snubbr.com

Nailing DOF. Every Time.
Maybe DOF precision is not really important. But, then I see some sample photos of people's faces where all the focus is packed on the tip of the subject's nose. I see people taking pictures of trees where the trunk is in focus, but the leaves are soft. These all seem like DOF (and focus) errors and I don't want to be held captive by some dumb autofocus system..

Google found me a slide rule that does DOF calculations (http://www.amazon.com/...ExpoAperture-Depth-Aperture-Calculator/dp/B000766SVW), but do any DSLR's incorporate this feature somehow? (I guess I could use this, but then how do I accurately measure distance to subject, a laser rangefinder? Mil-dot sniper scope? heh).

An example of what I'm talking about: On a 1.6 crop camera, I want 0.50m front-to-back DOF for a subject standing 5m away. According to http://www.dofmaster.com/dofjs.html:.

100mm, f/5.6 will get there.86mm, f/4 will get there.50mm, f/1.4 will get there, too..

Do DSLR's have such a feature? Thanks...

Comments (25)

Dslrs do not have an automatic dof feature it is dependent on the users knowledge of how fstops affect dof in certain situations and at what distance..

As for you remarks about objects being in focus, remember that you or I do not know what the photog had in mind. he may have used an fstop that on purpose put things into or out of focus. the ability to do so is one of the features that a dslr gives the user: a variable dof depending on fstop selected. it is up to the user to use correctly and for what purpose. it is called selective focus..

Try reading on the following websites-http://www.dofmaster.com/dofjs.htmlhttp://www.synvis.com/hyperfoc.htmhttp://www.synvis.com/prod01.htm.

I have the card above. I have a copy in my wallet and my photo bag...

Comment #1

AJLee wrote:.

Google found me a slide rule that does DOF calculations.

(http://www.amazon.com/...ExpoAperture-Depth-Aperture-Calculator/dp/B000766SVW), but do any DSLR's incorporate this feature somehow? (I guess I could use this, but then how do I accurately measure distance to subject, a laser rangefinder? Mil-dot sniper scope? heh).

Before you spend any money, take a look at this:.

Http://www.dofmaster.com/dofjs.html.

You don't need to measure the distance to the subject, just guess. The difference between the depth of field at five feet and six feet, say, isn't enough to matter..

The calculated depth of field is not a hard-and-fast figure. Take lots of pictures and found out how much depth of field you like for your images...

Comment #2

On some lenses (mainly fixed focal length and older push-pull zooms) there's a DOF scale you can use..

But, on a lot of SLRs, digital and film, there is a DOF preview button so you can see for yourself how much will be in focus..

Hope this helps.

AJLee wrote:.

Maybe DOF precision is not really important. But, then I see somesample photos of people's faces where all the focus is packed on thetip of the subject's nose. I see people taking pictures of treeswhere the trunk is in focus, but the leaves are soft. These all seemlike DOF (and focus) errors and I don't want to be held captive bysome dumb autofocus system..

Google found me a slide rule that does DOF calculations.

(http://www.amazon.com/...ExpoAperture-Depth-Aperture-Calculator/dp/B000766SVW), but do any DSLR's incorporate this feature somehow? (I guess I could use this, but then how do I accurately measure distance to subject, a laser rangefinder? Mil-dot sniper scope? heh).

An example of what I'm talking about: On a 1.6 crop camera, I want0.50m front-to-back DOF for a subject standing 5m away. According tohttp://www.dofmaster.com/dofjs.html:.

100mm, f/5.6 will get there.86mm, f/4 will get there.50mm, f/1.4 will get there, too..

Do DSLR's have such a feature? Thanks...

Comment #3

Thanks for the reminder. However, I've read about DOF previews dimming the viewfinder and liveview to the point of becoming of limited use to a lot of people. When I get my grubby hands on a 450D, this is one of the first things I'll be checking out...

Comment #4

Maybe not exactly what you want, but I know some Pentax DSLR's (I know my K100D definately has it) have a "preview" button which you can set to stop down the lens aperture to whatever you have set for the shot so that you can actually see the DOF through the viewfinder before taking the shot. I have found it to be very handy at times. The only problem is it makes what you see through the viewfinder dimmer (how dim depends on how small your aperture is)...

Comment #5

Steve Balcombe wrote:.

You don't need to measure the distance to the subject, just guess.The difference between the depth of field at five feet and six feet,say, isn't enough to matter..

The calculated depth of field is not a hard-and-fast figure. Takelots of pictures and found out how much depth of field you like foryour images..

