Re: [Elphel-support] Elphel's Circle of confusion size?
Sorry, it took me a while to answer this one, because I was 'focusing' on other things (with the excuse of the joke). Please elaborate how exactly you can utilize the Circle of confusion to check focus during shooting? What formula binds the CoC with the sensor format? It is more like a property of a lens... though I could find a table with sensor formats. The CoC is one of the values to calculate the Hyperfocal distance (http://www.dofmaster.com/equations.html), which in its turn is the basis for calculating the Near and Far distances of acceptable sharpness. According to Wikipedia (http://en.wikipedia.org/wiki/Circle_of_confusion), the CoC is calculated using the frame diagonal, so it would be directly related to the sensor/film (if this is case, then Elphel's CoC The software I posted the link will do the maths for us in field, because we won't have internet there. I was planning to do a script to do that, but then I decided to check if anyone had already done it. It was a nice surprise. As to how we'll use it, well, we have a simple problem: we will have a camera operator in the setting; its signal will be sent to the director and the director of photography via LAN cable to a central computer; then it is sent back to the camera operator via wi-fi to a smartphone, that will be used as viewfinder. That means the camera won't be able to change nor check the focus without the calculations - he will need to do the focus pulling previously. That's the reason. It may be arguable that by using a tablet instead of a smartphone this problem wouldn't be as critical. A better wifi hardware would provide a better preview (bandwidth and processing power) for the viewfinder. Even so, that probably wouldn't be enough to tense our nerves, which will throw us back to relying on the maths. =) Oleg, I'll check the focus helper, thanks for the link. ___ Support-list mailing list Support-list@support.elphel.com http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
Re: [Elphel-support] Elphel's Circle of confusion size?
Please elaborate how exactly you can utilize the Circle of confusion to check focus during shooting? Regards Sebastian On Thu, May 3, 2012 at 4:00 AM, flavio soares qazav...@gmail.com wrote: Hi there, I know this is an odd question, but does any of you know Elphel's Circle of confusion size? We'll have to make sure our focus is alright when we shoot, so I was looking at ways of doing this. Here (http://www.dofmaster.com/dofjs.html), if I use the settings for 1/3 inch and 1/2 inch sensors (the closests we'd have for Elphel's Aptina), it gives values between 0,011 and 0,016 mm. If I use this program though (http://sourceforge.net/projects/dofview/) that allows me to use a custom sensor size, it results in a 0,005 mm Circle of Confusion for Elphel's sensor (at full frame). Which one should I use? Thanks! flavio ___ Support-list mailing list Support-list@support.elphel.com http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com ___ Support-list mailing list Support-list@support.elphel.com http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
Re: [Elphel-support] Elphel's Circle of confusion size?
BTW, there's a focus helper. The usage is covered herehttp://wiki.elphel.com/index.php?title=Focus_helper . What formula binds the CoC with the sensor format? It is more like a property of a lens... though I could find a table with sensor formats. But in the end you would like to know the DoF at a certain distance and a certain F-number (or focal length), right? With a varifocal lens you would always need to know what focal length is set at the moment. Best regards, Oleg Dzhimiev Electronics Engineer phone: +1 801 783 x124 Elphel, Inc. ___ Support-list mailing list Support-list@support.elphel.com http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
[Elphel-support] Elphel's Circle of confusion size?
Hi there, I know this is an odd question, but does any of you know Elphel's Circle of confusion size? We'll have to make sure our focus is alright when we shoot, so I was looking at ways of doing this. Here (http://www.dofmaster.com/dofjs.html), if I use the settings for 1/3 inch and 1/2 inch sensors (the closests we'd have for Elphel's Aptina), it gives values between 0,011 and 0,016 mm. If I use this program though (http://sourceforge.net/projects/dofview/) that allows me to use a custom sensor size, it results in a 0,005 mm Circle of Confusion for Elphel's sensor (at full frame). Which one should I use? Thanks! flavio ___ Support-list mailing list Support-list@support.elphel.com http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com
