| Author | Thread |
|
|
02/08/2006 07:02:10 AM · #1 |
| When i first turn m camera on its zoomed out as far away as it can go. This seems to be the default setting. I can go from 2.8 to 8.0 on the Fstop. If i zoom in the Fstop will no longer go down to 2.8. its limit is like 3.2 now. Why is this? whats happening here? Is my camera messed up or is this just how it is? |
|
|
|
02/08/2006 07:07:24 AM · #2 |
f-stop is the focal length / apperature diameter ... the apperature diameter is simply the opening on the sensor end of the lens and iy is fixed so when you increase focal length the f-stop value increases
Message edited by author 2006-02-08 07:08:13. |
|
|
|
02/08/2006 07:10:23 AM · #3 |
| note also that increasing the focal length on a zoom length while keeping the f-stop to minimum atainable will enhance your DOF ( throws the background out of focus ) .. but it will decrease the amount of light getting in your camera ( so you must decrease shutter speed ) |
|
|
|
02/08/2006 07:10:46 AM · #4 |
Aperture is ratio of the size of the shutter opening to the focal length of the lens (i.e., how far "zoomed in" you are). If you zoom in far enough, the aperture can no longer open far enough to maintain the same f-number, so the camera will need to "stop down" to a smaller aperture.
This is normal in many consumer cameras and lenses.
A couple articles that explain this in a little more detail:
//wikitography.org/wiki/Aperture
//wikitography.org/wiki/F-number
~Terry
Message edited by author 2006-02-08 07:14:45.
|
|
|
|
02/08/2006 07:12:31 AM · #5 |
| I think your camera is telling you that when your zoom settings are adjusted your lens f stops will also adjust. Your range of f stops may be different depending where your zoom is set. |
|
|
|
02/08/2006 07:17:23 AM · #6 |
| i don think it has somethin to do with the shutter, correct me if i'm wrong but i think it has to do with the mechanism of the lens.. because on my 18-55 lense when i zoom in and out and use the DOF preview i don hear or see difference althought the f-stop changes .. my guess is the movement of the lense barrel against each other result in a narrower apperature when you zoom .... |
|
|
|
02/08/2006 08:28:48 AM · #7 |
Lenses have the max aperture marked on the lens. For the A510 there's probably something like 2.8-3.2 on the front of the lens.
What this is saying is that at wide angle the camera can open up to f2.8 but at the max zoom it can only open up to 3.2. |
|
|
|
02/08/2006 03:42:13 PM · #8 |
Does it have anything to go with the front opening? why does the A510 have a smaller opening then the A70? The are both 3.2mp and both have 3X zoom.
 |
|
|
|
02/08/2006 03:50:14 PM · #9 |
Cameras like yours have a minimum aperature at the widest angle, and minimum aperature at the longest zoom.
In your case, the camera is a 2.8-3.5
This means at the widest angle (W on your zoom button), it will be 2.8
at the Telephoto end (T on your zoom button), it will be 3.5.
Everyone else has explained the technicals behind this, but really this is all you need to know. When you are zoomed in, it'll be 3.5 because not as much light can get in to the sensor when zoomed in.
tada!
Has nothing to do with the physical dimensions of the outer lens elements. |
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2025 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 09/10/2025 07:07:25 PM EDT.
