p.3 #1 · 70-200f4L, is IS worth an additional $ 500.00?
Monito wrote:
This is what Jim Colwell means by "do the math".
That's right Alan.
Although, it doesn't cover the near/far angular velocity thing. Actually, it's more like angular displacement over time, but nobody seems to care about the math. Just wait 'till we get into the physics...
P.S. Tim, this 'extra' stuff discussion must cover at least the added cost for IS. Have you thought about Extenders...?
p.3 #2 · 70-200f4L, is IS worth an additional $ 500.00?
jcolwell wrote:
Although, it doesn't cover the near/far angular velocity thing. Actually, it's more like angular displacement over time, but who's doing the math...
Yes. As you know, near or far doesn't matter since the angular velocity on the sensor is the same and the net result is an effectively linear smear which can be usefully analyzed as a blur disk (circle of confusion) with the same parameters that affect depth of field (print size, degree of enlargement, visual acuity, viewing distance).
jcolwell wrote:
Just wait 'till we get into the physics...
p.3 #3 · 70-200f4L, is IS worth an additional $ 500.00?
Monito wrote:
Yes. As you know, near or far doesn't matter since the angular velocity on the sensor is the same and the net result is an effectively linear smear which can be usefully analyzed as a blur disk (circle of confusion) with the same parameters that affect depth of field (print size, degree of enlargement, visual acuity, viewing distance).
Yes, but it does matter for the "shooting bunnies" from a moving train scenario - what a despicable thing to do.
p.3 #6 · 70-200f4L, is IS worth an additional $ 500.00?
rabbitmountain wrote:
Dan, I don't understand your reply. You basically repeated what I wrote in other words. Did you read my entire post at all?
You were absolutely correct on the concept relating crop factor to shutter speed, I just wanted to reiterate that there is nothing sacred about the "rule of thumb" suggesting that 1/focal length.
p.3 #11 · 70-200f4L, is IS worth an additional $ 500.00?
jcolwell wrote:
That's right Alan.
Although, it doesn't cover the near/far angular velocity thing. Actually, it's more like angular displacement over time, but nobody seems to care about the math. Just wait 'till we get into the physics...
P.S. Tim, this 'extra' stuff discussion must cover at least the added cost for IS. Have you thought about Extenders...?
Dear jcolwell,
No I hadn't thought about extenders but I do own a calculator just in case my mental math skills can't keep up with FL x 1.6 x 1.4, or x 2.
I'm just a guy that would like to get a lens that lets me take the mental image I witnessed home with me on a data card for later review and possible sharing with friends and relatives.
I've pretty much decided based on what I read here that IS will have a real value to me as much of the time I will be using the lens will be on the early or later ends of the day and getting all the potentially available light gathered might need some assistance?
I've also decided that I will probably purchase a used lens. My girlfriend's impending car trouble has convinced me that my tax refund might not be as generous as I previously assumed?
p.3 #12 · 70-200f4L, is IS worth an additional $ 500.00?
Havnt read the thread but my thoughts...
Canon 20d is only 8mp so 1/focal length should be fine for shutter speeds.
Its also poor at high ISO, 800 is about all I would push it too.
If you shoot in Good light then the f4 non IS will be fine
If you shoot in anything less and the subject doesnt move get the IS version
If the subject moves get a 2.8 or IMO a modern body which will give you 3 stops of 'light' via ISO.
p.3 #15 · 70-200f4L, is IS worth an additional $ 500.00?
RobDickinson wrote:
No need to get embarrassed Monito!
Not me. Too late for you. Your mention of the pixel density of the 20D has been debunked already, as has the usefulness of the 1/focal-length guideline, which is almost useless.
p.3 #18 · 70-200f4L, is IS worth an additional $ 500.00?
RobDickinson wrote:
Only speaking from experience not math....
Getting the math right implies that you have the physics (chemistry and/or biography) right. It also implies that you understand what's really going on - optically speaking. Physcology isn't well-described by the 'physical sciences'. OTOH, physcology is what makes us what we are; subject to the physics, of course.
p.3 #19 · 70-200f4L, is IS worth an additional $ 500.00?
RobDickinson wrote:
Only speaking from experience not math....
Spare us. Read the thread.
The math trumps experience since it is clear, but the factors that can be plugged in vary. One person's experience with regard to camera shake and the print size they print at and the way their prints are viewed have little meaning without understanding the math involved because other people print other sizes for other purposes. Finally, much depends on an individual's motor neurons and physiology and caffeine.
Spare yourself any further embarrassment and read the thread.
p.3 #20 · 70-200f4L, is IS worth an additional $ 500.00?
jcolwell wrote:
Getting the math right implies that you have the physics (chemistry and/or biography) right. It also implies that you understand what's really going on - optically speaking. Physcology isn't well-described by the 'physical sciences'. OTOH, physcology is what makes us what we are; subject to the physics, of course.
I'm all for science but the 1/focal length rule has always been a rule of thumb subject to many variances and a staring point rather than and end point.
