[Rockhounds] achieving depth of field w digicam?

[Axel Emmermann]

Lanny,

Using f32 will reduce sharpness rather than increase it. This is due to
refraction of light around the edges of the iris.
You can demonstrate the effect by punching a hole in a cardboard with a
perforator and making one with a pin or small nail. Looking through both of
them at a distant object will clarify my point.
Lenses usually perform best at mid-range f-stops... F8 or 11.
Verily low f numbers yield low depth of field but extreme resolution of
detail due to the above effect of refraction.

Cheers 
Axel

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com 
> [mailto:rockhounds-bounces at lists.drizzle.com] Namens Lanny R
> Verzonden: woensdag 16 april 2008 18:24
> Aan: Rockhounds at drizzle.com: A mailing list for rock and gem 
> collectors
> Onderwerp: Re: [Rockhounds] achieving depth of field w digicam?
> 
> Hi Tim,
> 
> There are no magic answers with the basics of digital 
> photography; it is still bound by the same laws of the 
> physics of light.
> 
> However, for 1-3 cm fossils (or minerals) you shouldn't have 
> a problem with that lens. Use enough light so you can stop 
> the lens down to f16 to f32 and there will be more than 
> enough depth of field for fossils of that size to be in 
> focus. The depth of field focus problem is  
> really only a problem when doing things smaller (micro fossils or   
> minerals) so that you really need to magnify them, either 
> with a microscope or extension tubes.
> 
> On the odd occasion that you might need more depth of field, 
> shoot two or three photos to get the front and back in focus 
> and hand stitch the photos together in Photoshop or similar 
> software. It doesn't take very long to do it by hand, I was 
> doing that with micro minerals several years before automatic 
> stitching software became available. It becomes a lot of work 
> if you have several individual focus shots of each of several 
> specimens, but for just two or three shots of an occasional 
> "special" specimen, it's doesn't take very long.
> 
> Regards,
> 
> Lanny
> 
> 
> On Apr 16, 2008, at 8:14 AM, Tim Jokela Jr. wrote:
> 
> > This one goes out to the digital photography gurus out there.
> >
> > I was talking to a buddy last night about macrophotography of small 
> > fossils, 1-3cm stuff, and how capturing any depth of field 
> continues 
> > to be the major challenge. He suggested three ways of doing it: buy 
> > the $25,000 camera system made to do the job, take the picture 3 
> > meters away from the specimen and blow up the image, or 
> take multiple 
> > shots, focusing on different areas, and stitch them together with 
> > Helicon, Combine-Z, or the expensive new version of PhotoShop.
> >
> > All are basically horrible options.
> >
> > So, is there anything new and interesting in the world of digital 
> > photography that's giving depth of field to macrophotography in a 
> > simple, affordable manner? (My weapon of choice atm is a 
> Canon Digital 
> > Rebel with a 50mm macro lens.)
> >
> > Many thanks for any info!
> >
> > Tim Jokela Jr., tjokela at execulink.com
> > Business: http://www.element51.com
> > Pleasure: http://www.ontariominerals.com
> >
> > --
> > _______________________________________________
> > Rockhounds at drizzle Mailing List
> > Subscription Services:
> > http://lists.drizzle.com/mailman/listinfo/rockhounds
> > List Home Page, with a link to the List Usage Policy:
> > http://www.eclecticlapidary.com/Rockhounds/index.html
> 
> --
> _______________________________________________
> Rockhounds at drizzle Mailing List
> Subscription Services:
> http://lists.drizzle.com/mailman/listinfo/rockhounds
> List Home Page, with a link to the List Usage Policy:
> http://www.eclecticlapidary.com/Rockhounds/index.html
>