FROM: "Q.G. de Bakker" SUBJECT: Re: Kowa 250/5.6 vignetting at close focus DATE: Tue, 26 Mar 2002 00:15:40 +0100 ORGANIZATION: Tiscali bv NEWSGROUPS: rec.photo.equipment.medium-format Robert Monaghan wrote: > re: digital manipulation - > yep, I've been impressed by the PBS specials, such as the Empire of the > Bugs (?) where DOF went from bug level to distant fields etc. Amazing! > I suspect we will see some amazing microscopy shots now with digitally > enhanced imaging - esp. if C. Zeiss adds this technology to the 'scopes > http://www.cdm-optics.com/site/pr/zeiss-cdm.html Even layering of multi > images in photoshop is a potential solution to some DOF issues... "Amazing" DOF (like in this Empire of Bugs thing) can be achieved with quite down to earth ancient techmology. Pick a lens, any lens, and point it at anything of interest. Then, put a tiny object, like a bug, in the image space behind that lens. Next, pick a camera and macro lens, and focus it on the bug. Then move the first lens back and forth until the image it produces is picked up by the camera lens and you get both the bug and the background in focus simultaneously. Kind of back projection, but without a screen. FROM: w.j.markerink@a1.nl (Willem-Jan Markerink) SUBJECT: Re: Kowa 250/5.6 vignetting at close focus DATE: Mon, 25 Mar 02 23:34:16 GMT NEWSGROUPS: rec.photo.equipment.medium-format In article , "Q.G. de Bakker" wrote: >Robert Monaghan wrote: > >> re: digital manipulation - >> yep, I've been impressed by the PBS specials, such as the Empire of the >> Bugs (?) where DOF went from bug level to distant fields etc. Amazing! >> I suspect we will see some amazing microscopy shots now with digitally >> enhanced imaging - esp. if C. Zeiss adds this technology to the 'scopes >> http://www.cdm-optics.com/site/pr/zeiss-cdm.html Even layering of multi >> images in photoshop is a potential solution to some DOF issues... > >"Amazing" DOF (like in this Empire of Bugs thing) can be achieved with quite >down to earth ancient techmology. >Pick a lens, any lens, and point it at anything of interest. Then, put a >tiny object, like a bug, in the image space behind that lens. Next, pick a >camera and macro lens, and focus it on the bug. Then move the first lens >back and forth until the image it produces is picked up by the camera lens >and you get both the bug and the background in focus simultaneously. Kind of >back projection, but without a screen. No preference in focal length for that secondary lens _at all_? (for those cracking their brain to visualize this constellation: the line-up is: camera+lens1 - object - lens2) Btw, I am currently dabbling a bit in huge lenses from Diaskop and Epidiaskop....focal range 200-500mm, aperture f4.0-6.0 (up to 1300mm/f3.5 exists for sure, possibly larger, same aperture, but as these came on only the largest of Epidiaskopes, chances of finding one are slim to none) -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] FROM: Struan Gray SUBJECT: DOF dabbling (was Kowa 250) DATE: 26 Mar 2002 08:22:07 GMT ORGANIZATION: This line intentionally left bland NEWSGROUPS: rec.photo.equipment.medium-format Willem-Jan Markerink, w.j.markerink@a1.nl writes: > "Q.G. de Bakker" wrote: >> "Amazing" DOF (like in this Empire of Bugs thing) can >> be achieved with quite down to earth ancient techmology. >> Pick a lens, any lens, and point it at anything of >> interest. Then, put a tiny object, like a bug, in >> the image space behind that lens. Next, pick a >> camera and macro lens, and focus it on the bug. > >No preference in focal length for that secondary lens _at all_? The focal length of the secondary lens determines the relative magnification of the bug and the background. It's aperture determines their relative brightness. The background will of course be upside down unless you use a rectifying prism or relay lens too. It can be very hard to avoid bad aberrations in the outer parts of the image of the background, but c'est la vie. One of Attenborough's "Life" series of nature films had him talking to camera with a line of ants marching across the front of the frame, all in focus. I think this was the first time it had be used to wow the couch potato public. > Btw, I am currently dabbling a bit in huge lenses > from Diaskop and Epidiaskop....focal range 200-500mm, > aperture f4.0-6.0 .... Wide open? Don't get the sun in the frame - your bug won't last long :-) Struan PS: I'm taking a mill to the Kowa back plate. Making a circular hole is the only way to end up with a lens that will fit both a Super 66 and a 6/6MF. I can live with the depreciation. FROM: w.j.markerink@a1.nl (Willem-Jan Markerink) SUBJECT: Re: DOF dabbling (was Kowa 250) DATE: Tue, 26 Mar 02 12:28:18 GMT NEWSGROUPS: rec.photo.equipment.medium-format In article , Struan Gray wrote: >Willem-Jan Markerink, w.j.markerink@a1.nl writes: > >> "Q.G. de Bakker" wrote: >>> "Amazing" DOF (like in this Empire of Bugs thing) can >>> be achieved with quite down to earth ancient techmology. >>> Pick a lens, any lens, and point it at anything of >>> interest. Then, put a tiny object, like a bug, in >>> the image space behind that lens. Next, pick a >>> camera and macro lens, and focus it on the bug. > >> >>No preference in focal length for that secondary lens _at all_? > > The focal length of the secondary lens determines the relative >magnification of the bug and the background. It's aperture determines >their relative brightness. The background will of course be upside >down unless you use a rectifying prism or relay lens too. Hmm....freeze the bug, and hold it upside-down....:)) >It can be >very hard to avoid bad aberrations in the outer parts of the image of >the background, but c'est la vie. > > One of Attenborough's "Life" series of nature films had him >talking to camera with a line of ants marching across the front of the >frame, all in focus. I think this was the first time it had be used >to wow the couch potato public. Nice antsy feeling yes....:)) > >> Btw, I am currently dabbling a bit in huge lenses >> from Diaskop and Epidiaskop....focal range 200-500mm, >> aperture f4.0-6.0 .... > > Wide open? Don't get the sun in the frame - your bug won't >last long :-) Yup, no aperture (but as with any projection lens, one could insert a hand-made one, fixed f-number of course). Another project involves using a Diaskop lens on a 4x5" camera....there are *no* other tele lenses with such apertures (up to 1000/6), while optical quality is based on 9x12cm slides (projector opening 11x11cm). (the Episcope lenses might not be that high-quality, as they only had to project reflective subjects (and not just flat stuff either, I just bought an old manual for the Aldis Epdiascope, a huge contraption, and one of the applications shows a big globe put underneath the projector....:)) (lens for episcopy is 18.5" with 5" diameter, or f3.7) > > >Struan > >PS: I'm taking a mill to the Kowa back plate. Making a circular >hole is the only way to end up with a lens that will fit both a >Super 66 and a 6/6MF. I can live with the depreciation. You could always sell it as if it were a feature....:)) -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!]