I am looking for a standard lens for the Pentax 67 and fishing for any comments / advice on the difference between the 90mm and the 105mm. They are probably both very good optically and with little difference in the angle of view my current preference is for the 90mm, being smaller, lighter and cheaper (on the UK mint second hand market).

Has anyone any advice on other differences in the lenses and maybe why Pentax bother to offer two standards?

-- Tony Estcourt (tony.estcourt@talk21.com), April 05, 2001

Answers

Yes, quality variability is a problem with the 105. Mine is an SMC Takumar that was made in 1989. At f/22 at infinity or in macro situations, it can make nice prints in the 16x20 inch size. At f/8 it has made nice 24x30 prints. Other owners have had trouble with 11x14 prints at f/22. The 90mm is a seven element Double Gauss while the 105 is a six element. Generally, the use of the extra element in this design is used to reduce spherical aberration. The 90 has a better reputation than the 105. If you can get the 90 at a good price, go for it. SR

-- Steve Rasmussen (srasmuss@flash.net), April 05, 2001.

Tony,

I own the 105, but have used the 90. In my opinion, besides the obvious few degrees AOV, the only real difference between the lenses is you get an extra foot or so (.35 meters) of close focusing on the 90. The actual numbers are something like 1.03 meters min focusing distance on the 105 vs. .65 meters on the 90. Also, I know there is some construction differences on the lenses (i.e. elements/goups) but Steve is the expert on that subject so hopefully he'll chime in.

As for the lenses, I liked them both. If my primary use was landscapes, I would probably go for the 90 for the reasons you mentioned such as size and weight. My standard lens is mostly used for location portraits so I like the extra little AOV. Some say the 105 is not that great wide open, but I'm not sure why someone would should a normal lens on a 6x7 format at 2.4 anyway. But than again all our styles are different.

In the end, pick the one you like. They are both fine lenses.

-- Scott Laughlin (scottlaughlin@mindspring.com), April 05, 2001.

I would favor the 90 since I've found the 105 to be really soft at any thing other than f8 or f11. Actually, f2.4 and f22 are pretty much rubbish. A 90 that I had rented seemed to be much more consistent at each aperture than the 105. Other people on this board also have reported variability in the quality of the 105.

-- Carl Hungerford (chungerford@ibaset.com), April 05, 2001.

Yes, the 105 apparently is quite variable in quality. My 105 is good until about f-11. It goes to mush at 16 and 22, and is unusable at these settings. Test the lens closely, before sealing the deal! OTOH, the new 55mm f4 is a killer at all f-stops!!!

-- Gene Crumpler (nikonguy@att.net), April 05, 2001.

With a 105 built around 1973, I produced a 4 foot X 8 foot panoramic that was stunningly detailed (Ektar 25 negative film, shot at f/16, on a tripod with a Pentax polarizer). It was a landscape scene with a field of cut hay in the foreground, a valley with a river in the middle ground and a village with distant mountains in the backdrop. The picture was sunlit and taken around 4 o'clock in the afternoon. I have numerous other pictures made with this particular lens that exhibit extreme sharpness and contrast when shot meticulously at middle apertures (f/8 to f/16).

I acquired a new 90 f/2.8 a few years ago (around 1995)hoping to widen the angle of view a bit. This lens has proven to be an honest but unremarkable performer, easy to use up close and surprisingly even at all f-stops, but I have never taken anything spectacularly sharp with it (God knows why!). Contrast and colors are excellent but resolution of fine far-away details seems to be lacking. Of course my experience is only with these two specimens so no general rule can be established but I'd say the 90 has been a disapointment so far.

Richard LaRoche, Quebec, Canada

-- Richard LaRoche (RICHARD.LAROCHE@AGR.GOUV.QC.CA), December 19, 2001.

Richard, maybe it's the lack of Ektar 25!

-- Sal Santamaura (santamaura@earthlink.net), December 19, 2001.

Probably! Ektar 25 will be sorely missed. This is almost a tragedy for landscape artists that KODAK discontinued it. On the other hand, my 90 mm lens seems short-sighted compared to the 105, even using Velvia and infinity focus. Maybe I have an uncommon 90 (fairly good up close but disapointing for far-away scenes).

Richard LaRoche, Quebec

-- Richard LaRoche (richard.laroche@agr.gouv.qc.ca), December 20, 2001.