Can you clarify what you mean by DOF not being a "hard-and-fast" figure? If you mean that the DOF that is preferred for any given subject is up to personal taste, then I understand. But I really wonder if "winging" it is productive. If I can calculate this reliably then I think I can really use the camera to it's fullest..

As I understand it, it's a pretty strict mathematical relationship. At 50 ft, 200mm, and f/4, you'll always get a DOF of 2.86 ft. So if I try to take a picture of a big tree by focusing on the trunk, then every branch extending at least 1.43ft into the foreground or background will be soft. So one would get a soft picture overall, leading people to wonder if their expensive zoom lens is defective. But if you focus on a dog, then it'll be a dramatic picture with the dog in perfect focus and a blurred background. The implications are huge.

Shutter speed will have to be slowed considerably, or ISO increased to maintain a good exposure..

Isn't this the kind of thought process crucial for a good shot?..

Comment #6

GaryDeM wrote:.

Dslrs do not have an automatic dof feature.

A-DEP mode on many Canon DSLRs. Scroll about half way down this page:.

Http://www.dpreview.com/reviews/canoneos40d/page7.asp.

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #7

Come to think of it, let's say you're taking shots of a party enclosed in a space that is 30" by 30". If I'm near the edges of the room, and people are standing near the middle, then if I can get aperture and FL setting to lock in a DOF of at least 15" under the lighting conditions, I'll never have to focus. Just snap away...

Comment #8

AJLee wrote:.

Can you clarify what you mean by DOF not being a "hard-and-fast"figure?.

It's subjective, and is different depending on how much the image is enlarged and how closely it is viewed..

As I understand it, it's a pretty strict mathematical relationship.At 50 ft, 200mm, and f/4, you'll always get a DOF of 2.86 ft..

This is based on a person with "normal" vision viewing a certain size print (typically 8x10) from a specific distance (typically 10 inches). If you change the sensor size (and therefore enlargement), output size, viewing distance, or visual acuity, you change the DOF..

So ifI try to take a picture of a big tree by focusing on the trunk, thenevery branch extending at least 1.43ft into the foreground orbackground will be soft..

DOF is shorter in front of the subject, and longer behind. How much depends on how close you are to hyperfocal distance. At hyperfocal distance, DOF behind the subject is infinite..

Isn't this the kind of thought process crucial for a good shot?.

You get to trade off blur (shutter speed), DOF (aperture) and noise (ISO). It's up to you to figure out what compromise is best. What's even more crucial is seeing the shot before you whip out your camera. Figure out what you want to capture, then go about trying to accomplish it..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #9

AJLee wrote:.

Come to think of it, let's say you're taking shots of a partyenclosed in a space that is 30" by 30"..

" is inches, I think you mean ' (feet)..

If I'm near the edges of theroom, and people are standing near the middle, then if I can getaperture and FL setting to lock in a DOF of at least 15" under thelighting conditions, I'll never have to focus. Just snap away..

That's called zone focusing. Set the lens to a particular distance, shoot when the subject is in range. You won't get really sharp focus (unless you are lucky), because whatever the DOF is there's only one infinitely thin plane of sharpest focus..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #10

Ah, yes, of course. In my excitement, I used ". Hm.. a party in a 30" x 30" phone booth......

Comment #11

AJLee wrote:.

Can you clarify what you mean by DOF not being a "hard-and-fast"figure? If you mean that the DOF that is preferred for any givensubject is up to personal taste, then I understand. But I reallywonder if "winging" it is productive. If I can calculate thisreliably then I think I can really use the camera to it's fullest..

As I understand it, it's a pretty strict mathematical relationship..

[snip].

Yes, the size of the blur circle at the image plane is mathematically calculated, and from that we get the region within which the blur circle is so small that we call it "acceptably sharp". But what is "acceptable"? - that's where the variation comes in. Some people seek critically sharp photos at 30"x20", and others are happy with something which prints ok at 6"x4". But it's not just the print size; even comparing photographs at the same size it is a matter of judgement whether something is sharp enough or not. High contrast subjects look sharper; subjects with a blurred background look sharper by contrast with their surroundings. It is universally true that sharpness of the eyes in a portrait matters more than sharpness of the hair - but how much softness is acceptable?.

There is of course a difference between allowing something to be blurred because it is still adequately sharp, and allowing something to be blurred because blurred is ok. Depth of Field is about the first of those, but the two issues are inextricably linked..

