depth of field preview

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gregnash

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Ok so does anyone know how to properly use the DOF preview button? I have trying to figure it out because I went out and took some pictures yesterday and this weekend only to look at them on the LCD and think (ok they look alright) and then get home and dl them to the computer to have them either out of focus, DOF was off or they were just plain soft. I was trying to take some building shots yesterday of Bowers Mansion in Washoe Valley and there are I think 2 that look decent out of probably 15 shots. I really need to pick up my Understanding Exposure book and play some but I just dont have time during the light hours of the day to really play around.
 
gregnash said:
Ok so does anyone know how to properly use the DOF preview button? I have trying to figure it out because I went out and took some pictures yesterday and this weekend only to look at them on the LCD and think (ok they look alright) and then get home and dl them to the computer to have them either out of focus, DOF was off or they were just plain soft. I was trying to take some building shots yesterday of Bowers Mansion in Washoe Valley and there are I think 2 that look decent out of probably 15 shots. I really need to pick up my Understanding Exposure book and play some but I just dont have time during the light hours of the day to really play around.
Click to expand...

When you look through the viewfinder to take a shot, the lens is wide open. Pressing the DoF preview button will stop it down to your set aperture and show you the actual DoF. This will be greater than the DoF that you see through the view finder, but you might have a harder time seeing it because the image will get darker.

Any examples of the shots? How are you focusing? What lens, and what aperture/shutter speeds are you using?

If you're letting the camera pick focus, most of the time it's better to select the center focus point, use that to focus on your subject, and then recompose your shot. This won't work for macros or with very fast primes, but most of the time it's a good, fast way to know what you're focused on.

BTW, I moved this into a new thread for you, the other large thread was drifting on and off topic
 
No prob, thanks for moving it Fugu. Was actually gonna request that but go busy with reports. I will have to post a couple images when I get home as I cannot post from my camera here at work. I am using the only lens I have as of yet, Canon 50mm f/1.8 and I was trying different aperatures and shutter speeds to see what I was getting. Most were shot in either Tv or Av mode but like I said it was about 5pm and the light was pretty harsh. Think that it might be a good spot say after 6:30 or 7pm but at 5pm the sun is still sitting right over the mountain.

Here is a general pic of the area that I was trying to take the pic at.


Ok here is the image I was talking about.. I believe the exif is embedded
IMG_6674.jpg
 
If you shoot in Av mode, you control the aperture and thus directly control DOF. Tv mode can lead to thin DOF shots as the light gets dim and if you set a higher shutter speed.

DOF preview button is kinda a toy in a way, not a ton of use for most things and you usually just have to know your apertures and what you will get for DOF (about). Stopping down makes the viewfinder so dark in most cases it is hard to get an idea of what is going on.
 
I find the DOF preview button pretty useless to evaluate anything unless you are using a bright viewfinder and a larger sensor camera.

Shooting wide open can be challenging. You rely more on the autofocus on the camera being correct. Are you on one shot or AI servo?
 
I would switch to One Shot mode if it's a static scene. I don't trust AI Servo on <1D camera. I never use AI Focus mode. That's like One Shot but switches to AI Servo whenever it wants. You lense could not be focusing right and it's in shutter priority mode possibly (I'm not sure here in AI Focus mode). In AI Servo you can take photos without being in focus.

You also have some lense flare reducing contrast it seems. Are you shooting into the sun?
 
No reason to use AI focus for a static scene. Actually usually no reason to use it at all.

Even on the pro bodies it tends to be finicky. Most people find it better to select One Shot or Servo, not let the camera decide (and usually you will know anyways based on what you are shooting).
 
Ok thanks for the focus mode information so I will probably switch it over to AI Servo or One Shot then depending on what I am doing at the time.

There is some lens flare there that I did not notice before so that is part of the problem. Like I was saying I was shooting with a small aperature (from exif data looks like most of them were shot at 1.8 to 3.2) and I was shooting into the sun as it was about 5pm and the sun was getting low over the mountains. Guess I will need to either shoot it again in the morning on my way to work or invest in a hood for the lens. But then again a 50mm is not the best lens for this type of thing.

For this type of pic I should be shooting in what ISO 200, f/5.6 and a whatever shutter speed I want depending on the effect I would want with the fountain? Is that right... according to the Understanding Exposure book, it seems like f/5.6 is a mainstay opening.
 
f5.6 is even a bit shallow for a nice landscape shot like that.

You should be somewhere in the f8-f11 range if you want to get that scene in nice crisp focus.
 
The 50 is a nice lens, but can still be a little soft at 50mm. Stop down, be careful about flare, and watch your exposure.
 
Thanks for the help guys. I will try again on my way home tonight from work. I am thinking I will drop the ISO to 100 and then move a bit from that point. Thing is I was trying to shoot these with my cheap Walmart Tripod, which is anything but steady when extended. I will have to play with it again tonight and see.

From what you guys are saying I should be shooting with the following settings:
ISO: 100-200
f/: 8-11
ss: fairly fast, depending on where I am and what I want.
AI Mode: One Shot

Anything else?
 
Do not raise the center column of that tripod for a starter. That will add a lot of stability right there. If you are trying to get everything in focus, I would suggest more around f16. It looks like you may have some lens flare going on there too. If you don't have a hood shade the lens with your hand or hat
 
If it has lots of sections on the tripod, try not extending the last extension (usually the thinest) to improve stability.
 
Ok thanks for the tripod tips guys. Yeah unfortunately it is just a cheapo walmart one that we have had for a while. I think it will be ok as long as I do not extend the neck. I didnt get a chance yesterday on my way home but will try for it today and let you know how things come out. Hopefully this fall I will be able to take a digital photography class at the local community college to help me with composition and a better understanding of coupling all the settings.


EDIT: ok here is today's attempt.. Seems to have come out better

IMG_6737.jpg
 
Like Rage said for andscapes f/16 or higher is better for landscapes. Using f/5.6 or below is better for close ups to make good bokeh but, then you can go too low there as well and, only get part of the subject in focus. Also a good quality Circular Polarizer will haelp kill the glare too. To kill the lense flare just hold something in the suns path to shade the lense.
 
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