Hi

One thing that annoys me about Pentax is that they make very little attempt to standardise their filter sizes. If you buy your standard 3 lens kit you can easily end up with 3 different sizes which leads to a bag full of filters or (in my case) not bothering with them. It has weven affected my lens purchases.

What determines filter size ? I guess there must be some correlation to the speed of the lens but if we look at these cases.

1. the 55mm - 3 designs and 3 filter sizes from 82mm up 100mm ! 2. the 165mm 2.8 has a 67mm whilst the f4 L/S has a 77mm 3. why would a 75mm lens need an 82mm filter.

Contrast this to some other manufacturers - Mamiya RB/RZ all 77mm. Blad - B60 except for 40mm FLE and really long lenses.

Whilst obviously not a reason to change makes, isn't filter size one of those design issues where the convenience of the end user i.e. the customer ought to be considered ?

Tapas

P.S. Steve - I like the idea of a 35mm, I would then ditch the 45mm and go for a 35 / 55 combo. I still feel that redesigning the short teles is the priority.

-- Tapas Maiti (tapasmaiti@hotmail.com), May 12, 1999

Answers

Tapas, Marcelo: Some good points here. Lens designers do not design around a given filter size in most cases. They design to meet the perceived needs of the photographer. The filter size is a consequence of this. Mamiya is just a bit more customer oriented than Pentax. Maybe someday Pentax will use customer feedback to improve their products. Most of the 67 lenses could be 82mm with the remainder being 77mm. On their next redesign, I would propose a 200mm f/2.8, Double Gauss leaf shutter using ED glass and 82mm filter. Discontinue the 165mm. Redesign the 135 macro to close focus without the need for tubes. Discontinue the overpriced 100 macro. Redesign the 300 to have a tripod mount on the barrel, closer focusing and more accurate DOF scale. Reintroduce the non-ED 400mm to give the customer some choice in this matter.$$$$$ Redesign the 500mm to be a seven element, non-ED, superachromatic lens with f/6.7 speed and 82mm filter. Redesign the 105mm to accept an 82mm filter without changing the optics. Discontinue the 90mm. Etc. etc. You get the idea. The large front element used on the 75mm retrofocus(Angenieux, France, 1950)is used to increase the illumination at the edge of the field. The 45 and 55mm are not Retrofocus but are German based designs and for some reason can get by using smaller front elements. Seventy seven mm filters could be used in the outer bay telephotos'rear filter area(600, 800 & 400). SR

-- Steve Rasmussen (srasmuss@flash.net), May 12, 1999.

Hi everyone; thanks for contributing to this forum. Without you, Phil would erase us. My reason for suggesting the elimination of the 90mm was because of the price differential of the 90 and 105. They are both great lenses though. Scaling up lenses from the 35mm to 67 is a mistake in most cases. The 100mm macro example is good evidence of this. Scaling up a 50mm Double Gauss from the 35mm world to use as a wide angle 50mm on the 67 is impossible and I'm glad to see Pentax has not tried that. Scaling up can be used with certain focal lengths however (telephotos). I should mention a small error in my post above. The 45 and second version 55mm are German based designs. The present version 55 is a unique Pentax design as far as I can tell. I will be off line from this forum between May 28 - June 11. Doing a photo trip to the tropics. SR

-- Steve Rasmussen (srasmuss@flash.net), May 13, 1999.

Hi Tapas,

I agree with you that it is annoying to have different filter sizes. I have the 45/90/200 lenses which all have different threads.

It is interesting that the Mamiya RZ has all lenses in a 77mm size. I didn't know that. I got into MF recently (been shooting w/ my Pentax for less than 3 months now) but I know that back in November when I started looking into MF, if I had a ton of cash to spend, I would probably have bought a Mamiya RZ 67 Pro II because it's such an incredible system.

But I'm happy with the Pentax. Some things (filter sizes, a 35mm w/a, closer-focusing teles) could be fixed, definitely.

To go back to your original question: of course Steve will answer this better than I, but if Mamiya can do it, Pentax could have definitely standardized their filter sizes. If nothing else, they could've laid down the blueprints for all their lenses and simply picked the largest filter size of them all and stepped up the fronts of all other lenses to match that.

It would be nice if Pentax were a more "responsive" company--it seems to me that they're not very good listeners..

regards, Marcelo

-- Marcelo P. Lima (MPL4@cornell.edu), May 12, 1999.

Steve,

About discontinuing the 100 macro: I didn't understand why Pentax came up with this lens in the first place! I would think a macro would be more useful if it were more "tele" and thus gave you more working room. It doesn't seem as if they're using any kind of "consumer feedback" because this was a recent introduction. I also don't understand why Pentax designed this lens to provide 1:1 magnification with an ADAPTER when the equivalent focal length Nikon lens does this without any extras. I wouldn't discontinue the 90mm though. I really like this lens--I find it approximates better a "normal" lens for 6x7, and is closer to my old 50mm in 35mm than a 105 would be. Today I got back some chromes which surprised me; this lens also performs extremely well wide open. It seems as if our discussions invariably revolve around lenses; we should start lobbying (sending mail, whatever) to make them listen to our suggestions.

regards, Marcelo

-- Marcelo P. Lima (MPL4@cornell.edu), May 13, 1999.

Hi Steve, Marcello

Thanks for the input, Steve your lens wish list almost exactly mirrors mine (I don't really care if the 200mm has a leaf or not though).

The lens choices seem to mirror Pentax's 35mm line, for instance the new 100mm macro. They bought out a 1:2 100mm macro for the 35mm line up and I wonder whether it was just cheap to scale it up for 67 ?

I too looked at the RZ67II kit very strongly (same sort of price in the UK), I think it is a better designed system but much too big to travel with and not as fast to use.

I am not sure there is any effective method of lobbying Pentax !

Tapas

-- Tapas Maiti (tapasmaiti@hotmail.com), May 13, 1999.

I agree with all of you that Pentax does not seem to be particularly interested in getting input from the average user. I also own a Canon EOS system, and I think Canon is the same (though they may survey their Canon Professional Services members). I've always perceived Japanese companies as very adept at marketing and manufacturing. But camera makers don't seem to do a lot of market research among average users. Perhaps they do, and I'm not aware of it; or perhaps they do in the Japanese market. At any rate, I agree that future products would benefit from more input from users than seems to be the case today.

-- Michael K. Gardner (gardner@gse.utah.edu), May 13, 1999.