Patent: Canon EF 2.8x Teleconverter

dreamcat

428+2X畫質都下降左好多,
又唔Spport F8對焦..仲整個2.8X真係:L

唔通諗住出300mm F2.0 IS
http://www.canonrumors.com/2012/ ... 2-8x-teleconverter/

Patent Time
A patent showing a new teleconverter has made an appearance. It appears to be a 2.7 or 2.8x TC. What effect woud it have on aperture? A 400 f/2.8L IS II would become 1120mm at f/8. All well and good, but the missing f/8 autofocus on the 1D X makes this one a bit strange with the current line of camera bodies.

Patent Publication No. 2012-47869

    2012.3.8 Release Date
    2010.8.25 filing date

Example 1

    -83.98mm focal length
    Expansion rate β = 1.996
    Lens Construction 5 group nine

Example 3

    -41.91mm focal length
    Expansion rate β = 2.779
    Lens Construction 5 group nine

Canon’s patent

    Rear converter is to increase the focal length, F number, the residual aberration
    When doubled, twice the lateral aberration, longitudinal aberration is 4 times greater rate of expansion, because the F-number is also double, longitudinal aberration is twice per depth of focus
    Rear converter configuration consisting of three groups of positive and negative positive
    Reduce the aberration of the rear converter itself

d.kuyt

同意2x quality 都唔係好得...仲2.8X ?

另外F8 D新機唔support, 就算support 都應該又慢又唔準 la :L :L

rilarilakkuma

原帖由 dreamcat 於 2012-3-27 09:32 PM 發表
428+2X畫質都下降左好多,
又唔Spport F8對焦..仲整個2.8X真係:L

唔通諗住出300mm F2.0 IS
http://www.canonrumors.com/2012/ ... 2-8x-teleconverter/

Patent Time
A paten ...

好可能1Dx最終都support f8 AF呢！

Loka

Special made for 200 2.0L

hypothalamus

插F1.2 L鏡

AY2007

唔駛, 插f2.8 都係變 7.8. 可能仲有af.