Just a musing...

I am intending to get hold of the new 90-180 lens, and have wondered about focusing it. I do a lot of work in comparatively low light (for instance a summer's day in England!) of moving subjects. This means fast shutter speeds, and fairly wide apertures for a given film speed. Therefore, getting the depth of field right usually involves some very careful focusing.

Given that the new lens is f5.6, the viewfinder brightness will be less than I am used to at these focal lengths. I guess it will be harder to get the focusing quite right at the 180mm end of the range.

Any thoughts?

-- Ed Hurst (BullMoo@hotmail.com), March 18, 2002

Answers

George, when you report further tests on this lens, please post under the "Field Test" category.

-- Steve Rasmussen (srasmuss@flash.net), March 20, 2002.

I have this lens and have shot only two rolls of film using it so far. I haven't fully tested its imaging potential yet. Here are my immediate observations on other aspects of the lens. The lens is definately impressive and is well made to typical Pentax 67 lens standards. It is the same length as the 200mm f4, but is about a half inch wider in diameter. It has a very large and functional detachable hood that reverse mounts when not in use. The focusing and zooming rings are nicely damped and comfortable to use. The lens barrel moves in and out when focusing, but doesn't rotate, making for easier use of a polarizing filter. On my P67 the viewfinder is darker than with any other P67 lens I have used. The little bumps in the center focusing ring of the viewfinder never completely disappear, even when focus is achieved, as with my other faster lenses. I find this to be somewhat annoying. However, even with the darker image, I have no problem achieving accurate focus. I shoot landscapes though, and have plenty of time to focus. After I got the lens, I immediately purchased a dedicated Pentax brand rubber eye cup, to eliminate any extraneous light in the viewfinder, making it easier to focus. I am also considering getting a Hi-Lux brilliant mat focusing screen to hopefully help brighten up the viewfinder image. I understand that the screen in the P67II is much brighter than the screen in the P67 and earlier 6X7 models. Using this lens with the newer P67II body would therefore make for easier focusing. There is no depth of field scale on this lens, but there is an infrared scale. However, I don't consider hyperfocal indications important on a lens of this focal range. All things considered, I really like this lens. I can carry this single lens, instead of the 90mmf2.8, 135mm macro and 200mm f4 trio. I would probably not consdier using this lens with a 1.4X teleconverter, due primarily to the dark viewfinder image. When I have shot more film using this lens, I will report my findings on its imaging capabilities.

-- George Rhodes (betsy@colormewell.com), March 19, 2002.

Re. viewfinder brightness in P67ii and the new lens.

I have only ever had the P67ii (never the older versions), and despite the brighter viewfinder, still have problems with critical focusing on occasion - even with the f2.8/f2.4 lenses. I am lucky enough to have very good vision; the problem is basically the very small DoF of the system if you have to use the lenses fairly wide open (as I often have to do).

I'd be interested in hearing impressions of focusing this new lens...

-- Ed Hurst (BullMoo@hotmail.com), April 02, 2002.