dissatisfied with merlin head - by a new exemplar or alternative head?  

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Undertable
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dissatisfied with merlin head - by a new exemplar or alternative head?

by Undertable » Fri Mar 25, 2011 9:43 am

Hi there,
since over 4 weeks I`m wasting a lot of time with adjusting my modified merlin head`s NP. Unfortunately without successful results so far. I have to accept the fact that my merlin-exemplar must have misaligned axes which I`m not able to improve

What a pity but at this time i have only the options to use my merlin exemplar as it is only for use for gigapixel-panos and to buy a new head for 360x180 degree panoramic shots, either a further exemplar of the same (merlin) head, in hope that its axes will be OK or a new/other head. Perhaps an other model is also more suitable for 360x180 degree panoramic shots (smaller footprint/battery-cover).

An alternative head should be controllable by the hard- and software which i already own: claude`s BT-module, Nokia N810 + papywizard and also T&C-Controller (not in use so far).

Thanks for suggestions

Oliver

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by fma38 » Fri Mar 25, 2011 12:47 pm

I don't think that your Merlin axis are significantly misaligned, or at least, you should see it!

Could you tell us what you are expecting, and what is not working? You problem is maybe elsewhere...
Frédéric

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by mediavets » Fri Mar 25, 2011 12:50 pm

Undertable wrote:Hi there,
since over 4 weeks I`m wasting a lot of time with adjusting my modified merlin head`s NP. Unfortunately without successful results so far. I have to accept the fact that my merlin-exemplar must have misaligned axes which I`m not able to improve

I find that hard to believe.

What camera body and lens are you trying to use for shooting these 360x180 panos on the Merlin?

Have you modifed the dovetail mount and rail? If so, how? Can we see some pictures with the camera mounted on the head.

What a pity but at this time i have only the options to use my merlin exemplar as it is only for use for gigapixel-panos and to buy a new head for 360x180 degree panoramic shots, either a further exemplar of the same (merlin) head, in hope that its axes will be OK or a new/other head. Perhaps an other model is also more suitable for 360x180 degree panoramic shots (smaller footprint/battery-cover).

Of course motorised heads really come into their own when shooting very high res panos - it's hardly worth using one if you wish to shoot 360x180 panos using a fisheye lens. A manual pano head is quicker to use for that.

An alternative head should be controllable by the hard- and software which i already own: claude`s BT-module, Nokia N810 + papywizard and also T&C-Controller (not in use so far).

Thanks for suggestions

Oliver

How much do you wish to spend?

There's the Clauss Rodeon VR at about 4,000 Euros.

There's the Pixorb at about US$10,000.

And then there's the upcoming head from T&C (makers of the touch controller) for which no price has yet been announced.
Andrew Stephens
Many different Nodal Ninja and Agnos pano heads. Merlin/Panogear mount with Papywizard on Nokia Internet tablets.
Nikon D5100 and D40, Sigma 8mm f3.5 FE, Nikon 10.5mm FE, 35mm, 50mm, 18-55mm, 70-210mm. Promote control.

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by Undertable » Fri Mar 25, 2011 1:32 pm

thanks that you are interested in my problem.
Supported by the German forum "Panorama Community" I tried different adjustments and modifications several times.
The results got better and worse but I received no acceptable results in the end.
I made a lot of photographs from my activities and put them into this thread. Please have a closer look:

http://www.panorama-community.net/wbb/index.php?page=Thread&threadID=5882

Before I adjusted the NP as good a possible by looking through camera`s viewfinder and rotate the camera (aligning lines near/distance, jaw and pitch)
In the forum I was told that "sawtooth" (according to dict.cc) in the nadir shot indicates misalignment.

A user told me the ruler-method: needle fixed on the tripod, ruler on the floor, rotate and compare needle`s position at 0° and 180°. This seemed to be not so bad as it was. Another user recommended to rotate into nadir position, remove merlin`s battery cover and check if the axis is in the center of the photograph (crossed lines from photo`s corner`s).

I dertermined the right measure by putting under rings, sheet metal and aluminium foil an the i milled a new swivel arm.
By using the new arm nadir`s "sawtooth"-shape was approximately perfect but there were still stitching problems

After this I checked parallaxe by the ruler-method and determined that I have to shift the camera sideways.
Because I thought that DSLR-camera`s thread is always placed directly on their optical axes my camera-plate was not adjustable in this direction. So I milled a new 2-part camera plate and adjusted the necessary side-shift 1,5mm.

Then I started parallaxe adjustment (ruler-method) again by putting under and determining the right measure. This time I had to mill off 2,82mm. Done so the result of ruler-method seemed to be perfect. The needle stayed exactly on the same position during rotation 180°.

