Won't focus.. Quality Street!

jamlid

jamlid

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Name
Jamie
Edit My Images
Yes
[url]http://farm4.static.flickr.com/3462/3212781935_129d609d2c_b.jpg[/url]

Just been playing with my light tent and took this. Even though it was taken at f16, 2 second exposure on a tripod with flash on 1/2 power using cable release.. the whole tin wasn't in focus!

What am I doing wrong?

Oh yeah, gear is a Canon 400D, with a Sigma 28-200 at 36mm. :)


EDIT: Oh, this one did it too, the writing at the bottom of the label is out of focus, but the main logo isn't..

[url]http://farm4.static.flickr.com/3373/3212781515_65786e32e0_b.jpg[/url]

(i love cuticura! :D )


Staff Edit : Images changed to clickable links. Pictures must not exceed current forum limits as per the rules.
Please feel free to replace this with a fresh/resized image and remove this text :)
 
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My first guess would be that you aren't focusing on the right part of the tin to allow for the desired amount of front-to-back sharpness.

What was the focus point? Were you shooting AF or MF? Roughly how far away from the subject were you?
 
I'm about.. 50cm away from the subject, I used a manual focus and focused on the leaflet inside the tin.

Did the same with the cuticura one, but focused on the Logo.

Is this to do with hyperfocal distances?
 
I know what you're doing wrong and why but I'm not going to tell you. I could tell you, but I don't think it would help as much as being pointed in the right direction and helped to understand it for yourself.

Have a play with this and see if you can visualise how your focal plane is working in those two shots.
 
Christ, how Cryptic.

Jamlid - Keep in mind that your DOF tends to be 1/3rd in front and 2/3rds behind the focus point.

So you might want to try focusing in a little closer to the front, perhaps the edge of the tin or the top of the label.
 
glitch said:
I know what you're doing wrong and why but I'm not going to tell you. I could tell you, but I don't think it would help as much as being pointed in the right direction and helped to understand it for yourself.

Have a play with this and see if you can visualise how your focal plane is working in those two shots.
Click to expand...

Whilst that is a bit cryptic :D it's the same site I was going to point him to, and pretty much answers the question nicely too

(y)

DD
 
hyakuhei said:
Christ, how Cryptic
Click to expand...
Yes, you could just answer the question with a straight answer.

Or you could point them in the direction of a very useful tool that will not only help them to visualise them problem but also give them something they can play around with to help understand the theory and answer the bigger question. Then you can nudge them in the right direction if they need to know more.

Which is certainly a lot more help than your '1/3rd in front and 2/3rds behind' which is only applicable in certain, specific situations and requires you to have a full understanding of hyperfocal distance.
 
hyakuhei said:
Christ, how Cryptic.

Jamlid - Keep in mind that your DOF tends to be 1/3rd in front and 2/3rds behind the focus point.
Click to expand...

It's a lot closer to half and half when doing macro....it's pretty much exactly half and half at lifesize and greater! The lower the magnification the more the ratio will change so that there is more DoF behind the subject but I think on an APS-C sensor you're going to be doing full length portraits by the time you've lowered the magnification enough to have 2/3rds of the DoF behind the point of focus. With a wide enough angle of lens you could have 99% of the DoF behind the subject (like fisheye wide).

I don't like that 1/3rd, 2/3rds "rule" as it's more often wrong than right for me.
 
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