The DoF calculators do allow you to set your own standard, in a sense, by letting you adjust the "circle of confusion". The standard values do work pretty well - they are based on decades of experience as well as some science - but if you want to calculate depth of field based on your own more (or less) critical standard you can do that. But until you actually get out there and takes lots of pictures under varying conditions you won't know how the numbers relate to the real world..

Isn't this the kind of thought process crucial for a good shot?.

You are going through the right thought process now, by asking these questions. Out in the field experience and instinct matter more than calculators..

I sometimes cheat by taking the same shot two or three times at different apertures because I'm not sure how much depth of field will look best. Is this poor technique, caused by my inability to calculate the depth of field? Well, maybe, but it's no more or less valid than taking several differently-framed shots so you can decide later which composition you like. You never reach a point where experimentation is no longer useful - and happily in this digital age we can do it for free...

Comment #12

AJLee wrote:.

Do DSLR's have such a feature?.

Advanced DOF calculations, sophisticated histograms, and complex scripted operation from a DSLR? Are you kidding? For that you need a compact.  .

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #13

Some comments:.

- the DOF preview buttom will only work accurately on completely manual focus slr, due to the light deverted to teh AF-sensors. it is NOT accurate on dSLR, at least with fast glass. have a look here:.

Http://www.dphotoexpert.com/...live-view-versus-the-cheating-dslr-viewfinder/.

- live view is an option, but only the of the main sensor type ( thus not sony a3xx and not one of the modes at the oly e330)- get an old lens, they have DOF markings- at least canon dSLR have a A-Dep mode.

- for canon p&S is some additional software to run of the memory card which supplies thsi feature, look here http://chdk.wikia.com/wiki/CHDK.

R...

Comment #14

Schmaud wrote:.

Some comments:.

- the DOF preview buttom will only work accurately on completelymanual focus slr, due to the light deverted to teh AF-sensors. it isNOT accurate on dSLR, at least with fast glass. have a look here:.

Http://www.dphotoexpert.com/...live-view-versus-the-cheating-dslr-viewfinder/.

Interesting article, but I don't agree with his description of how depth of field appears in the 40D viewfinder. With a wide-open fast lens it is around f/2.8, not "f/4.5, f/5.6 or most commonly f/6.3". I don't really understand why, having gone to all that bother, he doesn't show us a real f/5.6 shot to compare with the through-the-viewfinder shot. That way he'd prove his assertion, or disprove it as I believe would be the case..

Good point about depth of field showing correctly in Live View though - if only the 40D screen was better, perhaps we'd actually be able to see it!!..

Comment #15

Steve Balcombe wrote:.

Interesting article, but I don't agree with his description of howdepth of field appears in the 40D viewfinder. With a wide-open fastlens it is around f/2.8, not "f/4.5, f/5.6 or most commonly f/6.3"..

Yep. On low end DSLRs it's typically around f/4, still faster than the article says..

I'm sure you get it, but to make the point clear to others. On low end DSLRs:.

At f/11 the viewfinder is too dim to see much difference in DOF..

At f/4 or faster you don't need DOF preview, as you'll only see f/4..

So DOF preview is only useful at f/5.6 and f/8. Two stops. Pretty much not worth the bother..

Good point about depth of field showing correctly in Live View though- if only the 40D screen was better, perhaps we'd actually be able tosee it!!.

Hopefully the next iteration will have a better screen. It's not bad, but it could be better. Have you tried the LV on a laptop? The writer of the article didn't discuss that. You can get LV on a laptop and have fine control over focus without touching the camera or getting up from your chair. You won't have vibrations the article's author mentions..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #16

Graystar wrote:.

Advanced DOF calculations, sophisticated histograms, and complexscripted operation from a DSLR? Are you kidding? For that you needa compact.  .

There are several people trying to get CHDK working on EOS DSLRs. I'm sure it will happen sometime in the not-too-distant future..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #17

Nickleback wrote:.

Steve Balcombe wrote:.

- if only the 40D screen was better, perhaps we'd actually be able tosee it!!.

Hopefully the next iteration will have a better screen. It's notbad, but it could be better. Have you tried the LV on a laptop?.

Yes, I have, I use Remote Capture quite often and Live View has added another facet to that. To be honest it hasn't so far been as useful as I thought it might be. If you have time to set up Remote Capture, you can just take a shot and check it on the computer screen, as was the only option with my 400D. Being able to see a preview adds very little in practice, once the novelty value has worn off..

