DX lenses and Depth of Field

[mmaathuis]

I was just wondering, will DX lenses make it harder to separte the subject from fore and background?

Do you think the build of the lens (less glass) will influence the ability to unsharpen the OOF objects.

Or (in other words), will a DX lens give you an overall sharper image than a non DX lens?

[KeithM]

It's all down to how the lens designer approaches the problem. He ( or she ) could allow the smaller image circle to reduce manufacturing cost by relaxing design constraints or improve the image quality by exploiting the smaller image circle !

Anyone worth their salt would, I suspect, endeavour to improve image quality. I don't *think* that would impact depth of field, just improve achievable image sharpness and maybe bokeh ( how good the out-of-focus bits look ). That would answer the first two questions perhaps.

The new 4/3 system lenses are allegedly designed to illuminate the sensor more evenly with the light rays striking the surface at right-angles to it across the whole sensor surface ( normal lenses illuminate the sensor at an angle towards the edges ) which is supposed to improved image quality. If DX lenses use the same optical design principles then they would produce better quality images. But then 4/3 lenses are also designed to 'talk' to the camera to compensate for any lens distortion ( eg: pincushion and barrel distortion at zoom lens limits ) and that won't be part of DX lens design.

Maybe someone on the forum has two similar lenses, one DX, one not and can post comparative pictures !

Keith.

[mmaathuis]

Thanks for the reply Keith.

The word that I was searching for was indeed the quality of "bokeh" with DX lenses.

It would be really interesting to see two of the same pictures with a DX and "normal" lens.

[Swampy]

I'm going to try and prove Theo wrong about mirror lenses though. I have a new toy that I'm playing with right now, but have to find the right subject still. May not happen until this coming weekend though, which is when I'll reveal the toy.

[mmaathuis]

Keith, or anyone.

Will a DX lens have the same Depth of Field range as its equivalent "normal" lens?

[NZDoug]

I had a 20mm 2.8AF Nikkor.
When I got the 12-24dx I shot scenes with the 20 and the dx getting the same angle of view on tripod and marking the angle of view with reference points.
The files were superior with the 12-24dx due to
slight fringeing with 20AF but otherwise identical.
So I sold the 20 as my camera bag weighs too much.
The 12-24dx is awsum:cool: