Talk:Four Thirds System
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[edit] Why it's not an "Open Standard"
Quoting the footnote at the bottom of http://www.four-thirds.org/en/about/benefit.html (as of 13:36 30 Jan 2008 UTC)
* Details of the Four Thirds System standard are available to camera equipment manufacturers and industry organizations on an NDA basis. Full specifications cannot be provided to individuals or other educational/research entities.
[edit] Name explanation
Can anyone explain the connection between the name "four-thirds" and the size of the sensor? The article presently contains the text
The name of the system comes from the size of the imaging sensor. The sensor used is a "4/3 inch" type sensor. The length is based on the diameter of particular size of Vidicon tube—the actual light sensitive area being smaller. The actual length of the sensor diagonal is 22.5mm.
So more specifically, my questions are: In what way does the name come from the size? In what way is the length based on the diameter of some Vidicon tube? Note that 4/3 inch = 33.9 mm, which is much bigger (50% bigger) than 22.5 mm. That is, the sensor is nowhere near 4/3 inch in diagonal. Fg2 04:56, August 11, 2005 (UTC)
- Indeed it's not the physical dimension of the sensor. There's a good explanation of the confusing fractional definitions camera manufacturers use here: http://www.dpreview.com/learn/?/Glossary/Camera_System/Sensor_Sizes_01.htm. 203.132.65.32 08:45, 23 December 2005 (UTC)
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- Thank you. I've wondered about that for a long time. Fg2 11:30, 23 December 2005 (UTC)
[edit] Image proportions:
I have asked this question on Olympus press meeting, and after few days, I have received e-mail from their technical division:
question: If the image circle is a part of a standard, does it mean that the sensor does not need to have 4:3 proportion? Can there be a camera constructed, by a manufacturer, meeting the 4:3 standard and have the square (1:1) image sensor put inside the same image circle?
Answer: yes just the circle is defined that the ratio of the sensor can also be different from 4/3, but 4/3 was determind as perfect measure.
—Preceding unsigned comment added by 217.113.234.202 (talk • contribs) 17 March 2006
[edit] Lens/body communication?
What data is communicated between lens and body?
Specifically, does the lens communicate the subject distance to the body, and can the body instruct the lens to focus at a specific distance? Abu ari 09:04, 2 April 2007 (UTC)
- Using the E400, I am yet to find such features, I am sure there are no such features.
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- I think the answer is "no" to both questions. But this is not the place to post questions like this, this page is for talking about the Wikipedia article itself. Try posting your question on a digital photography forum, for example: http://forums.dpreview.com/forums/forum.asp?forum=1022
- --RenniePet (talk) 23:52, 24 November 2007 (UTC)
[edit] Image sensor format
have removed this link - the four thirds system covers aspects in addition to just the sensor format - its more about the imaging circle and the lens mount than the sensor size.
For the record, I don't think the separate page is warranted - but that's probably a discussion left until after the issue of whether to delete the "full frame" page is decided. --Hmette 06:56, 7 April 2007 (UTC)
- Agree that the standard covers aspects in addition to just the sensor format... but it does cover the sensor format, not just the imaging circle. So why you'd remove the link escapes me. Expand the description by all means but don't remove useful content is my advice. Andrewa 09:55, 7 April 2007 (UTC)
[edit] Open Standard?
"Four Thirds is not an open standard, however, as it does not meet the "allowing anyone to use" criterion commonly accepted as the definition of an open standard." This sounds like point of view as there's no citation. On wikipedia's own Open Standard page it appears that the term itself has a broad array of interpretations and there is no clear definition of the term at all. I recommend removing this line or citing a source which shares the author's criticism as a way to highlight criticism of the standard's closed nature.
[edit] 300 = 600?
The explanation that a 300 mm lens has the same angle as a conventional 600 mm lens was bogus. The difference in angle is a direct result of the ratio of sensor size on many Olympus SLRs to a standard 35 mm frame. I suspect, but don't know, that telecentricity might make for a shorter 300 mm lens, but that doesn't change its focal length.
Groogle 23:20, 3 December 2007 (UTC)
- I've tried to restore the comparison in a more correct way. Let's talk about it here if you think I'm wrong. Thanks. --RenniePet 16:10, 4 December 2007 (UTC)
[edit] Sensor size comparison
The article says "Its area is ... around 15× larger than the 1/2.5" sensors typically used in compact digital cameras". Looking at the diagram, the area of the Four Thirds sensor is 225 mm², and the area of a 1/2.5" sensor is 25 mm². So shouldn't it say "9x larger"? Matthewk (talk) 17:01, 23 December 2007 (UTC)
[edit] Smaller sensor = more noise
I'm a fan of the Four Thirds System, but in the interests of honesty I think the statement about noise problems should say that it begins to be relevant from above ISO 400. It previously said "ISO 400 and up". Another editor changed that to "ISO 1600 and up". Wish that was true. Anyway, I've now changed it to "above 400", and added a link to a brand-new review of the Olympus E-3 in DPReview, where it says, for that model at least, "Noisier results than most competitors above ISO 400 (usable up to ISO 1600)". --RenniePet (talk) 00:24, 23 February 2008 (UTC)
