It depends on the bokeh charecterics of each particular lens.With 35mm camera I liked 80-85mm (=55-60mm on a half frame DSLR).

For example: Tamron 90mm macro works quite nicely for portaits but one has to stand off too far with APS DSLR, and the zone of sharpness is often not deep enough..

John.Please visit me at:http://www.pbase.com/johnfr/backtothebridgehttp://www.pbase.com/johnfr..

Marf wrote:.

Whats a good 35mm-equivalent focal length for blurred backgroundoutdoor portraits ? .

Somewhere around 100mm (in 35mm equivalent) is good for portraits. This is a ballpark number, not set in stone. What you want is a focal length that puts you far enough away for good perspective, but close enough that you don't need a megaphone. Around 10 to 15 feet..

Of course if you are shooting a group you'll probably need a wider angle lens and stand back a bit more, and if you are shooting head shots you could do with a longer lens..

As for getting good background blur, that depends on how far the background is relative to the subject and your camera. Aperture needed to achieve it depends on the format you are shooting. As a general rule, with 35mm systems, 100mm f/2.8 was fast enough to cover pretty much any situation, but of course faster (like f/2) gives you a bit more flexibility..

What this means for DSLR users:.

APS-C: 65mm f/1.3-1.84/3rds: 50mm f/1-1.4.

Many of these lenses don't exist, so you use what you can. On Nikon or Canon, folks tend to use 50/1.4 or 1.8, 60/2.8 macro, or 85 1.2/1.4/1.8. Similar lenses are available for Pentax and Sony. On Olympus, the 50/2.0 seems about right (if a bit slow), or you could use an adapter and something like the OM 50/1.4..

On the one hand, some say 50mm eq or 100mm eq would be good becausethen the model is not too far away,.

Ah, so you are shooting Oly. Yes, 100mm is a good place to start. Assuming you have a zoom lens that goes over/under 100mm equivalent, start shooting portraits at different focal lengths and see what you like. Don't worry about the background, just the framing and perspective..

On the other hand, maybe the Background Blur at longer focal lengths,200mm or 300mm, and maybe a bit smaller apertures, has the advantagethat der DOF is a bit less shallow, so more of the model is in focus,.

DOF is shallower at the same or even somewhat larger f-number as you move up in focal length. 200/5.6 has the same DOF at similar distances as 50/1.4. And at 300mm, unless you are shooting nose portraits, you'll need a megaphone..

Besides, if you want deeper DOF, just stop down. There's nothing stopping you from shooting 50/1.4 at f/4..

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

A lot of factors are involved..

You need a reasonable aperture to make sure the portaint subject is sharp, so that eliminates f1.2, f1.4, f1.8, f2, and even f2.8 under many circumstances..

The distance from subject to background is important..

What the background is matters; something like hedges and pine trees blur to unrecognizable faster than do thisng with distinctive shapes and sharpe edges, like building signs..

The design of the lens matters; Canon marks lenses in it's catalog as CA for Circular Aperture, meaning the fuzziness is supposedly better..

In the real world, you'd be better off picking your lens based on perspective, not on fuzziness that makes peoples eyes water when looking at a picture of a person..

The focal length controls the squashing or stretching of the face and body, the relationship between body and background, and, in some cases most importantly, how much of the background is in the shot..

A wide angle lens shows the whole fountain the girl is standing in front of. A tmoderate telephoto shows the sculpture in the fountain, and a longer telephoto just shows the water spout, which is blurry and soft anyway because water is fuzzy and soft, plus moving pretty fast..

People around here usually fail to define a portrait, so it's hard to answer their questions... are we talking about a picture framed like a passport photo, or are we talking about an outdoor portrait that shows the person from head to foot, stretched out on a picnic blanket, drinking from a bottle of champagne?.

You'd use a different lens, or zoom a lens to different focal lengths, for these two shots..

For a half body shot on a 1.5 / 1.6 camera at a low budget, f4 on a 50mm lens with the background twenty feet away and the person five feet away would work pretty well..

BAK..

Nickleback wrote:.

What this means for DSLR users:.

APS-C: 65mm f/1.3-1.84/3rds: 50mm f/1-1.4.

Many of these lenses don't exist, so you use what you can..

This implies that a Hexanon 57 / 1.2 on my 4/3rds cam ( which can manual focus very exact via 10x live view ) is a good lens for this purpose..

I was thinking about that lens but then thought, why not 85/1.8 or 150/2.8, but it seems that there is no reason to go more away than 57mm*2 ( 114mm) implies.

RegardsMartin..

BAK wrote:.

Are we talking about an outdoor portrait thatshows the person from head to foot, stretched out on a picnicblanket, drinking from a bottle of champagne?.

YesthanksMartin..

As you said I am talking 35mm terms..

