Originally posted by reeftool I see these kind of immediate responses whenever a question about these lenses comes up. Just being cheap doesn't necessarily mean it will have poor IQ that can't have passable results.
I think high resolution digital cameras and the pixel peeping we're accustomed to performing now have made it much harder for people to put lenses like this into any sort of proper perspective. Sure, viewing a picture from a "refracting telescope" type lens or a typical mirror lens at 100% will show it isn't nearly as good as we're accustomed to from shorter conventional lenses, or even longer conventional lenses if we're lucky enough to be able to afford them and strong enough to carry them. Still, for a basic full screen view or 4x6 print, quality can be more than adequate. Depends on how demanding you plan to be.
For me, wildlife photography is nothing more than a very casual pursuit - "ooh, what a pretty bird, I think I'll take a picture so I can look at it again". And for that, performing a little better than a crop from a shorter lens is really all I need. On the other hand, it's also for that reason that I ended up deciding on a mirror lens instead - same "passable for my purposes" quality, but a much smaller size more suited to someone who really can't see himself carrying around a lens as long as my arm in hopes of getting bird photos. If I were that serious I'd probably suck it up and get a 400/5.6 true telephoto (which would be smaller but much heavier and rather more expensive, if not completely unreasonably so). But even though I prefer mirror lenses overall, the "refracting telescope" style has advantages over a mirror that might be important to some - better bokeh, better contrast, brighter for the stated aperture (allowing somewhat faster shutter speeds for a given ISO).
The lens I chose may be unacceptable for others with different requirements, but just as surely, the lens someone else chooses might be unacceptable to me with my requirements. Which is why I think important for any review to try to be objective about the actual tradeoffs involved, rather than simply jumping to the conclusion that happens to make the most sense to the reviewer.
Quote: Marc, thanks for posting your shots.
You're welcome. Wish I had some others to show, but that's all I kept from the 15 minutes I played with the lens in the store parking lot.
BTW, a couple of things I should have been explicit about when posting that image.
First, it was taken handheld, albeit lying down with my arms propped on the ground if I recall correctly. Shutter speed was 1/750, so I figure I got a reasonable chance of decent sharpness, but no doubt the lens would be capable of a little better.
Second, DOF is incredibly shallow at that focal length and that focus distance, so if you were looking at anything more than the one leaf that was in focus and trying to judge sharpness that way, you were looking in the wrong spot. In the 100% crop, it's the leaf just the left of and slightly below center. That's really not bad for a 100% crop from a 600mm that barely costs $100. The more prominent leaves to the right are an inch or two closer closer and are are outside the focus zone (they are also starting to evidence of the CA that was more glaringly obvious in higher contrast situations). On the other hand, in the resized full images, even the slightly OOF leaves appear to rendered well enough for my limited purposes.