EF / MFT DOF is there a difference

I'm a little confused and i need to put in a order asap. I have just been told both of the BMC have the same crop factor is this true....

this would make my life so much easier

The crop factor is based on the sensor size. The size hasn't changed so it is still a 2.3x crop factor when compared to full frame. The only difference is that you can use a large variety of lenses and use lenses that are designed for sensors that are smaller than full-frame. The image circle for a m 4/3 lense is slightly larger than the bmc sensor but not as big as a full-frame. This opportunity allows you to find really fast lenses since it is designed around a small image circle.

In reality, it just allows you to find and use lenses of numerous mount types rather than only being able to use EF glass (generally speaking).

Faster lenses means the opportunity for more shallow depth of field and utilization of more low light scenarios.

Example:


http://www.bhphotovideo.com/c/product/7 ... _Lens.html


Image circle required to cover the whole bmc sensor ~18mm

M 4/3 ~22m

Full-Frame 35mm

A variety of fast, high quality, affordable glass exsists and a m 4/3 mount is highly adaptable to fit a range of different mount types. This gives you a larger range of lenses to choose from.

The two models are IDENTICAL, just a change in the mount.

Flange focal distance:

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

Because the m4/3 mount is so shallow, it is very easy to adapt lenses that require a deeper flange distance (EF, PL, ect).

As far as reviews, Philip Bloom (http://philipbloom.net/2012/09/05/bmd/), has done ~ 40 min review of the camera and it is pretty extensive. Mind you, this was on FINAL hardware for the now EF version of the Cinema Camera. There are a few other reviews out there as well and a whole slew of information on this forum and Bmcuser from John Brawley (http://johnbrawley.wordpress.com/) and others.

The camera reviewed and shipping now, is the same camera (outside of possible firmware updates) that people will received in December just with a different mount.

This is how it stands right now.

That picture shows differences in sensor size.

The AF-100 has a m4/3 Sensor which is slight larger than the BMCC Sensor, thus the difference.

A change in mount type does not change crop factor.

A change in sensor size does.

If what you are asserting is true, then putting an EF full frame lens on an m 4/3 camera would result in greater crop then a comparable size m 4/3 lens.

A 24mm full frame EF lens on a GH2 (m 4/3 mount) gives the same field of view as a 24mm m 4/3 lens on a GH2.

It's all about flange distance.

This "new" version is a change in mount.

same sensor, same crop factor...very simple.....
the distance changes because the MFT lenses are closer to the sensor because they have to cover less....but still enough for the sensor in the BMCC....

The crop factor is based on the sensor size. The size hasn't changed so it is still a 2.3x crop factor when compared to full frame.

But the distance between the lens/sensor is much closer with the M43 vs the EF.

That must have some effect on crop, and Blackmagic has been mum on this.

The two models are IDENTICAL, just a change in the mount.

Got it: You are willing to throw $3000 at a camera you've never seen any reviews
on (As of Sept 7/2012).

Call me crazy but: I'd like to see the comparison tests/review other's would too.

yes, i think you should wait to put your order in....sometime next year would be good for all of other crazy ones...
and don't trust the reviews that are out there...or the raw files...or footage....or since/logic when it comes to things like....crop factor....

M 4/3 ~22m

Full-Frame 35mm

Just a correction. Full frame is actually approximately 43mm diagonal. 36x24mm. 35mm motion picture film size is about 1.5 crop.

it is the same thing , same camera same everything , its just a different mount

same sensor, same crop factor...very simple.....
the distance changes because the MFT lenses are closer to the sensor because they have to cover less....but still enough for the sensor in the BMCC....

does this affect DOF ? meaning that : having same Fstop aperture , same image FOV crop between canon and an MTF lens ...

will the DOF be the same ?

the fact that the MTF lenses are closer to sensor make me wonder this ...

thanks
g

I'm a little confused and i need to put in a order asap. I have just been told both of the BMC have the same crop factor is this true....

Some have already answered this correctly but in case you are still confused, yes, the crop factor should be identical for the BMCC EF and BMCC MFT. The length of the diagonal of the active sensor area determines the crop factor you will see, assuming the image circle from the lens covers at least that area. You'll want to compare apples to apples, not apples to oranges; in other words the diagonal is determined for frames with the same aspect ratio for all cameras being considered to give the real crop factor for a given camera.

