Pentax Plus Megapixel Lens Test

By John Honovich, Published Nov 02, 2011, 12:00am EDT

Last month, we released the first ever Megapixel lens test where we did a shootout between 5 leading surveillance lens manufacturers - Computar, Evetar, Fujinon, Tamron and Tuss. Member feedback was very encouraging and the lessons learned in image quality differences was quite useful.

One comment, raised by CCTV legend Vlado Damjanovski, was to test Pentax's [link no longer available] Megapixel 'Plus' lens, a lens that he said performed quite strongly. We asked a number of camera manufacturers but it appeared that none of them used or had considering using Pentax lenses. However, with Vlado's recommendation and Pentax's marketing claim of 'innovation for installer friendliness' we decided to check it out.

The Test

We bought a Pentax Plus 2.8-8mm MP lens and did a series of shootouts against Fujinon's varifocal MP lens (YV2.1x2.8SR4A-SA2).

The shootouts were done in 5 different spots with a 720p HD camera:

  • 2 spots in the center of Field of View - one at 40 foot wide FoV (32 ppf) and the other at 80 foot wide FoV (16 ppf)
  • 2 spots in the fringe / edge of the Field of View -one at 40 foot wide FoV (32 ppf) and the other at 80 foot wide FoV (16 ppf); the fringe is important as image quality degradation is common here
  • 1 night time (under 1 lux) outdoors test to compare low light performance

While the image quality using the Pentax and Fujinon lenses were a draw in our test, the Pentax demonstrated far superiority in setup at a much lower price than the Fujinon. Given that the Fujinon was one of, if not the top in our HD lens shootout, this makes the Pentax Plus lens very impressive and worth stong consideration.

The Pentax lens is an especially strong fit for cameras that lack auto back focus / autofocusing capabilities as the Pentax lens provides, by far, the easiest setup/focusing of any lens we have ever tried. For cameras that include auto focusing, the Pentax still makes it easier to adjust the zoom level but the automatic fine focus capabilities of those cameras reduces the benfit of Pentax's approach.

DISCLAIMER: We only tested with a 1.3MP camera, the maximum rating for the Pentax lens. The Fujinon lens is rated for 3MP and may provide superior performance for higher resolution cameras.

Pentax Key Details

Three key details stand out for the Pentax Plus lens:

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  • It's cheap. We bought ours for $75 online. Most varifocal MP lenses, like the Fujinon cost over $100.
  • When zooming, the Pentax lens stays nearly in focus throughout the entire range. With typical lenses, the image gets completely blurred out and you lose where you are. With the Pentax, you do not need to guess or struggle where you are at.
  • When fine focusing, the Pentax lens allows for very discrete changes in focus level by clicking from level to level. This stops you from overshooting the focus, a common problem with continuous, smooth focusing mechanicms. See the video below for a live demonstration/explanation.

Lens Setup / Focusing

This short video compares the traditional lens setup and Pentax's:

Center FoV Comparison vs Fujinon

The comparison below show Fujinon and Pentax at a 40 foot wide FoV in the center of the camera.

The image quality is real close with the Pentax possibly providing slightly more details in the subject's face.

The next image is from 'far' away with a subject in an 80 foot wide FoV:

It is hard for us to determine any major practical difference.

Edge FoV Comparison vs Fujinon

Now, we switch to the fringe of the camera's FoV to look for performance variances:

It's hard to tell major differences between the two.

Next, we move to the far point on the fringe:

Again, major differences are really not noticeable.

Night Comparison vs Fujinon

Finally, we did a test at night with a subject on the right center.

The Pentax might be slightly better (you may see a little more of the chart the subject is holding) but overall the differences are essentially immaterial.

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