A while ago Sigma joined the L mount alliance along with Panasonic and Leica. Although it wasn’t really till recently that we started to see the true results of this collaboration when Sigma released their new fp camera. They also released several “designed for mirrorless” lenses like the 14-24 f2.8 Art DG DN. Those lenses are both smaller and lighter than their DSLR counterparts.
One of the new features of the 14-24f2.8 Art DG DN lens is the built-in rear filter holder. It allows you to lock in a gel filter, which you can cut using the template provided with the lens.
This is a relatively inexpensive way to reduce the amount of light coming into the camera. I used to cut ND gels to fit into my MC-11 adaptor and while they worked, the gels could easily scratch, bend and crease, while also reducing image quality a little. I don’t know, maybe it was the particular ND gel I used.
What if you wanted something that is more durable with better optical performance, but without needing a huge 150mm filter system to attach onto the front of the lens?
Build and usage
The first thing I noticed about these filters is just how small they are, they are slightly larger than an SD card and weigh next to nothing. Just for comparison here’s one next to a 150mm filter.
The size and weight difference between the rear and front fitting filters for this particular lens is pretty crazy! True! A front filter holder system will offer more creative freedom with the ability to use graduated filters, circle polarizers and more. BUT! The rear filter, once fitted, feels like using the lens as normal. The only difference is less light getting to the sensor. This has other benefits like being able to balance the Sigma fp with 14-24 f2.8 better on gimbals for video work.
Fitting the filter can be a little tricky at first since the rear slot is designed for a gel filter which is thinner than the optical glass used by Kase. If you sit the filter flat it looks like it won’t fit into the slot.
You need to tilt it at a 45º angle and it sort of just slips in, don’t try to force the filter into place as you risk breaking it and the last thing anyone needs is broken glass inside a lens.
I made a quick video on how to do this.
After doing this a few times it gets easier and I’m able to change them rather quickly on location now. It is probably best to keep a body cap with you. This way you can close off the front of the camera to stop unwanted dust getting onto the sensor while making changes. It is a bit of an inconvenience having to remove the lens, but worth it if you want to open up extra creative options without taking up much space in your bag.
Optically I have no complaints, the set comes with an ND8 (3stops), ND64 (6stops), ND1000 (10stops) which is a good range of filters. On testing them I couldn’t see any reduction of sharpness against having no filter at least on the 24mp sensor inside the Sigma fp. The color shift was around +200k temp +4 tint which gives the images a slightly warmer look but isn’t that noticeable and easily corrected in post.
The set comes with a plastic case just over 100mm square with foam inserts for the filters and a microfiber cloth to keep the filters clean from dust and fingerprints they will pick up during handling.
Personally, I feel the kit would be much nicer if each filter was in a small case similar in size to what is used for SD cards. Many camera bags often have little pouches for things that size.
After I got used to swapping the filters at home I decided it was time to try to create a nice image with them. I headed towards Falkirk, more specifically to The Falkirk Wheel. It’s a fantastic piece of engineering and is the world’s first and only rotating boat lift. I used the Kase filter along with the Sigma fp ISO6 mode to get a 500-second exposure. I tried to capture it in motion and I’m really happy with the results.
Are these rear filters for everyone? No. They can be a little fiddly and needing to remove the lens each time isn’t going to sit well with some people. On the flip side, the massive cost, weight, and bag space saved could be a more important factor for others. It’s nice that these rear filters are an option.
Having the ability to fit these filters along with my Sigma fp, 14-28mm and 45mm lens into a small Cosyspeed Streetomatic+ bag makes them ideal for me when wanting to travel light like during this visit to Glencoe with the family.
I can personally see them having a permanent place in my bag, and can’t wait to get more free time to put them to good use.
The Kase filters can be bought individually or as part of a set via this link or in the uk by email to email@example.com, cost is around £55/$70 per unit and about £145/$190 for a boxed set of three.