Pentax Spotmatic: What is the Bridge Circuit?

A voltage-independent Wheatstone circuit

By FozzFoster in Articles and Tips on Nov 30, 2021

Most of the Pentax Spotmatic cameras were designed to use a 1.35V PX-400 mercury battery to power their internal light meters. However, mercury was banned in batteries in 1996. So, what batteries can be used instead?

Fortunately, the Spotmatics (SP, SPII, SPIIa, SP500, SP1000) are designed with a balanced bridge circuit: This allows a photographer to use the readily available 1.55V silver-oxide S400PX batteries, regardless of that fact that they supply a higher voltage!

The bridge circuit in these cameras are relatively immune to changes in voltage and will still provide accurate light meter readings. Please enjoy this PentaxTips video below for the full details:

Hungry for more?  Check out our previous video on how to spot the legendary 8-element Super Takumar lens.

PentaxTips: Spotting the 8-Element Super Takumar 50mm f/1.4

Do I have the 'Zeiss Planar Killer'?

By FozzFoster in Articles and Tips on Oct 10, 2021

Pentax is known for its rich history of excellent and industry leading optics. However, being on top of the industry generally means you'll have rich competition! 

In the 1960's, when the M42 screwmount was in its heyday, Pentax and Zeiss were battlin' it out for the prestigious bragging rights of having the best commercially available optics.

Notably, we had the Zeiss Planar 50mm f/1.4 and at the time it was regarded at legendary status for it's sharpness and optical performance. Pentax response was to produce a lens that would exceed Zeiss's impressive reputation no matter the costs: enter the Pentax Super-Takumar 50mm f/1.4- designed to be the 'Planar Killer'! 

Rumor has it that Pentax actually took a loss with each sale of this 8-element lens just for showmanship and elbow Zeiss in the marketplace and jockeying for position! However, with the obvious financial risks involved with this competition, Pentax eventually replaced the original 8-element design with a more affordable 7-element design.

While both lenses certainly perform admirably, the reputation for the original 8-element version persists leaving a 'cult-classic' fan favourite lens in its wake.

In this PentaxTips video, we discuss how you can discern between the 8-element and 7-element variations of this lens.

Hope you enjoy!

The Pentax Macro eBook

In-depth coverage of Pentax macro and close-up accessories

By PF Staff in Articles and Tips on Sep 18, 2021

Over the years, Pentax has offered a multitude of macro accessories and lenses.  Despite this, information on the history, compatibility, and usage of much of this equipment remains sparse.

Today, we are happy to share forum member Murray O'Neill's comprehensive guide to Pentax macro and close-up accessories.  This free 180-page PDF eBook covers everything from eyepieces to close-up lenses  to extension tubes.  It supplements the existing and equally detailed eBook on Pentax bellows.

For the author, this was a lockdown project written for the benefit of the macro photography community as well as Pentax equipment collectors and enthusiasts. Enjoy!

Download The Pentax Macro & Close-up Accessories eBook

K-3 III How-to: Smart Function Set-up and Use

How to customize and use the Smart Function

By PF Staff in Articles and Tips on Aug 10, 2021

The Smart Function feature of the K-3 III can seem a bit convoluted at first, in particular since it works quite differently from the older DSLRs, the K-1 series and KP. The bonus, though, is that it is highly customizable and that it, when first set up, can be operated without removing the eye from the viewfinder.

The first thing to do is to decide is which five functions you want assigned to the Smart Function (SFn) button. The options are:

When you have picked your five, proceed to setting up your selection.

K-3 III How-to: Aperture Bracketing

How to use Aperture Bracketing with the K-3 III

By PF Staff in Articles and Tips on Jun 3, 2021

The K-3 Mark III is the second Pentax DSLR to offer aperture bracketing, the first one being the Pentax KP.

This feature is particular useful when shooting macro. It can be hard to evaluate whether or not you got the right depth of field by reviewing your images on the rear monitor when out in the field. A common technique to counter this is to shoot at several apertures and then select the frame with the right amount of depth of field when you get home to your computer monitor. We've always used that technique by painstakingly taking several shots at different apertures ("running the aperture").

With the K-3 Mark III you can automate this process and have the camera take three images at different apertures (but at the same exposure value) with one push of the shutter button.

Aperture bracketing is only available in Av and TAv mode; not in Hyper Program or any of the other exposure modes which do not allow for the camera to set the aperture.

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