At the moment there are 49 questions tagged with , 34 with and 7 with both.

It doesn't look like we need both tags.

I don't know any use for the phrase "neutral density" besides that in the filters. There are neutral density filters for light sources to lower their power (if they cannot turned down lower), but they are also neutral density filters. Which suggests that only should stay.

But is the more general term, so whatever else there is that has a neutral density, but is not a filter, would fit better into that tag. This tag has a tag wiki (which could be moved elsewhere). This suggests to keep only .

Or should we keep both and make one a synonym to the other?

4 Answers 4


I think a tag synonym makes sense.

I'd say keep neutral-density-filter. If we kept neutral-density, then people would be tempted to tag questions with neutral-density and filter, which we're saying is probably redundant. Keeping filter in the tag would make that less tempting?

  • Agreed, but it seems like tagging appropriate questions with both [neutral-density-filter] and [filters] would still makes sense.
    – scottbb Mod
    Apr 14, 2016 at 22:46
  • Yeah, I'm with @scottbb — some SE sites are stingy with filters, but I don't really see why not to use the various most relevant ones.
    – mattdm
    Apr 15, 2016 at 1:55
  • stingy with tags I assume you mean ;) Sounds to me like you both would prefer to have [neutral-density] and let them tag with [filter] as well, rather than the [neutral-density-filter] tag? I'm unsure which one should remain, or whether it really matters anyway. Thoughts?
    – MikeW Mod
    Apr 18, 2016 at 2:09
  • Yes. Questions about ND filters should be tagged both ways. People who search the specific tag should certainly find ND filter articles. But for people who search more generically, or perhaps don't think or know to search for the specific term, I think searching the generic [filter] tag should show ND filter articles (and all sorts of other filters as well).
    – scottbb Mod
    Apr 19, 2016 at 1:18
  • I guess it's similar to how camera-specific tags are often (but not always) used. For example, [nikon] and [nikon-d750] are often both tagged for articles with/about D750 bodies. (In the camera body case, they shouldn't necessarily always be doubly tagged, but I'd be hard pressed to write the rule distinguishing the cases).
    – scottbb Mod
    Apr 19, 2016 at 1:20

(Bit late to this party, but here's my 2p)

I think a filters category is useful in it's own right without a need for having filter repeated in the tags. I don't think the repetition would present a serious problem. But we should probably look at a wider tag review of all the similar tags...

  • [polarizer] x 75
  • [neutral-density] x 49
  • [neutral-density-filter] x 34
  • [nd-filter] x 9
  • [graduated-filters] x 8
  • [starbursts] x 5
  • [skylight] x 3
  • [close-up-filter] x 1

From this [neutral-density] would seem to be the more popular option and would be in line with the most commonly used of the filter tags.

There are probably a few more that I missed, but we're pretty inconsistent right now so it would be nice to fix it.

  • I missed the nd-filter entirely. Seeing this list it looks like having the types of filters separately is the better option to do something like [filter] + [neutral-density] and then optionally add [graduated] for example. We don't have [strobe-flashes] or [speedlight-flashes] either.
    – null
    Apr 18, 2016 at 18:23
  • 1
    @null But "strobe" and "speedlight" are clear nouns that are not typically used in conjunction with the added "-flash" / "-flashes". But we only say "ND" or "graduated" in lazy verbal conversation. Written communication would say "ND filter" or "neutral density filter" or "graduated ND filter". When you click on the tags page, in a list of tags, seeing "graduated" or just "nd" by itself would seem kinda weird, wouldn't it?
    – scottbb Mod
    Apr 19, 2016 at 1:46

TL;DR: the tag should include the noun (i.e., [neutral-density-filter] or [nd-filter])

I believe tag ontologies should consist of nouns, not adjectives. For example, the camera-specific tags. Should we have [canon], [nikon], and a bunch of [1200d], [3ds], [d800], [d5100], etc.? Using (and ostensibly, sorting) those sub-tags is a bit more difficult than if they were [canon-1200d], [nikon-d800], etc. (albeit, slightly more annoying to type).

If the tags are economized on the repeated word such that we use [filters] and [neutral-density], then do we also have [graduated] that can be applied in conjunction with the ND tag? So if I want to see the questions about GND filters, I have to click on [graduated], which from a user interface perspective, seem kinda weird.

And of course, we should consider the [variable] ND filters. I'd have to click on the [variable] tag, which seems really weird. Just seeing a tag list, the word "variable" doesn't seem to belong to the concept of filters. It could apply to all sorts of other things, depending on my mindset when searching or browsing the taglist. But [variable-nd-filter] is clear and unambiguous. (BTW, the current [variable-nd] just sucks, IMO.)

As an aside, ontologies are hard. There are no absolute right or wrong ways to sort these kinds of things out. But on the margin, there are better and worse ways. Considering how tags are used, applied, presented, etc., on Stack Exchange, we can guide ourselves to less-suboptimal solutions. We can only apply 5 tags to posts. If we eliminate the common words in the tags, questions about variable ND filters or graduated ND filters would require 3 tags just to properly minimally tag it, leaving only 2 other tag slots for context. Thus, for the hypothetical "How can I use graduated ND filters to improve a panoramic landscape scene shot using HDR?" question (it doesn't exist, oh how I wish it did for this example), I need six tags: [filters], [graduated], [neutral-density], [panorama], [landscape], [hdr], but I can only apply 5. Which one gets the axe? But if we had [graduated-nd-filters], I would only require 4 tags, leaving me the luxury to apply [overtagged] or something more appropriate. =)

  • 1
    Some good points here. I do believe we could set up some synonyms to allow more flexible use of tags here, but I do think that including a noun in the primaries is valuable.
    – jrista
    Apr 20, 2016 at 7:04

Weirdly, I can actually see a case for [neutral-density] and [neutral-density-filters] coexisting, and making a distinction. The neutral-density-filters tag being for physical lens ND filters, while neutral-density could capture ND gels for flash use and digital GND filters in post-processing, which are different subjects, but still fall under neutral density.

We'd have to edit the HELL out of the tag wikis, though and probably do a lot of tag cleanup and enforcing in the future. as this isn't exactly intuitive.

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