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Old 08-10-2011, 05:18 PM
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PCH (Paul)
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Question Can anyone help with a Canon 400D issue?

Hi,

I'm wanting to get a bit more than point and click out of my 400D. One of the first things I did was to just go thru the manual and play around with the controls and see how far I get.

I came unstuck quite quickly with a depth of field issue. Does anyone have a 400D who would be willing to try something for me, as I can't get it to work on mine. I'd like to refer to the page in the original manual that I'm working from, so if you have the manual that came with it, that would be great as you'll be able to see what I mean.

Only a bit of help needed, - it won't drag on endlessly - I promise
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Old 09-10-2011, 11:39 PM
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MGTechDVP (Mariusz)
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What is is?

Hi Paul,

Whats your dilema?


Mariusz
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Old 10-10-2011, 04:45 PM
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Astroman (Andrew Wall)
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Let us know what you want or what the problem is.. What page in the manual are you referring to? I think I still have mine tucked away somewhere...
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Old 11-10-2011, 01:08 AM
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Hi Mariusz and Andrew,

thanks so much for replying. I feel like a total wal' asking this question. I'm experimenting with some simple features of the camera, starting with depth of field.

If we go to page 68 of the manual, in my copy this section is headed "Av - Changing Depth of Field"

The image example I'm interested in is the picture on the left, - the 'blurred background'. I do actually understand what I'm looking at and how it's supposed to be achieved. I just can't, for the life of me, get my 400D to produce this image.

I find that when I set the top wheel to 'Av', if I set the standard lens to 18mm (wide angle/distant) everything is pretty much in sharp focus, with a very wide DoF, which is what I'd expect.

But when I zoom in to my subject by turning the lens to the 55mm f/l extreme, I would expect to find a narrow DoF would be available. Instead, I'm finding that once zoomed in (set to the 55mm setting), the largest the aperture will go is f5.6 - versus f3.5 at the 18mm lens setting. And this 5.6 f-stop setting prevents me from obtaining an image with a narrow depth of field.

The DoF I can produce of the chess board setup as on Pg68 of the manual has nothing like the narrow DoF that the pic in the book has.

Am I doing something wrong guys? Would you mind checking your 400Ds please? All suggestions much appreciated
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Old 11-10-2011, 05:16 AM
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Astroman (Andrew Wall)
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It's quite possible that the images shown in the book are not produced with the standard Kit lens. To me and I may be wrong here, the image on page 68 was done with a lens with a wide aperture, something like f1.8 or even f1.2. I think they did this as an example of what the AV setting does, not what the 18-55mm kit lens does.

I will throw my old kit lens on my Camera and give it a go when I am at work and post the images up later today for you.
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Old 11-10-2011, 06:35 AM
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Paul, you're not doing anything wrong.

The 18-55 is a reasonably wide-angle lens and it doesn't have a particularly large maximum aperture.
The picture in the manual is unfortunately a bit misleading and as Andrew says, is intended to illustrate the concept of shallow depth of field rather than what can be done with a particular lens.

Wide-angle lenses intrinsically have quite a large depth of field.

I'm just wondering if the 18-55 kit lens is the only lens you have or whether you bought the twin lens package. If you have a telephoto lens try the shot using it. You'll find you need to move back a bit but you should easily be able to achieve that very shallow depth of field with the aperture wide open.
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Old 11-10-2011, 12:07 PM
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Hi Andrew and Andy,

Is this an 'ah ha' moment I see before me?

Well thanks so much to you both for probably clearing this up for me. Andy, yes I do have the twin lens kit, so I can very easily fit the zoom lens as you suggest, and see how I go. I'll do that right away, - thank you.

Andrew, thanks so much for going to that trouble. It would be good to see how you go, although I suspect you guys have hit the nail on the head in saying that the pic on page 68 is for guidance only, - and not necessarily what the standard 18-55 lens is capable of. But nice to have my beginners findings supported by more expert opinion.

Thanks again guys
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Old 11-10-2011, 03:52 PM
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I am not sure if this helps but here are two images of the same scene, only difference is the lens and the widest aperture.

This one is of the 18-55mm f5.6 kit lens @ 55mm
http://i363.photobucket.com/albums/o...-001_55_56.jpg

This one is using a niffty fifty 50mm @ f1.8
http://i363.photobucket.com/albums/o...-002_50_18.jpg

both are focused on the front of the apple.
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Old 11-10-2011, 04:03 PM
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Ah, I understand now Andrew.

And the second pic with the nifty fifty is more or less the same narrow depth of field shown in the book. It would have saved a whole lot of misunderstanding if they had said the stock lenses weren't capable of producing that image. I suppose if I'd understood a bit more, I wouldn't have been so easily misled.

Anyway, I understand now, thanks so much to you and all who have replied, for your invaluable help.

All the best guys
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Old 11-10-2011, 04:04 PM
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HI Paul,

To get the very shallow depth of field I use a sigma 50mm f1.4 and a 150mm f2.8 lens.

Your problem is definitely the lenses you're using. F5.6 produces way to shallow DoF on a 18-55mm range.

f2.8 @ 70mm or faster at wide shots.

Mariusz
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Old 11-10-2011, 04:10 PM
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What is the "other" lens of the twin lens kit, 55-250 or 70-300, either way you can probably get some narrow depth of field with the it set to 55mm or 70mm and F3.5
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Old 11-10-2011, 04:17 PM
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Yeah, the pictures in the manual are definitely taken with an f/1.2, f/1.4 or f/1.8 lens.

Chuck on your 200mm lens, line up a subject, open the aperture up and experiment with camera-subject and subject-background distance, until you get the desired result.

Even at f/5.6 on a telephoto lens, you should be able to achieve creamy bokeh.

H
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Old 11-10-2011, 05:06 PM
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Hi All...

@Mariusz. Yes I now see how the supplied lenses are not going to give this result. Thanks

@ Trevor. The other lens is 70-300. It's still only f4 to f5.6 though. I've fiddled around and found I can achieve the sort of narrow DoF that we've been referring to in the manual, by zooming in to 300mm, not at the shorter f/l end as you suggested if I'm reading you correctly. So, even though at 300mm, the camera auto sets the aperture to a minimum of 5.6, that very narrow DoF is clearly there like in the pic. So that's good.

@ H. Exactly as you stated H - spot on.

Thanks so much to you all for taking the time and trouble to sort this problem out for me. It's genuinely much appreciated IIS to the rescue once again
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