snookphotograph
Posts: 26
Location: Leeds, United Kingdom
Registered: 4 Jun 2007
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Sigma 15mm
Posted: 5 Jun 2007 at 10:04 GMT
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Hello. i'm new to this forum, and have been looking at making a post for w while.
I was wondering whether anyone could give any advice on the sigma 15mm lens?how many shts do i need for a vr tour, and if there is any way of making the stiching easier?
Currently i'm using realviz 5.5.2
look forward to your help
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John Houghton
Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 10:36 GMT
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The number of shots will depend on what camera you have the 15mm lens mounted on. See the information provided at:
www.vrwave.com/panoramic/photography/lens_databas...
Stitching is made easier by care exercised when shooting the photographs. If you have the camera mounted on a spherical panorama head so that it rotates about the entrance pupil of the lens to avoid parallax, and you give all the images the same exposure and white balance, you should have few problems. If Realviz doesn't produce the results you want, try PTGui.
John
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snookphotograph
Posts: 26
Location: Leeds, United Kingdom
Registered: 4 Jun 2007
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 10:43 GMT
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Does PTGui work on a mac? using a manfronto tripod, and have a panoramic head. Have a 30d and a 5d camera.
Does a spherical head produce better results then a panoramic?>
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John Houghton
Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 14:54 GMT
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For single row panoramas, there will be little difference between a panoramic and spherical head. The Sigma 15mm is a fullframe fisheye on the 5D so if you wanted to do full 360x180 panoramas, a spherical head would be better because you can rotate the camera up and down for the zenith and nadir without introducing parallax effects. With the 30D, you would need two rows of 8 images + zenith and nadir, so a spherical head would be a necessity. PTGui does work on a Mac.
John
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snookphotograph
Posts: 26
Location: Leeds, United Kingdom
Registered: 4 Jun 2007
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 15:21 GMT
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is PTGui better than realviz sticher?
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Mark Houston
Posts: 80
Location: Ferndale, Michigan, United States
Registered: 23 Aug 2005
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 17:26 GMT
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Better? that's subjective. I like PTGui much better then of the Realviz software (I have not used the latest version of sticher). I found the earier versions of Realviz software to be buggy and hard to work with.
Now PTGui does have learning curve, but it's not that hard to master. There are plenty on web site that offer help and advice on PTGui.
PTGui is also by far the best deal for the price.
Mark houston
www.360michigan.net
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John Houghton
Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Sigma 15mm
Posted: 5 Jun 2007 at 17:42 GMT
updated: 5 Jun 2007 at 17:43 GMT
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Mark is right about it being subjective. PTGui and Stitcher have different capabilities, not to mention prices, that make it difficult to choose either as being "the best", whatever that means. Different people have different priorities. Some people like Stitcher, others like PTGui. Both can produce excellent results. I have used PTGui for more than six years and it has always been an exceptionally well featured product that works reliably. Only quite recently has Stitcher been able to stitch fisheye images and I don't have any personal experience of the current version. Consequently, I am not in a position to offer an unbiased opinion as to which is "best". Few people are!
If you look at the quarterly World Wide Panorama entries, you will find that the PTGui users outnumber the Stitcher users by 6:1. Is this because PTGui is better or because it is cheaper or because it is more cost effective? Who can say? You will have to give both a fair try and see which one meets your own particular requirements best. Just to confuse the issue further, others have strong preferences for Hugin (free), PTAssembler, PTMac or AutoPano Pro.
John
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JohnnyV
Posts: 11
Location: Coast, United States
Registered: 15 Jun 2006
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Re: Sigma 15mm
Posted: 26 Jun 2007 at 17:29 GMT
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I use PTGui on Mac. Nothing works better than PTGui and I've tried a few.
Also with the help of John H. and other helpful users there is a very large support system that is second to none.
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erik leeman
Posts: 28
Location: Netherlands
Registered: 24 Aug 2007
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 6:37 GMT
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Hi,
I use a Sigma EX DG 15mm F2.8 Fisheye on a Canon EOS 5D.
I must admit I bought it because the Canon version wasn't available when I needed it, but I have no regrets at all! Even when shooting straight into the sun flare is neglectable. Vignetting (a real problem with the 5D with many lenses) is slightly discernable, but only in the zenith and nadir if you make sure you have about 50% overlap between shots. With the 5D that means series of 10 shots around + 1 zenith and 1 nadir. The resulting equirectangulars are about 62Mp in size, or 365MB as 16-bit colordepth TIFFs.
If you want you can see some high-res results with that lens (and camera) under various light conditions here:
www.erikleeman.com/QT/fullscreen-english-DEVAL.htm
(note: the first 3 at the top were taken with 24 and 50mm lenses on a 20D)
For best viewing use the DevalVR full screen option!
