Toronto Photography Meetup Group

So Downtown Dan and I were discussing this at GOOF in the beaches at the Jazz Festival event.

Dans's original question is how someone can get the effect of good shallow DOF on cameras with sensors smaller than full frame, be them P&S, four thirds, or 1.5/1.6 crop dslr's.

The issue is that all things being equal, a photographer will frame/compose the photo the same way based on what they see in the viewfinder. The result of this is that FOV is the same, but on full frame the user is closer to the subject. As a result, the focus gradient is smaller, and boom, shallow DOF.

For those that don't understand this, take 5 mins to look at a DOF scale on a lens and you'll understand: focus distance is not a linear scale.

This is sorta indirectly related to the bokeh thread. I'm wondering if one of the four thirds users can chime in on the 25mm pancake lens. I read that is is a retro focal design, which as a rule of thumb does not have good bokeh.

Anyway, does anyone disagree with my logic, and how do we answer Dan's original question?

Use a longer lens. This is an example I did back when I shot with a 2mp ultra zoom (38-380mm equiv.) bridge camera that had a tiny 1/2.7" (0.37") sensor:
http://img.photobucket.com/albums/0803/Mikefellh/OlyC700stuff/dof.jpg

At 380mm it's actual focal length was 59mm, and that's why the background was starting to blur.




Actually, a better example would be to see how the three Olympus lenses that start at 14mm (28mm) do against each other in terms of bokeh as they all have different lens designs...and someone did a test comparing the three lenses at 42mm:
http://www.biofos.com/esystem/e400_tst.html#SECTION3

That works.

1.The subject should be further away from the background you want to blur up.

2.Photographing at the minimum distance with the widest aperture of the lens

Or simple cheating by selectively blurring up the background with pp which is the whole purpose of discussing the DoF


Daniel

True but there are ways to circumvent / improve that

1. Ensure the background is miles away from the subject
2. Use apertures as wide as possible
3. Using low iso 100 and underexposing the background do help as well

Nobody can define 'good' bokeh which is very subjective indeed


Daniel

It is defined.... whether you _like_ it or not is what's subjective. Most people simply don't understand it.

It's not the _amount_ of blur, it's the _quality_ of the blur.

Many people incorrectly use the term to mean the amount of blur. A slightly OOF background can exhibit good bokeh. You can have a highly OOF background exhibit bad bokeh like donuts or swirls.

Doubling of lines in the background or swirly effects is bad bokeh. OOF highlights that fade to the edge instead of getting brighter towards the edge is good bokeh - the opposite of this would be donuts.

For example, flare is an optical characteristic of a lens, and generally to be avoided, but it can be made to work to good effect. You can do the same with just about any "design flaw" or defect in any lens. A lensbaby is basically an uncorrected minicus or doublet that's not correctly centered, but you can use it to good effect or just cause everyone to be sick.

On DSLR's or the m43 bodies, you can choose a lens with a larger aperture. Some are using f1 or even f0.9 and f0.75 C-mount lenses on the G1/GH1/EP1. On 1.5/1.6x crop bodies, we have the Sigma 30/1.4 . You can also use a tilt/shift lens or lensbaby to change the plane of focus.

Going with a longer focal length is another option, but then framing and motion blur will be an issue, especially in low-light environments.

In the end tho, you basically need to go to a larger sensor/film to get more shallow DOF for the same FOV.

Well the bokeh of the lens can be described in a very objective way, describing degrees of good bokeh is very subjective (see one of I think Chris's many other threads on the subject where Mawz has described in technical detail the difference between Zeiss, Leica and different lens designs).

I agree people get mixed up between shallow DOF shots and bokeh but lets face it the common usage of the word bokeh is to describe a shallow DOF photo most often at night with bokeh "balls". The lens is shot wide open resulting in a circle aperture.

To a lesser degree even bad bokeh is subjective. Some of the master pieces in large format had swirly bokeh yet personally I would take my Mamiya TLR glass over the 2 Yashica TLRs I tried (both had slightly swirly bokeh).

Sorry I guess I digressed from the thread topic.

Medium Format 55mm around f5.6
<a href="http://www.flickr.com/photos/metrix_feet/2664389558/" title="Filipa Beneath The Tower by Metrix X, on Flickr"><img src="http://farm4.static.flickr.com/3246/2664389558_7fdd9265fa_m.jpg" width="236" height="240" alt="Filipa Beneath The Tower"></a>

Full frame 1953 Zeiss Contax 50mm at f1.5
<a href="http://www.flickr.com/photos/metrix_feet/2900052501/" title="Flower Shop On Queen F1.5 by Metrix X, on Flickr"><img src="http://farm4.static.flickr.com/3031/2900052501_687ea02d08_m.jpg" width="159" height="240" alt="Flower Shop On Queen F1.5"></a>

1.5 crop factor canon 50mm f1.4 at f2
<a href="http://www.flickr.com/photos/metrix_feet/2564757298/" title="After The &quot;What Woman Want&quot; After Party by Metrix X, on Flickr"><img src="http://farm4.static.flickr.com/3176/2564757298_90f9f449bd_m.jpg" width="160" height="240" alt="After The &quot;What Woman Want&quot; After Party"></a>


1.5 crop factor canon 100mm at f2
<a href="http://www.flickr.com/photos/metrix_feet/2967385126/" title="Inna On Track by Metrix X, on Flickr"><img src="http://farm4.static.flickr.com/3035/2967385126_0e089e181a_m.jpg" width="240" height="160" alt="Inna On Track"></a>

1.5 crop factor bellows macro old range finder or enlarger lens 135mm at f5.6

<a href="http://www.flickr.com/photos/metrix_feet/1216772805/" title="Thursday Walk in Miniature by Metrix X, on Flickr"><img src="http://farm2.static.flickr.com/1054/1216772805_c573f11983_m.jpg" width="240" height="160" alt="Thursday Walk in Miniature"></a>

Olympus c-4000 (.55" CCD) infrared converted 19mm f5.6
<a href="http://www.flickr.com/photos/metrix_feet/1486168188/" title="Infrared-21 by Metrix X, on Flickr"><img src="http://farm2.static.flickr.com/1235/1486168188_0e5314e49c_m.jpg" width="240" height="180" alt="Infrared-21"></a>

So yes get closer to the subject, use telephoto lenses and widest aperture. I don't know if I would use Chris's analogy as personally I shoot differently depending on the lens camera combination, a 80mm on a crop body is a zoom while on a Medium format it is a normal walk around lens.

This is a good tutorial on DOF including a nifty calculator.
http://www.cambridgeincolour.com/tutori ... -field.htm