Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Dec 27, 2003, 3:04 AM   #11
Junior Member
 
Join Date: Dec 2003
Posts: 25
Default chart

Thanks NHL for the help

Do you know where I can find a hyperfocal focus chart for free for the d-rebel? I downloaded the Dofmaster program but the apertuares settings weren't all there and some where off for the d-rebel.

Tanks
recca is offline   Reply With Quote
Old Dec 27, 2003, 8:16 AM   #12
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

FYI

http://www.johnhendry.com/gadget/hf.php
http://www.photofocus.com/zine7/hyperfocal.html

... Have fun! :lol:
NHL is offline   Reply With Quote
Old Dec 27, 2003, 3:16 PM   #13
Junior Member
 
Join Date: Dec 2003
Posts: 25
Default one more thing

When using the charts for hyperfocal distance should I be using 18mm or 28mm as my lens length? I mean there is a 1.6 mutiplier on the D-rebel. WHich is the correct number to use?

Thanks
recca is offline   Reply With Quote
Old Dec 28, 2003, 12:56 AM   #14
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

18mm, the true focal lenght!

The 1.6x come as the result of the crop (similar to the effect of a digital zoom), but it's not a real focal lenght multiplier like a teleconverter...
NHL is offline   Reply With Quote
Old Dec 28, 2003, 2:18 PM   #15
Junior Member
 
Join Date: Dec 2003
Posts: 25
Default reading but more questions

I'm reading and more questions seem to pop up

Rule of thumb:
1.)"keep the shutter faster than 1/60 at shorter than 60mm focal lengths."
2.)"keep shutter speed above 1/focal length. To keep shake reasonable when zooming. "

Are there situations in everyday shooting (barring nighttime photography) where you don't follow the above?

Was looking at canon lens and one of them had this description:
"minimum focusing distance remains constant throughout the entire zoom range" What does this exactly mean?

and this description on another lens

"extending from a wide 28mm all the way to 105mm telephoto, all with a fast constant f/2.8 maximum aperture" Does it mean that I can use f2.8 when I'm at 105mm?

Sweet spot:
I've been hearing about this for lenes but exactly what is it and what does it do?

f8 is the "who cares" aperture, as Bryan Peterson calls it in his book "Understanding Exposure: How to Shoot Great Photographs."
This is the aperture to choose when nothing else matters.

Now:
Using a hyperfocal chart, F8 will be 7 foot with near focus Distance at 3-4ft. F5.6 would be 10 foot with near focus distance at 4-5ft.

But if both 5.6 and f8 can give me sharp DOF why use a higher F8 when I can use 5.6 which gives me more light and a faster shutter speed? The only difference between the two is the near focus distance. If that distance does not matter then what is the difference betwee using F5.6 vs F8? Would F8 yield more detail? I mean if i was shooting with a 18mm lens moving the Fstop to a lower number like 5.6 would not yield you a wider angle shot right or does it?

Hyperfocal chart:
Knowing that f/5.6 or F8 will cause everything to be in focus from around five-ish feet on out is great but since I'm focusing with a camera that has absolutely no manual focus scale to it I'd pretty much have to know or focus on something that is exactly 7 or 10 feet in front of me. I would have to get it just right to cause the DOF info to hold true.
To be practical about it, I was thinking won't it be the same if I focus at infinity using F5.6 or F8 and know that everything from about eight feet and beyond is going to show up in fine detail. Would my theory work?

thanks
recca is offline   Reply With Quote
Old Dec 31, 2003, 11:03 AM   #16
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Quote:
Rule of thumb:
1.)"keep the shutter faster than 1/60 at shorter than 60mm focal lengths."
2.)"keep shutter speed above 1/focal length. To keep shake reasonable when zooming. "

Are there situations in everyday shooting (barring nighttime photography) where you don't follow the above?
... Yes, when you are on a tripod using a timer or a remote release (and static landscape)! :lol:


Quote:
Was looking at canon lens and one of them had this description:
"minimum focusing distance remains constant throughout the entire zoom range" What does this exactly mean?

and this description on another lens

"extending from a wide 28mm all the way to 105mm telephoto, all with a fast constant f/2.8 maximum aperture" Does it mean that I can use f2.8 when I'm at 105mm?
Yes, this is a constant aperture lens meaning the aperture stays fixed throughout the zooming range. This type of lens is better because the exposure value stays fixed, ie the shutter speed do not change as you zoom: For example on your kit lens as you zoom in the aperture decreases and the shutter turns slower as you zoom in; However you'll be paying in weight and cost because of the larger constant aperture lens... Most people will just opt for IS which is lighter and will compensate for the slower shutter speed, but this only helps in hand-held operation but not if the subject is moving requiring a faster speed anyway.

As to the minimum focusing distance, they are referring to the macro range which only applies to either wide or long setting on certain lenses. ie you can only focus close-up on one position or the other... A better design will not put a limit on its zoom usage.

BTW some lens focus even change while you zoom!


Quote:
Sweet spot:
I've been hearing about this for lenes but exactly what is it and what does it do?
Every lens has a spot or range where it'll perform best... and usually occurs the more the aperture is closed down... up to a point where the aperture is so small that the shutter speed is not usable anymore (ie even in landscape clouds move)


Quote:
Hyperfocal chart:
Knowing that f/5.6 or F8 will cause everything to be in focus from around five-ish feet on out is great but since I'm focusing with a camera that has absolutely no manual focus scale to it I'd pretty much have to know or focus on something that is exactly 7 or 10 feet in front of me. I would have to get it just right to cause the DOF info to hold true.
To be practical about it, I was thinking won't it be the same if I focus at infinity using F5.6 or F8 and know that everything from about eight feet and beyond is going to show up in fine detail. Would my theory work?
It should work... and F8 should yield more details @ the far and close edges...
NHL is offline   Reply With Quote
Old Jan 3, 2004, 8:41 PM   #17
Senior Member
 
Join Date: Dec 2002
Posts: 5,803
Default

As usual, I agree with all that NHL said. I just wanted to add a few more comments.

Quote:
Originally Posted by NHL
Every lens has a spot or range where it'll perform best... and usually occurs the more the aperture is closed down... up to a point where the aperture is so small that the shutter speed is not usable anymore (ie even in landscape clouds move)
I would have said that if you push the fstop beyond a certain point, the optical quality drops. You'll start getting distortion around the edges, and even can get chromatic aborations (I believe). The problem is that it isn't always at f8 where the lens is at its best. It often is, but not always.

So the choice of fstop is a trade off of optical quality vs. DOF vs. shutter speed. And the optical quality graph isn't a line (like DOF & shutter speed is) it's a bell curve.

Eric
eric s is offline   Reply With Quote
Old Jan 4, 2004, 9:05 AM   #18
Senior Member
 
Join Date: Nov 2002
Posts: 332
Default

I found National Geographic's Field Guide to Photography series very good reading - you can find them in any bookstore, about 6 books in the series. I also received a book for the holidays titled "Masterclass in Photography" by Michael & Julien Bussle that looks very promising, although I have not yet started reading.
fporch is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 2:11 PM.