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Sigma 4.5mm Fisheye Lens on Nikon D300 ( Panorama Sample made with 3 pictures ).
Roberto Gomez Torres 2008-Feb-06 07:43:00
Hello List,
A few days ago I bought one Sigma 4.5mm Fisheye lens.
Mainly to be able to create fast spherical panoramas with less pictures for
stitching.
Here I want to share with you my findings, a sample and files for you to
download and play with them.
1) The price of the lens.
I bought the lens on eBay where I found the best price after some weeks of
research.
The seller is located in Honk Kong an gave me a great service and help. Here
you can find the link to the add on eBay and the price I paid :
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=ADME:B:EOIB...
2) The Nodal point.
I spent the last weekend finding the best point for panoramas made with this
lens when using 3, 4 or 6 pictures.
Using "Really Right Stuff" panorama equipment I calibrated the lens distance
from the tripod for rotation.
The method I used was pretty similar to the one found here ( by Dave
Watts ):
http://dgrin.smugmug.com/gallery/2114189/1/109263193
The distance from the camera tripod mount to the point of rotation I am
using for this lens is : 10.8 cm.
3) Diameter of each fisheye image.
On my Nikon D300 the Sigma 4.5mm captures a circle image with a diameter of
2,280 pixels very close to the center of the camera sensor.
Since the Nikon D300 is capable of taking pictures with a resolution of
4,288 x 2,848 is clear that a lot of pixels are wasted.
4) The Camera Settings.
For this first sample I used the following setting on the Nikon D300:
- Manual Mode on Camera.
- Manual Mode on Lens.
- Aperture F/8.
- Exposure Time 1 Second.
- Format RAW 14 bits at 4,288 x 2,848 pixels.
- ISO 200.
- Metering Center Weighted Average.
- Color Space sRGB
5) Taking the Pictures.
For this shot I used a Bogen table tripod, a small Novoflex Ball Head for
Leveling, Panoramic Rotator, L-Bracket and Slide Rail made by "Really Right
Stuff".
Only took 3 pictures, each at 120? from the other.
In order to discard any possible vibration or moving the tripod I shot the
camera with a remote wireless camera shutter made by "Aputure".
The camera was mounted in portrait mode ( something I liked a lot since for
years I only took panoramic pictures in landscape mode ).
6) Converting the RAW Pictures.
Since RAW pictures can not be processed within PTGui Pro and are very heavy
for Internet download, I am included only JPEG version of the source files
with this sample.
First I converted the RAW pictures using Nikon Capture NX into TIF files
keeping all the possible color information including ICC profile.
Then with Photoshop CS2 the TIF files were converted to JPEG with the less
compression possible ( Here I applied a value of 11 from the scale that goes
from 0 to 12 ).
7) Stitching with PTGui Pro.
Once the JPEG files were ready I imported them to PTGui Pro v.7.5
Started with new values for the circle fisheye images with a 180? FOV, 4.5mm
and made a crop for each image with a diameter of 2,280.
Set in the Control Points section one vertical line for each image, auto
create the normal control points and optimized the values.
Deleted manually some wrong auto control points and ready.
With my Setting PTGui Pro gave me the following values for my template:
- Lens Type: Circular.
- Focal Length: 4.473
- Focal Multiplier: 1.5x
- Horizontal Field of View: 182.3?
The only processing I allowed for the Source Images within PTGui Pro was the
Exposure Correction with only the "Optimize Vignetting" setting Enabled.
After Stitching using PTGui and Blending with Smartblend the result
Equirectangular files has a resolution of 4,504 x 2,252 pixels.
That Equirectangular final image allows a maximum optimal cube face size of
1,434 pixels.
8) Downloading the Sample Files.
I have uploaded to my web site a ZIP archive with the 3 pictures in JPEG
format, the PTGui Pro project, the Equirectangular file and the QTVR Cubic
Panorama for you to play with.
The Panorama was taken at my small Home Office !
Here is the link to the ZIP file ( 16.7 MB ):
http://www.tiempo-digital.com/galeria/sigma_4_5_sample_01.zip
9) Viewing the Panorama Online.
Here is the link to view it on your browser:
http://www.tiempo-digital.com/galeria/fs-sigma_4_5_sample_01.html
10) To Do list.
Tomorrow I will be making some tests taking 4 pictures per panorama and also
will take some tilting the camera for 5? to 15? in order to obtain a better
Zenith coverage.
Next weekend I will go out for camping and will test this lens at the
outdoors, mainly I want to see how it works under the sun and possible lens
flares will show.
Please feel free to make me any question.
And would love to hear your impressions about this new lens !
Hope some of you thinking on buying this lens could find the report useful.
Best regards from Mexico City.
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Roberto G?mez Torres
Tiempo Digital
Mexico City, Mexico
www.tiempo-digital.com
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