I've also tried out DSLR Remote Pro which, fascinatingly, implements contrast-detect AF which is of course missing on the 40D. However it is slow and (to me) not particularly useful...

Comment #18

Advanced DOF calculations, sophisticated histograms, and complex scripted >operation from a DSLR? Are you kidding? For that you need a compact. .

Which camera is this from? Please do tell!..

Comment #19

Zadam wrote:.

Maybe not exactly what you want, but I know some Pentax DSLR's (Iknow my K100D definately has it) have a "preview" button which youcan set to stop down the lens aperture to whatever you have set forthe shot so that you can actually see the DOF through the viewfinderbefore taking the shot. I have found it to be very handy at times.The only problem is it makes what you see through the viewfinderdimmer (how dim depends on how small your aperture is)..

Nope - you can set the Pentax to show you the DOF Preview either through the viewfinder or on the screen...

Comment #20

AJLee wrote:.

Advanced DOF calculations, sophisticated histograms, and complex scripted >operation from a DSLR? Are you kidding? For that you need a compact. .

Which camera is this from? Please do tell!.

Could be any one of a number of Canon digicams. See the full list here:.

Http://chdk.wikia.com/...t_camera_models_are_supported_by_the_CHDK_program.3F.

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #21

AJLee wrote:.

Which camera is this from? Please do tell!.

Canon A710 IS running CHDK. :o).

Http://chdk.wikia.com/wiki/Main_Page..

Comment #22

Wow, thanks for the CHDK link. If CHDK is giving real-time DOF off of internal camera readings of aperture, FL, and subject distance, then that is awesome. Knowing the hyperfocal distance would be awesome for landscape shots..

Question is, do cameras get the subject distance right, within acceptable limits?..

Comment #23

AJLee wrote:.

Question is, do cameras get the subject distance right, withinacceptable limits?.

It depends. If CHDK ever gets ported to EOS, remember that not all EF lenses return distance info. Of the ones that do, accuracy for at least ring USM lenses seems pretty good. However it seems that once you get to hyperfocal distance the focus distance goes to infinity. So for example on the 17-40/4 L, the highest reported distance before infinity is about 6 feet..

Seen in a fortune cookie:Fear is the darkroom where negatives are developed..

Comment #24

JChristian wrote:.

Zadam wrote:.

Maybe not exactly what you want, but I know some Pentax DSLR's (Iknow my K100D definately has it) have a "preview" button which youcan set to stop down the lens aperture to whatever you have set forthe shot so that you can actually see the DOF through the viewfinderbefore taking the shot. I have found it to be very handy at times.The only problem is it makes what you see through the viewfinderdimmer (how dim depends on how small your aperture is)..

Nope - you can set the Pentax to show you the DOF Preview eitherthrough the viewfinder or on the screen..

Yeah but good luck trying to see how well things are in focus on the small low res screen... And I already mentioned seeing it through the viewfinder, so I'm not sure how "Nope" applies to what I said?..

Comment #25

Click Here to View All...

Sponsored Amazon Deals:

1. Get big savings on Amazon warehouse deals.
2. Save up to 70% on Amazon Products.


This question was taken from a support group/message board and re-posted here so others can learn from it.

 

Categories: Home | Diet & Weight Management | Vitamins & Supplements | Herbs & Cleansing |

Sexual Health | Medifast Support | Nutrisystem Support | Medifast Questions |

Web Hosting | Web Hosts | Website Hosting | Hosting |

Web Hosting | GoDaddy | Digital Cameras | Best WebHosts |

Web Hosting FAQ | Web Hosts FAQ | Hosting FAQ | Hosting Group |

Hosting Questions | Camera Tips | Best Cameras To Buy | Best Cameras This Year |

Camera Q-A | Digital Cameras Q-A | Camera Forum | Nov 2010 - Cameras |

Oct 2010 - Cameras | Oct 2010 - DSLRs | Oct 2010 - Camera Tips | Sep 2010 - Cameras |

Sep 2010 - DSLRS | Sep 2010 - Camera Tips | Aug 2010 - Cameras | Aug 2010 - DSLR Tips |

Aug 2010 - Camera Tips | July 2010 - Cameras | July 2010 - Nikon Cameras | July 2010 - Canon Cameras |

July 2010 - Pentax Cameras | Medifast Recipes | Medifast Recipes Tips | Medifast Recipes Strategies |

Medifast Recipes Experiences | Medifast Recipes Group | Medifast Recipes Forum | Medifast Support Strategies |

Medifast Support Experiences |

 

(C) Copyright 2010 All rights reserved.