Vivitar 2x telecovrter on Hassy 80mm DOF

Vivitar 2 x teleconverter on Hasselblad 80mm 2.8 Planar lens. To use the depth

of field markings on the prime lens barrel do I increase the exposure by two

stops? or am I being two simplistic!

How accurate are the depth of filed markings on Hasselblad lenses?

Any comments would be appreciated.

The 2x extender simply converts the 80mm lens to a 160 mm lends. The depth of field markings are for a 80 mm lens. For the depth of field go to a depth of field table for a 160mm lens (you can find them on the web) You can use the distance scale on the 80 lens with or without the extender to obtain the focus distance-which you will need.

You must of course also increase the exposure by two stops from what it would have been for the 80 mm lens -or if you use a meetering prism accept the reading since it gives you more or less the light on the film plane.

The 2x extender simply converts the 80mm lens to a 160 mm lens, but it also makes the f/stop two stops smaller than marked

at 80mm f/5.6 focused at at 15 feet

12.7 ft is the near limit of acceptable sharpness

18.3 ft is the far limit of acceptable sharpness

5.54 ft DOF

at 160mm f/11 focused at at 15 feet

13.8 ft is the near limit of acceptable sharpness

16.4 ft ft is the far limit of acceptable sharpness

2.65 ft DOF

Given that the circle of confusion will be greater , at least twice the size under ideal circumstances with the Vivitar 2 x teleconverter I'd say that the DOF would be almost the same according to the scale.

BTW, to get the came magnification with double the focal length you need to be at twice the distance, so with 160mm f/11 focused at at 30 feet you have 5.4 ft DOF

Hi Lauren

Used the Vivitar to take some shots of static shipping and also a ship moving down river. Images were excellent. Used a Polariser and 81A on Velvia 100 slide film so I lost 4 f stops but results justified it. Of course it was a very nice sunny day!

I intend to take it to Rhodes on holiday and will use it for ship photography, scenics etc. I would certainly recommend a Vivitar converter from a reputable source.

Regards Frank