What it's used by amateurs as a crutch and not by professional photographers?
On Tue, May 29, 2012 at 5:55 PM, [email protected] < [email protected]> wrote: > Diogo its used by amateurs as a crutch not professional photographers > > > T-Mobile. America’s First Nationwide 4G Network > > ----- Reply message ----- > From: "Diogo Girondi" <[email protected]> > To: "Nuke user discussion" <[email protected]> > Subject: [Nuke-users] Arri Alexa sensor size - camera tracking question > Date: Tue, May 29, 2012 13:47 > > > I'm not familiar with Nikon lenses, but Canon ones even if designed for > APS-C sensors are still named disregarding any compensation for crop > factors. Personally I never heard of lenses that state their focal lengths > compensated by a certain crop factor since that tends to vary from camera > to camera and it's not a characteristic of the lens it self. > > Canon EF-S lenses are a good example of this, they are designed to only > mount on EF mounts of bodies with APS-C sensors (1.6x crop factor) but > their focal lengths are still stated "1:1" taking a full frame if you will > as base, so you still have to multiply their focal lengths by 1.6. My EF-S > 10-22mm for instance when mounted on my 7D is becomes a 16-35mm and not the > 10-22mm written on the lens. > > > > On Tue, May 29, 2012 at 5:28 PM, Howard Jones <[email protected]>wrote: > >> The crop factor was based on the original question. Not my maths. A 100 >> mm lens on cropped back will give an equivalent lens angle (not actual) of >> a longer lens, with the original question this was 1.5. >> >> You are both agreeing with by stating the film back size gives a >> different fov (but not focal length - agreed) >> >> However, >> 1. If you can't get a 100mm lens that is designed for a crop film back, >> ie compensates for the sensor size, then you are correct that in this case >> the focal length is the same, regardless of sensor size, however the fov is >> different. >> >> However if you can buy a lens that has compensated for the sensor size >> and gives the same fov as a 35mm lens then there is a discrepancy. >> >> I'm under the (mis)understanding that the latter is available, however I >> can quite believe I'm mistaken. >> >> 2. We are all assuming nuke behaves correctly in this fashion. In the >> back of my mind, if you put the focal length into the camera tracker and >> then change the film back, it changes the focal length, but you can then >> change it back. >> >> I can't check this last point until tomorrow, but if it's the case then >> what does this mean for the solve? If its not the case then it's because >> I'm getting on and the mind plays tricks. >> >> Cheers >> H >> >> ------------------------------ >> * From: * Alex Fry <[email protected]>; >> * To: * Nuke user discussion <[email protected]>; >> * Subject: * Re: [Nuke-users] Arri Alexa sensor size - camera tracking >> question >> * Sent: * Tue, May 29, 2012 8:49:44 AM >> >> It doesn't matter what sensor the lens is designed for, it's focal >> length remains the same. It is what it is. >> >> What are you basing 27mm on? A crop factor of 1.5? Relative to what? A >> 35mm still camera? >> >> 35mm stills equivalent focal length descriptions should have no place in >> a discussion about tracking footage from a movie camera, they only exist as >> a crutch for stills photographers who grew up using their focal lengths as >> working slang to describe a particular field of view. >> >> >> >> On 29/05/2012, at 6:23 PM, Howard Jones <[email protected]> wrote: >> >> I'd agree with Randy here. If the 18mm prime is not designed for the film >> back then it would have an equivalent focal length of, in your example of >> 27mm (though that is just based on your example. ) >> >> However if it is a prime lens designed for the chip, then it is an 18mm >> lens, so no conversion necessary. >> >> However again, the solve you would get should work either way, but the >> relation between the point cloud and camera will vary and will begin to be >> an issue for objects that should be close to the camera. >> >> That is you can double a focal length and move an object twice as far >> away in nuke and it should look the same, except for objects very close, >> when distortion artefacts creep in, and I don't mean lens distortion >> characteristics here before any one jumps in, I mean if you stick a sphere >> right next to the lens and have a super wide angle, that isn't the same as >> an object further away with say a standard lens size. (eg 50mm for 35) >> >> So you can track and try 2 solves with 2 different lens lengths, and if >> there are objects close to camera you should see a difference in shape of >> any test spheres etc, otherwise it should still lock. >> >> I couldn't find anything quickly online to confirm your film back sizes, >> but someone has created a whole set of presets for cameras (Nathan?) which >> are very useful on nukepedia. >> >> H >> >> ------------------------------ >> * From: * [email protected] <[email protected]>; >> * To: * Nuke user discussion <[email protected]>; >> * Subject: * Re: [Nuke-users] Arri Alexa sensor size - camera tracking >> question >> * Sent: * Tue, May 29, 2012 7:21:12 AM >> >> He is right. >> >> T-Mobile. America’s