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Varying the Focal Length of LF Camera Lenses
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t.r.sanford
Joined: 10 Nov 2003
Posts: 812
PostPosted: Fri Jan 30, 2004 9:30 pm

Right; I used the "Curvatar" when I needed that fisheye look for an illustration that would be reproduced at a size smaller than the 4x5 negative. The image quality isn't stellar, but (of course) can be improved by stopping down.

The diameters of the afocal front attachments for digital cameras are increasing, e.g. there are quite a few for the Sony "707" and "717," which accept 58mm. accessories -- a respectable size, on the borderline between the old Series 7 and Series 8.

This may be the golden age of these supplmental lenses, given the demand for digital cameras, the reluctance of manufacturers to make interchangeable-lens models at reasonable prices, and the emergence of a truly worldwide marketing system for identifying a need, designing a sophisticated solution, and having it manufactured in great quantity by a well-equipped producer someplace where costs are very low.
Dan Fromm
Joined: 14 May 2001
Posts: 2165
PostPosted: Fri Jan 30, 2004 11:14 pm

Quote:

On 2004-01-30 13:30, t.r.sanford wrote:
Right; I used the "Curvatar" when I needed that fisheye look for an illustration that would be reproduced at a size smaller than the 4x5 negative. The image quality isn't stellar, but (of course) can be improved by stopping down.

The diameters of the afocal front attachments for digital cameras are increasing, e.g. there are quite a few for the Sony "707" and "717," which accept 58mm. accessories -- a respectable size, on the borderline between the old Series 7 and Series 8.

This may be the golden age of these supplmental lenses, given the demand for digital cameras, the reluctance of manufacturers to make interchangeable-lens models at reasonable prices, and the emergence of a truly worldwide marketing system for identifying a need, designing a sophisticated solution, and having it manufactured in great quantity by a well-equipped producer someplace where costs are very low.
I've said it once, I'll say it again. There were very fine afocal adapters made for Super 8 cine cameras. Remember that these things had to perform to very high standards. In addition to my 67 mm 1.4x Canon adapter, I have a 67 mm Canon wide adapter that works very well. Similar w/a adapters, but not, I think tele converters, were available from Nizo. Not sure why I'd want to use a w/a adapter on a Graphic, though.

Cheers,

Dan
t.r.sanford
Joined: 10 Nov 2003
Posts: 812
PostPosted: Sat Jan 31, 2004 1:47 am

No question; Canon always has made outstanding lenses. I have known serious students of the subject who preferred them to Nikon optics.

When you come to think about it, a good-quality afocal wide angle adapter would be a very valuable adjunct to a "Graflex" outfit -- what with inverse-telephoto lenses not having been invented in time to give that long-lived line any sort of wide-angle optics. My old "R.B. Series B" 2-1/4x3-1/4 has a 135mm. normal lens. Put a 0.7X WA attachment on, and it would become a 95mm. lens. That could be very helpful at times when you can't back up quite far enough!
Henry
Joined: 09 May 2001
Posts: 1662
PostPosted: Sat Jan 31, 2004 2:42 am


Posted: 2004-01-30 17:47 PST

No question; Canon always has made outstanding lenses. I have known serious students of the subject who preferred them to Nikon optics.

________________________
Ditto that for Minolta optics. I'd put my MC-Rokkor 135 lens up against Nikon's or anybody else's, any day. Also the Minolta 35 mm PC shift lens. They were making great stuff back in the '70s!

Henry
t.r.sanford
Joined: 10 Nov 2003
Posts: 812
PostPosted: Sat Jan 31, 2004 4:55 am

Yes, indeed. My first "real" camera, in 1956 or '57, was a Minolta "A" with 45mm. f:3.5 "Rokkor," a very good lens indeed. I now do my non-fun work with a couple of "Maxxums," and I have the highest regard for the lenses supplied for this line. A dealer of my acquaintance once commented that Minolta doesn't get the respect it deserves; but it surely has mine!
worldphoto
Joined: 05 Feb 2003
Posts: 199
PostPosted: Sat Mar 06, 2004 5:34 am

Okay, I've finished the testing and calculations on the set of Macnan three minus lenses. I gave the Macnan lens kit info earlier on this thread. The prime lens used is a 135mm Schneider-Kreuznach.
(1) Meniscus (crescent shaped) lens = minus(-) 3.77 diopters with a combined focal length of 225mm.
(2) Plano-Concave lens = minus(-) 5.9 diopters with a combined focal length of 350mm.
(3) Double Concave (biconcave) lens = minus(-) 6.8 diopters with a combined focal length of 475mm.
Harry


<font size=-1>[ This Message was edited by: worldphoto on 2004-03-05 21:39 ]</font>
RichS
Joined: 18 Oct 2001
Posts: 1468
PostPosted: Sat Mar 06, 2004 6:10 am

Great! But how to they _shoot_ at 225, 350 and 475???

worldphoto
Joined: 05 Feb 2003
Posts: 199
PostPosted: Sun Mar 07, 2004 4:00 am

Rich
There isn't enough interest to respond. My last post was to cap this thread.
Good Luck, Harry
GG too dark to focus at infinity? I would use my tape measure (9", 14" and 19") and stop down at least to f/16 or f/22 mark on shutter (effective aperture is smaller).

<font size=-1>[ This Message was edited by: worldphoto on 2004-03-10 11:28 ]</font>
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