Example: How good is Sigma 70-300mm F/4-5.6 DG Macro Lens

The question shows that some basic research has been done, and it's not one of those "shop for me!" questions we all love so much. But, essentially, it is "Can you give a quick review of this lens, please?"

Are such questions on-topic / "constructive"?

  • Can you explain a bit about this approach.i know in stack exchange we use meta for generic discussion which are common.Should i rephrases my question and put here on meta? Jan 4, 2012 at 3:05
  • Chat is for genera discussion. Meta is for questions and discussion about the site itself. On the main site, though, we want good, on-topic questions which can be reasonably answered. Equipment recommendations can be okay, but they're tricky to make useful. Asking people "so, what should I buy" isn't usually good, since it's a) highly dependent on opinions ("not constructive") and b) highly dependent on your specific situation ("too localized").
    – mattdm
    Jan 4, 2012 at 3:13
  • @whuber's answer below shows one way that questions about a specific lens can be asked that might work well.
    – mattdm
    Jan 4, 2012 at 3:14

5 Answers 5


Yes, assuming they are asked and answered appropriately.

One thing we aspire to is a collection of well supported answers. This means supplying either references or considered experience. A good way to elicit such answers is to pose these questions in the form

"I've done the research, I've read the reviews, but how does this product really perform when you're using it for X (or want to achieve Y) and how do you know that?"

That, I think, shows how this class of questions fits within our framework and indicates how we can add extraordinary value compared to many other Q&A or review sites.

  • I can buy that. Can you think of a way to encourage new lens review questions to fit within that framework? (I suppose putting something like it in the FAQ would be a start.)
    – mattdm
    Jan 3, 2012 at 5:21
  • 1
    @mattdm FAQ edits are a start (but they are hard to do well!). Mods might consider making such questions CW as a matter of policy. There are also mechanisms mods can use for creating and posting stock comments to encourage constructive answers. All of this is work for the mods, though. The hope is that in a short while the higher-rep community members will then understand the policy and the approach well enough to help out. If you are interested, I think I can dig up some examples of how other sites cope with similar issues.
    – whuber
    Jan 3, 2012 at 14:53

People are going to come to our site expecting to find information about equipment. This is the logical place to ask such questions.

That doesn't mean that we should accept such questions, but surely it should give us pause to think about what are we offering?

Choosing equipment is a major part of photography, and to ignore this would make our site less than it could (should) be. Of course, diluting our site with off-topic, un-answerable or too-localised questions would also be detrimental.

If we just point people to google, they don't know which reviews are trustworthy. I.e. there is too much noise.

Perhaps we could solve the noise problem by having pointers to good review sites?

For example, would it help to have a question which solicits a list (or index) of trustworthy review sites? Then when someone asks a review-type question, we could close their question and point them to our "index" question?

Fortunately, @Eruditass has already asked this question, which seems to be exactly what we need.

  • 3
    I'd be nice if the linked CW question weren't just "where can I find", but "which are trustworthy".
    – mattdm
    Feb 3, 2012 at 13:37
  • @mattdm, absolutely.
    – AJ Finch
    Feb 3, 2012 at 13:45
  • And along those lines, it really should be reorganized to have the answers as answers, one per site. Then they could be voted on individually. That's a lot of work, though, and I'm not volunteering. :)
    – mattdm
    Feb 3, 2012 at 14:07
  • I think there is probably a fine line between "shopping questions" and getting information you otherwise might not. I am "guilty", I guess, of asking a quasi-shopping question but knowing this was a possible sore point I tried to phrase it well. This is a real issue I'm facing, and I have not been able to get a conclusive answer by Googling or elsewhere. Here, I got a great answer (one counter to my expectations, I might add) and a good future reference.
    – djangodude
    Feb 3, 2012 at 20:04
  • +1 for finding a good middle ground instead of plain allow/deny. We should also have, and we do have some, replies about what to look for in the reviews, what is useful-for-what. May 31, 2017 at 11:14

My personal opinion on recommendations is that it is incredably difficult to ask them in a manner that would be relevant to future visitors, i.e. it wouldn't fall foul of:

This question is unlikely to ever help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet.

(emphasis mine; And yes, that really is the closure description for "Too localised")

Or even:

This question is not a good fit to our Q&A format. We expect answers to generally involve facts, references, or specific expertise; this question will likely solicit opinion, debate, arguments, polling, or extended discussion.

(i.e. "Not constructive")

There is no reason why it couldn't be subject of chat in the chat room; and there are ways of asking a question about recommending gear in a more quantitative manner (Things like, "In real terms, what difference in field of view will I get between the Acme 17-40 and the Acme 16-40?".

  • yes, please lets close them, they take a lot of time, and we get a lot of both subjective and also incorect answers like the one about Sony SLT's here photo.stackexchange.com/questions/19036/… Jan 12, 2012 at 7:32
  • 1
    Anyone with a reputation of 3000 (or more) can (and should, where relevant) vote to close a question. If you have less than that, you can flag the question as "doesn't belong here", and it'll be highlighted to all users with more than 10,000 reputation (so they can vote to close if they agree) Jan 12, 2012 at 12:25

I think a broad review is probably going to be too subjective and broad to be beneficial, however, I think within a scoped context this kind of question can be quite on-topic. (Which I suppose really means it is on-topic, but without scope it is too broad.) I don't think we can really answer "is lens x a good lens?" but something more like "Will this lens work well for goal x?" is answerable, beneficial and well scoped.

It isn't asking for best (which would be highly opinion based and prone to change over time). It isn't asking for a selection (which would be shopping and prone to change over time), but rather giving:

  • a fixed lens (which shouldn't change over time)
  • for a fixed role (clear scope),

which can be answered.

Yes, it is still mildly subjective, but I think it falls under good subjective as it is able to be answered with experience and strong points as to how the strengths of the lens are useful to the task at hand.


Personally, I do not think that these questions are on topic or constructive to the site, in the way they are. Anyone looking for a new lens or a lens for a particular subject or shot can do a simple Google search for it and find plenty of unbiased views, and recommendations.

I think these questions are often asked out of laziness.

However, as @whuber says, if they are asked in a more appropriate way to direct the question towards a very specific answer, rather than an an answer that is made up mostly of personal/emotive thought rather than fact, then they would be of more benefit to the community.

  • The update to the question I gave as an example kind of supports this view: it's "uh, okay, so tell me what to buy instead"
    – mattdm
    Jan 3, 2012 at 14:58
  • 1
    The OP obviously isn't paying attention to this, even though it is a comment on their question. Jan 3, 2012 at 15:37
  • 1
    @GraemeHutchison:sorry being new to photography field i am not sure what should be my inputs :), but that does not mean i am not paying attention :) Jan 4, 2012 at 3:03
  • Well this post was made about whether your question was on topic, a discussion was made about keeping the question away from "what shall I get?" questions and then you updated your question to become exactly that. Therefore, I don't think you were paying attention to this. Maybe you should edit the question to represent you paying attention to this meta question? :) @umeshawasthi Jan 4, 2012 at 9:00

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