mediavets
Posts: 1181
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Re: Ipix FC-E8 on sale for $49.99
Posted: 30 Mar 2009 at 22:57 GMT
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Rip-n-Burn said: I found that 4 shots around covers the whole shebang and I can/need to clone the nadir. I did notice the images were very fuzzy on the overlaps and determined it was the alignment of the lens on my homemade mount. It took me like 30 plus pano tests to "dial it in" to what was exceptable to me. (Keep in mind I have little to no experience with 360's)All in all I'm very happy with this lens for the price I paid. The information here on the history is very interesting as well. Thanks for sharing.
Does your camera have a manual mode or aperture priority mode?
If so set the aperture at around f8 or as near as you can get.
The FC-E8 does best at around f8 and I expect the IPIX FE is much the same.
Set metering to centre weighted.
Set focus to infinity if you have such a setting available to you.
After stitching and rendering downsize and sharpen your stitched image.
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 31 Mar 2009 at 0:34 GMT
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Rip-n-Burn said: I found that 4 shots around covers the whole shebang and I can/need to clone the nadir. I did notice the images were very fuzzy on the overlaps and determined it was the alignment of the lens on my homemade mount. It took me like 30 plus pano tests to "dial it in" to what was exceptable to me. (Keep in mind I have little to no experience with 360's)All in all I'm very happy with this lens for the price I paid. The information here on the history is very interesting as well. Thanks for sharing.
The position of the lens relative to the tilt pivot point may also be my problem. The first time I shot 4 around, the lens was -- what I thought -- too far forward but the
pano was pretty sharp all around.
Now I've moved it back a ways and I get the soft zones.
If you could post a link to a picture of your setup, that would help me figure out what was going on. Numbers won't help because I have a different camera etc.
Thanks in advance...
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John Houghton
Posts: 2839
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Ipix FC-E8 on sale for $49.99
Posted: 31 Mar 2009 at 7:52 GMT
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Ken, It's easy enought to establish the no parallax point by taking some test photos. However, if you are getting soft areas at the seams and the camera images are sharp in those areas, then you presumably have poor alignment of the images. Don't just throw the images into PTGui (as you said you did). Do a proper optimization to get the maximum cp distance down to 2 pixels (with a good spread of control points) and you should have good quality all round.
John
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mediavets
Posts: 1181
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Re: Ipix FC-E8 on sale for $49.99
Posted: 31 Mar 2009 at 8:21 GMT
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Ken Warner said: The position of the lens relative to the tilt pivot point may also be my problem. The first time I shot 4 around, the lens was -- what I thought -- too far forward but the
pano was pretty sharp all around.
Now I've moved it back a ways and I get the soft zones.
If you could post a link to a picture of your setup, that would help me figure out what was going on. Numbers won't help because I have a different camera etc.
Thanks in advance...
Here's a guide, the 'best' NPP is going to be pretty close to - or a little behind - the front edge of the metal body of the lens surrounding the front element. So a few test shots should help determine just what position works best with your camera.
FE lenses and convertors have no single NPP.
Andrew
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 31 Mar 2009 at 16:36 GMT
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John Houghton said: Ken, It's easy enought to establish the no parallax point by taking some test photos. However, if you are getting soft areas at the seams and the camera images are sharp in those areas, then you presumably have poor alignment of the images. Don't just throw the images into PTGui (as you said you did). Do a proper optimization to get the maximum cp distance down to 2 pixels (with a good spread of control points) and you should have good quality all round.
John
I've been doing some experiments with single pictures trying to get the sharpest possible. Starting to get something I can live with. Found that reducing CA does a lot for sharpness. My particular combination of camera and this fisheye seems to result in a lot of CA.
So far it's been stopping down to F8 (that's as small as I can make the aperture) and focusing on infinity. As mediavets suggested.
Also, I've been trying to find a zoom level that spreads the image circle as large as possible (to get more pixels in the image) and still have the advantage of a fisheye that can reduce the number of shots. If I zoom all the way in, then the fisheye just becomes a wide adapter -- that doesn't make any sense. So finding the right balance of image circle size and zoom level seems to be the key right now.
Today I do the grid thing to get a reasonable NPP.
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mediavets
Posts: 1181
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Re: Ipix FC-E8 on sale for $49.99
Posted: 31 Mar 2009 at 22:34 GMT
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Ken Warner said:
Also, I've been trying to find a zoom level that spreads the image circle as large as possible (to get more pixels in the image) and still have the advantage of a fisheye that can reduce the number of shots. If I zoom all the way in, then the fisheye just becomes a wide adapter -- that doesn't make any sense. So finding the right balance of image circle size and zoom level seems to be the key right now.
Ken,
With the FC-E8 on my Nikon P5100 I can only zoom in a little ( a couple of steps) before I get unacceptable vignetting.
You mileage may vary - as they say.
This is the article - by Luca Vascon - that originally inspired me to get a portable pano setup based on the FC-E8 and the P5100 (it's in Italian but readable via on-line translators):
www.nital.it/experience/immersiva-p5000.php
Andrew
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 1:03 GMT
updated: 1 Apr 2009 at 1:09 GMT
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Hi Andrew,
I found that if I zoom in so that the entire frame is filled except the very corners -- which looks like a vignetted image --- I get a wide enough field of view and a sharper image. I use the corner vignetting as an indicator as to how much I've zoomed in. My camera doesn't tell me the zoom level.
At that zoom level, there is enough overlap to shoot just 4 around. I shoot 10 degrees up and that seems to cover the zenith and leave a not so big hole at the nadir that I can patch with a down shot. The down shot takes more work than all the rest.
Also, I found that if I focus on near ground -- 10 feet or so -- the rest of the image is still in focus.
