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tarfearauko
01-10-2005, 03:27 AM
Hi again!

I am still playing with my 10D, trying to learn as fast as I can. I have been trying to understand how to use the DOF preview button with no success. I guess what it does is close the diafragm to the extend set in the composition but what I cannot get is:

- If the aperture is wide open (least DOF possible) the blades do not close (this is pretty obvious, I know that) and then the camera does not give me any feeling of which the DOF is.

- If the is, say f 8, I only can see a gradient of blurryness starting at the center of the image. What if my subject is off center?? furthermore, what is the gradient telling me.

In a nutshell, I have no clue about how this thing works (and, yes, I did read the manuals). Could somebody give me a hint here??

Thanks a lot, guys!

Mike Woods
01-12-2005, 07:49 AM
Hi again!

I am still playing with my 10D, trying to learn as fast as I can. I have been trying to understand how to use the DOF preview button with no success. I guess what it does is close the diafragm to the extend set in the composition but what I cannot get is:

- If the aperture is wide open (least DOF possible) the blades do not close (this is pretty obvious, I know that) and then the camera does not give me any feeling of which the DOF is.

- If the is, say f 8, I only can see a gradient of blurryness starting at the center of the image. What if my subject is off center?? furthermore, what is the gradient telling me.

In a nutshell, I have no clue about how this thing works (and, yes, I did read the manuals). Could somebody give me a hint here??

Thanks a lot, guys!


Just picked up the February issue of Photographic magazine and there is an article on depth of field with the last page showing a picture of the digital rebel's preview button. I haven't read it yet, but this might be a place for you to start. :)

jaykinghorn
01-12-2005, 09:32 AM
Hi again!

I am still playing with my 10D, trying to learn as fast as I can. I have been trying to understand how to use the DOF preview button with no success. I guess what it does is close the diafragm to the extend set in the composition but what I cannot get is:

You are correct that the DOF preview closes the aperture to give you a better idea of what will be in focus in the finished image.


- If the aperture is wide open (least DOF possible) the blades do not close (this is pretty obvious, I know that) and then the camera does not give me any feeling of which the DOF is.

Anytime you are looking through the lens of an SLR, you are effectively previewing the maximum aperture of the lens. The big advantage of doing this is that the maximum aperture lets in the most light. This makes focusing easier in low light situations.


- If the is, say f 8, I only can see a gradient of blurryness starting at the center of the image. What if my subject is off center?? furthermore, what is the gradient telling me.

Hmmm... I haven't used the DOF preview with the 10D, but none of the cameras I've ever looked through could be described as a "gradient of blurryness". Most often, the viewfinder becomes very dark. It does give an accurate representation of what will be in focus in the final image, but I find I only use it when I have lots of light. Otherwise, everything is simply too dark.

Best regards,
Jay Kinghorn
RGB Imaging

propwash
01-12-2005, 09:56 AM
Hi again!

- If the aperture is wide open (least DOF possible) the blades do not close (this is pretty obvious, I know that) and then the camera does not give me any feeling of which the DOF is.
In a nutshell, I have no clue about how this thing works (and, yes, I did read the manuals). Could somebody give me a hint here??

Thanks a lot, guys!

The purpose of DOF preiew is to give you an idea of what will be in focus on the finished picture. Most SLR's (I'm talking film SLR's here, not necessarily digital, becaue I don't have any experience with digital SLR's) show the image in the viewfinder through maximum aperture (lowest f-stop number). This makes it easier for you to focus and compose. If you have your lens set to maximum apertrure, when you hit the DOF preview button, you won't see any change, because the lens is already at max aperture, and that is what you have set. If you have the lens set a minimum aperture (highest f-stop number) when you go to DOF preview, the image in the viewfinder will darken due to the lens stopping down, but this will show you what your actual DOF will be with the smaller aperture. Hope this helps.

D70FAN
01-12-2005, 11:55 AM
The purpose of DOF preiew is to give you an idea of what will be in focus on the finished picture. Most SLR's (I'm talking film SLR's here, not necessarily digital, becaue I don't have any experience with digital SLR's) show the image in the viewfinder through maximum aperture (lowest f-stop number). This makes it easier for you to focus and compose. If you have your lens set to maximum apertrure, when you hit the DOF preview button, you won't see any change, because the lens is already at max aperture, and that is what you have set. If you have the lens set a minimum aperture (highest f-stop number) when you go to DOF preview, the image in the viewfinder will darken due to the lens stopping down, but this will show you what your actual DOF will be with the smaller aperture. Hope this helps.

The lenses (and hence the aperture iris) works the same as film.

tarfearauko
01-13-2005, 04:17 PM
Thanks a lot to all of you, guys. I have been reading through the Internet and got a better idea of my difficulties. Also, your explanations were just superb.

My "gradient of blurryness" was due to the fact that I tried the DOF preview indoor under pretty bad lighting conditions... the viewfider became so dark that I could only described it as a curtain of blurryness (actually I even forgot to mention the darkness in my explanation... damned newbies :rolleyes: ).

My experiments have been way more fruitfull after reading your posts and a couple of other websites.

Happy New Year and Happy Shooting!

toriaj
01-29-2006, 06:38 AM
I am considering buying the D50, and I wonder:
Since it has no DoF preview, is there enough detail on the LCD screen to see how the DoF turned out after you take the picture? Or do you need to download the pic onto the computer or print the pic to be able to see the DoF? Thanks.