For what it’s worth, I tested my 24 asph at the same time as the others. I have nothing to compare it to except the other lenses. But with that being said, I have to say this lens “wowed” me! It is incredibly sharp (superb) from the center to the edge up to f11, where it starts to fall off ever so slightly. I would have to give it the edge in sharpness over the 90 SAA, with the 35 asph’s and the 50 Summicron about equal, and coming in after the 90 SAA. Sharpness decreased a bit in the corners with the addition of the UV filter. Flare control was excellent, but the UV filter did increase flare slightly. Bokeh is nice and smooth. Color-cast is Leica neutral.

Definitely a keeper!

-- Jack Flesher (jbflesher@msn.com), March 08, 2001

Answers

It is indeed a mighty bit of melted and shaped sand.

Rob.

-- Robert Appleby (rob@robertappleby.com), March 08, 2001.

Jack

All your comments about UV filters confirm me in my practice that it is better to not use them.

-- Robin Smith (smith_robin@hotmail.com), March 08, 2001.

Robin:

It was a last-minute thought to test the lenses with the filters... As I'm sure you are aware, there has been significant discussion on the subject of filter use in this forum. I have always felt that filters must degrade the image to a degree, but I was not sure just how much. These tests showed me that the degredation exists, but also that it is a very, very minor amount -- probably not even noticeable to the average person. None the less, I'll stick with my practice of using a UV filter only when I know the lens may be subjected to a harsh environment -- which is almost never!

-- Jack Flesher (jbflesher@msn.com), March 08, 2001.

I can attest only from my informal use of the 24/2.8 ASPH that this is just one hell of a wonderful lens. I'm extremely pleased with it. Well worth the money, although my piggy bank is not happy at all these days with my Leica fetish.

Godfrey

-- Godfrey DiGiorgi (ramarren@bayarea.net), March 08, 2001.

What brand and type of filter were you using? I didn't notice any image degradation on similar tests I did with the B+W muliticoated filters. I had read were the APO lenses may be more affected by having a filter in front of them, but since I don't own any of them, can't confirm this.

-- Andrew Schank (aschank@flash.net), March 08, 2001.

Andrew:

I used only Leica brand UV filters for these tests. The filters are in "like new" condition, with no scratches, marks, etc., and appear to be coated, although I'm not positive of that. As for sharpness and flare, I simply reported what I saw. Certainly by my tests, the asph lenses showed more loss of sharpness than the non-asph. Since the asph lenses use some "rare earth" glasses, perhaps that supports what you heard regarding APO lenses.

Also note that the reverse was the case for flare, where the non-asph lenses showed more flare with the filters attached. As I pondered this anomaly for a moment, I realized that it made perfect sense: The sharper asph lenses are so sharp, that the minor degredation imparted by the filter can actually be detected; additionally, the newer asph lenses are probably designed with better flare protection than the older style lenses were, so the addition of the extra reflective surface makes very little difference.

-- Jack Flesher (jbflesher@msn.com), March 08, 2001.

About filters, I believe that a recent magazine test showed that Nikon filters are the least degrading, wth BW a close second. I don't believe Leica filters were considered. The new super multi coated blah blah BW's are said to be very good.

I never take them off!

Rob.

-- Robert Appleby (rob@robertappleby.com), March 09, 2001.

I use to be one of those..."It's cheaper to replace a filter than a lens" guys. Then about ten years ago it dawned on me that I never replaced a filter in over twenty years of serious photography.

Now all of my lenses are naked, with the optical formula being just as it was designed. Every element does something...even elements that are suppose to be neutral.

-- Al Smith (smith58@msn.com), March 09, 2001.

I'd like to take this moment to point out that no piece of glass is "neutral" in an optical formula -- even a flat piece, like a filter.

