Glen Do
Posts: 18
Location: Canada
Registered: 26 Mar 2008
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Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 2:17 GMT
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after many hours of using these forums i thought it would be a good time to finally join in. I've read the peleng vs sigma debates and decided to go the peleng way (sigma was too much). (peleng set to f8, unlock, infinity)
I also invested in a cannon rebel xt (350d i think). I'm using a sturdy primitive tripod and a king pano head. i have ptgui 7 and photoshop cs3.
Now some questions i have are when cropping with ptgui i don't know exactly the most effective way. Is it crop to the edge of my camera frame like
or inside the frame like
when i do this, i get some really funky results with ptgui.(bad results)
and i can't seem to get my max cp distance lower than 12 ~ 20. averages are around 2-6.
I sometime have difficulty stitching the zenith so I've experimented with about 5-10 degrees tilt up and then photoshoping the ground. but when i do this my nadar hole is pretty big.
my tripod hole can get rather large either way i shoot, is this because of the king pano head? i see it cuts off a good chunk if i crop it out.
any pointers to more tutorials for my camera?(i read jon's with the smartblend plugin, helps with parallax alot.)
Thanks.
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mhc1
Posts: 102
Location: Hamburg, Germany
Registered: 29 Dec 2005
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 7:33 GMT
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Hello Glen,
crop along the black rim in your image. PTGUI will only use the inner cicrle and the 1.6crop of Canon gives you less FOV than on Nikon- so you need as much as possible.
If you crop inside your image, your FOV is even smaller - just the cropped part.
The lower right black part is a part from your panohead.
I also have a very little part of the NodalNinja in my images - but it vanishes when stitched.
Just try a little an look which setup fits you best.
When titled up ap. 2-5° the zenith will appear much better and the nadir will be a little worst- only very little though and this has to be retouched anyhow.
ciao
miike
www.260de.de
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John Houghton
Posts: 1998
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 7:43 GMT
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Glen, Neither of your crops are optimum. You want to position the crop circle on the edge of the image circle in the corners - just before the point where the image begins to darken significantly. The lens fov parameter should then be over 180 degrees. Wherever you put the crop circle, the images should stitch perfectly well provided you have a reasonable overlap. Remember to include the shift parameters in the optimization.
The intrusive hardware in the bottom right of the images may or may not cause problems in blending (dark shadowy areas). Probably not, but even so, a nadir shot should cover these over. If necessary, you can apply alpha channel masks to the input images to mask out the head. See my tutorial at www.johnhpanos.com/tuts.htm .
John
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Smooth
Posts: 1432
Location: Australia
Registered: 21 Jul 2004
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Glen Do
Posts: 18
Location: Canada
Registered: 26 Mar 2008
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 17:13 GMT
updated: 27 Mar 2008 at 17:21 GMT
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thanks to both of you, i have stitched them together and it does cause a dark shadow backwards 'L' shaped.(6 of them).
the mask trick did the job!(john\s tutorial page) i reduced my tripod foot print by at least 30% making it an easy stitch. The extra fov made stitching a lot smoother too.
thanks a ton, and I'll get something up here soon!
edit:
Thanks smooth, finally good to talk to you, seen you on here quite a bit.
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Mark Schuster
Posts: 635
Location: Welwyn Garden City, United Kingdom
Registered: 25 Jan 2006
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 17:19 GMT
updated: 27 Mar 2008 at 17:46 GMT
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Glen says,
peleng set to f8, unlock, infinity
I've never seen a Peleng, leave alone used one, but does Glen mean he sets the focus to infinity? If so, that seems unusual for fisheyes with there enormous depth of focus. Will a Peleng user please advise!
Mark
PS I've got a hand-me-down 7.5mm fisheye from John Houghton. It has fixed focus, but John told me he had pre-set it at a couple of metres, or so, I think. If you are there John, is that right?
