Author Topic: ND filter instead reflex mirror  (Read 2938 times)

domasa

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ND filter instead reflex mirror
« on: April 30, 2017, 02:25:22 PM »
Camera EOS C300 has three internal ND filters:

ND 0.6 – 2-stop reduction
ND 1.2 – 4-stop reduction
ND 1.8 – 6-stop reduction

This is better than screw and unscrew ND Variable filter on lens after each change of luminance (filming in the dark church/sunny garden before church).

I use my 5D Mark III mainly on video. Why not use dark ND filter instead reflex mirror?  8)


Would be possible control reflex mirror in video mode? (flip-up/flip-down)

If yes - some company could be create ND filter (like "Mosaic Opto-Electronics, Inc." creates VAF filters)  :)

Reflex mirror replacement should be relatively easy:
https://shimworld.wordpress.com/2009/08/24/cleaning-the-5d-mk-ii-viewfinder/

ilia3101

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Re: ND filter instead reflex mirror
« Reply #1 on: April 30, 2017, 02:31:24 PM »
The mirror is stuck on to an opaque piece of plastic, with only a hole in the middle, so could work for 3x crop maybe - if you remove the second autofocus mirror thats behind it behind it aswell. You see I have experience with how it works; my mirror fell off a few weeks ago ;D some superglue fixed it.
You could cut a bigger hole out of the mirror holder, but tbh it probably isn't a good idea.

domasa

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Re: ND filter instead reflex mirror
« Reply #2 on: April 30, 2017, 11:31:51 PM »
The mirror is stuck on to an opaque piece of plastic, with only a hole in the middle, so could work for 3x crop maybe
:( This is bad news.

In my link replaced only focus screen. Not reflex mirror. Sorry for mystification.
Replace mirror probably require disassemble all camera :(

dfort

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Re: ND filter instead reflex mirror
« Reply #3 on: May 01, 2017, 01:19:22 AM »
Most professional video cameras have built in neutral density filters. That's one of the features that is hard to copy in a DSLR. There are a few Canon lenses that have a behind the lens gel filter holder.



Here's a link if you want to learn more about this feature. It isn't as convenient as the built in filters of a C100 or C300 but it is pretty easy to slip in a filter in the field compared to installing a VAF filter.

When I was a still photographer using 4x5 and 8x10 view cameras it was quite common to put gel filters behind the lens but this practices seems to have been largely forgotten. There are some huge filters designed to be used for wide angle lenses.



There is an interesting lens adapter called the ND Throttle that has a built in variable neutral density filter but unfortunately it only works on mirrorless bodies. As far as the Magic Lantern enabled cameras not even the EOSM is supported.

Switching out the mirror for an ND filter is an interesting idea but it isn't a trivial hardware hack. The camera will not record with the mirror down.
5D3.* 7D.206 700D.115 EOSM.203 EOSM2.103 M50.102

garry23

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Re: ND filter instead reflex mirror
« Reply #4 on: May 03, 2017, 07:24:28 PM »

dfort

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Re: ND filter instead reflex mirror
« Reply #5 on: May 03, 2017, 07:36:08 PM »
Hi @garry23 -- Oh yeah, now I remember you mentioned a while back that you're using medium format lenses with that ND Throttle.

I take it that this means no automation on the lens which I suppose if fine for landscapes but it looks like the OP is for weddings. Tough to follow a moving subject without auto focus.
5D3.* 7D.206 700D.115 EOSM.203 EOSM2.103 M50.102

garry23

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Re: ND filter instead reflex mirror
« Reply #6 on: May 03, 2017, 08:09:51 PM »
@dfort

You know me: don't do that videography stuff  :) ;)

Things work well on a tripod and allow you to work at a leasurly pace.