DOF problems

[kris142]

If you haven't noticed, my pics in the Sports section have terrible DOF where that whole background is in Focus as well and the subject.

Im shooting with a 18-70 f/3.5-5.6

I'm kind of getting confused as how to get more of a blurred BackGround.

I've been told to step farther away from the subject, but I've seen that you must be closer.

Just kind of confused.

Can anyone tell me how to get more of a blurred background?

Sorry for terrible wording once again.

Thanks
~Kris142

[loeee]

Kris, this is long, but please read it with patience. A photo is made by light hitting the sensor (used to be film) there are three things that effect the exposure: how sensitive the sensor is (ISO), how wide the lens opening is (f stop) and how long the shutter is open (shutter speed). The depth of field is influenced by the f stop. The larger the lens opening, the shallower the depth of field (more blurry background). If you are shooting manual, try to shoot with a more open f stop (the lower numbers mean a wider opening). If you are not shooting manual, start You can shoot in the aperture mode (aperture is a fancy word for the opening in the lens that the light comes through) and set your f stop at 3.5 (when you zoom in it will automatically go to 5.6). The camera will then automatically set the shutter speed for the correct exposure.

Does this help at all?

[kenwae]

The larger aperture, which is actually the smaller number, will yield shallow depth of field. An aperture of 3.5 would be wide open (at 18 mm on your lens) and yield the shallowest depth of field. At 70mm 5.6 would be wide open. You are probably shooting at an aperture of 11, 16 or 22 which would yield sharper backgrounds.

[kris142]

Thanks, It's all useful information, unfortunately that I already knew. I appreciate you taking your time to write this up.

I am shooting in M at the lowest aperture possible for the zoom I am fixed on.

[lputman]

Originally Posted by kris142

I've been told to step farther away from the subject, but I've seen that you must be closer.

I think this gets more in the focal distance which I am not adept on. So if your subject is further away from the background, your focal distance will vary rendering the background bokeh that you're seeking.

Here's a shot from a peewee football game that I took, the ball was closer to the side of the field that I was on. Using a 70-300 zoom lens, 220mm f6.3, you see the blur of the people on the other side of the field.

[cman78]

From reading your post it sounds like you may be shooting with settings that either have a very wide DOF or you may be around the infinity settings of your lens.

Check out this site Online Depth of Field Calculator It lets you put in all your settings including distance to subject. You can play around with it and find where the short depth of field would be on your lens given your environment. Just remember the settings from the page and try them next time your out shooting.

[The Viking]

Maybe the answer isn't in the camera?

In the original of this picture, everything were in focus. My solution was to try and post process it. (see my post in the software section HERE)

[kris142]

Thats a beautiful dog ^^..

I'll go on my other computer with the stuff on it and try that Calculator.

Thanks for the replies,
Keep them coming if you thing of anything...

[kris142]

Heres an example. CROP, LEVEL, CONTRAST, HUE all adjusted
The backround is blurred, but still more focused then I would like.
EXIF:

[lputman]

I would think that the spot you shot from didn't allow the rider to be far enough from the background. It could be more a matter of where you are positioning yourself in relationship to what's in the background and still be able to get the money shots.

[blumesan]

I think you already have all the information you need. Shoot at the largest aperture available and get as close to the subject as you can. If that still doesn't do the trick, you need another lens which will allow you to shoot at larger apertures (~ f/2.4) at your chosen focal length.

[Take12]

Originally Posted by kris142

Heres an example. CROP, LEVEL, CONTRAST, HUE all adjusted
The backround is blurred, but still more focused then I would like.
EXIF:

Yep, Kris, the background is "still more focused than [you] would like", because F/5.6 is not a very large aperture at all. Need more blur? Use a larger aperture (lower number)!
In the case of that lens of yours that is unfortunately not possible, of course. You will need another lens for more blur/less DoF.

Have fun!

[tekdiver500ft]

The longer the lens, the shallower the DoF for a given aperture. The greater the distance between the subject and BG, the less in focus the BG. The closer the camera to the subject, the shallower the DoF. When people tell you to get farther from your subject, they are assuming that you will use a longer lens to get the same amount of subject in the frame. BTW, the "lens conversion factor" involved in crop bodies is a myth. A 300mm lens is a 300mm lens, and will treat compression the same way, regardless of what body it is on. The only thing that changes is how much of the image circle makes it into the final image.

What you need to do, is shoot in Av, with the Aperture set to its widest setting (smallest number), get as close as possible to your subject, and keep subject as far from the BG as possible.

[Ed Shapiro]

Hey Kris!

This may seem off topic at first but do me a favor and read on.

It seemed that the new parents were having a problem with the new baby. He would keep them up all night- every night with incessant crying. The just could not figure it out- the baby hand no colic the dopers were clean and well fitted and no fever or rash was present. One nigh when the crying was particularly bad there were at their wit’s end. So there they were in the middle of the nigh with a screaming baby reading one of their books on child care. The screaming was so loud that Grandma, who lived next door, was awakened and came in to see if she could help, she reconnoitered the ongoing scene and said ‘PUT DOWN THE BOOK AND PICK UP THE BABY”! All the poor kid wanted was to be picked up for a while.

