Lens Performance-Wide Open

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Although not a scientific comparison, here is my opinion of the lenses I own as far as wide open performance is concerned. I am listing best to worst. 150mm---75mm----45mm----105mm----200mm-----300mm-----600mm. Would anyone care to add their opinion on the lenses not listed here? Where would you place them in this sequence? SR

-- Steve Rasmussen (srasmuss@flash.net), January 07, 2000

Answers

Most of the quality variation that I have heard of involves the mass produced 105mm. I would suspect that the smaller production lenses would be more consistant. There seems to be a consensus among users that a particular lens exhibits certain characteristics(except the 105). We can all agree that the 55 f/4, new version is quite sharp as well as the 75mm, as examples. So, it is hard to place the 105mm in a lineup of sequence of wide open performance. My 105 Takumar is middle of the road wide open but not the worst I own. Excluding it from the sequence gives the list more validity. Here's another cut at it. 150---135---75---45---90---55 f/3.5---200---300---600. Only the 300 and 600 are really unacceptable wide open. In other words, a customer would reject their images for being too soft. SR

-- Steve Rasmussen (srasmuss@flash.net), January 11, 2000.

Bill: with two 165s in their lineup, I doubt that Pentax will make any changes or update that focal length any time soon. Making a 165 f/2.4 that is tack at f/4 is difficult due to color correction problems. Pentax is using a Double Gauss for their 2.8 and an Ernostar design for the f/4 LS. The 2.8 at 165mm is about the limit of this design as far as focal length is concerned. Low dispersion glass becomes necessary once you reach this focal length for tack sharp images at f/4. What you are looking for can be made but it may be outside of Pentax's pricing philosophy. SR

-- Steve Rasmussen (srasmuss@flash.net), January 12, 2000.

Well, Steve, I own 4 P67 Lenses at the moment (55/3.5, 90/2.8 LS, SMC PENTAX 135/4 Macro and 135/5.6 Rodesntock enlarger lens on a Zoerk Multi-Focus system adapted for P67), and am just about to add the 75 and 200/4, new or used but latest models. I also had a brief flirtation with SMC PENTAX 105/2.4. I would list the lens performance wide open as follows:

135mm--135mm Rodenstock--90mm--55mm/3.5--105mm

The 105mm was a real Coke bottle bottom wide open. But superb stopped down to, say, f/11. Other lenses are satisfactory and the latest version 135's are unbelievable!!!

HOWEVER, I hope you know this comparison is totally useless because there are so many quality variations within the same lens series. We both could have a 165/2.8 and yours could be great, mine terrible. They don't make them as consistent as they used to...

If I will get my hands on a well-preserved 150mm, I will buy it also. I've heard nothing but praise about this lens.

-- Alex B. (samedobrefotke@hotmail.com), January 08, 2000.


I'm waiting on my Gitzo 1411 before I do formal tests with a lens resolution chart, but my initial impression is that the 105mm is a bit of a dog wide open. I'd say my sample of the 165mm/f4 is better wide open than my 105mm is at f4. That's shooting handheld while learning how to handle the 67II body, though, so my opinion is highly subjective. (I picked up my 55mm/f4 (new version) just before the holidays and haven't even shot a test roll with it yet.)

Even though my initial impression of the 165mm f4 is favorable, I'd probably dump it for an updated version of the 165mm/f2.8 if Pentax came out with one including better close-focus performance, like with a CRC-type floating element. I now realize that I'd much rather have the lens speed than the leaf shutter, the LS being rather pointless if you want to use TTL flash metering. I wonder how fast a 165mm Pentax could design with a 77mm filter ring and no leaf shutter. A 165mm/f2.4 that was tack sharp in the 3'-15' range at f4 would be great.

-- Bill Baker (wab@well.com), January 10, 2000.


Steve, here's an addition to your list. I bought two second hand SMC Pentax lenses the other day: 165/2.8 and 75/4. I would put them in the list like that: 135-165-75-90-55....

-- Alex B. (samedobrefotke@hotmail.com), January 20, 2000.


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