Posts Tagged lens

Review: Phoenix 500mm Catadioptric Lens

phoenix500 The Phoenix 500mmis a catadioptric lens. That means that it is very similar to a reflex, or mirror, telescope, and that it mixes mirror elements with refractive elements. The light comes in the front of the lens, goes right to the back of the lens, where it hits a large (full lens circumference) concave mirror, which then focuses all that light more tightly back in the direction it came. In the middle of the business end of the lens is another mirror, which then sends the light down the center of the lens back toward the camera, where standard refractive optical elements further magnify and focus the incoming light prior to hitting the film or sensor. A lens of this type is not only similar to a reflector telescope, it can actually perform as one, and you can find eyepiece attachments for just that purpose.

One of the significant benefits of a catadioptric lens is that you get less chromatic aberration, and so with subjects like the moon, which you expect to be grey, you actually get a grey image. With a standard refractor telephoto, you’re quite likely to get colored fringes on sharp bright/dark boundaries – this is an area where reflectors can and do excel, and this lens is no exception.
Read the rest of this entry »

Tags: , , , , , ,

Review: Canon EF 85mm f/1.8 USM Lens

c85mm

The Canon EF 85mm f/1.8 USM Medium Telephoto Lensis a moderate weight (15 oz), very well built lens. It does not come with the appropriate hood, the Canon ET-65 III. You get both a lens cap and a mount cap, all packed inside tight conformal foam to protect the lens during shipping. There’s also a very brief manual and the usual warranty paperwork.

The lens offers AF and manual focus, and allows manual focus even when AF is set to on, a very useful feature for low-light and other challenging focus situations. This is a USM lens, and as a direct consequence focus is fast and precise, just as you’d expect.

The AF/Manual switch is in a reasonable location, close to the camera body. There is a range indication on the barrel of the lens behind a transparent window which serves to keep dust and debris out of the workings of the lens. Manual focus is controlled with a broad, easy to manage textured ring about mid-body on the lens. During focus, nothing external on the lens body moves or rotates, so there are no complications for using polarizing filters, and no concerns about the lens “pumping” air and so causing dust contamination in either the lens or camera with use.
Read the rest of this entry »

Tags: , , , ,

Untangling FOV and "reach" for Canon Camera Bodies

A lot of people seem to be quite confused about the idea of camera “reach.” This idea relates to how much variance in magnification you actually get between different camera bodies. I thought I’d take a few minutes to clear this up once and for all. I assure you the following information explains the issue correctly. Once you’ve read and understood this post, you’ll have a perfect understanding of reach.

Read the rest of this entry »

Tags: , , , , , , , , , , , , , , , , , , , , ,