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<channel>
	<title>Carsten's Blog</title>
	<link>http://www.saager.org</link>
	<description>may contain traces of personal opinon</description>
	<pubDate>Sun, 04 Mar 2012 16:23:03 +0000</pubDate>
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		<title>Why many pixels really help</title>
		<link>http://www.saager.org/2012/03/04/why-many-pixels-really-help.html</link>
		<comments>http://www.saager.org/2012/03/04/why-many-pixels-really-help.html#comments</comments>
		<pubDate>Sun, 04 Mar 2012 16:19:53 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2012/03/04/why-many-pixels-really-help.html</guid>
		<description><![CDATA[The new Nikon D800 has a 36MP sensor. Bummer
Well it is relative. When you compare it to a D7000 - the pixel-density is the same: Crop-factor 1.5 yields 2.25 the surface and 16*2.25 =36).
So no worry about the lenses, when we disregard the border at larger apertures. Frankly, when do you need sharp corner when [...]]]></description>
			<content:encoded><![CDATA[<p>The new Nikon D800 has a 36MP sensor. Bummer</p>
<p>Well it is relative. When you compare it to a D7000 - the pixel-density is the same: Crop-factor 1.5 yields 2.25 the surface and 16*2.25 =36).</p>
<p>So no worry about the lenses, when we disregard the border at larger apertures. Frankly, when do you need sharp corner when shooting wide open?</p>
<p>One inconvenience is the larger file size (up to 70MB), but considering that I bought my computer with a 500GB drive 2 years ago, and now a 2TB turns along with it - do we really have to care?</p>
<p>The D800 also features crop-modes that utilize only a smaller section of the frame, this will keep the file-size down when the resolution is really not necessary (beware: a DX crop transforms the D800 into a heavy D7000, it is not downsampling the whole sensor!).</p>
<p>Yes, it is that easy, but there are many out there who think (or don&#8217;t think at all) that so many pixel must come for a price. Indeed, they come, but the only price is the list-price of the D800(e).</p>
<p>Besides the storage issue, two arguments float around:</p>
<ol>
<li>The pixel density is too high, diffraction will ruin the image, it is better to shoot with a lower pixel-count</li>
<li>Larger pixels perform better at high ISOs, better a lower pixel-count like in the D4</li>
</ol>
<p>You know my drill, first the short answer and then the lengthy derivation:</p>
<ol>
<li>Diffraction will only compromise details a lesser sensor won&#8217;t even resolve</li>
<li>You can downsample the file to reduce the noise almost perfectly equivalent to a sensor with larger photo-sites</li>
</ol>
<p>Yes, I use pixels and photo-sites synonymously in this article</p>
<p> <a href="http://www.saager.org/2012/03/04/why-many-pixels-really-help.html#more-276" class="more-link">(more&#8230;)</a></p>
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		<title>Hyperfocal</title>
		<link>http://www.saager.org/2011/09/25/hyperfocal.html</link>
		<comments>http://www.saager.org/2011/09/25/hyperfocal.html#comments</comments>
		<pubDate>Sun, 25 Sep 2011 15:26:35 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/09/25/hyperfocal.html</guid>
		<description><![CDATA[First some practical rule I use: I call it the 10/10 rule:
At f/1, 10mm the hyperfocal distance is 10m.
To get to real situations:

Divide 10m by the f-number you want to use (example f/5.6 gives ~1.8m)
Compute the square of your focal length and divide by 100 (example 28mm * 28mm ~ 800, hence 8 )
Multiply the [...]]]></description>
			<content:encoded><![CDATA[<p>First some practical rule I use: I call it the 10/10 rule:</p>
<p>At f/1, 10mm the hyperfocal distance is 10m.</p>
<p>To get to real situations:</p>
<ol>
<li>Divide 10m by the f-number you want to use (example f/5.6 gives ~1.8m)</li>
<li>Compute the square of your focal length and divide by 100 (example 28mm * 28mm ~ 800, hence 8 )</li>
<li>Multiply the two results (example 1.8m * 8 = 9.6m)</li>
</ol>
<p>This rule is reasonably exact, you can use it as well to find the right aperture (the near-field is roughly half of the hyperfocal): Say, you have a 50mm lens and need everything from 10m to infinity in focus.</p>
<ol>
<li>Multiply the min focus distance by 2 (example: the hyperfocal is then 20m).</li>
<li>Divide the lensfactor as computed in (2) above by the hyperfocal distance (example 50*50/100=25, 25/20 = 1.25m)</li>
<li>Multiply by 10 to get the required aperture (example 1.25*10 ~ f/13)</li>
</ol>
<p>You can shorten this by dividing the hyperfocal distance by 10 and execute only step 2, this gives numbers that are easier to compute.</p>
<p>This approximation is designed for &#8220;normal&#8221; APS-C cameras with a pixel-pitch of ~5µm. To be fair this makes sense down to f/8 - for smaller apertures the diffraction will get you unreasonably long hyperfocal distances. I recommend to fix the algorithm by setting the start distance of 10m to 8, 6 or 4m for f/11, f/16 or f/22.</p>
<p><strong>What is hyperfocal distance?</strong></p>
<p>Glad you ask, without much ado, hyperfocal distance is the focus distance from there even objects at infinity will still appear sharp. It is computed as</p>
