How deep is the Epic Dragon sensor recessed into the body?

[Josh Mitchell-Frey]

Hey guys, can anyone tell me an exact measurement for how far the Epic Dragon sensor is recessed into the mount?

I know I could measure from the sensor markings on the body to the edge of the Side SSD for instance, but the edge of the Side SSD isn't quite level with the inner area of the mount, and I want to get it as exact as possible.

Also, I know the sensor moves back and forth when setting back focus for a particular lens, but I'm looking for the theoretical sensor distance, assuming a perfect lens.

Any thoughts appreciated!

 

[Andre W.]

in an absolute perfect world, it would be 52.00mm However that distance is changed due to the OLPF. There has to be an offset for the OLPF and to what that offset distance is I'm not sure.

 

[Terry VerHaar]

Not to pick nits too much but "exact measurement" and "theoretical" are sort of at odds with each other. lol

 

[Erick Liu]

every camera is offset differently, you want something that exact, you would need some pro measuring equipment

 

[Josh Mitchell-Frey]

Thanks for your input guys.

Andre, I'm assuming you're referring to the flange focal distance of a PL mount lens, so the total distance between the back of the lens and the sensor. What I'm actually looking for is how much of that 52mm is part of the lens mount (the part you can disattach from the camera) and how much of it is *within* the camera because of the sensor being recessed.

To others who have dismissed my question as impossible because what I want is "too exact", I just want a figure that's exact *as possible*. If that's down to the nearest mm, or the nearest 10th of a mm, just as close as I can get. The measurement I want clearly exists somewhere, in order for RED to manufacture cameras that are consistently capable of focusing to infinity.

Anyone else got any ideas?

 

[Patrick Tresch]

If you have a camera I think you can measure it. From the film plane mark to the mount.

Leica M can be mounted on the body so there must be less than 27.8 mm.
(For ref : Sony E-mount is 18mm)


Pat

 

[Jeff Kilgroe]

every camera is offset differently, you want something that exact, you would need some pro measuring equipment

It varies by which lens mount is installed, otherwise it *should* rest at a specific distance, otherwise your lenses will not properly align focus with their witness marks and will have difficulty in reaching the hyper focal boundary. If the camera is properly collimated, even with readily available tools like the RED Focus, Optitek Optimator, IBE/Null system, etc.. Your flange focal distance will be correct within 5 microns (0.005 mm). Double that to 10 microns if we factor in typical human error and the fact that most peoples' eyes are not as good as they think they are.

In a PL mount camera, the image plane or surface of the sensor (or film) is 52mm from the face of the front flange of the mount. For the RED MX and Dragon sensors, the OLPF resides in front of the sensor, with it's front fascia at approximately 9mm in front, meaning there is to be 43mm of clearance in this situation. However, if the lens mount and sensor block are not properly collimated, this distance could be different and in that situation, the lenses would have to be re-collimated to compensate. Sad but true, I've seen a lot of lens sets from rental houses that are shimmed and collimated in a screwy way that pretty much guarantees they will only properly focus on the cameras from the same rental house. But that's a whole other area of discussion.

SLR lenses tend to have a lot more variance built in to compensate for less than perfect fixed camera components -- non-adjustable mounts and sensor positioning, sloppy AF systems, etc.. They tend to over-rotate and focus beyond hyperfocal/ infinity to guaranty that they can hit the mark. When considering distance to the image plane for common SLR mount types, Canon EF mount is 44mm, Nikon F mount is 46.5mm, Sony E-mount and Canon Mirrorless EF-M are both 18mm, Micro 4/3 is 20mm.... In actuality, all of these camera systems have less useable clearance than that, either due to an OLPF or other protective layer in front of the sensor or a mechanical/ mirror shutter system on [D]SLR cameras.

 

[Patrick Tresch]

Weapon is 26.14 from sensor to the body plane. Epic "could" be the same.

Pat

 

[Aaron michaels]

The Epic is 26.45 with an offset of 12.1 from the cage to the computer board 15cm in details 3.6 cm from the corner square of 12.1mm and 27.3 from top to bottom.

 

[Josh Mitchell-Frey]

Thanks Aaron! That looks like exactly what I needed to know. So based on that, if the sensor is recessed by 26.45mm, a PL mount (for example) would have to hold the lens 25.55mm from the body plane? Or does the presence of the OLPF shorten this distance slightly?