samuel green wrote:
Lenni Vilen wrote:
samuel green wrote:
Why are there no inexpensive prime telephoto lenses?
Relatively limited markert for such items - by far most consumers prefer a zoom to prime. Because of the low volume the production costs would go up limiting the number of potential customers even more.
That's circular. An f/6.3 500mm fixed can be simpler than a 150-500, so if they sold it for less, they might sell more, and get better economy of scale, allowing even lower prices.
It is only party circular. Even if such a prime available, it would not sell anywhere near the volumes of 150-500 even if it were a third cheaper. A good example is Canon's 200/2.8 prime - it's a bit cheaper and better performer than the 70-200/2.8 (and IS and 4IS versions), yet it's not exactly a great seller. Personally, if I were a Canon user and had a need for a 200, I'd buy it, but I rarely buy the lenses others do.
I use my 150 - 500 almost exclusively at 500 mm, and it's usually not close enough. Depends on the application of course, but if I carry something that heavy around, I'm gonna use the full zoom.
For you a prime would certainly be a better option, being lighter and better, and handling TCs better.
A sigma 150 - 500 (f 5) runs about $1000.
In the long end it is actually f/6.3 which is 2/3 stops slower than f/5 - this is quite significant for reasons of weight and cost. 2/3 stops may not sound like much, but if you start thiking on the physical size of the elements, it is very significant - you move from 79mm aperture to 100mm aperture - much much more glass needed.
So in order to keep the price down on the prime you'd have to keep it slow - the f/6.3 of the Sigma is already below the official limit of the auto-focus of typical consumer cameras of f/5.6 and hampers the AF performance.
Sure, but the zoom at 500 mm is exactly the same speed, but people buy it anyway. And the autofocus works fine at 500 mm.
The AF may work fine under many conditions, but it won't work as well when the conditions deteriorate, ie. it gets darker.
Also you'd have to do other compromises to keep the price down due to the low volumes - this would mean cheap optical solution - maybe 4 elements in two groups which would make foor a one long lens.
Again, that's a circular argument. Zooms are more popular because it's all anyone can afford right now at that focal length.
In the old theys there were practically no zooms and certainly no long zooms. Things have changed - vast majoriry of consumers prefer zooms to primes, regardless of the potential advantages of the latter. Only when speed is needed, primes tend to sell nowdays.
There is no reason to believe that somehow a
consumer prime just a bit cheaper than a zoom would sell enough to warrant making such a lens with quality. You'd buy one, if I were into birding, I'd buy one, but 90% of the consumers would ask if it zooms and when then buy something else.
A 500 mm same speed would be simpler to make, and should produce better results for the same cost, or cost less for the same performance.
If you want the same or better performance it no longer will be a simple lens to make and the manufacturing costs will be quite close to the zoom. And the sales volumes would be significantly smaller. While the Canon 200mm is not an ideal point of reference as it's a bit shorter it should still be considered as evidence. Personally I've never seen a 200/2.8 prime in the wild, but quite a few 70-200 zooms.
I suppose what you say must be true somehow, because no one makes inexpensive primes, but it still seems odd to me.
You'd still have to make the lens with significant number of large elements with good build quality. It would not be cheap to manafacture. Cheper than a zoom of the same top end, but not by awfully lot, if the sales volumes were similar.
The optical performance would likely be no better and maybe even worse then with the zoom, and the only real advantage would be lower weight.
Only if your economy of scale arguments hold. If there is an untapped market for less expensive long primes, then the performance would be better, and it'd be lighter and cheaper.
I wish there were such a market, but the very low end is catered by cheap and cheapish mirror lenses and the next level by the zooms which are quite decent performers nowdays. I don't see space for moderately priced slow primes there.
One would think there would be a market for a same speed 500 mm lens without zoom for a little less. But I have not seen a 500 mm prime lens at any speed by any manufacturer for less than $5k. Anyone know why that is?
If you want 500mm prime lenses for cheap, you can always try the mirror lenses. There's no aperture or AF and they're slow, small and light, but the price is low and some are quite decent performenrs. And all come with free donuts
Saw a couple on Amazon. DO you know any other places to get them?
Yes - eBay. There are Samyangs new ones (under several different brand names), both 500 and 800mm, and old Soviet made ones. And if quality if of essence, both the East and West German Zeiss 500 and 1000mm mirror lenses are excellet performers.
There are also plenty of 500mm or so conventional lenses out there, but in general those are to be avoided as they as typically modified telescopes with relatively poor performance.
