Gascar
Posts: 7
Location: United Kingdom
Registered: 19 Jan 2012
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Accurate bearings?
Posted: 22 Jan 2012 at 10:34 GMT
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I want to do some panos with depth of focus from infinity down to a oouple of inches from the lens. I can do the stacking for that, that's not the question.
It does mean though that the nodal point accuracy is particularly critical and has to stay held better than normal panos when the head's panned/tilted.
So I'm looking for a pano head which is "good" rather than one which is noticeably sloppy in the bearings, or the axes aren't so accurate, etc.
There are heads out there covering a wide price range. I don't need nadir/zenith points, so maybe they're ALL good enough, I don't know.
Has anyone used a variety of heads and noticed a difference in the aspects which concern me?
Thanks.
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DorinDXN
Posts: 2853
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: Accurate bearings?
Posted: 22 Jan 2012 at 10:44 GMT
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Any pano head from Nodal Ninja with one of those advanced rotators will suffice, those rotators have a knob for locking rotation, you can use it, also if the rotation is around NPP some autoalign features provided by software can help as well.
cheers,
Dorin
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jannefoo
Posts: 59
Location: Finland
Registered: 3 Jun 2009
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Re: Accurate bearings?
Posted: 22 Jan 2012 at 12:04 GMT
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The entrance pupil will move as you focus closer and closer. The longer the lens, the bigger the movement of the entrance pupil is. So you either have parallax in the foreground or in the background unless you recalibrate the head for every time refocusing.
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DorinDXN
Posts: 2853
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: Accurate bearings?
Posted: 22 Jan 2012 at 12:36 GMT
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OP said he can do focus stacking, so the calibration of the panohead is need to be done only once, for the merged photos which will act like a single photo from a special lens, the shoot for each set to be succesfuly merged "could" require a macro rail as refered in other thread.
cheers,
Dorin
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Gascar
Posts: 7
Location: United Kingdom
Registered: 19 Jan 2012
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Re: Accurate bearings?
Posted: 22 Jan 2012 at 23:02 GMT
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Yes, I'll leave the nodal point where it is when I focus. There's several ways to do that.
What is
one of those advanced rotators ??
Sounds interesting 
All I'm aware of is variations on a pair (or so ) of L or J shaped brackets with a bearing on one side. There's one Texan who produces a sort of U shaped thing with bearings each side more like a traditional ships-compass gimbal mount, and there's another a bit like a magnifying glass on a handle, shape.
I'll look for what you mean...
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mediavets
Posts: 1980
Location: Isleham, Cambs., United Kingdom
Registered: 8 Feb 2008
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Gascar
Posts: 7
Location: United Kingdom
Registered: 19 Jan 2012
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Re: Accurate bearings?
Posted: 22 Jan 2012 at 23:45 GMT
updated: 22 Jan 2012 at 23:46 GMT
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.... ah if you mean the ones with detents, yes they would be useful, and make it eeasier to convey the concern I have.
If I'm doing a matrix or 12, 4 columns by 3 rows I night take
C1R1 then C2R1 then C3R1 then C4R1 then
C1R2
if that column position has shifted at all, it's going to notice.
If the bearings aren't quite at 90º to each other, or there's slight sidaways play in a bearing, it'll matter.
If the traditional lamp-post in the parallax demo is replaced by a blade of grass...
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DorinDXN
Posts: 2853
Location: Timisoara, Romania
Registered: 14 Nov 2006
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Re: Accurate bearings?
Posted: 23 Jan 2012 at 7:47 GMT
updated: 23 Jan 2012 at 8:07 GMT
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I hope you'll read the specifications of the rotators.
The advanced rotators has click stops, mean a detent plunger stops the rotator at desired position AND as a extra they have a knob for locking the rotation, mean if you tighten the knob the rotator become secured in that position and you can take your set for focus stacking, after that you'll untighten the knob an the rotator can go to the next stops (deppending uppon the rotator model them the stops can be as dense as 3.5°)
I think all them have positions you need for, check that.
The bearings not need to be exactly quite at 90° for what you're doing, if you belive so then you need to learn to align the merged shoots.
The slight sidaways play will be almost none as you can secure both rotators in a particular position.
But are another causes which can produce plays, starting the with the rubber tips of your tripod and such, again knowledges of align within the stacks will help and inspect your setup and tighten all that can produce play.
cheers,
Dorin
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