To wit, in all of Nikon's high-end telephotos there is a "filter drawer" mounted in the barrel of the lens, and the factory supplies the lens complete with a UV filter in place in this drawer. The instruction book furhter states that the optical formula of the lens requires that a filter be in place in the filter drawer for optimum performance!!! (Of course, they recommend only Nikon brand filters be used, as they are optimized for the formula.)

-- Jack Flesher (jbflesher@msn.com), March 09, 2001.

I put all my lens caps in a closet years ago. I just like to grab the camera and shoot, not having to worry about where the cap is, etc. So, I have always used a filter as the protective (sacrificial) element at the front of the lens. Granted, I have never damages a filter.

Query, how many of you non-filter users are also non-lenscap people. I am talking about an unprotected front lens element 24/7/365. I have a problem doing this with expensive lenses (or even cheap one for that matter). Although I am compelled by Jack's reports of image softness with a filter in place (shriek, even a Leica filter!).

-- dan Brown (brpatent@swbell.net), March 09, 2001.

I always use lens shades and I never use filters. I don't use front caps on lenses that have fixed hoods without integral caps (like my tabbed 50 Summicron) because it's a PITA to take the hood off. I always use front caps on lenses with sliding hoods, such as my 90. I use the supplied hood caps on lenses like the 35 Summilux or the 28.

I always use back caps, typically a pair of caps glued back-to-back to make lens changing easier. I just drop the lenses into my bag front element down on the shade (if fixed) or the front cap (for a sliding shade), with a cap always protecting the back element.

I may be bold, but I'm no cowboy :-)

-- Paul Chefurka (paul_chefurka@pmc-sierra.com), March 09, 2001.

As I am a non-filter person I tend to keep the cap on, and I always use the hood. On my Rokkor 40mm I use a step up ring for the hood as the rubber hood was a pain and interfered with the aperture ring. It seems to work.

-- Robin Smith (smith_robin@hotmail.com), March 09, 2001.

"Ditto" what Paul said. Also, when I have a lens on a body in my bag, I do not bother with a front cap on the lenses that have rigid lenshoods; I rely on the lenshood for protection -- the cameras are ready to shoot with. For lenses with integral sliding hoods, like the 90 asph APO, I use the cap to protect the front element even when it is on a body in the bag -- the cap comes off only when the camera/lens combo is hanging from my neck -- which is why I preferr some of the earlier styles of Leica lenses. For the bit of lint that occasionally gathers on the open front element while in the bag, I carry a 1" wide soft, natural-bristle paintbrush with most of the handle cut off -- It makes the best lens brush I have found!

-- Jack Flesher (jbflesher@msn.com), March 09, 2001.

Here's a test that's worth doing now that we are on the subject. Take your sharpest Leica lenses, and try to hand hold them (the way we normally use them)and shoot the chart again. You'll find some surprising results at speeds even as high as 1/125 second that make the loss from a filter seem insignificant.

-- Andrew Schank (aschank@flash.net), March 10, 2001.

I am a filter user. I have never seen any image degradation, and feel safer with the filter on the lens. Leica UV filters are not multi-coated, interestingly enough. I have several of them, but have switched to B+W multi-coated filters after comparing the light transmission qualities of the two brands. Heliopan and Hoya also produce excellent multi-coated filters, but I believe only B+W produces 39mm multi-coated filters.

-- David Page (pagedt@attglobal.net), July 06, 2001.

Leica UV filter DOES not transmit 99% of the light, this can be checked by using a Leica UV filter as mirror to reflect sunlight on wall--- the reflection is quite bright as compared with my Carl Zeiss multicoated filter. The quality of Leica UV filter is questionable.

Check also the coating of the surface of your lens ( by reflecting sunlight )---- if the reflection is not very dim, then, with Leica UV filter on, the reflection from the front surface of lens will be reflected bach by the inside surface of UV filter, causing flare. Using a good quality multicoated filter from other make may reduce flare seen with Leica UV filter.

-- martin tai (martin.tai@capcanada.com), July 06, 2001.