| Real front lens diameter |
Left: 50.04+/-
0.05 mm
Right: 50.02+/-
0.05 mm
|
8 / 8.0 pkt |
| Real magnification |
7.98+/-
0.05x
|
3/3.0 |
| Transmission |
90.3+/-
1%
|
18/25.0 |
| Chromatic aberration |
Low in the centre, a bit higher than medium on the edge. |
6.1/10.0 |
| Astigmatism |
Negligible. Beautiful, point-like images of stars. |
9/10.0 |
| Distortion |
Distance of the first curved line from the field centre compared to the field of view radius: 88% ± 4% |
10/10.0 |
| Coma |
Starts in a distance of about 70% field of view radius and is medium on the very edge. |
7/10.0 |
| Blurring at the edge of the FOV |
Blur occurs in a distance of 78% ± 3% from the field of view centre. |
5/10.0 |
| Darkening at the edge the FOV |
Very low. |
4.5/5.0 |
| Whiteness of the image |
Very good. Slight green hue. Flat transmission graph. |
4.6/5.0 |
| Collimation |
Perfect. |
5/5.0 |
| Internal reflections |
| Left: |
Right:
|
 |
 |
Round pupils against black background – almost perfect. At the same time very good performance against bright light, both at night and during the day |
4.7/5.0 |
| Housing |
Relatively short, with a moderate weight for a 50 mm class instrument. The real weight amounts to 856 grams and is in perfect accordance with official declarations of the producer. The casing made of magnesium composites and padded with good quality, matt, black rubber armour that ensures you a firm grip. The rubber clings to the body of the binoculars very well but sticks out near the objectives a bit. Rubberized eyecups with five detention stops and 41-42 mm in diameter are a joy to use. Binoculars produced in Japan.
|
7.5/8.0 |
| Focusing |
Big, rubberized central wheel with ribs moves smoothly and is properly damped. Running through the whole distance range needs a turn through an angle of about 510 deg. Dioptre correction on the right eyepiece, it moves the outer element. I suppose in this class of equipment it shouldn't move at all.
|
4.5/5.0 |
| Tripod |
Quite comfortable access. |
3/3.0 |
| Interpupilary distance |
from 55.2 to 76.8mm
|
5/6.0 |
| Closest focusing distance |
1.65 meters |
2/2.0 |
| Eyepieces FOV |
An aparent field of view amounts to 59.9 deg (simplified formula) and 55.3 degrees (tangent formula). |
11/20.0 |
| Field of view |
Measured by us amounted to 7.51 +\- 0.03 deg and is in perfect accordance with the official specifications. A properly sized field for this class of equipment. |
7/8.0 |
| Quality of the interior of the barrels |
Inner tubes are dark and densely ribbed across their whole length. They could have been darker and more matt but still everything looks quite well. The bottom of the prisms is dark gray. Very clean. |
4.5/5.0 |
| Vignetting |
| Left: |
Right:
|
 |
 |
OL: 1.62%. OR: 0.87% |
6.5/8.0 |
| Prisms quality |
High quality BaK-4. |
8/8.0 |
| Antireflection coatings |
Green-yellow-pink on objective lenses, pink-green on the prisms, pink-yellow-green on the eyepieces. Low intensity. |
5/5.0 |
| Warranty [years] |
10 |
4.5/6.0 |
| Final result |
80.7%
|
153.4 / 190 pkt
|
| Econo result |
|
0pkt. |
Summary
Pros:
- solid, weather-sealed, compact casing,
- very good transmission in accordance with official declarations,
- excellent colour rendition,
- perfect correction of astigmatism,
- slight chromatic aberration in the field centre,
- negligible distortion,
- moderate coma,
- low brightness loss on the edge of the field of view,
- sharp images already from 1.65 metres,
- good blackening and cleanliness inside the tubes,
- excellent quality of coatings,
- high quality of prisms made of BaK-4 glass,
- round pupils against a relatively dark background.
Cons:
- noticeable chromatic aberration on the edge of the field of view.
