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

Reply
 
Thread Tools Search this Thread
Old May 9, 2004, 7:15 PM   #1
Junior Member
 
Join Date: Mar 2004
Posts: 28
Default

How do I control the depth of field when using the flash?
biggles is offline   Reply With Quote
Sponsored Links
Old May 9, 2004, 11:41 PM   #2
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

Can't you put the camera in the Av mode and increase the aperture?

What camera are we talking about? With most EOS, if the flash is on E-TTL putting the camera on manual will let you set both the aperture and shutter...

The problem is usually do you have enough power output on a single flash to cover the entire DOF, or you have to use multiple units
NHL is offline   Reply With Quote
Old May 10, 2004, 8:36 AM   #3
Junior Member
 
Join Date: Apr 2004
Posts: 27
Default

I don't know if we are talking about the same thing or not. I am still learning my camera, but I was taking my first shots the other night in program mode with the flash. Nothing fancy, just snapshots to try it out. Well almost everything came out either out of focus, where the camera had focused on a building 100 yards behind my subject, or underexposed. I was shooting RAW at 100.

Like I said they weren't supposed to be anything but tests, but I think out of the 7 shots one was exposed correctly. I used C1Rebel to work with them.

Any ideas, or do I just need to practice more? Maybe change the focus points???
FSUScotsman is offline   Reply With Quote
Old May 10, 2004, 8:47 AM   #4
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

FSUScotsman wrote:
Quote:
... where the camera had focused on a building 100 yards behind my subject, or underexposed. I was shooting RAW at 100.
This is way too far for the built-in flash! With a more powerful 420EX flash (with a Guide Number of 42), the farthest coverage is still only 10m @ f/4 :sad:
NHL is offline   Reply With Quote
Old May 10, 2004, 8:50 AM   #5
Junior Member
 
Join Date: Apr 2004
Posts: 27
Default

Oh no!!! I was trying to get the building!!! The subjects were about 10 feet away, but the camera STILL focused on the building. It had a couple of neon lights and I wondered if it picked up on them.
FSUScotsman is offline   Reply With Quote
Old May 10, 2004, 9:00 AM   #6
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

FSUScotsman wrote:
Quote:
Oh no!!! I was trying to get the building!!! The subjects were about 10 feet away, but the camera STILL focused on the building. It had a couple of neon lights and I wondered if it picked up on them.
10ft is about the max distance of the built-in flash if you zoom-in... If you try to take the picture of the whole building (ie wide @ angle) with the subjects you'll end up with a very uneven lighting with bright center tapering off at the sides, but you should at least focus on the subject.

Also use the night portrait mode (on a tripod if possible) you might be able to get some of the background this way. :|
NHL is offline   Reply With Quote
Old May 10, 2004, 9:51 AM   #7
Junior Member
 
Join Date: Apr 2004
Posts: 27
Default

Hmmm, let me start over.:lol:

I wasn't TRYING to get the building at all!!! The camera just seemed to pick up on the neon lights.
FSUScotsman is offline   Reply With Quote
Old May 10, 2004, 11:28 AM   #8
Junior Member
 
Join Date: Mar 2004
Posts: 28
Default

Try setting the focus point sto the centre one and make sure it turns red when you half press the shutter release.



My original question was perhaps a little premature as for some reason I had convinced myself that you couldn't set the aperture when using flash! I will give it a try and see what happens. I think I am getting confused as the shutter speed is a constant 1/60 second when the flash is in use and I assumed that you couldnt change aperture. This also made me think that I would not be able to hold the camera still enough at 1/60 to ensure an in focus image or is the exposure time dependant on the flash not the shutter?

Oh yes the important bit EOS 10D built in flash waiting to try the EX420. Lens is either a EF50mm F1.8, Sigma 18-55mmDC or EF28-135 Is depending on what I am looking at.

Many thanks so far for your comments.
biggles is offline   Reply With Quote
Old May 10, 2004, 12:46 PM   #9
Senior Member
 
ohenry's Avatar
 
Join Date: Dec 2003
Posts: 1,676
Default

If you take your camera out of the programmed modes and use manual, you can control your aperture and your shutter speeds. Depending on what you are trying to do would determine which mode works best. Av mode allows you to choose your aperture and the camera will select a shutter speed appropriate for the existing light. Your flash will then act as fill flash. Problem with this method is that you must have sufficient light to have a shutter speed that will allow you to handhold the camera (or use a tripod). You can also select Tv and control your shutter speed (the flash will synch at speeds up to 1/250 (higher if you select hi speed synch). Of course, here the camera will select the aperture based on the existing light so you can expect a wide open lens. The flash will again act as fill light but will need to use higher power to provide more flash. My preferred method is to put the camera into M mode and select the aperture speed that I want and the shutter speed that I want and then allow the E-TTL of the flash determine the amount of flash. For most indoor shots, I select 1/100 sec and f/8 and get good results. If I am shooting outdoors, I set my aperture and shutter speed to an appropriate exposure and allow the flash to provide fill for the shadows.

I'm using a 420EX

Hope this helps some.
ohenry is offline   Reply With Quote
Old May 10, 2004, 1:55 PM   #10
NHL
Senior Member
 
NHL's Avatar
 
Join Date: Jun 2002
Location: 39.18776, -77.311353333333
Posts: 11,547
Default

biggles wrote:
Quote:
... This also made me think that I would not be able to hold the camera still enough at 1/60 to ensure an in focus image or is the exposure time dependant on the flash not the shutter?
You're also correct here, the flash pulse is quite brief (much faster than the 1/60s camera's shutter speed) so you don't have to be as steady holding the camera as you were without the use of flash... You can also slow the camera down to lower speed such as 1/30s if you want more ambient light to come through instead of a blackened out background (this has the same effect as selecting the Night Portrait mode...)
NHL 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 4:52 AM.