surami wrote:

I want to set the correct NPP for my Merlin panorama system. What kind of rail do I need and what should I do?

What I have:
Canon 550D
Manfrotto 200PL-14 QR Plate (It would be nice, if I could attache my DSLR with this to the rail, but not a must.): http://www.digitcam.hu/pic/termek/tp.17 … ALLERY.jpg
Sigma 10mm F2.8 FE HSM Lens
Crown (How can I replace the original with this?): http://www.autopano.net/wiki-fr/action/ … wn_357.png

If the dimension from base of the camera to centre of the lens mount is 40mm or less, and the diameter of the lens barrel is 80mm or less, then you do not need to modify or replace the crown to set the camera/lens at the NPP.

If your dimensions are slightly greater than this then you may be able to achieve the NPP simply by using thinner/slimmer rail.

surami wrote:

mediavets wrote:

If the dimension from base of the camera to centre of the lens mount is 40mm or less, and the diameter of the lens barrel is 80mm or less, then you do not need to modify or replace the crown to set the camera/lens at the NPP.

If your dimensions are slightly greater than this then you may be able to achieve the NPP simply by using thinner/slimmer rail.

Thanks for the description.

So, as I see this list: http://wiki.panotools.org/Entrance_Pupil_Database , Canon 550D hopefully has less tripod mount height (H), then 40mm (I couldn't find the exact measure for the Canon 550D on the net) and based on this: http://en.wikipedia.org/wiki/Sigma_10mm … e_HSM_lens , the max. diameter of Sigma 10mm FE lens is 75.8mm.
So it should work with the one part of the L profile or which rail?

Yes, you could probably use one part of the L-bracket. You may need to remove the large knob otherwise it can get in the way of the vertical arm at higher pitch values. There's a description of how to do this (in French):
http://www.autopano.net/wiki-fr/action/ … e_fixation

Alternatively make a simple rail say from hardwood, like this:
http://www.kolor.com/forum/p37570-2009- … 570#p37570

Or purchase a simple rail, like this:
http://www.pulsar-optical.co.uk/prod/Sc … tailm.html

I use a rail of that type with a 1/4 bolt, a reversed wingnut and a washer by way of a camera screw.
http://www.kolor.com/forum/p56155-2009- … 155#p56155

Dissipative table mat for example 3M 1402.66x (x defines colour) works fine.
I also tested flat gasket but I reached not enough friction.

Last edited by Undertable (2011-11-18 19:32:28)

my best friend internet links Klingerit with gaskets. As I mentioned before I tried flat gasket first but got not enough friction.

edit:
The material was 1,9mm thick and it`s called novapress UNIVERSAL from Frenzelit. It looked promising to me first but was not applicable for this purpose (Merlin friction disks)

I guess You had to tighten the crown`s nut firmly?

Last edited by Undertable (2011-11-20 11:51:54)

following pic shows friction discs made of dissipative table mat, felt and rubber.
As i mentioned before the dissipative table mat (upper right, p9) works good for me.
The tested felt allowed too much compression, was instable and reached not enough friction.
The rubber disc was also but had too much friction in my case (there are many rubber materials with different properties)

Last edited by Undertable (2011-11-18 21:30:31)