I solved this problem for myself by NOT using words at all.
When I got my *istD, I used a Brother label maker to apply the 1.5
factor to all my 35mm lenses. So my 50mm lenses had a very small (2mm
x 15mm) label on them visible from the top that read D-75mm. All "crop
factors" and "multiplication factors" became no brainers when I looked
for a lens, as the "D" focal length was there for my brain to relate.
Yes, the camera "sees" the lens as a 50mm, but you and I knew it was a
75mm as far as our well trained brains thought the FOV was.
Works for me...
On Jan 16, 2009, at 07:24 , Luiz Felipe wrote:
Actually, when I started using different formats I used a numeric
relation. I started with 35mm, and had finished sorting out what use I
had for each lens, and all the sudden those beaultiful numbers stopped
making sense. Since they were numbers, its translation to their new
meaning was a... give the kid a hand of applause, a number! I wonder
if
I had scribed "wide" "normal" and "tele 1" and "tele 2" in red to 35mm
and blue to 120 format... Dad would have some harsh words to say.
Since I started pestering my father to teach me to photograph, lenses
come by numbers that don't describe their FOV. To understand their
meanings I have to take in context the film/ sensor size. Since I
can't
see photo industry all the sudden change their naming, I guess we're
about to continue calling lenses by its focal lenght - a number that
by
itself does not describe the field of view. And I fairly believe the
users switching formats will rely on a numeric relation to translate
their pet lenses to their new roles (this number to be named
henceforth
as "yellow aardvark").
Hate as I hate using words sometimes, I guess the idea of using a
number
to correlate the lens' focal lenght ( another number) to its role in a
new format will stick around. And Jaume, you're not alone - as soon
as I
started to look into APS sized pentaxes, I started looking for a new
wide angle. Guess what I did to translate their focal lenghts to my
35mm
perspective?? The right kid gets a cookie... The same number I used
when
I suddenly remembered my not-so-interesting 50mm would become a so-so
tele with a delightful aperture. Too bad that number is widely
referred
to as "crop factor". I guess "35mm-to-APS format conversion reference"
would be to long to type anyway.
Godfrey, I really am sorry to disagree with you - since I agree with
you
to some extent. Context - when it comes to lenses and quotes - makes a
lot of difference. Moving from the Hasselblad to the 35mm will not
transform the 150mm in a 275mm - but will change its role from a
"normal" lens to a "moderate tele". And the best way to grasp that new
role in a quick and dirty way will be multiplying the "reference focal
number for the format" (number, usually the focal lenght) by a
"groundhog rate" (yet another number, usually the ratio between
formats'
diagonal). Sadly this makes no allowance to the different proportions.
I am saying that to get the Hasselblad the "tele look" I get from my
100mm (in 35mm format) I'll need a lens longer than that, and I can
live
with the 150mm since it's available, and the almost enough wide 50mm
for
the hassel would make a better choice for the 6x7, and the 75mm (4.5x6
format normal) would behave as a lovely wide for the 4x5. That of
course
assuming their image circles would cover all the formats. After some
time, the numeric conversion stuff fades away - until the next format
change.
Luiz Felipe
Godfrey DiGiorgi escreveu:
On Jan 15, 2009, at 1:36 PM, Luiz Felipe wrote:
The problem here seems choice of words. You seem fed up with "crop
factor" but willing to apply "field of view equivalence" to
describe what happens when you change the size of the film or
sensor used to capture the image.
I only use equivalence terms when discussing the subject of crop
factor with users. I use neither of them when discussing lenses for
a particular camera system.
Call it aardvark or pink panther, there is a numeric relation that
will help me translate the lens to their new use. The same as my
120 and 4x5 experiences.
Do you call your 35mm camera lenses by a "crop factor" on your
medium format and large format camera lenses? "Well, the crop
factor for my Hasselblad 150mm lens makes it a 275mm lens for my
Pentax K1000."
Just nonsense. It's a 150mm lens, the focal length has a meaning
with respect to the FoV *in the context* of a particular format.
Period. If you need to equivalence those fields of view, call the
factor by which they difference an equivalence factor, not a crop.
Or just call it a telephoto lens for the 35mm camera and a portrait
lens for the Hasselblad.
Or simply state the FoVs: 150mm = 21/21/29 degrees horizontal/
vertical/diagonal on the Hasselblad, or 13/9/16 degrees for the
K1000. If that isn't informative enough, nothing is. It's a heck of
a lot more informative than a "crop factor".
Godfrey
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
to UNSUBSCRIBE from the PDML, please visit the link directly above
and follow the directions.
--
Luiz Felipe
luiz.felipe at techmit.com.br
http://techmit.com.br/luizfelipe/
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
to UNSUBSCRIBE from the PDML, please visit the link directly above
and follow the directions.
Joseph McAllister
[email protected]
“If I could tell the story in words, I wouldn’t need to lug a camera.”
–Lewis Hine
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
to UNSUBSCRIBE from the PDML, please visit the link directly above and follow
the directions.