Sooooooooooo- Put down the charts, shut off the computer and PICK UP THE CAMERA. Ok- It is good to know about the technicalities of depth of field and understanding how to use hyper-focal distances in cases of selective focus.
As you know I am a hands on kinda guy and much can be learned by outing you camera and lenses through their paces. I want you camera to become an extension of your hands rather than a clumsy tool that get between you and your subjects.

Find a wall and tack a newspaper on it at your eye level, page after page in a lined of about 15 feet. Makes sure the room is well lighted, place you camera in a tripod and focus on various columns and observe what goes in and out of focus at various distances, focal-length settings and apertures- get a feel for it. Check your images out on your computer and print some of the results to verify the results that you may have observed on the camera’s screen. For longer distances a well lighted brick wall will do the job. In either case start the camera position at a oblique angel to the wall and then move it in at that is almost parallel and observe the results.

Generally speaking, you will get more depth of field at smaller apertures, lenses of shorter focal-lengths and at further distances. Inversely, you will get less depth of field at wide apertures, longer lenses and at closer distances. In sports photography, many of the great images that you see published with very shallow depth of field are made with very long lenses- 300mm to even as much as 1000mm.

After making some of the aforementioned tests, do some practical shooting- close up detail shots, portraits, and scenic images. Then concentrate on practical usages. You can use shallow depth of field to shoot through a cage at the zoo and come up with a good close up image of an animal. You can use greater depth of field to frame a scene in an archway or included important foreground. You can wipe out a distracting background with shallow depth of field or bring important background detail into acceptable focus to tell a specific story.

If your auto focus system fails, with a normal or wide angle lens, you can scale focus if you know exactly how to use the depth of field scale on you camera. There are also specialized cameras that do not have reflex viewing or rangefinder focusing. Theses are super-wide and panoramic cameras and aerial cameras where scale focusing is required.

My philosophy for fast learning is “shoot first and ask questions later” as long as you are not on a job or any other critical situation. With film that was a pretty expensive venture but with digital imaging you can be a walking talking experimental optical laboratory. Once you see all of this through your camera, all the formulas will make better sense and by the time you have to out on a paying assignment, you will have it all down pat. Go for it!

Even the most cutting edge camera is nothing more than a piece of machinery until it becomes an extension of you hand and more importantly of your mind and your heart.

Ed

[Brooks]

You need a longer lens and a wider aperture. A 70mm focal length and an aperture of f/5.6 will not get you what you want on a DX chip. It's that simple.

[JohnC]

I'm with Brooks. You need longer and faster glass to blur the background in this situation. You could get less DOF with the 70mm lens by moving in a lot closer to the subject. But that probably would not be safe and probably would not be allowed (you would need to be on the track with the riders). When working from a fixed location the longer lens has a few things going for it. First, the subject is magnified more, so less DOF. Second, it has a narrower field of view, so you get fewer distractions in the background.

[Ed Shapiro]

Is this lens long enough? In the olden days press photographers used BIG BERTHAS, the were giant telephoto lenses that were designed to fit on the old 4x5 amd 5x7 Graphlex SLRs. The one pictured here is in the neighborhood of 1500mm. Theses were used to cover sports such as baseball from a press box high above the stadiums.

Ed

[Brooks]

Originally Posted by Ed Shapiro

Is this lens long enough? In the olden days press photographers used BIG BERTHAS, the were giant telephoto lenses that were designed to fit on the old 4x5 amd 5x7 Graphlex SLRs. The one pictured here is in the neighborhood of 1500mm. Theses were used to cover sports such as baseball from a press box high above the stadiums.

Ed

Ed,

Let's see.....1500mm on 4x5 film is similar to a 750mm on 6x7 film or perhaps a 350-400mm on 35mm full frame film or a 600mm on a DX chip...

That's might be long enough but you know, bigger is still better....always has been, always will be.

[Ed Shapiro]

The 5 x 7 RB Home Portrait model (1912-1940) has a slower top shutter speed of 1/500. Besides its function for portrait photography outside the studio, it was used with "Big Bertha" telephoto lenses of focal lengths up to 40 inches for long-distance sports photography.

This information from Graphlex data and here's the camera. Yup- the bigger the better!

Ed

[Ed Shapiro]

It's me again. Just when I though I had the "smart-ass award of the week- look what I found:

Article Summary

September 14, 2006 One of the displays worth visiting at Photokina when it opens in CologneCologne - Wikipedia, the free encyclopedia on September 26 will be the Carl Zeiss stand where the optical specialist will be showing the world’s largest telephoto lensTelephoto lens - Wikipedia, the free encyclopedia . Developed for long distance wildlife photographyWildlife photography - Wikipedia, the free encyclopedia , the supertele lens is purpose-built for the Hasselblad 203 FE and provides 21x magnification. At 1700 mm focal length and a speed of f/4 this lens put requirements on optical glas, lens assembly and quality assurance methods, never before encountered in photo lens manufacture. Hand-holding the lens is not an option, no matter how big you are – it weighs in at 256 kg and required Carl Zeiss to develop totally new ways of operating a telephoto lens, including servo controlled aiming and focusing.
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That little dot at the end of the lens is a Hasselblad