Go Back   Steve's Digicams Forums > Digital Cameras (Point and Shoot) > Canon

Reply
 
Thread Tools Search this Thread
Old Oct 16, 2004, 11:48 AM   #1
Member
 
noujwas's Avatar
 
Join Date: Aug 2004
Posts: 32
Default

Hello everybody,

I just discovered a new bug in the latest firmware (version 1.0.1.0) for Canon A75. After theyfixed the Apertureproblem in the Manual Modelast month, now it's the Shutter Speed turn.

For Canon A75 owners with the latest firmware installed, please set your CameratoManual Mode, turn the Flash ON (That's important) and select a Shutter speed value higher than 1/500 (e.g 1/640) and then press the shutter release button half the way. The shutter speed will change by itself back to 1/500!!! It will do this only if the Flash is ON. Turn the flash OFF then No problem.

Another thing I noticed after installing the latest firmware -I'm not sure if this is related to a problem only on my own camera (Maybe its sensor has a problem?)- is that the image automatic rotating feature sometimes doesn't work fine. I meansometimes vertical pictures are not rotated automatically by the camera even if the auto rotate feature is ON. Yesterday, I even noticed that one of my horizontal pics turned to be vertical in the play mode!

I'd like to have feedback from the Canon A75 owners.

Thanks

Noujwas
noujwas is offline   Reply With Quote
Sponsored Links
Old Oct 16, 2004, 11:54 AM   #2
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Many cameras have a maximum sync speed with flash. Some DSLR models won't sync faster than 1/125 to 1/200 second. That's probably what you are seeing (a limitation on the sync speed with flash to 1/500 second with your model).

As for the image orientation,I'm not sure how the sensor works. If the camera is tilted slightly forward or backwards, it may cause a problem with the sensor mechanism not being able to work properly.

Many models don't even have such a sensor.


JimC is offline   Reply With Quote
Old Oct 16, 2004, 12:07 PM   #3
Member
 
noujwas's Avatar
 
Join Date: Aug 2004
Posts: 32
Default

Thanks for the quick answer Jim. As usual, you're very helpful.

I wasn't aware of the "maximum sync speed with flash" but here's my question:

What would you do if the sun is right above your subject and you're forced to use flash to fill the shadows? Do you think 1/500 is good enough for not getting an overexposed picture (or maybeonly thebackground). I know you can fix that by closing the aperture but what if I want a shallow depth of field and I have to keep my aperture on f2.8 (The maximum I can get with the A75)?

Thanks again

Noujwas
noujwas is offline   Reply With Quote
Old Oct 16, 2004, 12:44 PM   #4
Member
 
noujwas's Avatar
 
Join Date: Aug 2004
Posts: 32
Default

I wish I could change at least the title of my topic now, maybe by just adding a question mark :roll:. If JimC is right then my title sounds stupid.
noujwas is offline   Reply With Quote
Old Oct 16, 2004, 1:18 PM   #5
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

noujwas wrote:
Quote:
What would you do if the sun is right above your subject and you're forced to use flash to fill the shadows? Do you think 1/500 is good enough for not getting an overexposed picture (or maybeonly thebackground). I know you can fix that by closing the aperture but what if I want a shallow depth of field and I have to keep my aperture on f2.8 (The maximum I can get with the A75)?
Shutter speed should not have any impact on the exposure from flash.

You will need to make sure whatever aperture/shutter speed combination you are using works well for proper exposure of the image. However, whatever combination you choose (slower shutter speed with smaller aperture, or faster shutter speed with larger aperture) should not make any difference on how the flash impacts the image.

The flash burst is very fast (typically between 1/1000 and 1/10000 second). So, shutter speed has no impact on how much light it provides to the image. Aperture does impact maximum flash distance and exposure. However, at closer ranges, most camera models aregoing to "throttle" the flash strength for proper exposure. Basically, it just uses a shorter burst length for less exposure, or a longer flash burst formore exposure, asneeded (based on the amount of light in the scene, and the distance to the subject).

If you want less depth of field by using a larger aperture, and shutter speeds are too fast for the flash to work, you can try using a neutral density filter (or a polarizer) to block some of the light coming into the lens.

However, you're still going to find it difficult to get a shallow depth of field with larger subjects using your model, even at f/2.8. This is because depth of field is based on the actual (versus 35mm equivalent) focal length of the lens, aperture, and focus distance. The lens on the A75 has an actual focal length of 5.4 to 16.2mm. So, you'll have dramatically greater depth of field for any given 35mm equivalent focal length, aperture and focus distance, compared to a 35mm camera.

To see how this works, load your camera model into this handy online Depth of Field Calculator. Make sure to use the actual focal length of the lens:

http://www.dofmaster.com/dofjs.html

Your best bet for blurring backgrounds is probably using software to simulate a shallow depth of field with the A75.


JimC is offline   Reply With Quote
Old Oct 17, 2004, 11:45 AM   #6
Member
 
noujwas's Avatar
 
Join Date: Aug 2004
Posts: 32
Default

Thanks for the long and detailed explanation. Ispent the wholeday yesterday doing tests with flashand now I understand more the way it works thanks to your post.

I tried the Neutral filter trick, even though I don't have a physical filter to attach to my camera, but the camera itself has a built-in effect called Neutral. I tried it with flash and it seems to reduce the flare.

I know that it's difficult to get ashallow DOF with the A75, that's why my plans are to buy a more advanced camera (maybe a DSLR) this year. I'm still learning photography with my A75 and I think my exposures and picturesare improving.

I usually apply Gaussian bluron my picsin PS to get a shallow DOF as you said.

Thanks for the interesting link. I downloaded the software both on my computer and my palm. It's really useful.

Thanks again

Noujwas
noujwas 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 2:57 AM.