Pentax Varifocal Plus Megapixel CCTV Lens
The new Pentax Varifocal Plus megapixel CCTV lens as captured in action at IFSEC 2009:
Pentax are well known for the quality of their CCTV lenses, but they have taken a long time to produce and launch their first megapixel CCTV lens. However, it seems that the wait may have been worthwhile as judging by the pre-production model demonstrated at IFSEC they’ve built in a new feature which might well see them take the lead in this sector.
Firstly, let’s explain what a vari-focal CCTV lens is – it is simply a lens which allows you to manually adust the field of view being monitored by the camera to exactly that which you wish your surveillance to cover.
Once upon a time we only had fixed focal length lenses available to us e.g. 4mm, 8mm,12mm, etc. These lenses provided a certain field of view, perhaps a horizontal viewing angle of 60° and that was what you got i.e. the view could not be adjusted. A set focal length lens provides a fixed field of view (horizontal and vertical viewing angle).
With the advent of the varifocal CCTV lens we were able to adjust the scene covered / field of view at the point of commissioning, so that only the area which we wished to cover was ‘seen’ by the camera. This allowed us to concentrate all of the camera’s available resolution onto the important area. For this reason vari-focal lenses are now used in the vast majority of all new CCTV installations.
With all of the currently available vari-focal lenses, as the field of view is adjusted, you then need to re-focus the lens at each scene setting. With their new ‘Varifocal Plus’ lens Pentax have developed technology which allows the lens to stay in focus as you manually zoom.
The guys on the stand weren’t revealing too much about how Pentax had achieved this first, they simply said that it utilised technology transfer from their lenses for the Digital Single Lens Reflex (DSLR) camera market.
Precise focusing of CCTV camera lens combinations is something which many end-users struggle with, so this new lens from Pentax should bring great benefit to many end-users and field engineers.
It’s a 1.3 megapixel lens and should be available Q3 2009 for a price in the region of just £99!
Click the image to the right to visit the new page in our webshop and to download the datasheet from there for further information.
NB This lens will only work with cameras which have a lens connection socket and can be back-focused with an adjuster ring at the front of the camera (if you need any further help or information then give us a call on 01304 827 609).
Tags: CCTV lens, IFSEC, megapixel cameras

June 8th, 2009 at 7:08 pm
Hello,
this type of lenses is – as ‘the guys on the stand’ mentioned – not a new idea. Their name is parfocal, some more info can be found on Wikipedia or google:
http://en.wikipedia.org/wiki/Parfocal_lens
About this lens: it is a pity, that it is for 1/3” only.
By the way – why posts on Your blog show so rarely last times? It is a shame, this website is a really useful reading.
Regards,
Marian
June 8th, 2009 at 7:44 pm
[...] Co w tym takiego nadzwyczajnego? Z punktu widzenia branży fotograficznej nic, pomysł jest znany od dawna i nazywa się obiektyw parafokalny (albo parfokalny – od angielskiego parfocal lens). W skrócie chodzi o to, aby obiektyw, mimo zmiany ogniskowej, utrzymywał ostrość w danym punkcie. Można sobie łatwo wyobrazić, że taka właściwość dość znacznie ułatwia pracę z kamerami megapikselowymi, gdzie ustawianie ostrości bywa nieco uciążliwe. Minimalny ruch pierścieniem i… przeskakujemy z ostrością na dalszy obiekt. Kolejna próba i… tym razem przeskakujemy na bliższy. W końcu trafiamy “w punkt”, ale pole widzenia nie odpowiada klientowi, więc zmieniamy ogniskową i zabawę z ostrością zaczynamy od początku… I tu właśnie wkracza Pentax ze swym nowym produktem, o czym przeczytałem na blogu use-ip. [...]
June 8th, 2009 at 8:15 pm
Hello Marian,
Thanks for the feedback and information about parfocal lenses. Sorry about the scarcity of Posts recently, I’ll try to keep it more regular in the future,
Best Regards,
Phil.