars.