Archived posting to the Leica Users Group, 2008/03/04

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Subject: [Leica] Narrow DoF on the Leica E-3
From: philippe.amard at tele2.fr (Philippe AMARD)
Date: Tue Mar 4 13:30:43 2008
References: <200803041501.m24EtxJT018223@server1.waverley.reid.org> <Pine.LNX.4.62.0803041225340.17368@mail.2alpha.com>

Peter, I like your idea of experimentingon this - just one remark ; from 
1.4 to 2 you do get "about 1/3 more light"  (well a little over, but not 
much more) or am I mistaken?

Remember also that the precise focal length may vary - a well known fact 
for Leica users, I know - but it may also affect other brands, and 
consequently the ratio Focal length / aperturediameter also varies.
Some brands (Pentax for instance)  had a 1.8 55 and a 1.4 50 , where's 
the trick? What amount of light actually gets through?

I never noticed anything about closing down, so I'll be trying too with 
other gear, but the phenomenon should be make independent I guess, 
thanks for the insight

phx


Peter Klein wrote:

> Richard:  Would you do me a favor?  Meter something once at a medium 
> aperture. Then take a series of equivalent manual exposures. Such as:
>
> 1/30, f/4
> 1/60, f/2.8
> 1/125,f/2
> 1/250,f/1.4
>
> Are resulting images the same exposure, or is f/1.4 much darker? If 
> you're game, try the whole range of f-stops. Do things get out of 
> whack again at f/11 or f/16?
>
> I noticed that with my E-1 and a Zuiko 50/1.4, I got only about 1/3 
> stop more light going from f/2 to f/1.4.  So the 50/1.4 was really 
> only a 50/1.8 for practical purposes. This might have something to do 
> with the angle the light hits the sensor wells, and something gets cut 
> off faster than about f/2.
>
> There were actually two factors. Not only did the sensor respond 
> differently at extreme apertures, but metering was also off at both 
> large and small stops. So the effects of the two factors combined, 
> making things very confusing until I separted them.
>
> The result was the the OM lenses couldn't be relied upon without 
> knowing a compensation factor for wide open and closed down. All this 
> behavior has been reported by others (with the usual Internet 
> flamefests over the cause, and whether the reporter knows how to use 
> his camera).
>
> I wonder if the E-3 is the same, or if it's more forgiving with OM 
> lenses.
>
> That said, if you have a OM Zuiko macro lens, try it with the E-3 and 
> you might just marvel at the image quality.  My 50/3.5 OM Macro gave 
> me image quality on the E-1 like no other lens I tried. And the 
> 100/2.8 makes a nifty 200mm-equivalent telephoto.
>
> --Peter
>
>> Who says it can't be done?
>> http://www.dragonsgate.net/pub/richard/PICS/_3031364.jpg
>> http://www.dragonsgate.net/pub/richard/PICS/_3031365.jpg
>> http://www.dragonsgate.net/pub/richard/PICS/_3031366.jpg
>>
>> The trusty 50/1.4 Zuiko at 1.4. The E-3 VF is definitely as good if
>> not better than the OM-4 when it comes to manual focusing.
>
>
>
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>

Replies: Reply from leica at screengang.com (Didier Ludwig) ([Leica] Narrow DoF on the Leica E-3)
In reply to: Message from pklein at 2alpha.net (Peter Klein) ([Leica] Narrow DoF on the Leica E-3)