<p>H =<em> f</em>*<em>f</em>/N/<em>c</em> + <em>f</em></p>
<p>where <em>f</em> is the focal length, N the f-number and <em>c</em> the diameter of the circle of confusion (CoC)</p>
<p> <a href="http://www.saager.org/2011/09/25/hyperfocal.html#more-275" class="more-link">(more&#8230;)</a></p>
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		<title>Tele lens subject separation</title>
		<link>http://www.saager.org/2011/09/11/tele-lens-subject-separation.html</link>
		<comments>http://www.saager.org/2011/09/11/tele-lens-subject-separation.html#comments</comments>
		<pubDate>Sun, 11 Sep 2011 20:04:12 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/09/11/tele-lens-subject-separation.html</guid>
		<description><![CDATA[A common knowledge item in photography is that tele-lenses allow you better subject separation. I had been interested in how much we are talking about.
You have for sure noticed that the subject separation (aka DoF, Depth of Field) is more pronounced at close distances. To make things comparable we have to define comparable scenes and [...]]]></description>
			<content:encoded><![CDATA[<p>A common knowledge item in photography is that tele-lenses allow you better subject separation. I had been interested in how much we are talking about.</p>
<p>You have for sure noticed that the subject separation (aka DoF, Depth of Field) is more pronounced at close distances. To make things comparable we have to define comparable scenes and from a photographer&#8217;s point of view the common denominator is the magnification. In common portrait scenes you have a magnification of 1:10 to 1:100. This means that that 1cm (or inch) on the sensor will represent 10 to 100cm (or inches) of the subject.</p>
<p>The basic optical formula tells us that the magnification is the relation of the subject distance and the focus distance. The constant coupling these lengths is the focal length of the lens. Short: Double the focal length and all other lengths will have to double too. If you shot your friend so that the face fills the whole frame with a 50mm, your will have to step back four times as far to achieve the same with a 200mm lens.</p>
<p>Here two images shot at 70 (right) and 210mm (left). The magnification of the subject is roughly the same and both pictures had been taken at f/5.6:</p>
<p><img src="http://farm7.static.flickr.com/6204/6137162424_2230583791_o.jpg" onmouseout="undefined" onmouseover="undefined" title="undefined" alt="http://www.flickr.com/photos/csaager/6137162424/" /></p>
<p>This comparison makes it easy to see the difference: The diameter of the bokeh circles on the water is three times wider. In other words: The blur that causes the subject separation is proportional to the focal length - at constant magnification and aperture!</p>
<p> <a href="http://www.saager.org/2011/09/11/tele-lens-subject-separation.html#more-274" class="more-link">(more&#8230;)</a></p>
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		<title>Just right on: Sony A77 + 16-50/2.8</title>
		<link>http://www.saager.org/2011/08/24/just-right-on-sony-a77-16-5028.html</link>
		<comments>http://www.saager.org/2011/08/24/just-right-on-sony-a77-16-5028.html#comments</comments>
		<pubDate>Wed, 24 Aug 2011 09:44:27 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/08/24/just-right-on-sony-a77-16-5028.html</guid>
		<description><![CDATA[I am thrilled by the new Sony A77 DSLR and its advanced kit lens SAL1650, a 16-50 f/2.8 zoom.
As I decided about my gear I ended up with Nikon&#8217;s D90.
Nikon failed so far on me by not delivering a D300s successor  (D400). The D400 will be very likely to use the same sensor like the A77, but will there be much [...]]]></description>
			<content:encoded><![CDATA[<p>I am thrilled by the new <a href="http://www.sony.co.uk/product/dsi-body-and-1-lens/slt-a77vq">Sony A77</a> DSLR and its advanced kit lens <a href="http://www.sony.co.uk/product/ddl-aps-c-lenses/sal-1650">SAL1650</a>, a 16-50 f/2.8 zoom.</p>
<p>As <a href="http://www.saager.org/2011/06/23/pentax-is-loosing-it.html">I decided about my gear</a> I ended up with Nikon&#8217;s D90.</p>
<p>Nikon failed so far on me by not delivering a D300s successor  (D400). The D400 will be very likely to use the same sensor like the A77, but will there be much to ask?</p>
<p>The weakness of Sony&#8217;s line up had been the lenses - either mediocre or quite good, but overpriced (Zeiss lenses). The combination Sony just announced seems to priced of what I expect to be the price of a D400 body.</p>
<p>If the image quality of the new combo will hold up against its technical parameters, Sony has a killer here</p>
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		<title>What you need as glass (Part X - Filter)</title>
		<link>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-x-filter.html</link>
		<comments>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-x-filter.html#comments</comments>
		<pubDate>Wed, 20 Jul 2011 21:11:42 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/20/what-you-need-as-glass-part-x-filter.html</guid>
		<description><![CDATA[This last of a series of what glass you will need. Now all lenses are through, it is just left what we can put in front to them.
