[beholder3]

[deleted]

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Last edited by beholder3; 08-11-2013 at 06:42 AM. Reason: [deleted]

[Lowell Goudge]

What you have tried to explain here, really , is that the longer the lens for a given background spacing, due to the combinination of depth of field, and the relative magnification of the background to subject that the out of focus blobs are bigger, and more pleasing with the long lens, than for an equally blurry background, but shot with a shorter lens, which results in a "confusing" background of dots.

I have been stressing this point for several years now. It really does come down to setup and not lenses. Tat is why the entire FF argument is so flawed People assume they will get better results with full frame without wanting to understand that there is actually science behind the images and itis just as possible to create the images with APS-C as FF

[Fogel70]

I think most photographers also take perspective into account, and with very long focal length the portrait might be too flat for their taste.
But I don't think that 135/2.8 lenses was popular by chance in the manual focus film days. They where cheap and gave enough DOF for portrait, but still with quite good background isolation.

[Lowell Goudge]

I think most photographers also take perspective into account, and with very long focal length the portrait might be too flat for their taste.
But I don't think that 135/2.8 lenses was popular by chance in the manual focus film days. They where cheap and gave enough DOF for portrait, but still with quite good background isolation.

Actually my favorite is a 200/3.5 preset for 1/2 body shots if you have enough space

[rparmar]

In many (not all) cases the photographer wants background blur and actively doesn't want shallow DoF, because the latter also leads to only one eye out of two being sharp or eyes sharp and nose plus ears unsharp - a lot of people do find this poor picture quality. They don't consider the nose in a portrait as "irrelevant background".

Your agenda is clear in starting your post by disparaging those who want thinner Depth of Field. Whether ultra-thin DOF is desirable or not is beside the point, and surely up to the taste of the photographer in question.

You then proceed to thoroughly confuse the situation photographers face when dealing with DOF. It's really not so complicated. There are only three relationships to consider.

1. Magnification of the image on the sensor is determined by lens focal length, subject distance, and the sensor size [1].

2. DOF is determined by magnification and aperture [2].

3. Blur can be calculated based on these same factors, taking into account the distance from the subject to whatever we want to blur (whether this is the foreground or background). I further note that the distribution of DOF in front (DOF-f) and behind (DOF-b) the focus plane is not constant. At the hyperfocal distance, DOF-b is infinite. At one-third of the hyperfocal distance, the ratio of DOF-f to DOF-b is 1:2. As the subject grows closer to the lens, this ratio approaches 1:1. This provides an easy way to visualise how blur will be manifest in a given optical situation.

To increase blur you can:
1. increase focal length,
2. increase sensor size,
3. increase aperture, or
4. increase distance between the subject and the background.

Far from being esoteric knowledge, I think that most photographers realise this!

Notes:
1. For a given circle of confusion.
2. Assuming the plane of focus is held constant, parallel to the sensor plane. Technical cameras or tilt adapters introduce further geometric complexity.

[rparmar]

Tat is why the entire FF argument is so flawed People assume they will get better results with full frame without wanting to understand that there is actually science behind the images and itis just as possible to create the images with APS-C as FF

While some people may have an over-simplistic view of DOF, your statement is equally flawed. All else being equal, a larger sensor will indeed give more options when it comes to DOF. It is certainly not just as easy to create this with a smaller sensor in all cases.

[JimJohnson]

There is only one focus point in an image. DOF is a range of acceptable focus in an image. And while there are obvious extremes, I think 'acceptable' means different things to different people in different images.

And I think there are still a lot of people who describe what they are seeking in their images' DOF the same way a friend was describing the home he was looking for: "I want a quiet house in the country near the airport because I travel frequently."

[Canada_Rockies]

Depth of field was defined as the range of focus where the points in an image look sharp from 1 foot away on an 8x10 inch print. Jim Johnson's comment is right on. There is only one point (or plane of points) that is actually in perfect focus in any image.

Those who want a "full frame" 24x36 image to get better control over depth of field would be better off with the 645 D. That gives you even better control. Better yet, get an 11x14 with tilt and shift to really control your depth of field.

[Sagitta]

I pretty much ignore most DoF arguments because everyone seems to think differently about them. Generally speaking, there are three stages (and everything in between) involved.

1 - extremely narrow DoF, background is basically a solid blur

2 - somewhere in the middle, background is recognizable in order to give 'pop'. Basically a layered effect. Some call it 'the 3-d' effect.

3 - superwide depth of field. Used for landscapes, etc.

Of course everything in between kind of just blurs into one another.

I've never bought a lens thinking "What kind of DoF will this give?" My priorities tend to be quality -> speed -> focal length, with of course price looming over everything because I tend to have a limited budget.

[alamo5000]

Personally I am no expert photographer, but my tastes in images that I have seen online or elsewhere, or things I like (and try to replicate) don't necessarily obliterate the background with razor thin DOF/bokeh combos. Background often adds context to a photo that could not be achieved in any other way. That said it all depends on your desired effect. Most of the time choosing a background (or selecting the right spot to get a good background) is just as important as the main subject at hand.

I am not always good at what I try to do with photography but I try and learn as I go.

[beholder3]

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[Pål Jensen]

While some people may have an over-simplistic view of DOF, your statement is equally flawed. All else being equal, a larger sensor will indeed give more options when it comes to DOF. It is certainly not just as easy to create this with a smaller sensor in all cases.

A larger sensor will not give more options regarding DOF. It is the opposite. If two lenses, say for APS and FF, have the same DOF wide open for the same angle of view, the small format will have more DOF options than the FF system for real world lenses. This is because they have the same minimum aperture, hence the APS lens has larger DOF range. In addition, the APS lens will have closer minimum focusing distance, and as a natural consequence have larger maximum magnification which gives more options for near/far relationships and DOF. This, among other things, explains why the "theory of equivalence" (read wide-open equivalence) is highly misleading and mostly irrelevant. And in addition comes "beholder3" points above.

[beholder3]

M[deleted]

[Lowell Goudge]

While some people may have an over-simplistic view of DOF, your statement is equally flawed. All else being equal, a larger sensor will indeed give more options when it comes to DOF. It is certainly not just as easy to create this with a smaller sensor in all cases.

But this is the whole argument. Just as easy. Either this is easy or just because people have had 60 up years of the 24x36 mm format to get accustomed to it. It is not impossible to get the same results with cropped sensors, it just requires people to think. Understanding the medium is part of being a photographer

[Sagitta]

But this is the whole argument. Just as easy. Either this is easy or just because people have had 60 up years of the 24x36 mm format to get accustomed to it. It is not impossible to get the same results with cropped sensors, it just requires people to think. Understanding the medium is part of being a photographer

Its not impossible, but the smaller you go, the smaller your object you want to separate from the background is going to have to be. These were all taken with a Samsung point and shoot (re: itty bitty sensor) and were about the best I could do to even have a noticeable background blur.