Wikipedia:Reference desk/Archives/Miscellaneous/2011 March 5

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March 5

Do you need to focus a telescopic sight?

When using a rifle with say, a 10X, telescopic sight, do you need to focus the scope like you would on a pair of binoculars or camera lens? Or does the scope have unlimited depth of field? Acceptable (talk) 06:38, 5 March 2011 (UTC)

As a deer hunter, I have not come across a scope that requires "focusin". There are those where subtle adjustments can be made, but not to the degree of binoculars or a telescope. Alignment is the biggest issue. -- David Able 06:44, 5 March 2011 (UTC)

I doubt if a hunter would focus the scope, so he can count the deer's whiskers, when he really wants to shoot. StuRat (talk) 07:21, 5 March 2011 (UTC)

As this is Wikipedia we have an article on Telescopic sight's that you might like to read.--Aspro (talk) 16:23, 5 March 2011 (UTC)

I don't specifically know, but it seems likely to me that a telescopic sight will be focused at "infinity", so that objects far away will be in good focus but objects nearby will be blurred. Looie496 (talk) 17:58, 5 March 2011 (UTC)

Nothing like that has an unlimited depth of field, as far as I know, but if everything you are interested in is beyond the hyperfocal distance then you can just keep the sight focused at infinity and everything will be in focus. I'm not sure what the hyperfocal distance for a typical telescopic sight is, but since 1) the sights are very small, 2) the distances involved are very large (otherwise you wouldn't bother with a telescopic sight) and 3) the acceptable amount of blur is quite high (you don't need to be able to see the object clearly, you just need to be able to see where it is in order to aim at it), it wouldn't surprise me at all if focusing at infinity worked fine the vast majority of the time. --Tango (talk) 18:40, 5 March 2011 (UTC)

Note the focus control on this telescopic sight. Cuddlyable3 (talk) 06:12, 6 March 2011 (UTC)

Note that that 'focus' control pictured is a diopter adjustment that allows the user to compensate for his own vision defects and obtain a sharp view of the targeting reticle; it has nothing to do with focusing on targets at different distances. (The system is fixed focus at infinity, and the reticle is in one of the image planes.) TenOfAllTrades(talk) 22:20, 6 March 2011 (UTC)

Mistake in this article

Hi,

In this page (Washington's Birthday) it is written the Presidents Day is related to Washington's birthday but in the little table on the right, it's written it's related to Lincoln's. —Preceding unsigned comment added by 89.204.153.189 (talk) 08:57, 5 March 2011 (UTC)

According to Snopes,[1] it's Washington. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:13, 5 March 2011 (UTC)

I don't think the article is mistaken. It's saying it's "related to" Lincoln's birthday, not that it commemorates Lincoln's birthday. It actually commemorates Washington's. The article explains it all in fine detail. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:16, 5 March 2011 (UTC)

Indeed. It just means that Washington's birthday is a bit like Lincoln's birthday, which is perfectly true. They are both birthdays of famous US presidents that are public holidays (at least in some states, in the case of Lincoln's). --Tango (talk) 18:43, 5 March 2011 (UTC)

• Washington day and Lincoln day are now celebrated as one combined holiday known as Presidents Day which takes place on Washington's birthday since it clearly could not take place on both of their birthdays.AerobicFox (talk) 05:21, 6 March 2011 (UTC)
  • Not really. President's Day is an unofficial term. The 3-day holiday is officially the Washington's Birthday holiday. Some states have chosen to throw Lincoln's birthday in with it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:29, 6 March 2011 (UTC)

Women skiers with facepaint

I was watching the on-going skiing world championship at my coworker's home, and there was a women's skiing event going on. I noticed that a couple of the skiers had the middle part of their faces (the nose and the part of the face around it) painted in a pastel colour, such as light blue or pink. What does this mean? Why do they do this? Is it a weird women's fashion thing or does it actually mean something? JIP | Talk 18:15, 5 March 2011 (UTC)

Heavier sunscreens are often opaque, and many are coloured - some brands don't come uncoloured. I have seen both men and women wearing them. --NellieBlyMobile (talk) 18:37, 5 March 2011 (UTC)

I concur, it's probably sunblock. You see cricketers wearing it quite often too. --Tango (talk) 18:44, 5 March 2011 (UTC)

As well as lifeguards. Dismas|^(talk) 10:19, 6 March 2011 (UTC)

http://zinka.com/ This stuff was big with skiers in the 80s, it might be making a comeback.129.128.216.107 (talk) 16:29, 9 March 2011 (UTC)

Where is this photo? (Somewhere in Utah)

Anyone know where this rock formation in Utah is? Photo says Arches, but I think it's mislabeled. --CGPGrey (talk) 21:15, 5 March 2011 (UTC)

Google images turned this up. Looks like the middle formation in the picture on this page: [2] ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:26, 5 March 2011 (UTC)

And this.[3] The rock formations are called the Courthouse Towers. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:29, 5 March 2011 (UTC)

It's also visible in the background of this picture. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:12, 6 March 2011 (UTC)

Ah, nice one Bugs, why use one edit when three will do. Caesar's Daddy (talk) 22:59, 6 March 2011 (UTC)

Increases the edit count! --Quartermaster (talk) 23:04, 6 March 2011 (UTC)

Something I'd never do, myself. --Quartermaster (talk) 23:04, 6 March 2011 (UTC)

Right. My initial response answered the question, and the other two responses provided more information as I found out more about it and became more interested in it. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:07, 6 March 2011 (UTC)