DOF scale on manual focus lenses

[shiang_wang1]

<p>I have a few questions about the color coding of the aperture letters and DOF scale on Nikon manual focus lenses.<br>

<br />Take 28mm F/2.8 for example.<br />The aperture F22, F16, F11, F8 all map to the same color bar in DOF scale. Perfect. <br />After F8 I am lost, particularly on F5.6 (white) and F4 (teal). The color doesn't match. This seems to happen around the infrared marking (red dot). On 55mm F/2.8 macro, after F11, aperture are all in white, presumably DOF scale are gone.</p>

<p>I guess it is meaningless to provide DOF in bigger apertures since DOF preview would have been more accurate. I like to know if that is the reason they don't provide it. The color mapping around the red dot still puzzles me.</p>

<p>Thanks</p><div></div>

[Sanford]

<p>The red dot is for infrared adjustment after you have focused normally. You are are right about the depth of field bars for wider apertures, useless but stylish. </p>

[Michael R Freeman]

<p>On this particular lens (Ai 28/2.8) there are no DOF markings for f/5.6 or f/2.8. The teal markings are the DOF scale for f/4.</p>

<p>You could "ballpark" the DOF marks for f/5.6 as roughly half-way between the teal (f/4) and salmon (f/8) marks. Would not be 100% accurate, as the scale is not linear, but then these markings are only close estimations anyway.</p>

[joseph_wisniewski]

<p>They skip f5.6 because the line would be too close to the f8 line. Notice how the gaps between the lines get smaller as the aperture gets larger. Same with f2.8, the marks would get even closer together.</p>

<blockquote>

<p>I guess it is meaningless to provide DOF in bigger apertures since DOF preview would have been more accurate.</p>

</blockquote>

<p>Actually, no. DOF preview is only accurate for smaller apertures. Focusing screens only scatter light over fairly limited angles. The trend started in the 70s, "bright screens" that scattered less light. It's not bad with an f2.8 lens, on older cameras, it still looks like f2.8. But when you use a faster lens, f2 and f1.4 look a lot like f2.8.</p>

<p>The latest autofocus and DSLRs are even worse, the scatter angle is about 10 degrees, more like f4, so on my old F100 or the newer D3, f1.4, 2, and 2.8 all look a lot like f4 on DOF preview.</p>

 

[Michael R Freeman]

<blockquote>

<p><em>On 55mm F/2.8 macro, after F11, aperture are all in white, presumably DOF scale are gone.</em></p>

</blockquote>

<p>On the 55/2.8, there are DOF marks for f/11, f/22 and f/32 only. These are really only useful for distances between 5ft and infinity, as the scale is so compressed that it is not that useful for shorter distances.</p>

<p>On any manual focus Nikkor, only the numbers on the aperture ring that are coloured have a corresponding DOF marks. White f/stop numbers have no DOF scale.</p>

[kelly_flanigan1]

<p>*****The whole take about how many tick marks to use is a matter of more information versus more clutter and confusion.<br>

Look at dials on old radios; look at a cars KPH or MPG guage; look at lenses DOF marks; look at an old slide rule; look at rulers; yard and meter sticks.</p>

<p>If Nikon added more or less DOF tick marks on your 28mm F2.8; many folks will complain. What the did has the least complaining.</p>

<p>The same goes with a meter stick; many have tick marks for cm and mm too. If the had just cm; or had 1/2mm; one would have folks complaining.</p>

<p>Look at the number of bars for battery charge or signal strength on a cellphone; if only 2 bars folks would go nuts; if ten they would say it is hokey too.</p>

<p> </p>

[JDMvW]

<p>Moreover, f/5.6 was what the lens needed to be set on for mounting and for the old manual "indexing", otherwise known as the "Nikon twist." f/"5.6" is probably white so it will stand out.</p>

<p>The lack of larger aperture marks is also linked to the distances between the various m and feet settings on the barrel of the lens. On most lenses these distances are about the same as the distance between the two 'teal' f/4 marks, so it wouldn't make much sense to have closer marks.</p>

[joseph_wisniewski]

<p>Arrr, Weinberg, you scurvy dog. That thar explanation makes sense! Now I've got to dig up my lens chest and see if the MF Nikkors 'ave yer pasty white f5.6.</p>

[joseph_wisniewski]

<p>Nope. It might make sense, but it's still wrong. I was doing OK with the Ai-S lenses. I checked my old 50mm f1.4, the 105mm f2.5, and the 55mm f2.8, all white 5.6. But the old 55mm f3.5 Ai micro-Nikkor goes...</p>

<ul>

<li>32 blue</li>

<li>22 white</li>

<li>16 yellow</li>

<li>11 mauve</li>

<li>8 white</li>

<li>5.6 teal</li>

<li>3.5 white</li>

</ul>

<p>Darn, and I thought I'd learned a new insight into the weird world of why Nikon "does stuff".</p>

[Michael R Freeman]

<blockquote>

<p>"<em>Nope. It might make sense, but it's still wrong."</em></p>

</blockquote>

<p>Indeed, there are quite a few manual focus Nikkors where the "5.6" is color coded to match a corresponding DOF mark, such as:<br>

AiS 50/1.2 (yellow)<br>

AiS 50/1.4 (yellow)<br>

Ai 50/1.8 (green)<br>

AiS 35/1.4 (yellow)<br>

AiS 24/2.8 (salmon)</p>

<p>... and I expect quite a few more. :)</p>

[shiang_wang1]

<p>Thanks for the explanation. I looked at 55mm f/2.8 macro which skips f16 and stops showing DOF after f11, on 135mm f/2.8, it skips f11, stops showing DOF scale after f8. So at least the relative aperture of the skipping and the stopping are consistent, where it stops has no rule.</p>

<p>I wouldn't have paid attention to the DOF scale until I was trying to calculate hyperfocal distance. I do find the scale is not too far off the actual calculated value, but then again, the scale is not linear, what do I know.</p>

<p>It is shocking to me DOF preview isn't accurate. It seems to work fine on FM2 and N90s (very subtle when I switch between f2 and f2.8), is it because of electronic DOF preview vs. mechanical? I will try it on F100.</p>

<p>Kelly brought up a sensitive subject. I've heard about the notorious battery meter on F100, and today I experienced it first hand when I was testing a newly acquired lense. It was full bar yesterday, suddenly became half bar after a few shots on the field, and totally not functional after a few min. Murphy's law did it to me, normally I carried extra batteries, but not today. It was a good sunset.</p>

[JDMvW]

<p>Wrong? nay, ye landlubbers. There are merely exceptions to the rule, also depending on the vintage of the lens.<br /> Anyway, what part of "probably" and "most" don't you understand? :)</p>

<p>By the way, what are these strange AiS? never heard of 'em.</p>

<p>At least numbering of subsequent Nikon models is semi-linear, unlike those of Canon EOS camera models.</p>

[joseph_wisniewski]

<p>What? You don't like a numbering sequence that goes...<br>

D30, D60, 10D, 20D, 30D?<br>

Would you prefer a Pentax, K10D, K20D, K7, K5?</p>

[JDMvW]

<p>The original EOS series (in film) was EOS 650 first and the 620 next, and after that in order: EOS 750, 850, and the EOS 630 in April of 1989, followed by EOS 1.</p>

<p>Try to make sense out of that or the more recent 7D.</p>