P&S Sharpeness Vs. DSLR: F Stop Conversion

[ted_reyes]

Is there an f-stop conversion for P&S cameras. I have a 10D and an

AE1 before that. Use of f-stop to control sharpness vs bokeh are the

same. However, my S70 only has f stops to 8.0. Does one still go to

the middle f stop to gain best sharpness?

[roger krueger]

Most P&S's have really slow lenses (relative to their sensor size.) 1 stop down from wide

open is generally best.

[andrew robertson]

Even wide open, unless you are shooting something close the very short focal lengths of

P&S cameras ensure deep DOF.

 

Most are in the neighborhood of 5-10mm at the wide end. Even at f/2.8 this ensures

deep DOF.

[mark u]

Depth of field depends on the sensor/film size as well as the aperture, focal length and focus distance you are using. The consequence is that you will get much greater apparent depth of field on your S70. Even wide open at f/2.8 at the wide end, the depth of field is similar to using about f/13 on your AE1 with a 28mm lens. At full telephoto, you have a 20.7mm lens, so the degree of background blur will be very limited. Because the pixels are small (about 2.4 microns square), lens performance is actually diffraction limited relative to the pixel size above f/4.

[g._armour_van_horn]

I've heard the term "diffraction limited" without knowing what it actually means. Does it mean that the image would get worse if they stopped down further? I ask because I recently bought a Nikon Coolpix 5400 in the hope that I would be able to shoot digitals with the same exposure as when I shoot slides. I got an adapter for the hotshoe to give me a PC synch socket, and went to set the aperture to f:/16 and was disappointed to learn it only goes to 7.9! Now I'm waiting for an 8X neutral density filter and an adapter so I can use my main lighting setup. I'm not concerned about DOF here, more is better for my work, but the workflow impact is severe.

 

Van

[phule]

G. Armour Van Horn,

 

"Diffraction is the spreading out of light when it passes through an aperture (such as a lens). The smaller the aperture, the more diffraction and the lower the sharpness of the image. There is no way around this. "

 

http://www.bobatkins.com/photography/technical/optics.html

 

More discussion about f/8 and small digital sensors here:

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005rsq

 

and here:

 

http://www.photo.net/equipment/digital/sensorsize/

[craig_gillette]

I'd suggest trying some sample shots, as the "go to the middle" is probably oversimplified. It may have been pretty wise when a lens went from f3.5 or so to f22, but with the tighter range on the digicam, you may find the sweet spot closer to one end or the other.