Depth of Field

[tonymidd]

Have a look at this Karl, it's quite illuminating, only wish it was easilly transportable!

http://www.photozone.de/3Technology/demos/depth.htm

scroll down and you'll find the calculator, put in the 35mm value for your lens. I tried a 15mm at f3.5 and focused at 3m the DoF is from 1.35m to infinity!!!!!!!!

[karl-tkd]

Cheers Tony......see if you like this one i use often:

http://www.dofmaster.com/doftable.html

I normally set mine if i'm using F16 at 2metre's (7feet) and i find that i get an excelent DOF......but have alook at the calculator to see what you think??

[tonymidd]

Cheers Tony......see if you like this one i use often:

http://www.dofmaster.com/doftable.html

I normally set mine if i'm using F16 at 2metre's (7feet) and i find that i get an excelent DOF......but have alook at the calculator to see what you think??

Two points; the table you quote uses .03mm coc the other has a variable coc.
There is a lot of difference between a coc of .03mm and the accepted pro figure of .02mm, tho' this is probably only really noticable to most in a large, say A3, print off a good printer. What both tables show is that with a wide angle you don't need to go down lower than f11 or 8 to get a good DoF for most uses.
Also you should use the widest aperture you can while maintaining the DoF this is 'cos lenses loose sharpness as you stop down due to diffraction. A f3.5 lens will be sharpest at about f6.3 or f8
Details here
http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm
It's an interesting test to set up a shot of say a set of railings to test these effects. An increse in DoF can be at the expense of sharpness.
I find it's all interesting stuff, if you are happy with the resuts you are getting by the methods you are using stick with them but if you can make the laws of optics work for you then I feel it's worth while finding out just how far you can go and maintain, or improve, quality.

[StagePhotography.co.uk]

hmmm all double dutch to me.....

I look through the viewfinder and I can
see the depth of field, and selecting
different aperture settings makes gives
differen depths.....

Simple and easy and no techy stuff...

[BarryM]

[QUOTE=karl-tkd;76912]Whats going on here......are we talking photography equipment or isn't this meant to be a mono thread, don't mean to sound like a bore, but i looked at the C&C for the images, adjusted for improvement but now its gone off the track.....???
/QUOTE]

I think its a very constructive C&C with some excellent information.

Oh never did get my head round that dof preview button, i understand it stops down the aperture for you, but still no idea.

[tonymidd]

Oh never did get my head round that dof preview button, i understand it stops down the aperture for you, but still no idea.

Got it in one mate, it stops the lens down to the working aperture so you can check the DoF. In theory very useful but in practice not a lot of use at small stops as the image becomes so dark.
I use this little disk calculator when needed. A lot of my shots are taken at or near wide open so a limited DoF is being used, comes from doing so many weddings :yahoo:

http://www.speedgraphic.co.uk/prod.asp?i=15273&1=ExpoDisc+Aperture+Depth-of-Field+Guide

[BarryM]

thats the bit i dont get, even although its stopped down for preview, i dont see any dof applied, image gets darker tahts all i see

[tonymidd]

thats the bit i dont get, even although its stopped down for preview, i dont see any dof applied, image gets darker tahts all i see

Remember for each stop you go down you halve the light coming thru the lens so the image has to get darker.
If you are using a f2.8 lens lets say the light coming thru has a value of 100 units by the time you reach f8 that 100 is 12.5 units f11 it's 6.25 f16 it's 3.125, get the idea? That's why the DoF button is not a lot of use at small apertures, instead use a DoF calculator or a hyperfocal distance table which will tell you the distance to manually focus at to get the maximum DoF for a given focal length and aperture. The latter is usually in the lens data sheet. In the 'golden days' people like Bresson and Winnogrand used this method with their Leicas, sometimes called 'pre-focusing', for their street work. A 35mm lens at f8 and focused at 6m has a Dof of 3m to 306m which is enough for street work. I, and many others, still use this technique as it speeds up taking grab shots.
I find the DoF button very useful at weddings as I'm shooting at one or two stops down from wide open to isolate the couple from their suroundings.

[BarryM]

thanks for that mate, il look out the link where there is a dof calculator taht u can print out and cut to make circles, so it gives a paper version of your one, might be handy for some here.

[StuG]

Ah interesting stuff Tony my impression of the dof button was much the same as Barry's, it just made the image darker. Thanks for the info.

[lostmysnorkel]

I've used the DOF Preview a couple of times, but unless your using a fast lens and only stopping down one or two stops, the image in the viewfinder is just too dark to see any real effect.

[BarryM]

a free one to download and print off.


http://www.dofmaster.com/custom.html

[tonymidd]

a free one to download and print off.


http://www.dofmaster.com/custom.html

Excelent, will have a go at that and the hyperfocal chart looks good.

[BarryM]

yeah i came across this about a year ago, but with no printer kinda forgot, it says it works better with card if ur printer can take it. Although knowing your printer Tony, im sure you could put plasterboard through it and it would be fine lol.

[tonymidd]

I've used the DOF Preview a couple of times, but unless your using a fast lens and only stopping down one or two stops, the image in the viewfinder is just too dark to see any real effect.

Under the tungsten studio lamps that I use for product work the image is usable and the DoF checkable down to about f11 but they are 650w each! Otherwise I agree with you. A lot depends upon what you are doing, modern food shots were the main item is sharp but areas in front and behind are not need the button as do shots like this one where every thing has to be sharp.

[tonymidd]

yeah i came across this about a year ago, but with no printer kinda forgot, it says it works better with card if ur printer can take it. Although knowing your printer Tony, im sure you could put plasterboard through it and it would be fine lol.

Not quite Baz, 1.5mm is it's limit tho I've not tried that yet. You could always laminate them which is what I'm thinking of doing.

[BarryM]

yeah tony, just run through the instructions one of which was laminating the disks once printed and trimmed.

[kya]

oh god its all like double dutch to me! :wacko:

[lionhart]

a free one to download and print off.


http://www.dofmaster.com/custom.html

I presume these don't take into effect the multiplier for APS-C sensors for DoF for the stated lens focal length.
So a 35mm lens would be 56mm for canon APS-C sensor, would we use the 56mm DoF chart?

The CoC is 0.01875.

[BarryM]

not looked at it properly but im sure there is a " digital " setting