A Work Commenced August 24 2024

Preamble 1

Preamble 2

Product: Zeiss SFL 8 x 30

Country of Manufacture: Japan

Chassis: Magnesium alloy overlaid by protective rubber

Exit Pupil: 3.75mm

Eye Relief: 18mm

Field of View: 142@1000m(8.1 angular degrees)

Dioptre Compensation: +\-4

Coatings: Fully broadband multicoated, Phase corrected Schmidt Pechan prisms, LotuTec coatings on ocular and objective lenses

ED glass: Yes, UltraHD

Field Flatteners: Yes

Waterproof: Yes, 4m

Nitrogen Purged: Yes

Close Focus: 1.5m advertised, 1.57m measured

Light Transmission: 90%

Tripod Mountable: Yes

Dimensions:12 x 10.7cm

Weight: 460g advertised, 462g measured

Accessories: Soft padded carry case, objective covers, ocular rain guard, padded neck strap, microfibre cloth, instruction manual

Warranty: 10 Years

Price: £1299(UK)

Back in 2014, Zeiss launched their new flagship binoculars embodied in the Victory SF, which were offered in both 8 x and 10 x 42 configurations. Then in 2020, two smaller models were launched, the Victory SF 8x and 10 x 32. While these offered class leading optical performance, they were rather long (15cm)and heavy(over 600g) in their compact class. The demand for something smaller and more lightweight impelled Zeiss to re-imagine their Victory SF series, and to create a new line of instruments offering top-notch optical performance in a more diminutive and lightweight package. In 2022, Zeiss answered their fans with the new SFL series, first introduced in 8 x and 10 x 40 configurations, but followed soon after with their smallest compact models yet developed: enter the 8x and 10 x 30 SFL.

Just like in the Zeiss Victory line, the SF stands for “ smart focus” while the L designates its light weight. So what did they do? Under the aegis of a newly head-hunted optical engineer from Swarovski, they made the lenses a little bit thinner(2mm) and smaller, which allowed them to be mounted in a shorter tube assembly. They also jettisoned the centrally placed locking dioptre mechanism to shave off even more weight, with the result that the new SFL 8 x 30, for example, tipped the scales nearly 150g lighter than the Victory SF 8 x 32. But there were other changes to the optics. The Ultra FL glass was replaced by Zeiss’ proprietary Ultra HD( UHD), of slightly lower grade. The field of view shrunk a bit too. Compared with the Victory SF 8 x 32( 8.8 degree field), the 8 x 30 SF sports an 8.1 degree field. In addition, while the SFL line does have field flattening optics, it’s not the ultra-flat system exhibited by the Victory SF series, as I was to discover during field testing. Light transmission took a small dive too: down from 92 percent in the case of the Victory SF to 90 in the case of the SFL series. The reader will note that these SFL binoculars are not made in Germany, but in Japan, under the supervision of Zeiss. In this capacity, they share that distinction with the Zeiss Victory Pocket series. Here, I’ll be taking a close look at the Zeiss SFL 8 x 30 model.

Ergonomics

This is one small binocular. Check it out compared with the Zeiss Conquest HD 8 x 32.

Despite its small size, the Zeiss SFL 8 x 30 is surprisingly easy to handle.  Its short bridge allows the barrels to protrude enough to enable the user to wrap their fingers round them for a secure grip, although those with larger hands may struggle a little with it. The black rubber armouring is lightly textured which also helps with gripping the instrument. The eyecups are well made and very comfortable to view through for prolonged periods. They can be unscrewed from the eyepieces to assist cleaning, though I did discover that if they’re not screwed in securely they can be accidentally unscrewed while extending the cups upwards.

A little extra care is definitely required here. It’s not an issue for me, as I leave the cups permanently extended. There are four positions, each of which locks into place firmly with an audible ‘click.’ Eye relief is plenteous: I can easily engage with the entire field while wearing my eye glasses. 

The focuser is excellent: big and easy to engage with. Just 1.4 revolutions clockwise brings you from closest focus to infinity and beyond. I was delighted to see that there’s a decent amount of ‘post infinity’ travel too which will be music to the ears of those of you who have extreme short-sightedness. A single finger can rotate it smoothly and accurately. Just a slight turn of the wheel brings objects into sharp focus from close up to far off. While there is no play or backlash in the movement, it does show some resistance to movement near the end of its anticlockwise travel. 