And fixing CA the very first thing after converting from RAW (RAF) to TIF really helps a lot.
Our setups are different so what each of us does doesn't exactly apply to the other but it's helpful to compare.
Setting the focal length in PTGui is tricky though. I'm using .21 as the focal length multiplier. Seems to work. But I don't really know what value is correct.
I tried some shots to see if I could find a reasonable NPP . I tried shots over a 2 cm range and really couldn't see much difference. The last pano I made, the lens was set so I could just see the end of the NN3 on the side of the image when zoomed out but when I zoom in like I described, then I don't see it. So I'm a little farther back than what you suggested. Worked ok -- once. Try more tomorrow.
I'm still figuring things out...
Ken
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John Houghton
Posts: 2839
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 6:55 GMT
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Ken Warner said: Setting the focal length in PTGui is tricky though. I'm using .21 as the focal length multiplier. Seems to work. But I don't really know what value is correct.
The focal length and multiplier values are completely irrelevant if you have the edges of the image circle in the corners of the frame. With lens type circular, set the crop circle on the edge of the image circle and set your fov to 180. PTGui will evaluate the true fov in the optimization, which you can then use in future stitches.
I tried some shots to see if I could find a reasonable NPP . I tried shots over a 2 cm range and really couldn't see much difference.
You cannot be doing your test for parallax properly if this is so, though it it true that differences will probably only be evident if you have things close to the camera in the overlap areas. Try the tape on the window test described in www.johnhpanos.com/epcalib.htm .
John
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 18:16 GMT
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So PTGui will figure out the necessary fov? That's handy.
Will the lens parameters calculated from a reasonable stitch -- once I get one -- be true enough to apply to other sequences shot similarly. I don't believe I can completely reproduce all the settings and variables from shot to shot. There's just too many moving parts and an NNx will shrink or stretch depending on the temperature.
I've shot at 15F and 85F That has to have at least some effect on the offsets. We are dealing in mm's. It doesn't take much variation in temps to cause noticeable stretching or shrinking.
So are lens parameters really trustworthy over the long haul?
And I finally found a pretty good NPP for the zoom level I'm using. I put a grid on the window and put the camera about a meter back and shot front, left and right.
Now that I'm looking close at a better target, I see that 2mm's does make a difference. I'm going to let myself be satisfied with an error of + - 2mm.
The NPP a lot farther back than I anticipated. The front metal of the lens is at the tilt axis of the NN3 so part of the lens is actually behind a portion of the NN3. If I zoom out so that it's a complete circle, I can see part of the tilt axis area. And if I put my hand on the tightener knob, I can see my fingers.
But when I zoom in as I described, then that part is clipped.
Lastly, I crop just a few pixels inside the purple fringe on the corners.
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mediavets
Posts: 1181
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 18:37 GMT
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Ken Warner said:
The NPP a lot farther back than I anticipated. The front metal of the lens is at the tilt axis of the NN3 so part of the lens is actually behind a portion of the NN3. If I zoom out so that it's a complete circle, I can see part of the tilt axis area. And if I put my hand on the tightener knob, I can see my fingers.
I think that's what I suggested?
Andrew
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John Houghton
Posts: 2839
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 19:09 GMT
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Ken Warner said: So PTGui will figure out the necessary fov?
Ken, The fov parameter determines the size of the warped image on the spherical stitching surface. If the fov of an image is 90 degrees horizontally, it will cover a quarter of the 360 horizontal view on the stitching surface. If you set the fov to 180, it will cover half of the 360 view - i.e. the warped image is twice as big. If you have 4 shots around, linked with control points, when you include the fov parameter in the optimization, the fov will be adjusted (and hence the size of the images) so that the images exactly fit together around the stitching surface - neither too big nor too small.
PTGui is only interested in the fov, but the focal length and sensor size or crop factor will be used to estimate the initial fov when necessary. If you take control and do your own optimization, you can choose what gets optimized and what doesn't. You can apply the settings from a successful stitch to a similar set of images using Apply Template, and then optimize using those settings as a starting point. This is generally better than starting from scratch.
John
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 19:28 GMT
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mediavets said: Ken Warner said:
The NPP a lot farther back than I anticipated. The front metal of the lens is at the tilt axis of the NN3 so part of the lens is actually behind a portion of the NN3. If I zoom out so that it's a complete circle, I can see part of the tilt axis area. And if I put my hand on the tightener knob, I can see my fingers.
I think that's what I suggested?
Andrew
Yup... That's what you said. But there was some fine tuning to be done.
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 1 Apr 2009 at 19:32 GMT
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John Houghton said: Ken Warner said: So PTGui will figure out the necessary fov?
Ken, ... when you include the fov parameter in the optimization, the fov will be adjusted (and hence the size of the images) so that the images exactly fit together around the stitching surface - neither too big nor too small.
John
Ah, that's fixes the gap in my understanding. I didn't connect the fov optimization with the setting of the lens parameters. And I didn't realize the importance of the fov setting. I get it now...
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Rip-n-Burn
Posts: 3
Location: United States
Registered: 19 Mar 2009
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Ken Warner
Posts: 643
Location: Mammoth Lakes, United States
Registered: 14 Aug 2004
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Re: Ipix FC-E8 on sale for $49.99
Posted: 17 Apr 2009 at 1:17 GMT
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The lens he has now don't have a rear lens cap and are used. The previous stock was new.
But if you can get one for 40-50 bucks, they aren't bad but don't expect a two shot stitch with any quality.
I now shoot 6 around zoomed in a bit to fill the frame. I get ok quality for a compact camera but nothing even close to a real camera/lens setup.
It's a handy lens to shoot from a monopod with. Small and on a compact camera on a monopod, it's very portable and being a fisheye very forgiving on parallax error.
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