Wikipedia:Reference desk/Archives/Miscellaneous/2014 March 10

= March 10 =

Macro lenses and normal lenses: depth of field
Would a macro lens have greater or lesser depth of field than a standard lens (for the purposes of this question, both would be viewing the same object as the same size in the view screen)? I plan on buying a lens for bug hunting, but I'm not sure which to look into. — Crisco 1492 (talk) 08:15, 10 March 2014 (UTC)
 * Related question: would a macro filter affect the depth of field of a standard lens? — Crisco 1492 (talk) 09:28, 10 March 2014 (UTC)
 * macro lenses generally have a small depth of field, and that would go for filters too. However this is normally because of the increased magnification. You are talking about an object that can be viewed either with a macro lens (I assume at far distance) or a standard lens (I assume at somewhere near its closest distance). I think that in this case the depth of field only depends on the aperture - the smaller the aperture the deeper the field of focus. However I am only about 70% sure of this so wait for other answers. -- Q Chris (talk) 11:22, 10 March 2014 (UTC)
 * Your assumption is correct regarding what I mean (although my question also includes shooting from the same position with a macro lens and a (longer) telephoto lens). I suspect that there will be no difference, but I am not sure... — Crisco 1492 (talk) 11:53, 10 March 2014 (UTC)


 * I think you would be better off buying a specialized macro lens; you will have to address the problem of a low depth of field anyway (you need a lot of light to be able to shoot at high F numbers). You can use focus stacking to address this. So, you just take many pictures with slightly different focus settings and then combine them using GIMP or photoshop (you can clone the parts that are in focus from each picture into a new image). This allows you to take pictures with larger apartures which will actually increase the sharpness of the picture. The smaller the aperture is, the less sharp the part of the image that you focus on will be, due to the diffraction limit. So, you can then magnify the pictures more before signs of unsharpness appear comparing to shooting at very high F numbers and, of course, the entire picture will be in (almost) perfect focus. But note that at larger apertures, the effects of lens imperfections become more apparent, so the there is a sweet spot for the lowest F value that leads to maximum absolute sharpness. That's why I would always go for the better quality lens. Count Iblis (talk) 16:15, 10 March 2014 (UTC)
 * Except that focus stacking doesn't work as well on live animals, as even a smidge of movement will ruin the possibilities. I've read a bit on macro photography, so I understand a little bit about the different techniques for improving shots (for instance, shooting along a flat plane of the animal, such as in this shot). I am just curious what benefits there are to a macro lens over a zoom lens, and if they have noticeable DOF differences. — Crisco 1492 (talk) 23:43, 10 March 2014 (UTC)


 * Ignoring deviations from ideal lens behavior, the depth of field is a function only of the aperture and the distance from the aperture to the focal plane. Geometrically, if you imagine a cone whose base is the aperture and whose apex is somewhere in the focal plane, and extend it past the apex to a double cone going out to infinity, slices through that double cone give you the size of the circle of confusion at that distance. Different lenses will give you different bokeh, but I don't think they can do anything about the basic geometry of DOF. -- BenRG (talk) 07:12, 11 March 2014 (UTC)
 * Alright, that makes sense. Thanks. — Crisco 1492 (talk) 08:42, 11 March 2014 (UTC)

Looking for a Republic of Ireland (High Court?) judgement
Hi,

I couldn't find on BAILII the "AAMO" judgement mentioned here.

Thanks. Apokrif (talk) 11:38, 10 March 2014 (UTC)


 * http://www.bailii.org/ie/cases/IEHC/2014/H49.html Dalliance (talk) 13:19, 10 March 2014 (UTC)
 * Thanks. Apokrif (talk) 18:04, 10 March 2014 (UTC)

US participation in Crimean War
I have a question. I'm reading in J.A. Michener's ALASKA that during the time Russia and the US are considering the sale of Alaska, both the Crimean war and then the Civil War interrupt the negotiations. Michener writes that in the Crimean conflict Russia's one stalwart supporter and friend was the United States, despite a declaration of neutrality. Then in return Russia protects the Union from European intervention in our Civil War by sending a flotilla into NY harbor and another to SF harbor. The Alaska sale concludes after the Civil War ends. Did he make that up? I can't find anything about either US participation in the Crimean War or Russia's involvement in the Civil War anywhere else. — Preceding unsigned comment added by 50.0.74.95 (talk) 19:45, 10 March 2014 (UTC)


 * "U.S. Civil War: The US-Russian Alliance that Saved the Union" talks about the two countries' common interests and friendship and the Russian Baltic Fleet visiting New York and the Far East Fleet doing the same in San Francisco. Going the other way, this summary states "while the official policy of the United States was strict neutrality [in the Crimean War], many private citizens involved themselves in the conflict." There's also a preview of "Americans in the Crimean War". The New York Times article "The Russians Are Coming!" covers both the arrival in New York and Russo-American relations. Clarityfiend (talk) 21:51, 10 March 2014 (UTC)