Before digital, portrait lenses were from 70-80 to 135mm. the distance to the subject was a constant, usually 10-12-15ft depending on the studio setup. what one did was leave the subject distance the same and switch lenses to get different views. the 75mm or so was for the 3/4 or full shot depending on exact distance, while the 135mm was for the face only..

The reason one didnot change the subject distance was to keep the perspective reasonable and pleasant. closer or further one ended up with pronounced noses or flattened faces..

For digital use you would have to convert to your digital crop factor from your sensor; be it 1.3, 1.5, 1.6, or 2.0..

Even if you have one, do not use a macro lens, they are extremely unflattering for portraits because of their ability to resolve details. no one will thank you for a macro portrait with every blemish the person the has being shown. if you use a macro lens to only alternative is to spend hours on the pc in pp getting the blems back out. it is simpler to use a nonmacro lens. the standard kit lens that comes with most dslrs will work fine...

Nickleback wrote:.

Marf wrote:.

On the other hand, maybe the Background Blur at longer focal lengths,200mm or 300mm, and maybe a bit smaller apertures, has the advantagethat der DOF is a bit less shallow, so more of the model is in focus,.

DOF is shallower at the same or even somewhat larger f-number as youmove up in focal length. 200/5.6 has the same DOF at similardistances as 50/1.4..

This is true, but it is arguably not the most useful comparison. Photography is composition-driven, so the key comparison with a head-and-shoulders portrait taken with the 50 mm lens is another head-and-shoulders portrait using the 200 mm lens. Obviously that means the 200 mm shot is taken from further away. The result, which is surprising to some, is that at the same aperture the depth of field is *the same* but the background blur is greater..

What this means in practice is that you can have adequate depth of field *and* lots of background blur, simply by using a longer lens. Yes the perspective will be flatter - as with so many things photographic, it's a trade-off...

Thanks but I want background blur first, I learned now that background blur is not 100% connected to dOF, there should also be a Background-blur calculator .

Ledittmar wrote:.

Http://www.tamroneurope.com/...fentiefenvergleich.289.0.html?&L=0&L=2.

RegardsMartin..

I agree with your post except that macros do not resolve more detail than non-macros. maybe primes do resolve more detail than (non-olympus) zoom lensesregardsMartin..

Marf wrote:.

Thanks but I want background blur first, I learned now thatbackground blur is not 100% connected to dOF, there should also be aBackground-blur calculator .

Ya mean like this one....

Http://www.bobatkins.com/.../photography/technical/bokeh_background_blur.html..

Depends on on your lens, the background you will have and the distance of the background too in addition to the aperturehttp://budding-nature-photographer.blogspot.com/..

It would be great if I could enter the subject distance..

When I move the subject distance slider then the distance varies between 100038383782906m , 999616309445889 m and 10000, m.If I enter the value via keyboard the same nonsense happens after clicking startregardsMartin..

Marf wrote:.

It would be great if I could enter the subject distance..

I agree - I don't understand why Bob didn't implement that..

When I move the subject distance slider then the distance variesbetween 100038383782906m , 999616309445889 m and 10000, m.If I enter the value via keyboard the same nonsense happens afterclicking start.

I don't have any such problems, the slider is clumsy but it works. It's an old 16-bit Windows application, maybe there are compatibility issues. I'm using WinXP SP2; I downloaded VBRUN300.DLL from Microsoft today via the link on the Blur Calculator page...

I tested it on my Win-98 "internet pc" and there it was not useable.Ok, maybe it's operating system dependant.I will try it again in a few days, on my Win XP or Win XP sP2 computerregardsMartin..

It does also not work on my Win XP.This software is not useable.ButThanks for the "Background blur calculator" keyword,I found an alternative with google:http://www.robertseber.com/calculators/backgroundblurcalculator.htmlregardsMartin.

Typing errors are intended to provide a basis for global amusement..

Despite I love my Olympus cameras and also have 'the last Sony Mavica', I would like to have a Samsung forum here on dpreview because they have interresting new pocket cams...

Now I simply make 2 sample calculations with 2 lenses on FourThirds sensor size..

Focal Length 70mm / 100mmAperture 1.4 / 2.0Subj Dist 7m / 10mDOF calculated with the Dpreview calculator: 0.477 m / 0.682 mBackground blur with the "ALTERNATIVE" BG Blur calculator: 2.24% / 2.24%.

The BG blur calculator was temporary modified on my hard disc to show 2 digits after the comma. The Background distance I used was almost infinte ( 9900000mm )..

Surprising result: With bigger Focal lengths it's possible to maintain the same BG Blur with increased (comfort) DOF..

RegardsMartin.

On Foutthirds I can use the lens wide open, so the examples are real. I know there exists no 70mm F1.4 lens, but a 57mm F1.2 which should provide almost the same results..