After this I checked the NP as exactly as possible by rotate vertical (sticked Needle on the window/lines of building behind)

After this i tried some panos and in my opinion the results are anything else than good. It should be added that I use two different stiching software which lead to very different results:

PtGUI (newest) shows bad "sawtooth" shaped nadir but with enabled option "heavy and lens shift" it is able to stitch halfway decent (with wavy edges)

Autopano Giga (I have to work my way into it presently) shows a better nadir (less "sawtooth" effect) but has still some stitching errors. By the way I used APG`s import-function and the .xml-file generated from papywizard during the run.

That`s the situation and I don`t know what to do next.



Oliver
Last edited by Undertable on Fri Mar 25, 2011 2:36 pm, edited 1 time in total.

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by mediavets » Fri Mar 25, 2011 2:14 pm

Undertable wrote:thanks that you are interested in my problem.
Supported by the German forum "Panorama Community" I tried different adjustments and modifications several times.
The results got better and worse but I received no acceptable results in the end, please have a look.
I made a lot of photographs from my activities and put them into those thread. Please have a closer look:

http://www.panorama-community.net/wbb/index.php?page=Thread&threadID=5882

Regards
Oliver

I don't read German but I have tried to read all that thread using computer translation.

Looking at the pictures I'd say that your mods. to the mount are quite adequate - if not seriously over engineered. If you are using a Canon 400D body was it necessary to modify the dovetail mount at all?

When shooting 360x180 leveling the head precisely in quite unnecessary as you can correct the level when stitching.

Some of the panos look OK to me, but obviously you are not satisfied. That balcony scene is quite challenging with stuff very close as well as stuff far way.

I suspect the real issue is that Sigma 10-20mm lens. I've seen many users run into problems trying to stitch image sets shot with that lens at 10mm. Like most very wide angle rectilinear lenses it produces complex distortions which seem to cause stitchers problems. Have you tried shooting panos with that lens on a manual pano head? If you have were the stitching results any better?

Anyway, lets concentrate on what you are disatisfied with when stitching your panos because I don't think the problem lies with the axes of rotation of the Merlin mount.

Are you shooting with all manual settings - focus, white balance, aperture and shutter speed?

What stitcher would you pefer to use APG or PTGui?

Can you make a sample image set available for download on-line - preferably as JPEGs in a ZIP file - so we can have a look and try to stitch the images?
Andrew Stephens
Many different Nodal Ninja and Agnos pano heads. Merlin/Panogear mount with Papywizard on Nokia Internet tablets.
Nikon D5100 and D40, Sigma 8mm f3.5 FE, Nikon 10.5mm FE, 35mm, 50mm, 18-55mm, 70-210mm. Promote control.

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by Undertable » Fri Mar 25, 2011 3:49 pm

Hi Andrew,

mediavets wrote:If you are using a Canon 400D body was it necessary to modify the dovetail mount at all?

As I started with panos I devloped and milled a hand-operated adapter:
http://www.dslr-forum.de/showpost.php?p=2375528&postcount=66 (in its first version)
http://www.dslr-forum.de/showpost.php?p=3478490&postcount=79 (with some improvements)
I had (and still have) 3 cameras with identically constructed bottom areas to use for panoramas, 2 EOS350D (IR-modified 670/700nm) and a EOS400D. So I made a camera-plate with special EOS350/400D-seating for best repeatability.
It was my intention to use the same camera plate on both, hand-opretaed adapter and merlin.

mediavets wrote:When shooting 360x180 leveling the head precisely in quite unnecessary as you can correct the level when stitching

But I think it`s necessary in one way when beeing in nadir position and check if centre of merlin`s lower bolt is in in the middle of the photo. Not in the direction which I have to put something under but I think in the other direction. Normally that direction should fit without any adjustment but in my case it doesn`t (1,55mm variance as I determined later). I`d like to note that this isn`t caused by my camera plate (verified with 3D measuring arm).

mediavets wrote:Some of the panos look OK to me, but obviously you are not satisfied. That balcony scene is quite challenging with stuff very close as well as stuff far way

There are stitching errors in all of the panos. I don`t like that. One guy told me that the balcony scene ist is difficult because of strong contrast. He suggested to try a indoor pano with tons of details. I did so (my room, the other pano) but there are stitching errors, too

mediavets wrote:I suspect the real issue is that Sigma 10-20mm lens.

It`s Canon 10-22
mediavets wrote:I've seen many users run into problems trying to stitch image sets shot with that lens at 10mm. Like most very wide angle rectilinear lenses it produces complex distortions which seem to cause stitchers problems.

This crossed my mind, too but I thought this wouldn`t be the problem because the critical areas would covered by overlap (what a sentence - it must sound horrible in English, sorry)

mediavets wrote:Have you tried shooting panos with that lens on a manual pano head? If you have were the stitching results any better?