If, why &#8230;
First screw off the UV/protection filter and tuck it deep into your bag for the visit of a steel work in full production. Filters degrade IQ. [...]]]></description>
			<content:encoded><![CDATA[<p>This last of a series of what glass you will need. Now all lenses are through, it is just left what we can put in front to them.</p>
<p>If, why &#8230;</p>
<p>First screw off the UV/protection filter and tuck it deep into your bag for the visit of a steel work in full production. Filters degrade IQ. In daylight it is less visible, but once you botched some night shot in the winter where you stood freezing at -10°C, because all exposures caught an inexplicable flare you know better.</p>
<p>If you are really concerned, get a high quality filter from Tiffen, B+W, Heliopan or Hoya (Hoya sells different grade, do yourself a favor and buy the most expensive one). UV is not an issue, clear filters are what you want. Prepare to spend €50 for a 77mm filter.</p>
<p> <a href="http://www.saager.org/2011/07/20/what-you-need-as-glass-part-x-filter.html#more-272" class="more-link">(more&#8230;)</a></p>
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		<title>What you need as glass (Part VIII - Macro)</title>
		<link>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-viii-macro.html</link>
		<comments>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-viii-macro.html#comments</comments>
		<pubDate>Wed, 20 Jul 2011 18:56:25 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/20/what-you-need-as-glass-part-viii-macro.html</guid>
		<description><![CDATA[This is part VIII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.
Any lens can double as a macro with close-up lenses and extension tubes, BUT most normal lenses don&#8217;t  perform best at close focus and adding close-ups/extensions will push macro lenses even further. [...]]]></description>
			<content:encoded><![CDATA[<p>This is part VIII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.</p>
<p>Any lens can double as a macro with close-up lenses and extension tubes, BUT most normal lenses don&#8217;t  perform best at close focus and adding close-ups/extensions will push macro lenses even further. Short macro lenses often don&#8217;t go to 1:1 magnification, they are close focus lenses for exaggerating perspective. Useful focal lengths are 60-200mm. 1:1 magnification is always reached at four times the focal length, so do the math what working distance you get and how to do lighting (At 1:1 you loose 2 stops that have to be taken into account as well for the diffraction limit). All macro lenses are good, a smooth manual focus ring is a big help. So you should get a 200mm macro? Yes, if you are really serious about it and can wait that some renewed version comes out. Nikkor 105/2.8VR and Tamron 60/2 are exceptional lenses at the moment. The VR is useless in macro range, btw. -the back and forth movements can&#8217;t be corrected by VR and AF will give up as well.</p>
<p> <a href="http://www.saager.org/2011/07/20/what-you-need-as-glass-part-viii-macro.html#more-271" class="more-link">(more&#8230;)</a></p>
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		<title>What you need as glass (Part IX - Special lenses)</title>
		<link>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-xiii-special-lenses.html</link>
		<comments>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-xiii-special-lenses.html#comments</comments>
		<pubDate>Wed, 20 Jul 2011 16:52:26 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/20/what-you-need-as-glass-part-xiii-special-lenses.html</guid>
		<description><![CDATA[This is part IX of a series of what glass you will need. Each part will discuss a certain lens type and its applications.
There are three kinds of special lenses:

Fisheye
Effect lenses
Perspective Control (PC)

They are special, for special application, so you will need them rarely unless you already specialized in a special field.
]]></description>
			<content:encoded><![CDATA[<p>This is part IX of a series of what glass you will need. Each part will discuss a certain lens type and its applications.</p>
<p>There are three kinds of special lenses:</p>
<ul>
<li>Fisheye</li>
<li>Effect lenses</li>
<li>Perspective Control (PC)</li>
</ul>
<p>They are special, for special application, so you will need them rarely unless you already specialized in a special field.</p>
<p> <a href="http://www.saager.org/2011/07/20/what-you-need-as-glass-part-xiii-special-lenses.html#more-270" class="more-link">(more&#8230;)</a></p>
]]></content:encoded>
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		<title>What you need as glass (Part VII - Wide Zoom)</title>
		<link>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-vii-wide-zoom.html</link>
		<comments>http://www.saager.org/2011/07/20/what-you-need-as-glass-part-vii-wide-zoom.html#comments</comments>
		<pubDate>Wed, 20 Jul 2011 12:09:30 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/20/what-you-need-as-glass-part-vii-wide-zoom.html</guid>
		<description><![CDATA[This is part VII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.
