Approve the Cookies
This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and our Privacy Policy.
OK
Index  •   • New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Guest
New posts  •   • RTAT  •   • 'Best of'  •   • Gallery  •   • Gear  •   • Reviews
Register to forums    Log in

 
FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
Thread started 10 Nov 2010 (Wednesday) 21:23
Search threadPrev/next
sponsored links
(this ad will go away when you log in as a registered member)

1D4 - Auto ISO in Tv, Av, & M

 
MikeV99
Senior Member
251 posts
Joined Sep 2007
     
Nov 10, 2010 21:23 |  #1

Can anyone provide definitive information or point me to authoritative sources that will answer the following questions. Background:

C. Fn 1-8 Safety Shift settings
0 Disable
1 Enable (Tv/Av) Yes
2 Enable (ISO speed)

"Enable ISO speed safety shift works in the Program mode, shutter-priority mode, and aperture-priority modes. When the subject’s brightness changes erratically and the correct auto exposure cannot be obtained, the camera will change the ISO speed automatically to obtain a correct exposure."

Disable Safety Shift.

Q1. C Fn. 1-8: 0; Tv, Auto ISO. What ISO is picked by the camera if metered aperture is within its limits? I.e., what is the relationship between aperture and ISO?

Q2. C Fn. 1-8: 0; Tv, Auto ISO. What ISO is picked by the camera if the metered aperture is at its minimum or maximum? I.e., what is the relationship between aperture and ISO?

Q3. What is the relationship between C Fn. 1-8: 2 (Safety Shift ISO speed enabled) and Auto ISO?

Q4. With Manual Shooting Mode and Auto ISO the ISO level with be set according to the metering. How does one achieve exposure change as measured by metering other than by turning off Auto ISO and adjusting exposure manually?

Q5. What is the relationship between Auto ISO and C Fn. 1-8: 2?

Thanks.

Mike


.
-- Mike -- The older the boy, the bigger and costlier the toys!

:) My Gear List :)

  
  LOG IN TO REPLY
apersson850
Cream of the Crop
Avatar
12,095 posts
Gallery: 4 photos
Likes: 328
Joined Nov 2007
Location: Traryd, Sweden
     
Nov 10, 2010 22:01 |  #2

Now I don't have any 1D Mark IV, but I do have a 7D. I consider it interesting to compare them, so I apologize for somewhat hijacking your thread, but I do it anyway.


  1. The 7D would use the lowest possible ISO (normally 100) unless the picture is underexposed. If it is, it will rise ISO up to 3200. On a 1D Mark IV it goes to 12800, unless you have changed the ISO limit. ISO expansion isn't used by Auto ISO.
  2. Same answer as in 1.
  3. I assume ISO safety shift would change a manually selected ISO value, if there otherwise would be over- or underexposure, but not touch it otherwise. As stated above, Auto ISO would always start from the lowest ISO.
  4. You can't. There is no exposure compensation available when using M and Auto ISO.
  5. I would assume Auto ISO with C.Fn I-8-2 is identical to Auto ISO with C.Fn I-8-0.
Now I'm also interested in hearing from someone who actually has a 1D Mark IV.

Anders

  
  LOG IN TO REPLY
MikeV99
THREAD ­ STARTER
Senior Member
251 posts
Joined Sep 2007
     
Nov 11, 2010 10:41 |  #3

Thanks for the answer. However, what I am seeing is not quite what you explain. I do see differences between C Fn 1-8:0 and 2. Also, if it is C Fn 1-8:0 with ISO Auto, it changes both the shutter speed/aperture (depending on Av or Tv) and the ISO. Unfortunately, I have not been able to watch the settings and determine a rule from them. I too would like to hear from someone that uses the 1D MK IV.


.
-- Mike -- The older the boy, the bigger and costlier the toys!

:) My Gear List :)

  
  LOG IN TO REPLY
apersson850
Cream of the Crop
Avatar
12,095 posts
Gallery: 4 photos
Likes: 328
Joined Nov 2007
Location: Traryd, Sweden
     
Nov 11, 2010 10:54 as a reply to  @ MikeV99's post |  #4

I would expect that.
If you use Tv with Auto ISO, at least my camera starts with the lowest ISO (100) and adjusts the aperture over the entire range.
If the smallest aperture isn't small enough, there is overexposure.
If the largest aperture isn't large enough, it starts rising the ISO. If the ISO reaches the top limit, but that's still not enough, there is underexposure.

If you instead use Av and Auto ISO, it starts with the lowest ISO and makes the exposure time shorter if the light gets brighter.
When it gets darker, it lengthens the exposure time, until it reaches a reasonable limit for hand-held shooting. The exact value depends on the lens' focal length. From there, it keeps the exposure time constant but rises the ISO, until it hits the upper limit. Then it starts lengthening the time again.

This is the 7D, but I would assume a 1D Mark IV does something similar.


Anders

  
  LOG IN TO REPLY
MikeV99
THREAD ­ STARTER
Senior Member
251 posts
Joined Sep 2007
     
Nov 12, 2010 12:08 |  #5

This thread (external link) also provides a nice answer.

Regards,

Mike


.
-- Mike -- The older the boy, the bigger and costlier the toys!

:) My Gear List :)

  
  LOG IN TO REPLY
sponsored links
(this ad will go away when you log in as a registered member)

2,031 views & 0 likes for this thread
1D4 - Auto ISO in Tv, Av, & M
FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
AAA
x 1600
y 1600

Jump to forum...   •  Rules   •  Index   •  New posts   •  RTAT   •  'Best of'   •  Gallery   •  Gear   •  Reviews   •  Member list   •  Polls   •  Image rules   •  Search   •  Password reset

Not a member yet?
Register to forums
Registered members may log in to forums and access all the features: full search, image upload, follow forums, own gear list and ratings, likes, more forums, private messaging, thread follow, notifications, own gallery, all settings, view hosted photos, own reviews, see more and do more... and all is free. Don't be a stranger - register now and start posting!


COOKIES DISCLAIMER: This website uses cookies to improve your user experience. By using this site, you agree to our use of cookies and to our privacy policy.
Privacy policy and cookie usage info.


POWERED BY AMASS forum software 2.1forum software
version 2.1 /
code and design
by Pekka Saarinen ©
for photography-on-the.net

Latest registered member is mjp321kia
904 guests, 295 members online
Simultaneous users record so far is 15144, that happened on Nov 22, 2018

Photography-on-the.net Digital Photography Forums is the website for photographers and all who love great photos, camera and post processing techniques, gear talk, discussion and sharing. Professionals, hobbyists, newbies and those who don't even own a camera -- all are welcome regardless of skill, favourite brand, gear, gender or age. Registering and usage is free.