viking
Posts: 73
Location:
Registered: 19 Feb 2006
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sigma 8mm fisheye.
Posted: 4 Mar 2006 at 18:56 GMT
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Thinking of getting myself the sigma 8mm fish eye for my Nikon D100 and D200. But should I "desfish" the images before I use them in ptgui and in realviz sticther? How many pictures do I need to take to get a full sperichal panorama?
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Aaron Spence
Posts: 121
Location: Gold Coast, Australia
Registered: 29 Sep 2005
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Re: sigma 8mm fisheye.
Posted: 5 Mar 2006 at 9:52 GMT
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G'day Viking,
With the 8mm you will need 4 shots around and 1 up on the D100 or D200. You won't need to defish them before using ptgui, but you will for stitcher. You may need to shoot more shots as a result for stitcher I'm not sure. Although I heard a fisheye plugin was going to be available for stitcher soon, which may make it a moot point.
If you want sharper & higher rez images you could go for the Nikon 10.5mm, which will mean 6 around plus 1 up, plus 1 or 2 down depending on your needs.
I'd only recommend the 10.5 using more shots if you are planning to buy a head that will allow batch stitching (ie 360Precision) otherwise you will be making much more work for yourself in post processing.
Thanks,
Aaron.
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 5 Mar 2006 at 12:59 GMT
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with the 8mm sigma.. I dont need any special panhead thats made for sperichal? I have a manfrotto 303 non SPH model.
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 6 Mar 2006 at 17:20 GMT
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Hmm, reply someone please 
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John Houghton
Posts: 3487
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: sigma 8mm fisheye.
Posted: 6 Mar 2006 at 18:24 GMT
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You don't really need a spherical head when using the Sigma 8mm, unless you specifically want to take zenith shots with the camera pointing vertically upwards. You might want to do this indoors where parallax might be an issue or if you want to maintain high quality. (The Sigma gets quite soft at the edges). Generally, you can get away with the camera angled up slightly to ensure adequate coverage of the zenith. Outdoor sky shots are in any case not normally a problem by simply turning the camera up through 90 degrees.
John
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Pelle Piano
Posts: 56
Location: Farsta, Sweden
Registered: 18 May 2004
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Re: sigma 8mm fisheye.
Posted: 6 Mar 2006 at 19:43 GMT
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If you want a chepaer alternative than the Sigma, there is the Peleng 8mm for about $200.
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 6 Mar 2006 at 20:55 GMT
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Thanks for you reply.
Is it a lot of post processing to get a spherical panorama from the 8mm sigma? I do only need PTgui and photoshop nothing else? Thinking of getting pictures of the interior in my car. Can I make easy a 350x180 panorama of that? Hoe many pictures do I need?
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VistaGrande
Posts: 281
Location: San Antonio, Texas, United States
Registered: 12 May 2004
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Re: sigma 8mm fisheye.
Posted: 6 Mar 2006 at 23:49 GMT
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yes, you can make a 360 x 180 with a 8mm sigma. I use PTGUI with my sigma 8 using 6 shots around (one every 60 degrees to allow for a nice 50% overlap) using a DSLR with a 1.6 ratio to that of a 24x36 area, makes the 8mm a 12.5mm, thus cutting off the longer side edges.....
David
www.VirtualBigBend.com
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 7 Mar 2006 at 6:38 GMT
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Hmm, what setting do you use in PTgui so it will defish the fisheye images? You dont do nothing with them?
No photoshopping?
50% overlap sound nice. 
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John Houghton
Posts: 3487
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: sigma 8mm fisheye.
Posted: 7 Mar 2006 at 7:52 GMT
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In PTGui, you specify the lens type as Circular with an initial anglular field of view = 180, and then identify the outer edge of the image circle by making a circular selection on one of the images using the Crop tab. This ensures that the images get remapped correctly. Adjustment of fov and correction of minor distortions to align the mages accurately is achieved using the optimizer. Can't guarantee no photoshopping will be necessary, as stitching errors are always possible for a variety of reasons.
John
John
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 7 Mar 2006 at 10:19 GMT
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I read somewhere that its not possible to callibrate a fisheyes lens... Well, how do I avoid paralax? I will take interior QTVR's.
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Jon
Posts: 55
Location: United States
Registered: 10 Jun 2005
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Re: sigma 8mm fisheye.
Posted: 7 Mar 2006 at 14:19 GMT
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Yes you can "calibrate" a fisheye lens; at least well enough to stitch 360x180 panos. As you have seen here, many people shoot interiors with fisheye lenses.
Regards
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 8 Mar 2006 at 8:48 GMT
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Do I calibrate an fisheye lens like every other lens?
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viking
Posts: 73
Location:
Registered: 19 Feb 2006
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Re: sigma 8mm fisheye.
Posted: 8 Mar 2006 at 12:52 GMT
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how do I add the button picture in ptgui?
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John Houghton
Posts: 3487
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: sigma 8mm fisheye.
Posted: 8 Mar 2006 at 13:24 GMT
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Calibrating a fisheye lens is basically the same as for any other lens. It's best to do a full 360 stitch and for a subject choose something that has lots of features in all directions for control point purposes. A large interior like a cathedral is very good. Everything is relatively far away and therefore not likely to cause parallax problems. As for adding a button picture, I'm not sure what that is! A tripod cap?
John
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