Wide zooms (below 35mm FX/24mm DX) obliterated the wide angle primes.  Besides the obvious goal of getting a large field of view, getting dramatic perspectives by getting really close is what makes these [...]]]></description>
			<content:encoded><![CDATA[<p>This is part VII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.</p>
<p>Wide zooms (below 35mm FX/24mm DX) obliterated the <a href="http://www.saager.org/2011/07/09/what-you-need-as-glass-part-ii-wide-prime.html">wide angle primes</a>.  Besides the obvious goal of getting a large field of view, getting dramatic perspectives by getting really close is what makes these lenses so interesting.<br />
 <a href="http://www.saager.org/2011/07/20/what-you-need-as-glass-part-vii-wide-zoom.html#more-269" class="more-link">(more&#8230;)</a></p>
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		<title>What you need as glass (Part VI - Tele Zoom)</title>
		<link>http://www.saager.org/2011/07/19/what-you-need-as-glass-part-vi-tele-zoom.html</link>
		<comments>http://www.saager.org/2011/07/19/what-you-need-as-glass-part-vi-tele-zoom.html#comments</comments>
		<pubDate>Tue, 19 Jul 2011 11:10:29 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/19/what-you-need-as-glass-part-vi-tele-zoom.html</guid>
		<description><![CDATA[This is part VI of a series of what glass you will need. Each part will discuss a certain lens type and its applications.
Tele zooms cover the range 70/5omm+. Candid shots, sports, wildlife are typical applications (adding a close-up lens makes most of them as well capable macros).
Almost all tele zooms are actually too short [...]]]></description>
			<content:encoded><![CDATA[<p>This is part VI of a series of what glass you will need. Each part will discuss a certain lens type and its applications.</p>
<p>Tele zooms cover the range 70/5omm+. Candid shots, sports, wildlife are typical applications (adding a close-up lens makes most of them as well capable macros).</p>
<p>Almost all tele zooms are actually too short for wildlife. You need at minimum 300mm here + some feature like AF lock are handy.</p>
<p>It is fair to categorize in three groups</p>
<ul>
<li>Consumer tele</li>
<li>Pro tele</li>
<li>Long tele</li>
</ul>
<p> <a href="http://www.saager.org/2011/07/19/what-you-need-as-glass-part-vi-tele-zoom.html#more-268" class="more-link">(more&#8230;)</a></p>
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		<title>What you need as glass (Part V - Standard Zoom)</title>
		<link>http://www.saager.org/2011/07/19/what-you-need-as-glass-part-v-standard-zoom.html</link>
		<comments>http://www.saager.org/2011/07/19/what-you-need-as-glass-part-v-standard-zoom.html#comments</comments>
		<pubDate>Tue, 19 Jul 2011 10:25:01 +0000</pubDate>
		<dc:creator>carsten</dc:creator>
		
		<category><![CDATA[Photo]]></category>

		<guid isPermaLink="false">http://www.saager.org/2011/07/19/what-you-need-as-glass-part-v-standard-zoom.html</guid>
		<description><![CDATA[This is part V of a series of what glass you will need. Each part will discuss a certain lens type and its applications.
Zoom lenses are are rather modern concept that came with the SLRs going consumer. The first zooms had a moderate zoom range and rather small apertures - in film zoom lenses were [...]]]></description>
			<content:encoded><![CDATA[<p>This is part V of a series of what glass you will need. Each part will discuss a certain lens type and its applications.</p>
<p>Zoom lenses are are rather modern concept that came with the SLRs going consumer. The first zooms had a moderate zoom range and rather small apertures - in film zoom lenses were much more popular and of much higher quality. The marketing was more &#8220;Get two (three) lenses in one&#8221; appealing to the casual photographer how didn&#8217;t carry a bag with all the gear or had different bodies hanging around his neck. Who ever tried to mount a M42 lens while walking quickly sees the benefit.</p>
<p>This class of consumer zooms still exists, but it had been complemented by pro-class zooms that obliterated prime lenses in many applications or even outperforms them.</p>
<p> <a href="http://www.saager.org/2011/07/19/what-you-need-as-glass-part-v-standard-zoom.html#more-267" class="more-link">(more&#8230;)</a></p>
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