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Depth Of Field Help Please


Kirislin
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I had a play with my Canon today in monochrome and wanted a very shallow depth of field. I put it on AV and twiddled the dial but the lowest I could get it to go was f4. What do I need to do to get it lower? I'm new to this.

Linda

It sounds like the lens you were using will only go down to f/4.

The only option...

Buy a faster lens :)

What lens were you using?

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I had a play with my Canon today in monochrome and wanted a very shallow depth of field. I put it on AV and twiddled the dial but the lowest I could get it to go was f4. What do I need to do to get it lower? I'm new to this.

Linda

It sounds like the lens you were using will only go down to f/4.

The only option...

Buy a faster lens :)

What lens were you using?

aaaaaaaah! so now it starts to make sense, all this talk of faster lenses. I got the kit lenses with the Canon 400D that since I've bought it I hear they're not so good.

Can you hear my teeth gnashing in frustration?

Edited by Kirislin
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  • 2 weeks later...
It sounds like the lens you were using will only go down to f/4.

The only option...

Buy a faster lens :)

What lens were you using?

How can I tell by just looking at my lens what the f stop range is? forgive me if I am not saying it correctly, I dont know camera speak. there's lots of writing on it but no mention of f stops whereas on my dear old film Minolta (that I never learned to use properly :rofl: ) it shows an f stop range of 3.5-22, well, I think thats what it is.

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It sounds like the lens you were using will only go down to f/4.

The only option...

Buy a faster lens :)

What lens were you using?

How can I tell by just looking at my lens what the f stop range is? forgive me if I am not saying it correctly, I dont know camera speak. there's lots of writing on it but no mention of f stops whereas on my dear old film Minolta (that I never learned to use properly :rofl: ) it shows an f stop range of 3.5-22, well, I think thats what it is.

Yep - that's it - it'll open as wide as f/3.5 and close down to f/22.

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It sounds like the lens you were using will only go down to f/4.

The only option...

Buy a faster lens :)

What lens were you using?

How can I tell by just looking at my lens what the f stop range is? forgive me if I am not saying it correctly, I dont know camera speak. there's lots of writing on it but no mention of f stops whereas on my dear old film Minolta (that I never learned to use properly :rofl: ) it shows an f stop range of 3.5-22, well, I think thats what it is.

Yep - that's it - it'll open as wide as f/3.5 and close down to f/22.

But I cant see anything like that on the digital Canon lens so how does one know, just by looking at the modern lens?

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What lenses have you got, which 'kit' lenses did you get?

Anyway, the smaller the number the faster the lens is.

So if you have a 5.6 lens, an f4 or f2.8 (or f1.8) would be 'faster'.

I've got the twin lens kit with EF-S 18-55 & EF 75-300 there's not mention of fstops that I can see. :rofl:

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Have a look at the FRONT of the 18-55 (take lens cap off), anything there?

OK, I'll write everything I see

this is the EF-S 18-55

CANON ZOOM LENS EF-S 18-55mm 1:3.5-5.6 then there's a funny symbol like ll with a line top and bottom, probably greek then further round CANON INC. and further again a symbol like circle with a line through it and then 58mm

On the EF 75-300 I dont need to take the cap off it's just written around the edge

all the same as the first CANON ZOOM LENS EF 75-300mm then 1:4-5.6 and again the circle symbol 58mm

so, does any of that tell me f stops :rofl:

I wish I could find a camera course nearby

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Have a look at the FRONT of the 18-55 (take lens cap off), anything there?

OK, I'll write everything I see

this is the EF-S 18-55

CANON ZOOM LENS EF-S 18-55mm 1:3.5-5.6 then there's a funny symbol like ll with a line top and bottom, probably greek then further round CANON INC. and further again a symbol like circle with a line through it and then 58mm

On the EF 75-300 I dont need to take the cap off it's just written around the edge

all the same as the first CANON ZOOM LENS EF 75-300mm then 1:4-5.6 and again the circle symbol 58mm

so, does any of that tell me f stops :)

I wish I could find a camera course nearby

I have purchased the exact same camera and kit lenses. I've too heard that the lenses aren't too crash hot. I'll follow this thread as I am interested in peoples replies. I've looked into doing a WEA course but the current one has already started so the next one will be a couple months away. I realise I will have to purchase another lens or a couple more but still unsure what to buy for the kind of photos I want to take. It all seems so complicated and confusing :rofl:

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The 18-55 is...... 3.5 to 5.6

The 75-300 is..... 4 to 5.6

basically Id consider them 5.6 lenses, cheapie

kit lenses aimed at the beginner. They do ok for most people.

I have a friend with those lenses and she is really enjoying

photography.

The 58mm refers to the diameter (thread size) if you are buying

filters for the lens etc.

Ripley mentioned a 1.8 lens, that is a NICE little lens.

Edited by chezzyr
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CANON ZOOM LENS EF-S 18-55mm 1:3.5-5.6

CANON ZOOM LENS EF 75-300mm then 1:4-5.6

so, does any of that tell me f stops :rofl:

There is all the detail you need. The last values are your lowest f/stop values at the different ranges

So at 18mm it is 3.5 and 55mm it is 5.6

At 75mm it is 4 and 300mm it is 5.6 as well.

Both are miniumum values, with the max usually around f/22 but I wouldn't go above f/16 unless you have fantastic lighting or slow shutter speed.

I'm on a course at the moment through WEA in Adelaide - we did f/stop and shutter speed last week and depth of field this week... there are some good tables out there which show you the depth depending on your focal length, distance from target and of course f/stop.

It takes a while, hang on in there :)

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This lens

CANON ZOOM LENS EF-S 18-55mm 1:3.5-5.6

will go to a maximum aperture of f3.5 at 18mm and f5.6 at 55mm. Does that make sense? It depends on how much or little you've zoomed. Not sure what the minimum aperture is.

Same rationale applies to the other lens.

ETA Woops, too slow :rofl:

Edited by ruthless
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This lens
CANON ZOOM LENS EF-S 18-55mm 1:3.5-5.6

will go to a maximum aperture of f3.5 at 18mm and f5.6 at 55mm. Does that make sense? It depends on how much or little you've zoomed. Not sure what the minimum aperture is.

Same rationale applies to the other lens.

ETA Woops, too slow :)

No :o sigh I will read everyones descriptions again and try really hard to stop my eyes glazing over. thankyou all, I appreciate it.

Tahna, you and I can be confused together, sooner of later the penny has to drop.....surely

I feel like such a :rofl:

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You have a zoom lens, when you rotate it it goes in and out and gets you closer or further away from the subject. Sorry if I'm making this too basic :rofl: Fully rotated and fully zoomed is 55mm, and the maximum aperture ie shallowest depth of field you'll get will be f5.6. If you don't zoom at all, the lens is at 18mm and you can shoot at f3.5 [even shallower DOF].

Put your camera on AV and watch the display as you zoom in and out, the f value will change.

The pros around here will probably laugh at my crappy explanation, but hopefully it helps you understand. Don't be afraid to ask questions :)

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