# Using a crop lens on 1DX Mark II for 4K UHD Video? Would it work?



## mikekx102 (Apr 9, 2018)

Hi, I've done a search on this topic and can see that non-canon crop lenses (that don't protrude into the camera body) work on the 5D IV with its crop factor of ~1.7x, but I'm wondering if this will work on a 1DX Mark II also. Please tell me if my working is wrong, and your thoughts 

Okay, so what I'm after is to be able to capture Image Stabilized shots with an Ultra-Wide lens. The perfect lens would be a 16-35mm F2.8L IS, but according to my other thread, that is unlikely to happen:
http://www.canonrumors.com/forum/index.php?topic=34809.0

The full frame resolution on the 1DX Mark II is 5472x3648. Using Pythagoras the diagonal for the full frame is 6576 pixels. If I crop my 4K DCI video footage to UHD, I'm using the centre 3840x2160 pixels of the frame: 4401 pixels diagonally (well the hypotenuse). This is a 1.49x crop.

Canon EF-S crop factor = 1.6
Nikon FX crop factor = 1.5

Thus if I use a Sigma / Tokina lens designed for crop cameras I can get an EF mount lens with a 1.5x crop factor which would work well with a cropped UHD output from my 1DX Mark II, yeah?
1.49x is close enough to 1.5x ?

So I could capture the equivalent of 15-36mm footage in 4k UHD with IS with a Tamrom 10-24mm F/3.5-4.5 Di II VC HLD. This lens also takes filters.

Is that mathematically correct? Thoughts?


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## sanj (Apr 9, 2018)

Very interesting. Will wait to see if this works out for you. I do not have any crop lenses or would have tried it out for you right away...


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## the.unkle.george (Apr 9, 2018)

Check out Dustin Abbott's review of the Tamron 10-24mm:
https://dustinabbott.net/2017/04/tamron-10-24mm-f3-5-4-5-vc-hld-review/

Down under "Interesting Video Option", he covers that it does seem to work OK for 4k cropped video. Even at 13mm, it covers the full frame, so it would work for 1080p too.

Also, the Canon EF-S 10-18mm will work with a little modification. The extrusion on the back of this lens will hit the mirror, but I've seen some people pop the plastic ring out of the lens and trim it down, and then it clears OK. 
http://photography-on-the.net/forum/showthread.php?t=1388461


Given that Magic Lantern is squeezing 4k out of a 5d III, I see no technical reason why Canon couldn't reduce the crop factor on the 5d IV with a firmware update. They just need some pressure from the market to do so.
http://www.magiclantern.fm/forum/index.php?topic=19300.0


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## ajfotofilmagem (Apr 9, 2018)

There are reports and videos on Youtube, successfully using APSC lenses on full frame cameras. Typical 5D or 6D.
But does the mirror mechanism in 1DX have the same size?
You may have a chance to pick up the mirror with the back element of the lens.


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## bhf3737 (Apr 9, 2018)

The image circle limits the maximum sensor size for which a lens can be used.
You need a lens that its image circle (at all focal lengths in case of zoom) falls right on the vertices of rectangle representing cropped size of the sensor. A super 35mm video sensor requires around 32mm image circle and Canon APS-C lens can provide image circle of about 27mm.
I guess you are on the right path by calculating the diagonal size of the cropped part of the 1Dx sensor but you should measure it in mm rather than pixels and match it with the third party lens, e.g. Tamron, that you want to use.
To the extent I know, the image circle covered by lenses is usually not published externally as part of the spec for the lens, except for a few tilt-shift lenses. 
For zoom lenses, the image circle changes (i.e. breathing), for example, Canon EF-S 10-22 f/3.5-4.5 at 12mm has the image circle of about the size of a APS-H sized sensor and by 18-22mm range it is big enough for a FF sensor.


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## asmundma (Apr 14, 2018)

Can report on the 18-80 cine lense which is fantasic for c200. It does not work any good on my 1dx2. its S35 (1,5 crop) and 1dx2 is 1,3 or 1,4- for the longest end work a little bit, but for shorter mm it a lot of vingnetting. In practice useless.


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## mikekx102 (Apr 15, 2018)

asmundma said:


> Can report on the 18-80 cine lense which is fantasic for c200. It does not work any good on my 1dx2. its S35 (1,5 crop) and 1dx2 is 1,3 or 1,4- for the longest end work a little bit, but for shorter mm it a lot of vingnetting. In practice useless.



Brilliant! Good to know. I am thinking I should get a full frame lens anyway so that it's more versatile than just being used for 4K Video.

Thanks!


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## ethanz (May 1, 2018)

Use the Canon 16-35 f4 IS L with the 1dx. I use it and it works great. Very wide with 4k video.


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## Khufu (May 2, 2018)

I see someone mentioned an EF-S option; I would generally advise against this...

I have a modified EF-S 55-250mm IS STM which fits my 5D3 body but the camera knows what it is, and does not want it there! I don't think the IS works, and the Autofocus doesn't play along nicely either.

I think third party lenses are more likely to just get on with what they're meant to do, in terms of IS/VC and Autofocus, but FF Canon bodies KNOW what EF-S lenses are and don't like them being there!


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## Ah-Keong (May 2, 2018)

Can consider the Sigma 18-35mm and 50-100mm....

with focus breathing. Hope Sigma would introduce a say 10-18mm f/1,8?


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