I really like the right eye dioptre on the SFL. It’s got excellent resistance to movement. Simply rotate it into your preferred position and leave well alone.  

Zeiss claim that the SFL is watertight to 400mbar water pressure. Why they use millibar units is a bit of a mystery to me. Isn’t immersive depth much more accessible to the average Joe? Both Swarovski and Leica publish depths and not pressure. Quite sensibly I’d say. Indeed I note that the two well known binocular reviewers linked to in the preambles above parrot this nomenclature too. C’mon guys: a bit of high school physics will clarify this for your readers. Follow this procedure: 

Optics

Examining how the binocular coped with shining a bright white light source from across a room showed very good results. Internal reflections were well controlled and unlike the Zeiss Conquest HD I tested it against, it didn’t show a prominent diffraction spike. I did however pick up some faint ghosting when examining the blue super full Moon shortly after local midnight on August 21. 

Examining the exit pupils showed excellent results as you can see below.

Optically, the view is very impressive: wide, bright, tack sharp within its generous sweet spot, with plenty of high resolution details on display. It is significantly better, for example,  than the image served up by the Conquest HD 8 x 32 I tested along side it. Glare suppression is excellent against the light. Colours are vividly but naturally portrayed.

There is some mild pincushion distortion off axis and I detected some softening of the images near the field stops. The nature of this edge-of-field softening became all too clear when I monitored the bright star, Vega, high overhead. The bright white luminary remained tightly focused within the inner 60 per cent of the field or so but thereafter began to distort. At the field edge it was quite noticeably bloated. Because I was able to focus much of this out showed it was field curvature in the main. The same was true when I trained the SFL on a waning gibbous Moon in the wee small hours of August 24. While it was tack sharp within its sweet spot, it became quite blurry near the field stops. Which brings me to the subject of field flattening optics. Clearly not all field flatteners are created equal. Comparing it to the ultra flat field of my full size Sky Rover Banner Cloud 8 x 42 APO, for example, which showed pinpoint stars right across a significantly wider field from edge to edge, the result for the Zeiss SFL was rather disappointing, especially considering its rather steep retail price.

Chromatic aberration was essentially absent from the centre of the field but crept up as I moved my test subjects off axis. Near the edge of the field, the images of dead tree branches against a uniformly bright overcast sky showed significant lateral colour. It was noticeably more pronounced than in my control binocular(the Banner Cloud mentioned above). Again this was a bit disappointing as I know of much cheaper binoculars that have much better colour correction. These results were also clearly seen when examining a silvery white Moon.

Notes from the Field

Close focus was measured at 1.57m: very good indeed, though I was half expecting it to be a tad shorter, based on all the comments I read or heard about during my researches, which almost invariably claimed sub 1.5 m close focus. The view is very comfortable: perhaps the most comfortable compact I have personally experienced. Panning showed up no rolling ball effect which I attribute to the influence of Dr Holger Merlitz, whose research findings were taken into consideration by Zeiss in the overall optical design of the SFL series. 

The big selling point of the SFL series, of course, is their light weight, and at 462g it certainly is light! But this can be somewhat of a disadvantage in some circumstances, as I discovered when I brought it out during a blustery spell prior to the arrival of Storm Lilian during the third week of August. With strong winds whipping by me in the open air, I found it much more challenging to hold steady compared with a full size 8 x 42 under the same conditions.

Conclusions & Recommendations

Without question, the Zeiss SFL is a premium compact binocular that excels in many areas: feather light, small size, a comfortable wide field of view and razor sharp optics within its sweet spot, but it doesn’t quite reach the dizzying heights of optical performance seen in the current line of ultra-flat field APO binoculars in the 32mm format. It will appeal greatly to daytime birders and those who like to travel.

Still, for me at least, like all compact binoculars I’ve gradually discovered, it leaves something to be desired compared to the more immersive and engaging views garnered by top quality full-size instruments. So something to bear in mind.

Very highly recommended!

Dr Neil English is the author of Choosing & Using Binoculars: a Guide for Stargazers, Birders and Outdoor Enthusiasts. Please support his ongoing work by purchasing a copy of the book.

De Fideli.