Lets determine the diagonal for a full-frame still camera like the Canon 5D. As you know the BMCC uses an aspect ratio of 16:9 for its image. So the diagonal for the full-frame camera with an aspect ratio of 16:9 is 41.3 (square root of 36*36+20.25*20.25).

The MFT has a diagonal of 21.6mm and a crop factor compared to a full-frame still camera like the Canon 5D of about 2 (41.3/21.6).

The BMCC EF and BMCC MFT both have identical active sensor dimensions for the image frame and that area has a diagonal of about 18.125 (the square root of 15.81*15.81+8.88*8.88) with a crop factor of about 2.278, lets call it 2.3 (41.3/18.125).

Hope that helps.

I am new here and I have been reading lots about this argument and I think i can solve one piece of this question about crop factor. I think what they were talking about is the MTF makes a s--- load of adaptors that can mount onto the MTF. There are more MTF adaptors that convert to other lens mounts. Where the confusion is that each adaptor adds to the cropping that takes place because they push the lens away. If you mount a MTF lens onto the MTF BMCC there will be increased cropping when you say.. put the MTF to EF adaptor then put a EF lens onto the MTF to EF. Each mount is a different size and thus each one introduces a different "Crop" or as I think the confusion is "Magnification".

Here is the note that MTF says for the MTF to EF.

"The MTF Services Ltd Canon EF to Micro 4/3 Adapter is a mechanical adapter with no electronics. It lets you fit any Canon EF mount lens to Panasonic's AF101 and Lumix cameras. Its addition introduces a magnification of 2x with full frame lenses. "

I think it is safe to assume that with the BMCC sensor size you will get more than a 2X magnification.
I could be wrong about this last assumption... But I think its a fact that each mount adaptor has a magnification factor. Just brows the catalogue... http://www.mtfservices.com/home.html?pa ... egory_id=2

Nope... Your assumption is incorrect. An adaptor does not introduce any magnification unless there is an optical element in it. Most so not has optical elements. All they do is correct the Flange Focal Length (http://en.wikipedia.org/wiki/Flange_focal_distance) so that the lens will function as it was designed to.

I'll repeat what I posted in another discussion:

Focal length is an optical measurement. It has nothing to do with the sensor size.
http://en.m.wikipedia.org/wiki/Focal_length

A 50mm is a 50mm no matter what camera you put it on - a BMCC, Super35/ASP-C, Full Frame, Medium format, Large Format etc. still a 50mm.

What changes with the sensor/film size is the crop into the image circle.

So if you are used to shooting on Super35 film cameras with PL lenses you don't say "oh this is a 50mm on a Canon 5D so it must now be a 75mm on my Arri Alexa". It's still a 50mm.

The crop factors are there to give you a guide as to what your lens crop will look like based on your point of reference. For many coming from the 5D that point of reference is Full Frame 35mm (2.3x) and for those coming from Arri Alexa or a 550D it would be Super35/ASP-C (1.5x).

So if you took a 24mm Nikon lens that you have been using with an adaptor on a 550D and used it on the EF mount BMSS the 550D image would cropped by 1.5 (not magnified). If you put that lens on a Nikon to MFT and put it on the MTF BMCC the image would cropped by 1.5 (not magnified).

Both images would look the same on the BMCC no matter what mount.

I am new here and I have been reading lots about this argument and I think i can solve one piece of this question about crop factor.

There is no question.

It's the same.

jb

Wow rick nice response, If I was ever confused, I am no longer
If I give you my phone number, would you add it to your contact list?

Not joking

That goes for John Brawley also

A while ago I did a quick FOV test on my 60D and 17-55mm lens by zooming the lens to 24mm and this showed me approximately the field of view I would see on my Cinema Camera with the lens at 17mm.

This will deepen the depth of field because I am now a longer distance to the focal plane after having to back up to get similar framing.

Wow rick nice response, If I was ever confused, I am no longer
If I give you my phone number, would you add it to your contact list?

Not joking

That goes for John Brawley also

Thanks for remarks, Darryl. It's an honour to be in the same company as John if only for a moment. You know how to reach me.

Rick Lang
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