Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Feb 5, 2018, 9:33 PM   #1
Junior Member
 
Join Date: Jun 2014
Location: CA
Posts: 5
Default how do I get the entire photo/subject sharp?

I just got a (new to me) Canon T4i with 18-55 kit lens. I make and sell jewelry. I’d really like to get a clean and sharp and in focus as I can photo of the entire piece. I’ve gotten close….how do I do that? What type of settings do I need? I do shoot in manual. I cant buy another lens. I'd like to learn with what I have first. thx!

Last edited by rosyjazz; Feb 5, 2018 at 9:44 PM.
rosyjazz is offline   Reply With Quote
Sponsored Links
Old Feb 5, 2018, 11:06 PM   #2
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,281
Default

For close-up work, you should have a lens which is more suited, called a macro lens. These tend to be sharper over the whole photo. However, there are things you should try with your existing lens first, such as making sure you have enough light, use a tripod, and set your camera to aperture priority, using a small enough aperture for a good depth of field (larger aperture number, such as f/8).
VTphotog is offline   Reply With Quote
Old Feb 6, 2018, 7:56 AM   #3
Senior Member
 
TCav's Avatar
 
Join Date: Sep 2005
Location: Washington, DC, Metro Area, Maryland
Posts: 13,663
Default

The Canon 18-55 has a minimum focus distance of 10 inches, which is pretty good for what you want to do.

That's not 10 inches from the front of the lens; that's 10 inches from the image sensor or Focal Plane. The position of the Focal Plane is identified by the circle with a horizontal line through it, which is on the top of the camera, on the left side (looking at the back of the camera), right above the strap mount.

The trick is to get as much Depth of Field (DoF) as you can, and the only way to do that is to stop down the lens. That is, use a smaller aperture (numerically larger f-number.) Unfortunately, with that lens at the minimum focus distance, even with the smallest aperture, at a focal length of 55mm, the maximum DoF is about an inch total, front to back. That means only things from 9.5 inches to 10.5 inches from the focal plane will be in focus. Even at a focal length of 35mm, with the smallest aperture, the total DoF is still only about 2 inches.

And even with those settings, you'll need to adjust other conditions in order to get a sharp, properly exposed photo.

Using those apertures to maximize your DoF, you'll need to use a lot of light, and/or long exposure times (risking motion blur due to camera shake), and/or higher ISOs (risking image noise.)

I suggest you consider a tripod in order to avoid motion blur due to camera shake. If you can fit everything onto a table top, there are good, inexpensive tripods that will do what you need and are easy to use and adjust.

Another problem is that lenses, at their smallest aperture (largest f-number) tend not to be very sharp. This is caused by something called Diffraction limit, which is a limitation on light passing through a small opening. So even with the sharpest lens on that camera, the images will start losing sharpness once you start using f-numbers larger than f/14.

So, at f/14 (for maximum sharpness) at a focal length of 55mm, you'd need to use a subject distance of 22 inches from the focal plane in order to get a total DoF of 2 inches, 27" for a DoF of 3", and 31" for a DoF of 4". At a focal length of 35mm, at f/14, you'd need a subject distance of 17" for a DoF of 3", 20" for a 4" DoF, and 24" for a 6" DoF.

(You can play with these settings yourself at DoFMaster.com to see how you can adjust the gear you've got to capture your subjects.)

So, while what you want to do is possible, it will probably take some experimentation on your part to get results you'll be satisfied with.
__________________
  • The lens is the thing.
  • 'Full Frame' is the new 'Medium Format'.
  • "One good test is worth a thousand expert opinions." - Tex Johnston, Boeing 707 test pilot.

Last edited by TCav; Feb 6, 2018 at 7:59 AM.
TCav 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 8:34 AM.