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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Using DSLR as directors veiwfinder, Epix & R1

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Aaron Bernakevitch

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Hello

Recently I have been using the iPhone app artemis as a quick and dirty directors viewfinder for my R1. I recently discovered that a canon 7d is pretty darn close to the field of view as my R1. (has anyone else seen this?)

I am wondering if anyone can speak to this

The Red has an active sensor of 4096 by 2304 and the 7D produces at maximum resolution images that are 5,184 x 3,456.

Would these two different resolution sizes not produce drastically different fields of view?

Am i missing something here in the math?


Also I am wondering how close the 5d will be to the epic-x's 5k sensor and if any one can drop some numbers on that, to see if it would be suitable or reasonably close to the field of view on the epic-x


Also another weird fact I found on wikipedia

The Canon 7D

Sensor 22.3 × 14.9 mm CMOS
Maximum resolution 5,184 × 3,456 (17.9 recorded megapixels)

And the Canon 5D

Sensor 35.8 x 23.9 mm CMOS
Maximum resolution 4,368 × 2,912 (12.8 megapixels)

Why does the 5d have a larger sensor but render a smaller maximum resolution then the 7D?

I'm sure the answer here is simple if some one could please elaborate,
 
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The 7D has smaller pixels. It's the sensor size that you want to pay attention to here. The 5D will give a very different FOV than the RED due to the size, the resolution is irrelevant. If you want a director's viewfinder for the RED, the 7D is definitely the way to go.
 
Sensor area and photosite count, or sensor "resolution", are two separate specs. You can cram a gazillion photosites in a tiny sensor if you want. FOV is affected by sensor/negative area. The larger the active sensor area the wider FOV you will get, all other things remaining equal.

This is one of the reasons I bought a 7D (before the T2i came out). However, the 4.5k sensor is a bit larger than Mysterium. I am pretty sure it will be close, but you can't get an APS-C camera with a PL mount and expect exact results by mounting the same lenses. Which is a shame. It will still help though.

You could get a 5D and tape off the screen to show what a 4k, 4.5k or 5k FOVs would be, but it would be far too small, unless you used a loupe/VF like the Z-Finder from Zacuto which magnifies the image quite a lot. You could also use a monitor, but that sort of defeats the purpose making it bulky and would require more attention with batteries, etc.

I think a T2i or 7D would be a good place to be. You can share the little monitor with one person or two on playback to discuss blocking. You wouldn't have too hard of a time guesstimating optimal focal length our of a set of cine primes. And you can keep a zoom on the DSLR, so you won't be taking up the lenses, getting more dust on their rear elements. 0.02
 
Awesome, thanks for the insight

Will the 5d be close to the Epic? What is the physical sensor size of the epic-x?

Also, If the Red physical sensor size is 24.4mm x 13.7mm (344.28mm*2) and the 7d 22.3mm x 14.9mm (332.27mm*2) Then is it fair to say that they differ by a ratio of Red:7D -> 344.28:332.27 -> 1:0.965

So The 7d shows 96.5 % of the field of view on the red?

Please correct me if I am wrong here
 
Aaron Bernakevitch said:
Also another weird fact I found on wikipedia

The Canon 7D

Sensor 22.3 × 14.9 mm CMOS
Maximum resolution 5,184 × 3,456 (17.9 recorded megapixels)

And the Canon 5D

Sensor 35.8 x 23.9 mm CMOS
Maximum resolution 4,368 × 2,912 (12.8 megapixels)

Why does the 5d have a larger sensor but render a smaller maximum resolution then the 7D?
Click to expand...


Canon 5D you are mentioning here is PREVIOUS version of 5D. new one is called 5D Mark II and it's resolution is 21 megapixels. there is a link on the wikipedia to that new version (5D Mk II) also.

http://en.wikipedia.org/wiki/Canon_EOS_5D_Mark_II


all the best
filip
 
Yes i am referring to the 5D MK 2. I speak about it so much I just call it the 5D now

Please use these numbers for any forthcoming math

Sensor 36 x 24 mm CMOS
Maximum resolution 5,616 × 3,744 (21.1 megapixels)
 
I use my Nikon D700 as a viewfinder all the time. It has a "DX" mode that lets you set the sensor capture size to the non-full-frame size (Nikon call it DX), which is extremely close to the RED ONE.

If you then have a zoom lens that covers the range that you RED has (eg 18-85mm), then it becomes a very useful tool for lining things up quickly.
 
Any one care to comment on the field of view for the 5d mk2 vs epic x

Thanks for all of the input so far
 
The number of pixels has absolutely nothing to do with Field of View. The physical dimensions of the active area of the sensor (image area) is what you need to know.

You can use the formula :
subject dimension (o)/subject distance(d)=image dimension (i)/image distance(f)

o/d=i/f

to calculate the size of the image on your sensor of any object you are photographing.

A simpler method is to use something like the lens comparison feature of the p-cam app for the iphone, which will do the comparison for you. Dave Eubank has loaded the sensor areas of the RED camera as well as a bunch of still cameras into the app.

