# Solved: Update From Aurora Aperture About Focus Shift Issue With Rear Mount NDs



## Canon Rumors Guy (Jan 27, 2018)

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Aurora Aperture has responded to a <a href="http://www.canonrumors.com/major-problem-with-the-aurora-aperture-nd-filters-for-the-canon-ef-11-24mm-f-4l/">review by Dan Carr that we posted last weekend</a> about a focus shift when using the 12-stop and 16-stop rear mount ND filters from Aurora Aperture’s CR Format Filter Set.</p>
<p>The problem when using the two darker ND filters is that you cannot see through them to use autofocus or liveview focusing, so the standard practice with front mount filters is you focus, then put the filter in place and shoot.</p>
<p>For photographers that experience the issue that Dan has, here is the <a href="https://aurora-aperture.com/2017/09/15/aurora-cr-canon-rear-mount-format-filter-set/">official workaround from Aurora Aperture</a>.</p>


<blockquote><p>Auto and manual focus is possible when using the 3 and 6 stop filters with camera’s liveview function.</p>
<p>The CR filters may cause a slight focus shift so pre-focusing without a filter then adding a filter may not result a precise focus shot.</p>
<p>When using the 12 and 16 stop filters, users may use techniques of DOF or smaller aperture to overcome this. Or use a 3 stop filter to pre-focus first and lock the focus manually or carefully not touching the focus ring, then swap the 3 stop filter with the 12 or 16 stop filter.</p></blockquote>
<p>Thanks to Aurora Aperture for letting us know how to deal with this issue should it arise.</p>
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## beachcolonist (Jan 27, 2018)

An unsatisfying compromise now passes for "solved"?


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## Canon Rumors Guy (Jan 28, 2018)

beachcolonist said:


> An unsatisfying compromise now passes for "solved"?



Rear filters solve a problem and create other ones. As Dan said to me, he wishes you could just buy the 3-stop and 6-stop as a pair and not bother with the 12-stop and 16-stop.

Me personally? I've never found much use for anything darker than 6-stops, I guess if I need a 10+stop filter, it's too light out and I should just wait a couple of hours.


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## Jack Douglas (Jan 28, 2018)

Canon Rumors said:


> beachcolonist said:
> 
> 
> > An unsatisfying compromise now passes for "solved"?
> ...



I'd go for a pair at a lower price too.

Jack


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## bitm2007 (Jan 28, 2018)

So if you want to use Aurora Aperture 10 stop or 16 stop filters, you need to have or purchase a 3-stop or 6-stop as well, at an additional cost of course !


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## infared (Jan 28, 2018)

LOL! Take the lens off the camera, replace the filter, then put the lens back on the camera? All while not touching the focus ring or moving the camera?!?!
That's funny. 8)


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## StoicalEtcher (Jan 28, 2018)

bitm2007 said:


> So if you want to use Aurora Aperture 10 stop or 16 stop filters, you need to have or purchase a 3-stop or 6-stop as well, at an additional cost of course !


Agreed - if their product causes a "slight focus shift" that necessitates a work-around, then you would hope that the purchaser of a 10 or 16 stop filter might also get a free "blank" to use at the pre-shot stage to get the focus correct.

I still feel though that the whole process is convoluted, and wouldn't want to be pre-focusing, then removing the lens in the field to switch in a back filter (perhaps fixing focus using a strip of gaffer tape on the lens) , then re-attaching the lens to take my shot....etc.... rather than simply using a suitable filter holder in the first place (Lee systems Sw150 as an example, but other makes are available  )


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## ahsanford (Jan 28, 2018)

infared said:


> LOL! Take the lens off the camera, replace the filter, then put the lens back on the camera? All while not touching the focus ring or moving the camera?!?!
> That's funny. 8)



+1. This is a painful workaround and not a solution.

- A


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## infared (Jan 28, 2018)

ahsanford said:


> infared said:
> 
> 
> > LOL! Take the lens off the camera, replace the filter, then put the lens back on the camera? All while not touching the focus ring or moving the camera?!?!
> ...


You could have a sturdy tripod with weight on it and still move the camera doing that song & dance.....I am not even going to get into how much this whole mess gets in the way of, um..."taking a photograph". LOL!


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## Steve Balcombe (Jan 28, 2018)

So when I'm shooting over seawater I'm required to remove the lens, leaving the mirror and sensor exposed to the sea spray, swap a filter over with my salty wet hands, then refit the lens. Then if the camera is still working, take the shot?

Got it.


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## neuroanatomist (Jan 28, 2018)

Steve Balcombe said:


> So when I'm shooting over seawater I'm required to remove the lens, leaving the mirror and sensor exposed to the sea spray, swap a filter over with my salty wet hands, then refit the lens. Then if the camera is still working, take the shot?
> 
> Got it.



Don't knock it, seems like an ideal solution for indoor shooting, where there's ample need for 10-stops of darkening.


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## Valvebounce (Jan 29, 2018)

Hi bitm. 
In fairness the 12 and 16 stop filters are in the same kit as the 3 and 6 stop filters so no there is no additional cost involved! 
Still a cludge not a solution plus it seems like they read the responses to the original post raising attention to the issue detailing this “workaround” then regurgitated them back to us! 

Cheers, Graham. 



bitm2007 said:


> So if you want to use Aurora Aperture 10 stop or 16 stop filters, you need to have or purchase a 3-stop or 6-stop as well, at an additional cost of course !


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## IglooEater (Jan 29, 2018)

Canon Rumors said:


> beachcolonist said:
> 
> 
> > An unsatisfying compromise now passes for "solved"?
> ...



I have. I’ve found my 10 stop slightly lacking before. Smoothing out moving water in full sun at wide aperture. ;D ;D can’t say I got any worthwhile shots though... :


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