Re: telephoto lens


DBLEXPOSURE wrote:
> Well, you can get to 1200mm with a Canon 600mm f/4 IS USM and a 2X. Get a
> large megapixle camera so you can crop in another 2x and maybe still read
> the numbers. This is gonna cost ya though.
>
> 1/4 mile aint that far but 5 inch letters and a moving target at that
> distance makes me think that any motion blur or focus issues are gonna
> jeopardize the legibility of the numbers.
>
> EOS-1Ds Mark II Camera would give you 16.7Mega Pixels to work with plus a
> 1.3X conversion factor on the lens gets you to 1500mm with a 2x crop in
> Photoshop and you equivalent to 3000mm.
>
> You would have a great setup for birding or sports photography..
>
> This is not the cheap rout and there may be a better way.
>
> I will yield the floor to other opinions
>

1200mm seems like more then what is needed, that would yeild a image of
close to .4mm in the image plan. Assuming a crop factor of 1.6 this
would be about
1.7% of the frame, for a 3000 pixel wide image that is a letter that is
51 pixels high.

It only take about 10 pixel high letter to be very readable.

Scott
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> "DBLEXPOSURE" <celstuff@xxxxxxxxxxx> wrote in message
> news:5tCdnVUT6tBiEP_eRVn-qw@xxxxxxxxxxxx
> >
> > "TerryD" <TerryD@xxxxxxxxxxxxxxx> wrote in message
> > news:11m51vcm35jbb68@xxxxxxxxxxxxxxxxxxxxx
> >> Hi All,
> >>
> >> I need to be able to read aircraft registration numbers from one quarter
> >> mile away. These numbers are about 5" or so tall. What size telephoto
> >> lens will do this?
> >>
> >> What brand of lenses represents the best value (performance/price) today?
> >> Thx.
> >>
> >>
> >> Terry
> >>
> >>
> >>
> >
> > To what are you going to attach this lens?
> >
> > Do you care about quality of the image or do you just want to read the
> > numbers.
> >
> > Are the aircraft moving or sitting still?
> >
> > What are the lighting conditions?
> >
> > And for what purpose? (Curios to know what you are up to)
> >
> > A large prime tele with IS (Image stabilization) is gonna set you back
> > allot of $$
> >
> > Cheap long teles are available but offer very little in the way of quality
> > images.
> >

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