BetterPhoto Q&A
Category: Tips for Taking Wedding Photos

Photography Question 

Amanda Baker
 

Fast Lens and Depth of Field


Hello,
I have a Sigma 28-70 2.8 lens and a Canon 50mm 1.8 that I am hoping to use at a wedding I have coming up. I will be shooting in Raw and planning to shoot in Aperture priority mode. Since I will be using a fast lens at the wedding to help with low light, how do you get enough depth of field so that, for example, you're not just getting perhaps the bride in the picture in focus and the groom blurry? I am using two Canon 20D's. One of these will have a flash and the other will not. I will have an assistant using one of the cameras.
Thank you so much!


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March 23, 2008

 
wildlifetrailphotography.com - Donald R. Curry

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  The larger the aperture number (smaller aperture opening)the greater the depth of field. You may have a depth of field viewing button on your camera. Push the button while looking through the viewfinder, and you can check the depth of field for a particular aperture setting. Of course, a larger aperture number means a slower speed. This could present a problem in low light. conditions. You will need to use a flash if this is the case.


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March 23, 2008

 

Alan N. Marcus
  Hi Amanda,
As Mr. Curry expressed, depth-of-field is a function of aperture setting. Tiny aperture openings like f/22 – f/16 – f/ 11 yield the greatest depth-of-field; f/22 having the greatest.
As you know, the depth-of-field zone extends back towards the camera and away from the camera as measures from the point focused upon. You need to know that this zone is not split down the middle. The depth-of-field zone extends further away from the point focused upon (away from the camera) than it does back towards the camera. In fact, depth-of-field extends 2/3 away and 1/3 back towards you from the focused distance. You can put this knowledge to good use; when shooting a group, have the middle person extend a hand towards you, focus on this hand. This way you are not focused on the center point; but forward of center. This maximizes your chances to get everybody in focus.
Depth-of-field is a function of focal length. Your zoom operating at 28mm yields the greatest depth-of-field. Your 50mm wide open (f/1.8) has very shallow depth-of-field.
I have never found any pre-viewing technique for depth-of-field to be useful.
Use a flash whenever possible. Hopefully, the flash will allow you to use the smaller apertures to maximize depth-of-field.
Depth-of-field is a function of subject distance. Greater distance yields increased depth-of-field. Try to step back as you compose; this yields greater depth-of-field and forces you to allow some extra room surrounding the principal subject. Extra head room and the like can be put to good use; it allows you to crop for effect and/or allows you to deliver print sizes 8x10 or 5x7 that are a mismatch with regard to your camera’s format.
Alan Marcus (marginal technical gobbledygook)


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March 23, 2008

 

Amanda Baker
  Thank you for your help.

I understand how you get more depth of field with a largest aperature and that the larger aperature lets in the most light so this is great for low light situations but if I use a large aperature in the church during the wedding without the flash I am worried about only getting a small area of the picture in focus when I may need more of the picture. It seems like you sacrifice depth of field but gain the ability to capture a photo in low light. Is there any way you can compensate for this? So that you can get more depth of field but use a great aperature (smaller number) to allow photos in low light with no flash? Thanks


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March 24, 2008

 

Alan N. Marcus
  No – No – No – A thousand times NO.

Tiny apertures produce more depth-of-field. Large apertures produce shallow depth-of-field.

You are confused by the numbers. The f/numbers starting at the left are tiny apertures. As this list goes right the aperture (entry opening) increases.

32 – 22 – 16 – 11 – 8 – 5.6 – 4 – 2.8 – 2 – 1.4

Theses are the full f/stops. Each allows twice as much light to enter going right - - that’s 100% per increment. Going left each reduces light entry by half - - that’s a 50% reduction. There are between values that are in 1/2 or 1/3 stop increments f/1.8 is one of these.

Alan Marcus


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March 24, 2008

 

Pete H
  Amanda,

To answer your question directly; NO!
Wide open apertures will NOT allow you to have a deep DOF.
Your DOF is even more limiting with telephoto lenses.


Pete


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March 25, 2008

 

Amanda Baker
  Thank you so much for your responses. I actually do understand the f-stops and the numbers and that you do not get much depth of field with a f-stop such as 1.8 but you get a lot of depth of field with one such as f-16. What I'm unsure about is shooting in low light with no flash. I realize you can use an aperature such as 1.8 and get great pictures in low light but then you sacrifice your depth of field, if you shoot with a smaller aperature you are not letting in enough light for the low light even though you may get the depth of field you need. I guess you have to compensate with a higher ISO and slower shutter speed. Is that correct?


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March 25, 2008

 
- Greg McCroskery

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  Amanda,
It's obvious that you understand the f-stop/aperture opening relationship. I think you are probably worrying about a non-issue. In just about any church, you should be able to shoot the ceremony at f2.8 - f4 (ISO 400 - 800) using a tripod and get more than enough DOF --unless you plan to shoot from right in front of the altar. I generally shoot a ceremony from the back of the aisle, or the choir loft and have no problems. Your camera has a sensor that is somewhat smaller than a full 35mm frame sensor which gives you the benefit of greater DOF at any given aperture. I use an Olympus E-3 which also has this characteristic, and ironically is often criticized for its lack of shallow DOF -- there are advantages and disadvantages to every system depending on the circumstances. Hope this helps.
God Bless,
Greg


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March 25, 2008

 

David E. Bunkofske
  I have shot hundreds of weddings with manual setting at 5.6, 125 sec. Always great results.
Enjoy yourself and have fun. Dont worry
David


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March 25, 2008

 

Amanda Baker
  Thank you so much!


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March 25, 2008

 

Amanda Baker
  Thank you so much!


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March 25, 2008

 

Bernard
  David
Just curious! what ISO, and lens manufacturer, and were many shots unuseable.


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March 27, 2008

 

Diane Dupuis
  It helps if the people you are shooting are in line with each other. I.e. the bride and groom standing next to each other will probably both be in focus with a 1.8 aperture than if one was standing further behind the other... Good luck!


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March 29, 2008

 

Bernard
  David
viewing your website was very educational, quality deep depth of field is posible with a f5.6 lens. why not post your website address in this tread, as an addendum to the answers of Amanda's question


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March 29, 2008

 

David E. Bunkofske
  You can see what depth of field at F5.6 will do at www.reflectedimages.ifps.com


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March 29, 2008

 

Nancy
  We have used both lenses of your type. Bumped up the ISO and used a mono pod for any shutter speed under 125-200. Ask the church personal for some pre-shoot time. If not close by maybe a church with simular lighting.


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March 30, 2008

 

Amanda Baker
  Thanks to all your responses.

Nancy, what aperature do you perfer in the church? Also why do you use a mono pod for any shutter speed under 125-200. I always thought you only really have to use a tripod or mono pod if the shutter speed is slower then the length of your lens.


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March 30, 2008

 
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