panorama software,virtual tour software
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2007-03-27
#1

Problem with Sigma 8mm

As you can see on the following shots taken with a 8mm Sigma DG + various Canon bodies, the image is cropped at top and bottom and I can't, of course, stitch the photos with the 4 barrels method, becaus I don't have 180...

A few months ago, I had a 8mm Sigma non DG and no problem with a 20D as you can see here :

 

Here are the cropped photos with various bodies :

20D + 8mm

30D + 8mm

400D + 8mm

350D + 8mm

And with a 5D, same lens  (full frame) :

Did anybody encounter the same problem ?

Does anybody has an idea ? Does it comes from the 8mm which should be defective ?


Phil, French Guiana
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2007-03-27
#2

interesting... I can see the circle differences. 

We have the Sigma 8 f3.5  I will see if I can duplicate the process with our Canon 350d, 20d and 5d and will post results here for comparision.


/s/
Dave
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#3

I am using a Sigma 8 f3.5 EX DG with my Canon 1Ds MarkII to creat panos from 3 shots.  Here is a single shot from it.


RTFM
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#4

I used our Sigma 8 f3.5 on the 350d, 20d and 5d.  You are welcome to right click and save this image to your hard drive for comparision.


/s/
Dave
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#5

OK dave, thanks...

As I can see on your photos, the top and bottom of the circle are cropped in the same way as mines... And I think you can't stitch them with the "4 barrels" template ?

Is your lens a DG or not ? 

This would mean that the DG is not a full 180 lens with APS sensors, instead of the non DG, as you can see on the first photo of my precedent post.

If other users of Sigma 8mm DG or not could post samples, this would be helpfull !

 


Phil, French Guiana
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2007-03-27
#6

I don't see anything that is wrong? The sensor is different between cameras and yes the Sigma F/3.5 8mm gives a slightly more zoomed cropped image. But this in no way effects the stitching of 4 drum images using Panoweaver 4 or Panoweaver 5. There will only be a very small hole at the Zenith and Nadir that can easily be patched or cloned in.

Tilting your camera up 4 to 6 degrees will close the Zenith hole completely, though it will enlarge the nadir hole the same amount. Doing means you only need cap or patch the Nadir.

Also note that every camera is slightly different and the sensors can be out of position to each other by up to 1mm.

Just remember when setting the "enclosing circle" to take into account that it will go slightly of the page/image at the top and the bottom. The circle must be centered.

Regards, Smooth


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2007-03-27
#7

Yes, our Sigma 8 f3.5 is the DG.  The DG helps reduce the lens flares.

I just went out and shot a 4 +1 zenith.  Yes, as Smooth suggests you can stitch 4 at 90 only and you will get a small black square in the top and bottom.  Tilting the lens up say 5 degrees and you will close the hole in the top.  Typically I usually put advertising circle in the bottom.


/s/
Dave
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#8
This is a great thread, as my knowledge of lenses is limited. I would like to get a Sigma when I can upgrade my equipment, and as Dave said, I like the DG feature concerning lens flair. I use a FC-E9 now, and I know theres no comparison but... I guess my question is why wouldn't sigma make the lens like 185 degrees? so we have some overlap, would that degrade the quality say back to the FC-E9?
Roadkill
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#9

Roadkill,

Sigma make the lens at 180 degrees (but this is only true on a full sized sensor) I.E: A film/analogue SLR camera or a Canon 5D, 1Ds or Kodak full sized sensor DSLR. All other DSLR's have a multiplying crop factor with Nikon being 1.5x and Canon being 1.6x. The Canon 1D (not 1Ds) has a crop multiplying factor of 1.3. Think of these as default zoom.

You can see this clearly from the samples supplied. Notice the full frame sensor (Canon 5D and Canon 1Ds) is full circular 180 degrees.

Now shooting with these higher professional cameras that give a full circular image allows you to stitch as little as 3 images which make life easier but! You will also notice that much of the sensor is not used and you waste a lot of pixels to "black" nothing area. The offset to this is that the professional full size sensor cameras have much larger Megapixel sensor that compensates.

Really this is why using a full frame fisheye (15mm/16mm) is better suited for higher resolution shots using the Canon 5D/1Ds as you don't waste those precious pixels. Or you can adapt a Nikon/Nikkor 10.5mm Full Frame Fisheye to the professional Canon body.

I think the real answer is possible to use the new Tokina 10-17mm zoom fisheye on these cameras to get the best of both worlds.

You will get some saying you are better off with a small crop sensor and shooting more images. (That is hard to argue!) But the 5D for me is still the way to go because it can be used for so many other options and "All" SLR lenses work the way they were intended on a 35mm camera.

Also understand the Nikon FC-E8/9 are not always 185 degrees. It depends on what camera they are fitted too. On some they are less than 180 degrees and on others more than 190 degrees.

Finally, I have owned many Nikon's and many Canon's. I absolutely love my 5D but only slightly over my previous love the Canon 10D. I'm sure the 20D and 30D along with the 300D, 350D, 400D are all very good for their owners as well.

Hard to find a bad word about the Nikon DSLR range either.

Regards, Smooth


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2007-03-27
#10

Because the Sigma 8 optics only are 180.  So we could take 3.  And I need more overlap.. I take 4.  You are correct with the Sigma 8 you can not take 2 because the lens is 180. 

The Nikon FC-E9 I think is 183 and that gives you a very narrow 1.5 degree overlap on each side (yes I know there are no sides to a circle image) but you know what I mean.


/s/
Dave
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#11

Thanks guys, I think I get it now. I'm lucky because when you two helped me a while back with my ebay lens you pointed me to the FC-E9 that gave me a full circle with my Canon S3IS (1.6X). I have had so much fun with it, but now that I'm addicted I want a Sigma and new camera - now I have new knowledge and a direction.

Thanks again guys!


Roadkill