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Binoculars review

Pentax AP 8x30 WP

Pentax AP 8x30 WP
13 October 2016
Optyczne.pl 
The Pentax AP WP series consists of two Porro prism sets of binoculars: the 8x30 and the 10x30. These are quite classic optical systems with a 2-piece achromatic objective lens and a 2+1 eyepiece. The producer claims that all air-to-glass surfaces are multi-coated by antireflection layers.

The WP symbol in the name of the binoculars indicates that these products are waterproof up to a depth of 1 meter and nitrogen-purged as well.

Pictures
  • Lornetka Pentax AP 8x30 WP
  • Lornetka Pentax AP 8x30 WP
  • Lornetka Pentax AP 8x30 WP
  • Lornetka Pentax AP 8x30 WP
Manufacturer data

Manufacturer:

Pentax
web site

Distribution / Sales:

FOTOZAKUPY.PL
web site

Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
8 30 123/1000(7o) BaK-4/Porro 17.2 mm 458 g 749 PLN
Results of the review
Real front lens diameter Left:   30.19+/- 0.05 mm
Right:  30.2+/- 0.05 mm
8 / 8.0 pkt
Real magnification 7.89+/- 0.1x 3/3.0
Transmission 85.7+/- 1% 11/15.0
Chromatic aberration Medium in the centre, huge on the edge. 3.8/10.0
Astigmatism Distinctly sparkling stars. 4.4/10.0
Distortion he distance of the first curved line from the field centre compared to the field of view radius: 32% ± 5% 3/10.0
Coma Appears in a distance of 65-70% of the field of view radius and is high on the very edge. 5.6/10.0
Blurring at the edge of the FOV Blur occurs in a distance of 90% ± 3% from the field of view centre. 8/10.0
Darkening at the edge the FOV Not especially bothersome. 4.1/5.0
Whiteness of the image Very slight pink-red hue. 4.2/5.0
Collimation Perfect. 5/5.0
Internal reflections
Left: Right:
Pentax AP 8x30 WP - Internal reflections - Left Pentax AP 8x30 WP - Internal reflections - Right
Visible lighter areas near exit pupils.
2.8/5.0
Housing Small, shapely Porro with relatively long and narrow tubes. Black rubber armour, slightly rough, doesn’t stick out anywhere. Comfortable to hold in your hands. Rubberized eyecups with smooth regulation. 8/8.0
Focusing Significantly big central wheel with comfortable ribs and a range of 190 degrees. It moves smoothly and is well-dampened. The work of a classic ocular bridge is even – it rocks sideways only under heavy pressure. The binoculars don’t get defocused when you put a lot of pressure on eyepieces. Individual focusing done through a narrow ring on the right eyepiece. It moves the outer element. 4/5.0
Tripod Quite comfortable access. In our 8x32 devices test we awarded all binoculars an average value of 1.5 points because the tripod exit is rarely used in this type of equipment. 1.5/3.0
Interpupilary distance from 53.9 to 72.8mm 3/6.0
Closest focusing distance 3.15 meters. 1/2.0
Eyepieces FOV Apparent field of view of 53.9 degrees. 5/10.0
Field of view Measured by us amounted to 6.83 +/- 0.04 degrees and it was by as much as 0.17 of a degree smaller than stated in the specifications. Not especially impressive field for this class of equipment. 4/8.0
Quality of the interior of the barrels Dark, matt tubes. Grey bottom and glue. Some specks of dust. 3.7/5.0
Vignetting
Left: Right:
Pentax AP 8x30 WP - Vignetting - Left Pentax AP 8x30 WP - Vignetting - Right
OL: 2.26%, OR: 0.44%
5/8.0
Prisms quality Good quality BaK-4. 8/8.0
Antireflection coatings Green-purple on objective lenses and eyepieces. Green on the prisms. Medium intensity. 4.5/5.0
Warranty [years] 5 years 3.5/6.0
Final result
67.1%
114.1 / 170 pkt
Econo result 0pkt.

Summary


Pros:
  • handy, shapely and solid casing,
  • sensible transmission,
  • very good colour rendering,
  • sharp image almost to the very edge of the field of view,
  • slight brightness loss on the edge of the field,
  • good quality prisms made of BaK-4 glass,
  • sensible coatings on all air-to-glass surfaces,
  • properly darkened tubes,

Cons:
  • too high chromatic aberration,
  • noticeable astigmatism,
  • problems with distortion correction,
  • slightly truncated exit pupils.


The result of the small Pentax 8x30 is a slightly negative surprise. I expected the binoculars would score over 120 points because, at first glance, they made a rather favourable impression. Good build quality and proper quality control at this price point is nothing to be ignored. The casing is very handy, covered by good quality rubber armour; the device comes without any glaring slip-ups or shoddy workmanship, with all materials being of sensible quality. What’s more, the binoculars are fully submersible and nitrogen-filled which make the Pentax stick out among other small Porro devices.

Also the transmission graph is quite sensible for the amount of money you have to pay for the binoculars.


On the one hand it is a graph typical for cheaper, greenish antireflection coatings with a dip in the middle of the range. On the other hand the transmission exceeds 90% for the red part of the spectrum and a distinct local maximum for blue light means good colour rendering.

Still if you look at optical properties of the tested binoculars you find some reasons to complain. The Pentax doesn’t feature an impressive field of view so you could expect it would be corrected properly. Unfortunately it is not the case. You don’t have to worry only about the sharpness of images which is kept on a good level for the majority of the field. There are some problems with chromatic aberration correction and the correction of astigmatism and distortion. The coma is corrected only averagely well. Add to that a bit truncated exit pupils which are surrounded by too light area and our assessment of the Pentax 8x30 optics is not especially favourable.

The final score of 114 points and the price of 179 Euro place the Pentax AP 8X30 WP in a difficult position, especially if compared to direct rivals. The Nikon Prostaff 7s 8x30 or the Kenko Ultra View OP 8x32 DH seem to be a cheaper and a bit better devices; even the small Delta Optical One 8x32 might be an interesting alternative.