18

It's important to realize that you don't actually look directly through the lens with an SLR! If you did, a periscope style arrangement would do just fine. What you are actually doing is looking at an image projected onto the focussing screen by the lens. This image is flipped left/right and up/down by the lens, and then up/down again by the main mirror. ...


16

It's important to understand that the image through the lens is inverted in both the lateral (x ↔︎ -x) and vertical (y ↔︎ -y) dimensions. Mathematically, this is the same as a 180° rotation about the z-axis (optical axis). Thus, the upright image entering the lens, after being refracted and focused, leaves the lens flipped both vertically and horizontally. ...


6

Based on an update in the comments it looks like you're trying to build some kind of stereoscopic mount or device to capture two images in one exposure. A prism offers better light transmission. Mirrors are significantly lighter. Mirrors offer some ability to modify their geometry. Mirrors are significantly cheaper to produce. Which is right for you ...


3

Absolutely, yes. But possibly not in the way you're thinking. The obvious disadvantage is the challenge of getting sharply focuses images while focusing manually. I have great vision, but I still struggle to focus sharply. You can change the type of focus screen with some dSLR models and that can add some focus aids like split-circles and prism collars; ...


3

A larger viewfinder might help slightly, but probably not as much as you hope. You probably won't notice any difference in focusing ability between a pentamirror and pentaprism. The best way to increase your manual focusing ability is to replace your camera's focusing screen with one that has split prism and microprism focusing aids, just like the ones you ...


2

Prisms have fewer air-to-glass transitions than a series of mirrors, and therefore better image quality. This is why SLRs and DSLRs with pentaprism viewfinders are usually preferred over pentamirror finders — although the latter are lighter and cheaper, both of which can also be significant advantages.


1

The 7D viewfinder is significantly larger and brighter than the T3's. The T3 has 0.8X magnification of 95% of an APS-C sensor. The 7D has 1.0X magnification of 100% of the same sized sensor. That's about 16.95x11.3 mm for the T3 compared to 22.3x14.9 mm for the 7D. That's a 4:3 ratio in size! The 7D's pentaprism is also noticeably brighter than the ...


1

Seems like an arduous project: The viewing screen of the SLR is ground glass. This is liken to etched glass (roughened surface). Its job is to provide a toothed translucent surface that captures the aerial image produced by the camera lens. The mirror is just a device to bend the image forming rays upward so they are square with the viewing screen. The ...


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