Type of lens for shallower DOF?

salils

salils

Well-known member
I'm a little new to the SLR world (but more experienced in the video world) so please excuse my ignorance. Is there any type of lens for SLR cameras that will give a shallow depth of field? Besides just getting a lens that I can have a very wide aperature like f1.7, is there anything else to keep in mind? I recently purchased a Pentax K100D Super and the Pentax Zoom Super Wide Angle SMCP-DA 18-55mm f/3.5-5.6 AL Autofocus Lens I'm looking for a lens for portraits and stuff that will give me a narrower depth of field. Is there any way to achieve this with out purchasing an expensive adapter like people do for video cameras? (ie: Letus 35)
 
The only thing that can create a more shallow DOF is higher aperture, or something like a tilt/shift lens.

The reason that people use adapters on video cameras is so they can use high aperture SLR lenses, then it's the lens and not the adapter that changes the DOF.
 
You can pretty much get a shallow depth of field with any lens you throw on the D-SLR depending upon where you stand in relation to the subject. Of course, the general rule of thumb...the longer the focal distance the shallower the depth of field.

For portraits...check out some of Alveraz's photos...he posts his client's headshots all the time and I think he said he uses the 85mm...and the field is'a shallow.
 
A general rule of thumb is use longer focal length lenses and shoot wide open,
that will give you a shallow DOF and will blow your background out.
 
Exactly what CharlieG said... Shoot things at the longest possible focal length and you will get a drastically more shallow DOF. You can get 200mm zoom lenses for around $100 used at KEH.com
 
Jeremy Ordan said:
Exactly what CharlieG said... Shoot things at the longest possible focal length and you will get a drastically more shallow DOF. You can get 200mm zoom lenses for around $100 used at KEH.com
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I don't believe a longer focal length will affect DOF, it only magnifies the out of focus area.
 
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So unless you want to take a tape measure and your TI-85 with you before you shoot, get a faster lens.

Shooting with fast glass is by far the easiest way to resolve the issue, although I still use the distance method for my DVX as I've never bought an adapter. The only problem with creating a smaller DOF with slow glass is that you either have to be very close, or very far and zoomed in. It doesn't always work for the shot you need. Of course the only problem with fast glass is $$$$$.
 
technically the only thing that effects DOF is sensor size/focal length and aperture. The bigger the sensor the the shallower you are going to be able to achieve at a wider focal length. If you have an infinity MP camera it is true that you could crop or magnify an image and achieve the same shallow DOF as using a telephoto lens but this is the real world.
 
the distance to the subject exempifies the DOF but the DOF exists wether or not there is a subject in the picture. It sounds picky because of course you would place the subject at a certain distance to get a shallow looking photo but I was just trying to explain the technical factors that contribute to the DOF of a photo.
 
egproductions said:
the distance to the subject exempifies the DOF but the DOF exists wether or not there is a subject in the picture.
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Huh? I understand what you are saying but poor Salilis. His head must be spinning. And, if you didn't have a subject, how could you capture a shallow depth of field? If you had NOTHING in the photo, no two relative objects with which to achieve a shallow dof, you'd have either all blur or infinity.
 
I should actually step back a little and say that the focus distance can accentuate the DOF. The closer the focus point the shallower your picture looks. Just a stupid note, "Subject distance" can be misleading because you don't always focus on your subject although I guess what you are focusing on could be considered your subject (see what I mean?)
 
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Yup. Perfectly.

So, to recap Salilis....the longer the focal length of the lens the easier it is to get a shallow depth of field. But you can get it from much shorter Focal Distance lengths...just depends on where you position yourself from what your aimin' at!
 
I really like the idea in the wiki of focus-stacking. Is there a way to automate the process in photoshop instead of manually masking out images?
 
Jeremy Ordan said:
And we have one already here at DVXUser: http://www.dvxuser.com/V6/showthread.php?t=893&highlight="Depth+Field+Tutorial"
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Hmm...I saw the wiki you sent me but...
"In what is considered the bible of cinematography, "A Hands-On Manual for Cinematographers", David Samuelson states at the conclusion of his section on depth of field : "Depth of field remains the same, regardless of lens focal length, so long as the image size (and f-stop) is the same."
http://www.bluesky-web.com/dofmyth.htm
 
salils said:
"In what is considered the bible of cinematography, "A Hands-On Manual for Cinematographers", David Samuelson states at the conclusion of his section on depth of field : "Depth of field remains the same, regardless of lens focal length, so long as the image size (and f-stop) is the same."
http://www.bluesky-web.com/dofmyth.htm
Click to expand...

Yes, Salils...but there is a very critical component in that quote that might be muddying up the waters for you...its the "...so long as the image size...is the same" part. If you are 100 feet from an object and using a 70mm lens or you are 100 feet from an object and using a 100mm lens, the image size does NOT remain the same. The 100mm lens would have a shallower depth of field and the object would be larger. If, however, you had the 100mm lens and you stepped back the required number of feet to frame the image identically to the 70mm lens, the depth of field would be equal, because the image would be the same size.

So, all things being equal...assuming you are standing in one spot and pointing your camera at the same target your depth of field will depend upon the focal distance of your lens because the image size will be determined by this component. You use a 70mm lens your image will be one size, you use a 100mm your image/subject will be another. Make sense?
 
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