Yes, I did a lot of panos with that lens. Not the very best but acceptable to me. Some of them:
http://www.flickr.com/photos/undertable/sets/72157622434990195/

But in the past I always made more Photos for one panorama:
12 shots each 30 degrees @ +45°
12 shots each 30 degrees @ 0°
12 shots each 30 degrees @ -45°
+ nadir
+ zenith

with my manual adapter I`m able to make a lot of photos very quickly, just count the clicks and fire the cable trigger.
Because of Merlin`s slowly move forum user recommended to reduce my count of photos to minimum. In my case for the 10-22 he suggested:
4 shots @ -60°
8 shots @ 0°
4 shots @ +60°
That`s the way I did during the last 4 weeks

mediavets wrote:Are you shooting with all manual settings - focus, white balance, aperture and shutter speed?

Yes, of course

mediavets wrote:What stitcher would you pefer to use APG or PTGui?

I used PtGUI for a long time and I like it. During summer holiday last year i shot some panos which were non-stitchable because of big areas in the sky without clouds. Difficult for PtGUI to find CPs and too difficult for me to place them by hand. After I read about APG`s ability to use a .xml with positioning data I bought APG and I want to use it in future more and more.

mediavets wrote:Can you make a sample image set available for download on-line - preferably as JPEGs in a ZIP file - so we can have a look and try to stitch the images?

Yes, with pleasure. I have still the whole material which I posted in the other forum. Does image shack support zip-files? I`ll check this...

Thanks for your interest
Oliver
Last edited by Undertable on Fri Mar 25, 2011 4:08 pm, edited 1 time in total.

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by mediavets » Fri Mar 25, 2011 4:48 pm

Oliver,

What to say....

If you shoot the same pattern of shots with the Merlin as you do with you manual head are the results similar?

If so then the answer is that this lens does better with much more overlap, although the pattern you suggest must give massive overlapping which normally is not desirable.

If that means it's too slow shooting with the Merlin then I guess the answer is to shoot with the manual head.

I feel that when using a 10-20mm WA lens at 10mm a motorised head offers little advantage over a good manual head. On the other hand when shooting with longer focal lengths a motorised head is a great help especially when coupled with APP/APG import wizards.

There is no single lens/camera/pano head setup that's ideal for every type of pano. Do you have a prime lens - say a 50mm - that you could use to try shooting a high res. 360x180 or a partial pano? Those 50mm primes usually show very little distortion and I find images shot with this type of lens stitch very well.
Andrew Stephens
Many different Nodal Ninja and Agnos pano heads. Merlin/Panogear mount with Papywizard on Nokia Internet tablets.
Nikon D5100 and D40, Sigma 8mm f3.5 FE, Nikon 10.5mm FE, 35mm, 50mm, 18-55mm, 70-210mm. Promote control.

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by Paul » Fri Mar 25, 2011 5:01 pm

You can call me to talk about your problem.
Phonenumber via PN
Paul

close, but no cigar ... ... ...

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by Undertable » Sat Mar 26, 2011 6:21 pm

Hi Andrew and Paul,

@ Paul: Thanks for offering phone-support. I tried to call you 2times yesterday but had no luck. Doesn`t matter I`ll try it again, perhaps tomorrow...

mediavets wrote:If you shoot the same pattern of shots with the Merlin as you do with you manual head are the results similar?

I tried this today and to my surprise the results were as bad as with the merlin: strange looking nadir and stitching errors.
mediavets wrote:If so then the answer is that this lens does better with much more overlap, although the pattern you suggest must give massive overlapping which normally is not desirable

I`ve made tons of panos in the past with exactly this lens and manual head without any trouble. The only difference is the number of shoots and different angles as I worte yesterday:
Undertable wrote:But in the past I always made more Photos for one panorama:
12 shots each 30 degrees @ +45°
12 shots each 30 degrees @ 0°
12 shots each 30 degrees @ -45°
+ nadir
+ zenith
...because of Merlin`s slowly move forum user recommended to reduce my count of photos to minimum. In my case for the 10-22 he suggested:
4 shots @ -60°
8 shots @ 0°
4 shots @ +60°

I tried following:
8 shots @ -45°
8 shots @ 0°
8 shots @ +45°
and the result was fine!

4 shots @ -45°
8 shots @ 0°
4 shots @ +45°
works also fine!

That means 60° is too much for the 10-22 lens @ 10

Tomorrow I`ll check this with the merlin but I think it will work then, too.
I`ll post the result here then.

mediavets wrote:If that means it's too slow shooting with the Merlin

It could be faster indeed but that`s no problem. Main thing is that it`s working

mediavets wrote:Do you have a prime lens - say a 50mm - that you could use to try shooting a high res. 360x180 or a partial pano? Those 50mm primes usually show very little distortion and I find images shot with this type of lens stitch very well.

Yes I have a Canon EF 50mm 1:1,4. Some day I`ll try it out

Regards
Oliver
Last edited by Undertable on Sat Mar 26, 2011 6:25 pm, edited 1 time in total.


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