Timeline for How are the red focus point indicators displayed on a DSLR's focusing screen?
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| Feb 15, 2019 at 20:13 | history | edited | mattdm | CC BY-SA 4.0 |
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| Apr 13, 2017 at 12:43 | history | edited | CommunityBot |
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| Apr 25, 2014 at 2:33 | history | edited | mattdm |
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| May 23, 2011 at 18:45 | history | edited | mattdm |
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| May 23, 2011 at 18:03 | vote | accept | mattdm | ||
| May 23, 2011 at 7:04 | answer | added | Leorex | timeline score: 24 | |
| May 20, 2011 at 11:22 | history | edited | mattdm | CC BY-SA 3.0 |
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| May 20, 2011 at 3:11 | comment | added | Evan Krall | Also, the X100's hybrid viewfinder uses a beam splitter and a backlit LCD off to the side. | |
| May 20, 2011 at 3:08 | comment | added | Evan Krall | The D3100 uses a different system than the D3000 or D7000 (and other Nikons, I assume). Instead of the brackets or squares, it actually has LEDs that light up. | |
| May 19, 2011 at 17:43 | answer | added | Jerry Coffin | timeline score: 4 | |
| May 19, 2011 at 16:11 | comment | added | Jerry Coffin | @ysap: right -- I wasn't trying to say they need to be huge, just that there are reasons they are (and probably just about need to be) larger than most typical transistors. Most of the materials that produce other colors are at least as difficult to produce in fine feature sizes. Fabrication is hard enough that most LEDs are produced on 3 inch wafers where most CMOS is now done in 300 mm (12 inch) wafers (and though it's not used for production yet, they're working on 450mm/18in wafer fabrication). | |
| May 19, 2011 at 14:50 | history | tweeted | twitter.com/#!/StackPhotos/status/71226290576953344 | ||
| May 19, 2011 at 14:39 | comment | added | ysap | @JerryCoffin - Thanks. I don't expect the power of miniaturized LEDs to be like this of a regular one. Then, if the problem is the material, then make it in another color. I understand, form what you comment, that it is currently impossible to fab GaAlAs diode in 45nm process, but for this application you don't really need such miniaturization. Nor do you need a great power, given the proximity to the sensor (eye). | |
| May 19, 2011 at 14:35 | comment | added | Jerry Coffin | @ysap: There are a couple of reasons. First of all, a red LED will normally be gallium aluminium arsenide. At least TTBOMK, nobody knows how to fab it at nearly as fine if feature sizes as typical silicon CMOS processes do. Second, a smaller feature size means lower power dissipation capability (and therefore lower brightness). A typical LED produces 8-9 lumens/watt. The new higher-power LEDs are quite a bit different, but probably not applicable here. | |
| May 19, 2011 at 14:07 | answer | added | sastanin | timeline score: 13 | |
| May 19, 2011 at 14:03 | comment | added | ElendilTheTall | @ysap: Interesting. @MattDM: The black brackets in my Nikon D5000 viewfinder certainly look like liquid crystal 'images'. | |
| May 19, 2011 at 13:53 | comment | added | ysap | @ElendilTheTall - LEDs are P-N junctions like any other diode, or transistor to that matter. As such I don't see why you can't nake them as tiny as a lithographed transistor. | |
| May 19, 2011 at 13:44 | history | edited | mattdm | CC BY-SA 3.0 |
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| May 19, 2011 at 13:27 | comment | added | ElendilTheTall | Just FYI, Nikon DSLRs don't use the red light system - a black bracket appears around the selected focus point. I don't think they can make LEDs small enough to have them actually fixed to the focus screen, I would imagine they are reflected onto it. | |
| May 19, 2011 at 12:59 | history | asked | mattdm | CC BY-SA 3.0 |