Oh, I ONLY shoot RAW (essential!!!) and I use PTGui for stitching and Pano2QTVR (Pano2VR beta) for generating the .mov (.flv) versions.
Hope this helps.
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DorinDXN
Posts: 1695
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 12:40 GMT
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Hi Erik. WOW! this is the greatest bunch of great panoramas in one site. Congratulations!
I want to ask a few questions rising from your post and from your panoramas.
1) You said that you have no regrets, but in short, do you think that the Canon 15mm fisheye is better (even a few) or Sigma 15 mm used by you is better (no need to explain, only your oppinion is good for me)
2) What do you use for correction of CA?
3) Do you use AEB in static scene or extract normal/under/over variants from RAW then merge or none of those?
thanks for sharing your great work,
Dorin
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irieman
Posts: 154
Location: East Sussex, United Kingdom
Registered: 8 Jul 2006
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 15:00 GMT
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Very nice shots Erik - slightly surprised that you need 10 around as I only use 6 with the Canon 15mmFE on a 5D and I've never read anywhere that you need more - or is that so that you can get the pixels count up?
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DorinDXN
Posts: 1695
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 15:53 GMT
updated: 25 Aug 2007 at 15:54 GMT
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irieman said: ... slightly surprised that you need 10 around as I only use 6 with the Canon 15mmFE on a 5D and I've never read anywhere that you need more - or is that so that you can get the pixels count up?
In what way you consider that the number of shoots with 15mm will determine the number of pixels?
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erik leeman
Posts: 28
Location: Netherlands
Registered: 24 Aug 2007
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 18:43 GMT
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Thanks guys, I'm glad you like them.
I know I can 'cover' 360 degrees with much less shots, and I'd do that if that was all I wanted. But if that was so I'd buy myself an 10.5 or 8mm and shoot even less. For some applications and/or subjects that would certainly be good enough, OR in the case of VERY dynamic scenes, even the ONLY way to capture them.
What I am after however, is image quality and detail. I will sometimes take 20 or more shots so I can use only the sharpest central band of each shot. Also with enough shots unavoidable lensflare can be largely eliminated most of the time by layering and careful masking. I tackle scenes filled with moving people by 'going round' three or four times, so I have enough raw material to make a composite with hardly any visible flaws. The enormous amount of time (and disk space) processing all that material costs is a problem though.
@ Dorin:
1. I cannot compare the Sigma to the Canon 15mm because I only own one of them. However I can compare it with the other (Canon) lenses I do own: the EF100mm f/2.8 USM macro, EF50mm f/1.4 and the EF24mm f/2.8 and I can honestly say I really like that Sigma : )
2. I use Rawshooter Premium for processing my RAW files, and as far as I know it has a 'built in' capability for reducing CA. Other than that I do nothing. The fact I only shoot (for VR) with apertures between f/8 and f/11 might help counter CA. Shooting with ample overlap to eliminate the bad edges from the stitch altogether contributes most I think.
3. I'll apply every technique I can think of to increase dynamic range (DRI), except HDR/LDR. My goal is to do it so no one can tell, it HAS to look natural. Of course anyone who does this kind of work will know it cannot possibly be done without dirty tricks ; )
Please ask if you want to know more.
In case you're interested, rough and processed versions of my equirectangulars can be seen in my Flickr stream:
flickr.com/photos/erik-nl/
Regards,
erik leeman
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bigwade
Posts: 271
Location: Netherlands
Registered: 19 Oct 2005
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Re: Sigma 15mm
Posted: 25 Aug 2007 at 19:22 GMT
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The Sigma is a newer design than the Canon.
At FredMiranda Forum you can read user reviews.
CA can be corrected in CS3 and the best aperture is f5,6/8
(at f11 the image is less sharp overall)
6 around + T+B will do with a lot of detail.  )
Equi size about 5700x11400.
Another option is a (shaved) Tokina 10-17 , hardly flair at all ! but has to be stopped down to f11 for good corner sharpness
I have both.
Have Fun
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BarneyM
Posts: 1
Location: Melbourne, Australia
Registered: 5 Sep 2007
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Re: Sigma 15mm-No of shots vs Resolution
Posted: 5 Sep 2007 at 9:21 GMT
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Hi
The number of shots to capture 360° horizontal x 180° vertical is determined entirely by the lens FOV and camera sensor size and resolution.
For example, the Sigma 15mm F2.8 EX DG Diagonal Fisheye has a FOV approx 142°x92° on a Full Frame camera.
Used in portrait mode on a panorama head, 3.9 images in portrait mode cover the full circle and produces approx 12700 pixels for a full circle, using a FF 16MP camera such as EOS 1Ds MKII.
Taking more images is essential, to produce a good overlap, but will not increase the resolution, which is fixed by the camera and lens.
To achieve a higher resolution, use a longer lens (which produces more pixels per degree of angle) and more images.
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