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Is it time to send the rest of my lenses for conversion

 
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jnswickard



Joined: 22 May 2007
Posts: 47
Location: Dana Point

PostPosted: Tue Nov 25, 2008 10:55 pm    Post subject: Is it time to send the rest of my lenses for conversion Reply with quote

Bo-ming,
Having converted all the lenses available for conversion is it now time to send my 28-80mm Vario-Sonnar, 70-200mmVario-Sonnar, and 50mm Planar? Cool
Please advise.
Thanks,
Jack
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Dec 01, 2008 8:01 pm    Post subject: Reply with quote

We are almost there... Our supplier says the initial samples are promising and it looks like the next batch of mounts will be okay.

However, I will be on vacation in mid-December. If you start sending in your lenses on or after 12/15, I will come back just in time (on 12/20) to pick them up and work on them during Christmas time.

We have significant backlog right now and pardon me if I become unresponsive at times. I will however try my best to finish all the work before I leave on 12/8.

Thank you!

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I am a bird and I uncovered the E, EF and N-mount communication protocols!
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frank



Joined: 05 Feb 2008
Posts: 17
Location: Boston, USA

PostPosted: Thu Dec 04, 2008 7:16 pm    Post subject: Reply with quote

Bo-Ming,

If you have success with 70-200mm, would you please tell us whether the max f stops keep the same, which is still 3.5-4.5?

Thanks,
Frank
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Fri Dec 05, 2008 10:30 am    Post subject: Reply with quote

Hi Frank,

The display, if your camera is configured to display aperture in 1/3 stop steps, is as follows:

focal lengthdisplayed aperture
70-80f/3.5
80-130f/4
130-190f/4.5
200f/5.0


Please rest assured that this is just the display. Wide open is wide open regardless of what the display says.

The lens is exactly halfway between f/4 and f/5.6 at 200mm.

Your camera can be configured to either display 1/2 stop aperture or 1/3 stop aperture. Not a problem if configured to display 1/2 stop, but should we round up or round down if configured to display 1/3 stop? It just so happens that Canon has decided to round down to the nearest slower 1/3 stop in this scenario.

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I am a bird and I uncovered the E, EF and N-mount communication protocols!


Last edited by conurus on Fri Dec 05, 2008 6:00 pm; edited 1 time in total
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frank



Joined: 05 Feb 2008
Posts: 17
Location: Boston, USA

PostPosted: Fri Dec 05, 2008 2:58 pm    Post subject: Max f stop change Reply with quote

Thanks Bo-Ming. This solved my long term confusion. I thought that the actual lens opening were 5.0 instead of 4.5 made from the lens manufacture.

Thanks again.
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sun Dec 07, 2008 12:11 am    Post subject: Reply with quote

Responding to customer demand we modified the display as follows


focal lengthdisplayed aperture
70-90f/3.5
95-160f/4
160-200f/4.5


Again this change only affects the display. The actual maximum aperture of the lens is determined by the optics, not by the electronics.

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jnswickard



Joined: 22 May 2007
Posts: 47
Location: Dana Point

PostPosted: Sun Dec 07, 2008 5:12 pm    Post subject: Reply with quote

Do I presume that regardless of display that exposure is still correct?
Jack
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Dec 08, 2008 9:23 am    Post subject: Reply with quote

I don't think one eighth of an f-stop is going to make much of a difference. However if you transfer a reading from a handheld light meter to the camera, setting the camera to f/5.6 for example will in reality set the aperture to f/5.8.

At 200mm the lens is exactly halfway between f/4 and f/5.6 so to stop down to f/5.6 you stop down half a stop.

However if we fake the display by adding one eighth of an f-stop to the maximum aperture, f/4.5 is now displayed but to stop down to f/5.6 we will be stopping down five-eighths (5/8) of an f-stop.

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