Depth of field

johnny s

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I've been using a Canon S3i for quite some time now and generally it has served me well. My serious photography days are over, the dark rooms gone as has most of my equipment for d&p.

Simple question that has probably been asked elsewhere, would a cheapish dslr give me back the depth of field that I once could achieve with my 35mm setup ?. I'm really fed up that my portraits of the grandchildren have everything in almost pin sharp focus beyond the subject, when I want an out of focus background that does not detract from the subject. The only way I can achieve a limited d of f is to have the background miles away from the subject, which is not always possible and requires out of doors photography rather than a more formal/informal shoot in the home

Digital is great, but I would like the range of possibilities that I had when using 35mm gear.

Thanks for bearing with me.

 
S

soulman

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Not quite, APS-C sensors are about half the area of 35mm film. An 85/2.8 lens will have the same DoF as a 85/4 on film but cropped to 130mm approximately. You tend to have to step back a little and shoot wide open, not as big a problem as you're only using the centre of the lens' image circle which tends to be the sharpest bit.

 

chrisB

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It will.

If you get a properly fast lens like 50mm f1.4 (which btw is cheap)

To get exactly the same DOF as your 35mm you'd need a full frame DSLR (which can give you extremely shallow DOF) but for what you want a crop body will to just fine.

BTW DSLRs offer a lot more possibilities than your old 35 mm camera.

 
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mikehit

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DOF depends on distance (greater distance gives more DOF), lens focal length (wider lens gives more DOF) and aperture.

For photos of you grandchildren, assume you have APS-C and 35mm bodies and use the same aperture on both: you will change either your lens (APS-C needs wider lens) and shoot from the same distance; or use the same lens and stand further away (stand further away with APS-C). Both of these means using APS-C gives greater DOF. But is this a problem in practice? The difference is one stop of aperture (f4 on 35mm body has about the same DOF as f2.8 on APS-C)

But what effect do you want? If you want a really narrow DOF and need aperture of f2.8 on 35mm body, then you are unlikely to get the same narrow DOF with APS-C unless you spend good money. If you are happy with f5.6 (or higher) on 35mm sensor, then using f4 (and higher) with APS-C sensor will do it just as well. Fortunately lenses f4 (especially primes) need not be particularly expensive; but zoom lenses at f2.8 are expensive and big.

To be honest, very few people need the narrow DOF given by a f2.8 aperture on a 35mm body. I think a 50mm f1.8 prime on APS-C body will do most situations indoors.

 
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johnny s

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Thank you all for your comprehensive replies, truthfully without them I really wouldn't have had a clue regarding f stop difference and full frame/ aps-c.

I have been looking at the Canon 450d with its 18 - 55 lens, ideally a prime lens with the widest aperture ( financially ) available should do the trick if I decide to go ahead. I am really looking at acceptable ' memory ' photographs. My experimental special effect days are well and truly behind me, I have become an advocate of the kiss ( keep it simple stupid ) technique.

Thanks once again.

 

topoxforddoc

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If you want to understand DOF on a digital camera, try this iPhone App, Advanced DOF. The interface is just like an old fashioned lens with focus and aperture rings.

Charlie

 

rockmeister

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John, I think you have the answers, but simply,

if you control aperture, you control DOF.

Any cam therefore with an 'A' or 'Av' setting gives you that choice.

Even more logical would be to find something with 'old fashioned' aperture control ring on the lens as well.

Many non DSLR cameras will allow the first, a few the second also, and you may well use something much less bulky much more frequently (and enjoyably).

Lens choice? If it isn't a zoom, then a standard or slightly wide might suit for 90% of your pics. You can nearly always take a couple of steps forward or back anyway!... 35mm to 50mm.

Aperture of the lens? The 'faster' the better really, it gives you more choice. In practice f2.8 or thereabouts is about what comes on most zooms and is ok, but for those dramatic out of focus backgrounds you really need something faster. Maybe f1.8?

Finally, remember that DOF decreases dramatically as you close in on your subject (which is why, with macro lenses DOF can drop to as little as 1mm), that DOF increases with wider angle lenses, and reduces with telephotos. :)

Egg sucking lecture now ends!

I'll go do some trawling now and see if I can actually find a camera that has all the above:dunno:

bear with, bear with....

ok...if you like digital, screen/menu type controls, and live with no viewfinder,look at Sony's RX100

if you prefer 'old fashioned' manual controls, and want a viewfinder, then Fuji's X100s is a no brainer really, if you can swallow the cost.

Both have DSLR quality. :)

 

johnny s

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Thanks Rocky for your interest and information, for comparison I have just dug out my Olympus OM2n setup and had a little play.

Zuicko 50mm f1.8 - aperture wide open and using legs as the zoom, depth of field as expected and with the background 4-6 feet away, the background does not compete with the subject.

Canon S3is lens - set to approx. 50mm, f2.7 (35mm equiv.) and at the same distance as the Zuicko, almost everything is in focus, the background competing with the subject.

Canon S3is - standing further back from the subject approx. 10 ft and using the zoom facility ( f-stop automatically adjusts to f3.5 ) depth of field reduces considerably and is comparable to the Zuicko 50mm at close quarters.

The digital machine is doing exactly the opposite regarding d of f compared with the 35mm format.

So after 30 odd years of using the best zoom in the world ( my legs ), to get the effect I like , with the digital format, I am doing exactly the opposite.

Old habits die hard I'm afraid and the digital format has made me a lazy photographer, everything used to be done inside the camera and the darkroom, now its click away and photoshop the image. Whoops gone a little off topic, the ramblings of a retiree.

Bearing in mind the above - digital portraits to be done in a largish room using the zoom facility at the widest aperture. :) Not the ideal solution, but probably good enough for my ' memory ' photographs of the family. Thanks again.

 

mikehit

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Digital is so easy to process, you could take the view that for most indoor shots 35mm lens on f1.8 and crop to best framing - the quality of an APS-C camera you will lose little if any quality even with quite an aggressive (50% linear) crop so you have a good digital zoom.

And sod the purists... :shock:

 

johnny s

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Digital is so easy to process, you could take the view that for most indoor shots 35mm lens on f1.8 and crop to best framing - the quality of an APS-C camera you will lose little if any quality even with quite an aggressive (50% linear) crop so you have a good digital zoom.And sod the purists... :shock:
:)

 

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