Binoculars review

Delta Optical Titanium 8x42

Delta Optical Titanium 8x42
11 July 2012
The Delta Optical Titanium series made its debut on the market in August 2006, launching a very successful Porro 8x56 model, which you can find in shops to this day. Not long after that launch other devices – the roof prism Delta Optical Titanium 8.5x45 and 10.5x45- appeared as well. Currently they aren’t available anymore because in 2007 they were replaced by 8x42 and 10x42 roof prism models, produced in Japan, also already taken off the shelves. At the end of 2007 a new Porro 9x63 model was added to the line-up. It is still available. In September 2008 the company launched other Porro models – this time 7x50 and 10x56 devices. One year later a new pair of 8x56 binoculars, featuring ED glass, was released.

In March 2011 another 8x56 ROH model with Schmidt-Pechan roof prisms, was launched and five months later – two Porro 8x42 and 10x42 instruments joined in.

As you see the Titanium series is very diversified, including both Porro and roof prism pairs of binoculars which are not alike when it comes to the appearance and optical parameters. Currently in this line-up you can find a quite tight group of Porro devices, similar when it comes to their design and parameters (8x42, 10x42, 7x50, 8x56,8x56 ED, 10x56, 9x63 models) and the Delta Optical Titanium 8x56 ROH which sticks out noticeably because it features different prism and casing.

The 8x42 model, tested here, is a classic Porro construction with popular parameters. According to the producer it is supposed to guarantee a great image quality for an affordable price. It boasts efficient Porro prisms made of high quality BaK-4 glass, good coatings which ensure the transmission level on one air-to-glass surface amounts to 99.5% and is 93% for the whole instrument. Additionally all the optical parts are put inside a solid, aluminum casing which is waterproof and nitrogen-filled. Buyers get a set of caps, two straps, a cleaning cloth for optics and a sturdy, hard case in the box. This model comes with a five-year warranty.

  • Lornetka Delta Optical Titanium 8x42
  • Lornetka Delta Optical Titanium 8x42
  • Lornetka Delta Optical Titanium 8x42
  • Lornetka Delta Optical Titanium 8x42
Manufacturer data


Delta Optical
web site

Distribution / Sales:

Delta Optical
web site

Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
8 42 132/1000(7.5o) BaK-4/Porro ? mm 750 g 479 PLN
Results of the review
Real front lens diameter Left:   41.88+/- 0.05 mm
Right:  41.85+/- 0.05 mm
7 / 8.0 pkt
Real magnification 7.82+/- 0.1x 3/3.0
Transmission 83.2+/- 1.5% 11/25.0
Chromatic aberration Slight in the centre, significant on the edge. 5/10.0
Astigmatism Not very bothersome. 7/10.0
Distortion Distance between the first curved line and the centre of the field compared to the field of view radius: 68% ± 5% 8/10.0
Coma Appears in the distance of about 70% from the centre and reaches the borderline between medium and high values on the edge. 6.6/10.0
Blurring at the edge of the FOV The blur occurs in the distance of 77% ± 4% from the field of view centre. 5/10.0
Darkening at the edge the FOV Slight. 4.2/5.0
Whiteness of the image Good. Quite flat transmission graph in the wide range of colours. 4.1/5.0
Collimation Perfect. 5/5.0
Internal reflections
Left: Right:
Delta Optical Titanium 8x42 - Internal reflections - Left Delta Optical Titanium 8x42 - Internal reflections - Right
Noticeable but not bad for a Porro construction.
Housing Classic Porro construction. Quite handy and padded with slightly rough rubber which ensures a firm grip. Rubber eyecups. Waterproof and nitrogen-filled. The rubber next to objectives comes off slightly. Produced in China. 6.5/8.0
Focusing Classic ocular bridge. A comfortable central wheel with the range of 540 degrees. Its work is a bit uneven, it squelches and you can see some grease on it. The pressure on eyepieces doesn’t defocus the instrument. The bridge moves sideways a bit and its movements are a tad uneven. Individual focusing on the right eyepiece moves the outer element. 3.3/5.0
Tripod There is a comfortable exit. 3/3.0
Interpupilary distance from 52.4 to 74mm 5/6.0
Closest focusing distance 3.55 metres. 1/2.0
Eyepieces FOV Apparent field of view of 56.7 deg (according to simple formula) and 52.8 deg (according to tangent formula). 8/20.0
Field of view Measured by us amounted to 7.26 ± 0.04 degrees and it was narrower than stated in the specifications. A sensibly wide field of view for this class of equipment. 4.5/8.0
Quality of the interior of the barrels Black and mat inner tubes, the bottom is gray but not shiny. Black glue near the prisms. Some microscopic specks of dusts on the prisms. 4.1/5.0
Left: Right:
Delta Optical Titanium 8x42 - Vignetting - Left Delta Optical Titanium 8x42 - Vignetting - Right
OL: 0.69%, OR: 2.98%
Prisms quality Good quality BaK-4. 8/8.0
Antireflection coatings Greenish everywhere. Medium intensity. 4.5/5.0
Warranty [years] 5 3.5/6.0
Final result
126.3 / 190 pkt
Econo result 0pkt.


  • well controlled astigmatism,
  • slight chromatic aberration in the field centre,
  • very well corrected distortion,
  • sensibly corrected coma,
  • low brightness loss on the edge of the field of view,
  • good colour rendering,
  • good quality of prisms and coatings,
  • correct blackening of the inner tubes,
  • good price/quality ratio.

  • significant chromatic aberration on the edge of the field of view,
  • slightly truncated exit pupils,
  • inconsistent specifications concerning the field of view.

Porro prism pairs of binoculars from the Titanium series have already managed to accustom us to their good performance and a very good price/quality ratio. The 8x56 ED model, which scored as many as 132.2 points, fared the best. Binoculars without ED glass performed a bit worse but still they were good - for example the 8x56 model was given 125.9 points and the 7x50 model got 118.3 points. The instrument with 8x42 parameters had a result of 122.8 points which made it fit well the trend set by the whole Titanium line-up.

Olympus EXPS I 8x42 and Delta Optical Titanium 8x42

Still you should remember we deal here with a cheap pair of binoculars produced in China. There are no miracles in either optics or mechanics so at this price point you must expect some shortcuts here and there. You can notice them looking, say, at the shape of exit pupils, the correction of chromatic aberration on the edge of the field of vision, a bit too low transmission level for a Porro instrument or the external design. There is no accounting for tastes so perhaps there are people who actually like the look of the DOT 8x42; we, however, do not belong to that group to put it mildly.

The company once again didn’t avoid some confusion concerning the field of view. You have an inscription on the binoculars informing that it amounts to 7.5 degrees. On the site of the producer they say ‘128 by 1000 meters’ so 7.3 degrees. The field, measured by us, was 7.26 degrees. Still, our complaints end here. The binoculars don’t have any serious slip-up which is really a great achievement at this price point. What’s more, they correct most of basic optical aberrations well or very well. The field, although not described in a consistent way, is decently big – almost one degree wider than the field of another Porro device with the same parameters, the Olympus EXPS I 8x42. However, still it can’t compare to the field of the Nikon Action EX 8x40.

If you take into account a 5-year warranty period, given by a company which has been present on the Polish marked for more than a dozen years, a rich accessory kit, the fact that this instrument is fully waterproof, nitrogen-filled and its price is really affordable, it would be difficult to complain about anything at all.