What you need to know about the RED (I got this from the FAQ on Red.com):

RED 4K 22.2mm x 12.6mm
RED 3K 16.65mm x 9.36mm
RED 2K 11.1mm x 6.24mm

You can use this if you want to have a viewing screen for a camera or director's finder marked to the correct dimensions.

You give the 7D sensor as 22.3mm x 14.9mm

So at 4K, your 7D sensor is 0.1mm larger horizontally than the RED image area, which means you will be pretty darn close if you are looking at the width of the image. Vertically, you will be off, because the sensors have different aspect ratios. At 3K and 2K the image areas are much smaller, so you would need to figure a way to accurately crop your viewing area. Camera rental houses are used to doing this and can mark the viewing screens of a director's finder or removable screen from an SLR, but I don't think this is an option with the 7D.

I have a Canon 40D which has inexpensive removable viewing screens. I had a couple of these ruled with lines so that I can frame for Super 35 1:1.85 and 1:2.35 aspect ratios. RED 16:9 is pretty close to my 1:1.85 screen vertically, and is right on horizontally. The 7D doesn't have interchangeable screens, so you can't do that with your camera, but maybe the live view in video mode will be close enough.
 
Reds photosites are 0,0054mm (x 4096 =22,11mm)
7D photosites are 0,0043mm (x 5184 =22,3mm)

pretty close horizontal-wise.

I always like to know the size of the photosites, makes calculation easier in my opinion, especially when shooting cropped.

Manuel
 
I find any of the Nikon DX cameras work very well as director's finders, especially as I use Nikon glass. The Nikon DX sensors are 15.8 x 23.6mm and The RED Mysterium X is 12.6mm x 22.2mm at 4K. You can also take lighting notes with them.
 
Paul Thats great thanks sir :)
 
5k looks smaller than I thought when compared to S35 and 4k...

...think I'm too used to seeing charts with the smaller areas pushed to a bottom corner.

I suppose the big and easily noticeable difference is between 4k and 5k, but I would like to see where 4.5k falls in there.

Thanks Paul for linking us to that great (albeit a bit too low res) chart from Abel. Thanks Abel for putting it together.

sensor_area.jpg
 
I used a Canon 40D for previewing a 3D shoot on Friday. I was able to quickly determine what primes to use on each shot. Sensor size is almost exactly the same as RED.

Phil
 
Sorry, I’m still new to cameras and trying to understand Image sensors, here are my questions and any help would be greatly appreciated..

1. I’m trying to understand Image sensors. Okay so if the 7D shoots 1080 HD video approximately close to a 2k image, is it using all of it’s 18mp for the HD video??

2. and what roughly would a Red one 4k and Epic mx 5k be at as far as MP count?

3. I know that the MX sensor is slightly larger than the Red Ones so the MX sensor will have a larger image or (field of view) but does 4k affect the size of the image or (field of view)? Example, if you set a 7D and a Red One side by side, the 7D being at 1080 and the Red One being at 4k, both with the same focal length, would the image be roughly the same size?? I understand it as the Red Ones 4k footage would just be more pixel dense over the 7Ds 1080p and both would have roughly the same size image ??

4. This is a part of question 3. but from what I understand the images from both cameras should be close in size or (Field of View) with just varying pixel density.. I ask this because if you “Google” 1080p, 2k, 4k and 5k you can find sizing charts that show that 2k is larger than 1080p and that 4k is much larger than 2k and that 5k is larger than them all; they’re like little box diagrams, the biggest box being 5k and the box inside the 5k box is a 4k box and inside the 4k box there will be a 3k or 2k box, all the way down to 1080, 720 and SD.. This is what confuses me, because if the size of an image or (Field of view) is determined by actual sensor size and not pixel count why would these carts show that a 5k image is physically larger then them all?? This link is for the sizing diagrams/charts I'm talking about.. http://www.red.com/cameras/technology/
The box diagrams like I’m talking about are similar to this one at Red.com, it’s the diagram all the way at the bottom on the left, see how the 4k box is much larger than the 2k box?? If the Image sensor in my Canon 7D is roughly the same size as the Red Ones Mysterium sensor why would the 2k box be so much smaller??

I’m sorry I feel this question is much easier to understand than how I’m taking it and I might feel like I know the answer to my own question but I’m just failing to make some kind of small connection..

Please, any help with solving my dilemma would be greatly appreciated:) -Paul an amateur.. :)
 
1. No, it skips a lot (photosite) lines, because the camera's electronics can't keep up with the amount of information that should be recorded. It does however use the full sensor area. (line skipping also generates other issues aside from a softer image)

2. About 11.5MP and 14MP. Each frame is as good as a still.

3. Resolution and sensor area are independent. The sensor area affects FOV, resolution doesn't.

4. Those boxes represent the relative sizes of the recorded images as they would compare when displayed on the same screen. They are not a comparison of FOV resulting from using the same lens on different sensor areas.

Hope that helps. 0.02
 
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