First Nationwide 4G Network >> >> ----- Reply message ----- >> From: "Darren Coombes" <[email protected]> >> To: "Nuke user discussion" <[email protected]> >> Subject: [Nuke-users] Arri Alexa sensor size - camera tracking question >> Date: Tue, May 29, 2012 01:01 >> >> >> Thanks for the reply Alex, I'll have a look. We have someone here saying >> that the 18mm lens would not be an 18mm lens in our tracker settings, I >> just want to make sure what they are saying is right. >> >> Cheers. >> D. >> >> On 29/05/2012, at 4:57 PM, Alex Fry wrote: >> >> The "crop factor" is described by the sensor measurements you input. >> Your 18mm lens is still 18mm, no conversion is necessary, your field of >> view has changed, but not your focal length.. >> An 18mm lens has a different field of view if its mounted on micro4/3, >> DX, super35, 35 stills, 70mm or medium format, but it remains an 18mm lens. >> >> Have a play with Nuke's camera node, tweaking the focal length, >> haperture & vaperture knobs to get a feel for the relationship they have to >> each other. >> >> -Alex >> >> On 29/05/2012, at 4:27 PM, Darren Coombes <[email protected]> >> wrote: >> >> Hi, we have some plates shot with the alexa on a 18mm prime lens. >> I Need to camera track this material. >> >> On the Arri website, it says the sensor size for the alexa is 23.76 x >> 13.37mm when using the ARRIRAW setting with 1.78:1 aspect ratio. >> >> in the camera tracker settings, would I put the film back size as 23.76 x >> 13.37mm? >> And then I guess i need to find out the crop factor for that sensor size >> and use that when entering the focal length of the lens? >> >> So if we shot on a 18mm lens, and theoretically the crop factor was 1.5 >> (not sure what the actual crop factor is yet), you would times 18 x1.5? and >> that would give the right focal length? >> >> Can someone point me in the right direction with this? and is my theory >> of this right? or am i missing something? >> >> Thanks. >> >> Darren. >> * >> * >> * >> * >> * >> * >> *Darren Coombes* >> * >> * >> *Compositor* >> >> *www.resolutiondesign.com.au* <http://www.resolutiondesign.com.au/> >> >> >> *resolution: sydney australia* tel: *+61 2 9360 9908* fax: >> +*61 2 9360 8908* >> *22* burton st: east sydney: *2010* post office box: *614* >> darlinghurst: 1300* *abn: *3305 196 1856* >> >> *2010 Silver One Show Entertainment Award: Online Branded Entertainment * >> *2009 Gold Promax/BDA Award: Best Broadcast Design Image Spot * >> *2009 Winner Creative Review Hotshop Award: Post Production / VFX* >> *2009 Finalist Creative Review Hotshop Award: Broadcast Design* >> >> >> The information transmitted, together with the attachments, is intended >> only for the person or entity to which it is addressed and may contain >> confidential and/or priviliged material which may be subject to copyright. >> Any review, retransmission or other use of, or taking of any action in >> reliance upon, this information by persons or entities other than the >> intended recipient is prohibited. If you received this in error, please >> contact the sender and delete the material from any computer or network. No >> warranty is given by the sender that any attachments to this email are free >> from viruses or other defects. >> >> >> <Unknown.jpeg> >> >> _______________________________________________ >> Nuke-users mailing list >> [email protected], http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> >> _______________________________________________ >> Nuke-users mailing list >> [email protected], http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> >> >> *Darren Coombes* >> *Compositor* >> >> *www.resolutiondesign.com.au* <http://www.resolutiondesign.com.au/> >> >> >> *resolution: sydney australia* tel: *+61 2 9360 9908* fax: >> +*61 2 9360 8908* >> *22* burton st: east sydney: *2010* post office box: *614* >> darlinghurst: 1300* *abn: *3305 196 1856* >> >> *2010 Silver One Show Entertainment Award: Online Branded Entertainment * >> *2009 Gold Promax/BDA Award: Best Broadcast Design Image Spot * >> *2009 Winner Creative Review Hotshop Award: Post Production / VFX* >> *2009 Finalist Creative Review Hotshop Award: Broadcast Design* >> >> >> The information transmitted, together with the attachments, is intended >> only for the person or entity to which it is addressed and may contain >> confidential and/or priviliged material which may be subject to copyright. >> Any review, retransmission or other use of, or taking of any action in >> reliance upon, this information by persons or entities other than the >> intended recipient is prohibited. If you received this in error, please >> contact the sender and delete the material from any computer or network. No >> warranty is given by the sender that any attachments to this email are free >> from viruses or other defects. >> >> >> >> _______________________________________________ >> Nuke-users mailing list >> [email protected], http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> >> >> _______________________________________________ >> Nuke-users mailing list >> [email protected], http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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