Why Cosina (Voigtländer, Zeiss, etc.)?
LEICA M9 Update
I don't understand why anyone would cheap-out with Voigtländer lenses on an M9. Lenses are free compared to an M9, and cheap lenses compromise the M9's quality.
The Voigtländer 12mm, 15mm and 21mm lenses work poorly on the M9. Forget them. Their rear nodal points are so close to the sensor that they have red-tinged left sides and blue-tinged right sides. It's nasty. They work great on film, but forget it with the M9.
The M9 is programmed with profiles to work perfectly with all current Leica ultrawides, so they are not a problem. The M9 has no such firmware for use with lesser lenses.
Honestly, do you have any idea by how many thousands of dollars a year your M9 is depreciating? Do you realize that lenses only go up in value? The silliest thing people do is buy fancy cameras and cheap-out on lenses. Do not buy Voigtländer lenses to save money. Only buy them if they do something Leica can't.
Lets look at the numbers:
LEICA M9: $7,000 new. Used value in 3 years: $2,500. Cost per year: $1,500. (used value in 10 years: $500. Cost per year: $650.)
Voigtländer 21mm f/4: $400 new. Used value in 3 years: $300. Cost per year: $33. (used value in 10 years: $500. Cost per year: the world pays you $10/year.)
Leica 21/2.8 ASPH: $4,400 new. Used value in 3 years: $3,200. Cost per year: $400. (used value in 10 years: $5,200. Cost per year: the world pays you $80/year.)
Used Leica 21/2.8 (non-ASPH): $1,500. Used value in 3 years: $1,800. Cost per year: the world pays you $100/year. (used value in 10 years: $2,500. Cost per year: the world keeps paying you $100/year.)
Any time Leica cameras come up, people have always wondered how well discount non-Leica lenses work.
Ask yourself: if you have the money to throw away at an M8.2 or any other Leica, new or used, then why can't you afford a lot less money to invest in the lenses it deserves, which don't depreciate like the M8?
I'll get into details, but don't buy Voigtländer lenses to save money. Buy a Voigtländer lens if it does something that Leica can't do, like the extraordinary 15mm f/4.5 Voigtländer lens, but don't bother with lower-performance lenses like the Voigtländer 28mm f/1.9 just to save money instead of getting the Leica lens you really want.
I bought a $400 Cosina 21mm f/4 (Voigtländer) for use on my Nikon SP rangefinder camera. The lens works magnificently. I suspect the optics of other third-party lenses are probably fine, and I'll let you know as I get to testing them. For the Nikon SP, the only other choice is the unavailable Nikkor 21mm, which sells for about $8,000 used (if you can find it) because it's a collectors item, so the Cosina was the only 21mm lens I could get.
I haven't tried the Zeiss lenses for Leica, but most of them are Japanese (probably also made by Cosina) and the ones I've tried in other mounts are nice optically, but only third-party quality in their mechanical feel. I'd consider Zeiss if Zeiss offers something unique, like the 18mm f/4, but not to save money on something made by Leica.
If you're sinking serious money into a serious camera, why would you want to save a tiny fraction of that amount by buying second-rate lenses which will be part of your system for far longer than that camera body?
Yes, third-party lenses might save you a little, but what they might save you is negligible in comparison to the cost of bodies, especially digital bodies. With off-brand lenses, you lose half the pleasure of why you bought Leica in the first place.
Cameras come and go, especially digital, while the lenses you buy today will still be making you great photos 50 years from now.
The lenses you buy today will be the only lenses you need for any Leica (or Voigtländer or Zeiss or other M-mount camera) for decades to come. Why saddle yourself with "settle for" lenses, when you could own the best instead?
The reason it makes so much sense to stick with Leica lenses becomes all the more obvious when we look at some numbers, especially for digital.
A film camera has about ten years of model life before it's replaced with a newer one you'll want instead.
A digital camera has only two years of model life, even in Leica.
The Leica M8 came out in 2006, and was replaced by the M8.2 in 2008. As I write this, the M8.2 costs $6,000, but in two more years, good luck fetching $3,000 for it used. In five years, when hopefully Leica has a full-frame M9, the M8.2 will probably be worth a lot less than a 1954 M3, or about $800.
Money spent on digital bodies is money you'll never see again. It's gone in 18 months.
Now consider lenses. Lenses you buy today will serve you well for decades to come. Because of this they also hold their value for decades to come. I just bought a brand-new Leica 28mm f/2.8 ASPH, and it didn't cost much more than what people are paying for used copies of inferior older designs. The same applies for all Leica lenses: regardless of age, they still fetch a lot of money when resold.
Lenses don't cost anywhere near as much as they appear, because you get your money out of them when you're done. Buying a lens is like buying a house (holds its value), but buying a digital camera body is like buying fresh food (very perishable).
Even the most expensive Leica lenses usually don't cost as much as a digital body. M8? $6,000. Crazy Leica 90mm f/2 APO Aspherical? $3,500. Leica 21mm f/2.8 Aspherical? $4,300. You'll get far more life out of any of these lenses, and far more money out of them when you're done with them, than you will on any camera.
If you're only shopping for reasonable lenses, why would you cheap out to save $2,000 if you have no problems throwing $6,000 at an M8.2?
Sure, off-brand lenses will take swell photos. If you have no problem throwing away $6,000 for a few years of use of an M8.2, why on Earth would you humiliate yourself with cheap lenses just to save a fraction of that same $6,000?
This becomes even more egregious when you realize that your lenses are investments that will serve you well and hold or increase their value over the decades. You'll change cameras, but do yourself a favor and buy the lenses you really want. Whatever lenses you buy, you'll be using the same lenses for many years or decades as your cameras change.
If you want to save money, buy off-brand Leica M bodies, like the Zeiss Ikon, but don't cheap out on your lenses.
If a third-party offers a lens that you need and Leica doesn't make, like the tiny and excellent Voigtländer 21mm f/4 or Voigtländer 15mm f/4.5, go for it, but don't get fooled into thinking that a lower price today means a lower cost to own and enjoy.
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