[Leica] math challenged

[mark at rabinergroup.com (Mark Rabiner)]

> "Yes, but the wides are the normals for the 1.3x crop, so you want the 
> wider
> VF."
> 
> 
> 
> Whoa, you lost me.
> 
> If a 50mm lens taking in a 40 degree wide field of view is considered 
> 'normal'
> (Mark, forgive me) in 35mm photography,
> then with a 1.3 crop factor, isn't a 35 going to take in approximately the
> same 40 degree field of view?
> 
> 40 degrees is 40 degrees, regardless of the focal length of the lens that 
> is
> projecting that slice of space, and you adjust the VF magnification to 
> suit,
> which means going with a narrower (than 0.71) VF doesn't it? Don't the 35's
> 'normal' framelines (40 degrees) float well in from the edges of the M8's 
> 0.68
> VF? The M3's 0.91 VF has 40 degree wide framelines that pretty much fill 
> the
> window. 
> 
> I went to the Leica site looking to see if they had a series of frameline
> views for the M8 like they have for the ala carte options for the MP/M7 but
> couldn't find anything.
> 
> 
> 
> 
> ----- Original Message ----
> From: Richard Man <richard.lists at gmail.com>
> To: Leica Users Group <lug at leica-users.org>
> Sent: Saturday, September 5, 2009 2:44:36 PM
> Subject: Re: [Leica] math challenged
> 
> Yes, but the wides are the normals for the 1.3x crop, so you want the wider
> VF.
> 
> It really only matters regarding focusing accuracy, and with the 1.3x
> crop, you get more DoF on the same aperture, so the lower mag factor
> is canceled out. Certainly you see people shooting F1 all day long on
> the M8 with spot on focus so the RF/VF is not an issue in that regard.
> 
> On Sat, Sep 5, 2009 at 12:22 PM, H. Ball Arche<h_arche at yahoo.com> wrote:
>> OK, so I just learned that the M8's have a 0.68 VF. My question is, what 
>> does
>> that translate into, relative to the crop factor of that sensor?  In other
>> words, is it like what an approximately 0.45 VF would show you on a FF
>> camera?
>> 
>> Since 0.72 has been the 'standard' VF since the M2, I'd have figured that 
>> in
>> the M8 they would want to reproduce the same relative field of view, lens 
>> for
>> lens, narrowing it appropriately.
>> 
>> If I'd've bothered to wonder about it I would have figured the M8 VF to be
>> 0.86, or 0.91 like the M3 - something narrower than 0.72.
>> 
>> The 0.68 field of view VF in the M8 must REALLY favor the wides, taking 
>> in a
>> much broader field of view than would the 0.58 VF with the same lens on a
>> full frame camera.
>> 
35 * 1.33 = 46.55
So you get a lens which in regular 35mm 24x36 photography has a field of
view a 46.55mm lens would have.
As "true" normal is 43.3 you're doing ok.
The "normal" angle would be the angle you get from the 43.3 lens.
Which is the angle you get with most normals on most formats.
Like an 80mm lens with 6x6cm format.
 


Mark William Rabiner