Alley in Pisa, Italy

by Lars Kotthoff

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Tag Info

Hot answers tagged

23

There are several related questions here. Are mirror lenses good at all (opinion) Are mirror lenses good for wldlife shots in daylight. Are cheap mirror lenses value for money. Relevant: I own a Minolta 500mm AF f8 "Reflex" lens- the only model of AF "mirror" lens ever made AFAIK and one of the better quality ones around. I think that as long as you ...


14

The loss of contrast is due to the central obstruction; that is, the "hole of the donut" that blocks light from getting through the center of the lens. In a diffraction-limited telescope or lens, the point spread function—basically an image of a point source, like a star—is the Fourier transform of the aperture. For a circular aperture, like ...


13

There are mirrors available for most SLR cameras, but their limitations make them fairly special purpose instruments. Most use catadioptric mirrors, which have a central obstruction that limits the minimum focal length that can be used -- it would be very difficult to keep the central obstruction small enough for the focal lengths most photographers use ...


6

A slower aperture means you need to take a longer exposure to get the same brightness as a faster aperture with a shorter exposure. As long as you have an equatorial mount with smooth, accurate tracking, this shouldn't cause problems. The atmospheric seeing is also an issue for ground based telescopes, and with long exposures it causes rings to appear ...


6

Cost and ease of design. The main purpose of mirror telephoto lenses is to make them much more cheaply and compact than a conventional refractive lens can be produced. This is easiest to accomplish by coating the back side of a negative meniscus lens (known as a Mangin mirror) instead of creating a parabolic first surface mirror that would need to be shaped ...


5

What I Would Make You know what you want. A bar that has a slide mount tripod plate on one side, and two screw mounts on the other, one of which is adjustable height. Sounds like a chunk of t-slot bar would be ideal. To make the vertical risers two angle brackets and a chunk of the t-slot can be used. This plan will require a drill and a hack saw. When ...


4

There are some mirror based lenses, such as Nikkor 500 f/8 mirror. You can see it here: http://www.kenrockwell.com/nikon/5008.htm. It does confirm what Jerry wrote, that all mirror lenses are fixed aperture and with high focal length.


4

For the price some of them aren't bad. You can get good reach at a cheap price. However, they have many disadvantages The out of focus background will be poor. Horrible donut-shaped bokeh Many of these lenses have poor contrast and color Fixed aperture, so can't control depth of field You will find good images online taken with these, but I think ...


1

What you need is a modular "rail system" commonly used in videography for mounting the camera body, matte box etc to a common pair of rails, than that rail rig to a tripod (and/or hand/shoulder grips) You will need to buy various bits and create your own setup depending on your levels/needs etc, see (for example) ...


1

Here's an example of mirror bokeh that I think works. This image was contrast-enhanced in Photoshop -- you'll never get this much contrast out of a mirror lens! (This is a scan of 35mm film.)


1

Something not mentioned so far: vignetting. I'll go out on a limb and say all mirrors exhibit a certain amount of vignetting -- certainly more than a comparable refracting lens. This might be a problem, or it might not. Shooting a bird or a plane in the sky makes it quite noticeable; shooting a bird in a bush, not so much. Beyond that, I'll say the bokeh ...


1

I have an old Nikkor 500mm F8 mirror lens, and I've loved it for 30 years. Yes, its a fixed F8. Its fine for sports and I would expect long distance wildlife. Its light and easy to hand hold, but you have to be shooting at 1/250 or faster. I find the color and contrast to be more than acceptable. I use it on my Canon 50D, the Canon doesn't seem to notice ...


1

Advantages of mirror: lower weight and shorter length Disadvantages: horrible bokeh and (much) greater diameter (think filters!) Only useful (and available?) for long focal distances (400mm and up)



Only top voted, non community-wiki answers of a minimum length are eligible