UFC Filter Slider M48i (for mounted 2" filters)

The purpose of these washers is indeed to prevent the thread protruding too much. Below is the original message we published back in 2017 when we got aware of this issue. It is a mistake that none of this information made stayed on the product page, we will fix that asap. We regret the fact that some of our cell-mounted 2" filters and those of other manufacturers slightly extend over the back of the 2" (M48) filter slider. Unfortunately, some filter threads from our production actually have a 0.3 mm longer thread. We had tried to provide the maximum optical height for filter holders from other providers - and that unfortunately has gone to our own disadvantage.
We are currently producing very thin spacer rings, so that our, as well as the filters of other manufacturers can not be threaded in too far. We will be pleased to send you these on request. For the moment, we ask you not to thread the filter completely so that the thread does not overlap.

You are right, we noticed this ourselves. For this reason we include spacer rings with each 2" filter slider since mid of 2017 to prevent this from happening. We had the following message for a few months on our website until this was resolved, apparently you purchased the slider from one of our earliest batches which didn't yet include these spacers. Please contact us via email so we can find a way to send you those spacers. Here is the original message: 05/2017 – Please note: We regret the fact that some of our cell-mounted 2" filters and those of other manufacturers slightly extend over the back of the 2" (M48) filter slider. Unfortunately, some filter threads from our production actually have a 0.3 mm longer thread. We had tried to provide the maximum optical height for filter holders from other providers - and that unfortunately has gone to our own disadvantage. We are currently producing very thin spacer rings, so that our, as well as the filters of other manufacturers can not be threaded in too far. We will be pleased to send you these on request. For the moment, we ask you not to thread the filter completely so that the thread does not overlap.

The C8 EdgeHD has got 133mm backfocus from the SC-thread, the Atik 13mm from the T-2-thread, so we have 120 cm backfocus. You need: 2459128 - 2" UNF-adapter (2" SC-thread) - 1mm length 2459110 - UFC Filter Changer Base - 13mm length 2459115 - T2-adapter - 2mm length Which gives a remaining backfocus of 104mm. You can use either the UFC-extensions (larger, and bring the filter closer to the camera): 2x 2459143 - 40mm UFC-extension (=80mm) 1x 2459141 - 5mm UFC-extension (=5mm) 1x 2459145 - VariLock, set to 19mm Or you use a combination ot T-2-extensions, which would be cheaper, but increase the distance to the camera, e.g. 2x Baader T-2 / 40 mm Extension Tube (T-2 part #25B) # 1508153 (=80mm) 1x Baader VariLock 29, lockable T-2 ExtensionTube 20-29mm (T-2 part #25Y) # 2956929 set to 24mm In addition, you need filter slider; for mounted 2"-filters Baader UFC 2" (M48) Filter Slider # 2459112 With the VariLock, you can also take in account the focus shift introduced by the filter; add 1/3 of the filter thickness to the length of the setup (e.g. 0.66mm for a 2mm thick filter)