0 cent lightbox test

[TheFrost]

Today I put together a simple lightbox, just made of two envelopes, and 3 sheets a paper, shooting through the top sheet of paper.

http://farm3.static.flickr.com/2739/4465356989_9e3948ed73_o.jpg

The result is not bad, considering I used the very cheap Tamron 70-300 zoom lens.

Weird thing is, I tried the same shot at 55mm with my 17-55, and had problems gettings the whole front of the lens sharp. I thought the DOF would be roughly the same for the same angle of view?

PS: I know I should have remove the UV filter...

[shaftmaster]

I'm not sure what you mean by same angle of view, unless you mean the same size of subject. Since the 70-300 and 17-55 don't have any common focal lengths, the distance to the subject would have to be different to achieve the same subject size within the frame. Since the 17-55 would've had to be closer to the subject to achieve the same subject size within the frame, the DOF would correspondingly decrease.

Nice job on the zero cost lightbox. I've done something similar when taking pictures for eBay listings.

[TheFrost]

I meant indeed the same subject size. And yes, of course, at 55mm I am much closer, but somewhere in my head I thought I would be, say, at 4 time the distance when shooting with 220mm. That logic is wrong ?

[shaftmaster]

You can use this online tool to calculate the depth of field for any combination of camera body, focal length, aperture, and distance:

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

[tysonh]

nice, looks like a success to me!

[TheFrost]

I tried the dof tool, and it is true that the dof is exactly the same, shooting something at say 50cm with 50mm or 200cm with 200mm. Not completely sure if the two give the same image. Anyone ?!

But there is another effect. The distance between the base and the top of the 10cm object at 50cm is about 1cm, where at 200cm this distance is just 0.25cm. Interesting.... (to me at least).

(furthermore, I realized that to create the 55mm shot I was getting very close to minimal focus distance).