The summary of our Zeiss SFL 8x50 test we would like to start with description of its parameters. The binoculars is not as big and heavy as it seems looking at its class. Its length amounts to 160 mm and it weighs 855 grams. At first glance the field of view is not impressive, just 7.5 degrees, and it means using eyepieces with an apparent field of view of 60 degrees (according to the simplified formula). It is a very good level but of course many 8x binoculars are able to provide a field on a level of 8-9 degrees. Still, if you take a closer look such features you get in, by and large, 30-42 mm class instruments. If you limit yourself to 8x binoculars with objective lenses as big as 50-56 mm you find out that exceeding 7 degrees is no mean feat.
Also Zeiss had some difficulties – look at the
the following chart, presenting a comparison between basic parameters of different historical 8x50 and 8x56 Zeiss models. First Porro prism binoculars feature a field of 7.4 degrees, in case of the Dialyt you notice a significant step backwards, with a field of just 6.3 degrees. Wide fields of 7.5 degrees returned only with 8x56 Design Selection instruments and first Victory specimens. In case of the following Victory series the field decreased once again to 7.4 degrees.
The next chart shows the situation when it comes to the newer constructions. The launches of the first Conquest series devices moved us backwards to a level of 6.3 degrees, that of the Dialyt. The new Conquests HD and HDX managed to get to a sensible level of 7.1 degrees and the top-of-the-range Victory HT 8X54 provides you 7.4 degrees. If you compare to that the 7.5 degrees of the SFL 8x50 it looks really well.
It's worth adding that the SFL 8x50 also provides a very comfortable eye relief distance, amounting to as much as 20 mm, and a possibility of setting the focus already from a distance of 1.65 meters (in the specifications you see a slightly longer distance, that of 1.8 meters). For the 50 mm class it is a result really worth recognition.
As we are still talking about parameters and information from specifications you also should notice that the producers state a transmission value of 90%. Of course we didn't hesitate to check and verify this declaration – let's glance at a graph below.
The average transmission amounts to 90.3% in the centre of visible range and it fits the official values stated by the producer. Impressive? In fact the situation is even better. The 8x50 class model is an instrument designed to use in poor lighting conditions and at night. In such conditions our organ of sight bases mainly on rods that are more sensitive at shorter wavelengths than cones which work mainly during the day. Zeiss optimized the transmission graph is such a way so the binoculars work the best in conditions they are created for. As a result in area near 500 nm, where the rods have the peak of their sensitivity, you get a transmission of 91.5% and, at the same time, it is the maximum result of the tested model across the whole visible spectrum.
As if it wasn't enough we also get fantastic results for purple light where the transmission distinctly exceeds 80% and a relatively flat performance across the whole range. That's why the binoculars render very natural colours.
Of course all the results, described here, are an effect of using the excellent Schott glass with high transmission and anti-reflection T* multi-coatings. They shimmer with sage green and yellow hues, differing from the cheaper MC coatings that are more intensive and feature more saturated greens.
The Zeiss SFL 8x50 impresses not only with its coatings, transmission, and colour rendering, but also with excellent astigmatism correction and distortion correction. It features low brightness loss on the edges of the field and has no problems connected to coma. If you want to pick holes in its performance you can mention two things: chromatic aberration on the edge of the field and its sharpness on the edge. They could have been a tad better.
Still you have to remember that the casing of these binoculars was optimized when it comes to dimensions and weight. A better aberration correction and the correction of sharpness on the edge of the field of view could have meant an increase of the dimensions of the binoculars and the eyepiece, a bigger weight and also most probably an increase of the price. Then this model would hardly fit the SFL series because all its parameters and the price would qualify it as the highest Victory FL series.
In my opinion compromises were needed here and the producers chose them very sensibly. As a result we got a top-of-the-range piece of equipment packed inside a casing of sensible dimensions and weight. They also managed to keep the price around 2000 USD. As a result the SFL Zeiss series I consider to be one of the most interesting offers, available on the market of sports optics.