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John Houghton
Posts: 1998
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 27 Mar 2008 at 18:44 GMT
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Mark Schuster said: PS I've got a hand-me-down 7.5mm fisheye from John Houghton. It has fixed focus, but John told me he had pre-set it at a couple of metres, or so, I think. If you are there John, is that right?
Mark, Yes, that is correct. I had to choose a shim of suitable thickness to set the focus position to approximately 2m: quite bit larger than the assumed hyperfocal distance at the maximum aperture.
John
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Mark Schuster
Posts: 635
Location: Welwyn Garden City, United Kingdom
Registered: 25 Jan 2006
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 28 Mar 2008 at 12:03 GMT
updated: 28 Mar 2008 at 12:06 GMT
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John, You say, I had to choose a shim of suitable thickness to set the focus position to approximately 2m which applies to my old (and now well loved) 7.5mm fisheye, but the reason I mentioned it at all in this thread was to find out whether or not Glen is setting-up the focus of his Peleng optimally. Could you, or anyone, comment on this.
(I am assuming that, unlike my fixed focus lens, Glen's Peleng has a manual focussing ring)
Mark
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Glen Do
Posts: 18
Location: Canada
Registered: 26 Mar 2008
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DorinDXN
Posts: 1554
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Mark Schuster
Posts: 635
Location: Welwyn Garden City, United Kingdom
Registered: 25 Jan 2006
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 30 Mar 2008 at 12:02 GMT
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Glen,
I still wonder about focus. Your camera bag, on the ground a few metres from the camera, doesn't seem all that sharp, then neither does anything else. Isn't there a Peleng user out there who can advise Glen about focussing?
Mark
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Peter Patricelli
Posts: 109
Location: Eugene, OR, United States
Registered: 20 Dec 2006
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 30 Mar 2008 at 13:11 GMT
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Glen,
Pelengs are notorious for flare problems. That is simply an inherent problem with the lens which will pop up in certain lighting situations, such as direct sunlight where the sun in striking the lens from a variety of angles during the rotational shoot. In general for all lenses I try to choose an outdoor position where the lens is shaded.
Pelengs, in addition to the flare problem, may not be a sharp as more expensive lenses. I have one and that was my conslusion, anyway. But they have their place and a are a very good, inexpensive, training lens for someone just getting into 360 panos.
Peter Patricelli
www.flyfishingfotography.com
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Shantic
Posts: 272
Location: Puerto Vallarta, Jalisco, Mexico, Mexico
Registered: 12 Apr 2005
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 30 Mar 2008 at 19:43 GMT
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I have to disagree on the sharpness, it is not tack sharp but if focused correctly its not bad either. make sure you are using the correct adapter, mine was to thick so I had to reduce it in a (don't know what they are called in english, but its a shop where they make metal pieces) shop
and always use infinity to focus.
the flare IS a problem, but I dealt with it by placing my hand over the direct light (sun or whatever) than taking one normal, one covering the light and then mask out my hand in photoshop, a little more work, but it works very well 
But now I have a Sigma 8mm f/3.5 and I would never go back to a peleng, as much as I learned from it
Shanti
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Peter Patricelli
Posts: 109
Location: Eugene, OR, United States
Registered: 20 Dec 2006
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Re: Canon rebel xt + peleng 8mm, help?
Posted: 30 Mar 2008 at 23:49 GMT
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Shantic, or anyone else,
With a manual focus lens, and especially one which is probably never being used outside the USSR on a camera for which it was designed (the Peleng), if setting the lens manually to the infinity stop, how would one know if in fact that stop was PAST optimal focus? The adapter which comes with the lens, in my case for a Nikon, hardly inspires confidence in terms of high-tech tooling. Looking thru the viewfinder and lens for precise focus with a fisheye is very problematic, for me anyway. It seems to me that a setting at less than infinity and depending on hyperfocal DOF issues would insure one was not being bitten by the incorrect infinity stop possibility. Or, for that matter, why would anyone ever set a fisheye being shot at f8 specifically for infinity?
Peter Patricelli
www.flyfihingfotography.com
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