Rear mounted filters for Canon lenses

[Canon Bob]

Several Canon wide-angle lenses have a filter mount on the rear to enable users to fit gelatin filters. Late last year, Aurora Aperture sought Kickstarter funding to produce glass ND filters (3, 6, 12 and 16 stop) along with a easily installed mount.
I took the opportunity to run some tests today and the results look quite good. Optically the filters don't degrade the image beyond what can be expected when adding more glass into the light path. Colour shift is marginal and easily corrected on the first 3 strengths whilst the 16 stop offering has a obvious shift of the greens (although still usable).

Shots and crops for colour assessment and optical quality are here for anybody looking to add ND's to their 8-15, 11-24, 16-35, 17-35, 17-40, 14mm or 15mm fisheye

Shots here..... 5DSr and EF11-24 @f/8

Manufacturers website here.....

 

[HoppyUK]

For the very few ultra-wides that have a rear lens slot but can't take a normal screw-in filter, this is a great idea

 

[Brian G]

Interesting concept, and as the owner of an 8-15mm Fisheye, I had wondered where this type of filter could be obtained.

However, I was a bit confused by the listing of the EF 16-35mm f/2.8L USM, EF 17-35mm f/2.8L USM and EF 17-40mm f/4L USM lenses, as these lenses will all accept conventional screw-in filters.

PS. Anyone know of a UK supplier of these?

 

[Canon Bob]

However, I was a bit confused by the listing of the EF 16-35mm f/2.8L USM, EF 17-35mm f/2.8L USM and EF 17-40mm f/4L USM lenses, as these lenses will all accept conventional screw-in filters.

PS. Anyone know of a UK supplier of these?

Whilst those lenses have a front filter thread, they also have a mount for rear filters if additional vignetting is undesireable.

As far as UK suppliers....I believe that Aurora only deal direct.

Bob

 

[Brian G]

Whilst those lenses have a front filter thread, they also have a mount for rear filters if additional vignetting is undesireable.

As far as UK suppliers....I believe that Aurora only deal direct.

Bob

Thanks.
Re-reading the kit details with my brain engaged, I noticed that in addition to the filters you also get a rear lens mount filter holder.

Clicking "Buy" on their website gets you a list of dealers, none of which are in the UK, although I believe that Amazon US will ship to the UK.
I was interested in the cost, rather than making an immediate purchase.

 

[HoppyUK]

Whilst those lenses have a front filter thread, they also have a mount for rear filters if additional vignetting is undesireable.

As far as UK suppliers....I believe that Aurora only deal direct.

Bob

That was an appealing feature of rear-mounted NDs, but the new evaporated metal-deposit NDs now available as normal front mounts from, well just about every brand, are pretty much immune to vignetting as well as being very neutral, with high IR suppression, multi-coating and an easy-clean finish. They're not expensive either, and have at least partially pulled the rug from under Aurora.

 

[Canon Bob]

Thanks.
Re-reading the kit details with my brain engaged, I noticed that in addition to the filters you also get a rear lens mount filter holder.

.

The holder is a replacement for the original 'as delivered'. It's simply installed by removing the original holder (3 screws) and popping the new one in.....neccessary as the Aurora glass filters are thicker than gelatin and hence too tight.
I obatined my filters through the Kickstarter campaign and additional holders were supplied FOC on request (I received 3 for the 3 lenses I had)

 

[Canon Bob]

Just a note about Aurora Inc, the manufacturer.

They launched a new Kickstarter campaign yesterday. This is for two variable ND filters, 1-7 and 5-11 stops in all the usual sizes. Backers from their earlier campaigns were tipped off ahead of the start and they achieved the campaign goal inside 24 hours..... reflecting in part how highly their products are rated by existing users..

Bob