Velocity Reviews > Depth of field

# Depth of field

rda
Guest
Posts: n/a

 01-01-2005
Another question about the Sigma 20mm 1.8 (I just cannot afford the Canon
17-40L).

If I use f1.8 from a distance of around 20' from my subject would a group
shot be sharp, or would I have to stop down?

Sorry to bother you guys all the time.

Happy New Year !

--
rda
www.rdaphoto.co.uk

Joseph Meehan
Guest
Posts: n/a

 01-01-2005
rda wrote:
> Another question about the Sigma 20mm 1.8 (I just cannot afford the
> Canon 17-40L).
>
> If I use f1.8 from a distance of around 20' from my subject would a
> group shot be sharp, or would I have to stop down?
>
> Sorry to bother you guys all the time.
>
>
> Happy New Year !

If they were all the same distance from the lens they should all be in
focus, there are a lot of other factors related to sharpness.

If they were standing one behind the other a couple of feet apart, then
the answer is you would need to stop down.

--
Joseph Meehan

26 + 6 = 1 It's Irish Math

dylan
Guest
Posts: n/a

 01-01-2005
any use ? http://www.dofmaster.com/dofjs.html

"rda" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Another question about the Sigma 20mm 1.8 (I just cannot afford the Canon
> 17-40L).
>
> If I use f1.8 from a distance of around 20' from my subject would a group
> shot be sharp, or would I have to stop down?
>
> Sorry to bother you guys all the time.
>
>
> Happy New Year !
>
> --
> rda
> www.rdaphoto.co.uk
>
>

rda
Guest
Posts: n/a

 01-01-2005

"dylan" <(E-Mail Removed)> wrote in message
news:cr6hnm\$kv\$(E-Mail Removed)...
> any use ? http://www.dofmaster.com/dofjs.html
>

It would seem that for 20' the depth of field would be from 13.2' - 41.2'.

Thanks

--
rda
www.rdaphoto.co.uk - comments welcomed (on the photos, I know the site is
crap)

skroob
Guest
Posts: n/a

 01-01-2005
I am looking into this lens myself, and have a question or two for the
group.

I have a D70 with the following lenses (18-70mm 3.5/4.5 DX, 70-300 4/5.6 ED,
28mm 3.5 PC, Sigma 12-24mm 4.5/5.6)

I was looking at adding the Sigma 20mm 1.8 to cover me in low-light
situations where my SB-800 flash would be frowned upon (such as in a
Cathedral).

I should mention at this point that I shoot architecture 95% of the time,
where its important for great sharpness and elimination of depth of field
(not a problem set to infinity focus). However, with this lens, i want to
get into artistic and portrait photography.

Is this a wise choice?

"rda" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Another question about the Sigma 20mm 1.8 (I just cannot afford the Canon
> 17-40L).
>
> If I use f1.8 from a distance of around 20' from my subject would a group
> shot be sharp, or would I have to stop down?
>
> Sorry to bother you guys all the time.
>
>
> Happy New Year !
>
> --
> rda
> www.rdaphoto.co.uk
>
>

rda
Guest
Posts: n/a

 01-01-2005

"skroob" <(E-Mail Removed)> wrote in message
news:gtBBd.36341\$(E-Mail Removed)...
> I am looking into this lens myself, and have a question or two for the
> group.
>
> I have a D70 with the following lenses (18-70mm 3.5/4.5 DX, 70-300 4/5.6

ED,
> 28mm 3.5 PC, Sigma 12-24mm 4.5/5.6)
>
> I was looking at adding the Sigma 20mm 1.8 to cover me in low-light
> situations where my SB-800 flash would be frowned upon (such as in a
> Cathedral).
>
> I should mention at this point that I shoot architecture 95% of the time,
> where its important for great sharpness and elimination of depth of field
> (not a problem set to infinity focus). However, with this lens, i want to
> get into artistic and portrait photography.
>
> Is this a wise choice?
>

I found a few sample images taken with this lens on pbase.
http://search.pbase.com/search?q=20m...ch+Photos&c=sp

Note, only some are taken with the Sigma.

--
rda
www.rdaphoto.co.uk comments welcome (on the photos, the site is crap)

Bart van der Wolf
Guest
Posts: n/a

 01-01-2005

"rda" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> "dylan" <(E-Mail Removed)> wrote in message
> news:cr6hnm\$kv\$(E-Mail Removed)...
>> any use ? http://www.dofmaster.com/dofjs.html
>>

>
>
> It would seem that for 20' the depth of field would be from 13.2' -
> 41.2'.

Yes, theoretically in the 14-34 feet range everything would be
perfectly in focus, but I doubt the lens will perform uniformly
throughout the Field of view when used wide open...

Bart