300mm f4

<p>I bought a 300mm f4 for birds. Seems a little soft on the focus. I tried the AF fine tune on my D300. Are these known for their softness? Definitely not tack sharp.</p>

<p> </p>

<p>Is it the AF-S D version on or the AF one? The older version may have less precise autofocus as it relies on the camera's focus motor and mechanical linkage for AF.</p>

<p>I'd say the 300/4D AF-S is very sharp even wide open but maybe slightly low on contrast at f/4. By f/5.6 it improves both resolution and contrast. At f/5.6 is should give high enough resolution on any modern sensor to be satisfied. In my experience lenses that are f/4 or slower don't really require fine tuning to give good results, but there may always be an exception. In my experience the AF-S 300/4D really shines in the near to intermediate distance range. The autofocus of this lens is a bit on the jittery side. </p>

<p>What shutter speeds are you using? If you're hand-holding you probably don't want to use any slower speed than 1/1000s on a DX camera. If you can go faster like 1/2000s it would be better. If you can support the lens using a tripod then you can be more flexible on the shutter speed, but still birds can move very fast and the detail on them is very fine. If you can post an example with exposure details and information about camera support and technique used, it would be helpful. </p>

<p>What kind of method did you try for AF fine tuning?</p>

<p>As Ilkka said, the AFS version of the 300mm f4 is tack sharp, and on mine it's tack sharp even wide open, where I normally shoot it. The only issue I've ever had with the AFS 300 f4 is that in really low light, it's not quite as snappy to focus as the f2.8 version, but then again it costs about 1/4 of the price of the f2.8.</p>

<p>In daylight, you should be getting tack sharp images.</p>

<p>Best,<br>

-Tim</p>

<p>As mentioned, the 300mm F/4.0 AF-S is a very sharp lens, also on DX.</p>

<p>It has one flaw though, the tripod ring / collar which is included with the lens ( well some of them, some ppl do not seem to have an issue with this collar..). I got much improvement by subsstituting it by a Kirk version..</p>

<p>So maybe your "soft Images" could be caused by some vibration issues ? </p>

<p>Here is an older article about this issiue : <a href="http://www.dpreview.com/forums/post/50913294">http://www.dpreview.com/forums/post/50913294</a> </p>

<p>My AF-S 300/4 is pretty good wide open and properly sharp once stopped down.</p>

<p>If your query relates to tripod use, there is a (much discussed) issue with the original tripod collar being a tad too flexible and fouling sharpness. I still use the original collar but jam a high density piece of rubber in between the lens case and the foot which works for me for most exposures with my D700 which tends to have a very clunky shutter actuation.</p>

<p>If the OP's lens is the non-AF-S version I sympathize with him. My 300mm f4 AF front focuses on every camera I tried it with, six so far, digital and film. I sent it in to be checked and it checked out fine. It does focus precisely in Live View on my D7100, otherwise it requires a AF fine tune setting of +20. It is tack sharp wide open when it is in focus.</p>

<p>My solution so far is to adjust the mirror stop on my old D80 and a spare F100. That makes the 300mm focus correctly on these cameras but makes them inaccurate for all my other lenses except, curiously, my 180mm f2.8 AF, a lens very similar in design to the 300mm.</p>

<p>Al</p>

<p>CPM and Matthew mention an important point - if you test this lens properly on a tripod, then sadly enough the fact that you're testing it right may yield the wrong results. The tripod collar is really no good, and it actually may give worse results. I've got the Kirk collar on it, and that's a whole lot better.<br>

Optically, a very, very fine lens. Mine never disappoints as long as I do my work right.</p>

<p>The tripod collar that was supplied with the early versions of the 300/4D AF-S was vibration prone and I initially used a piece of plastic between the tripod foot and barrel that was machined to match both shapes and the vibration disappeared. But I now have a recently purchased copy of the lens and the tripod collar is not the same; it doesn't have any vibration issue that I can detect and my old piece of PVC doesn't even fit in the gap between the lens barrel and the foot; the gap is narrower in this version of the foot. I couldn't detect any difference between using EFCS and regular mechanical front curtain at slow speeds with the lens that I now have (using the D810) so it seems the collar is fine. A similar thing happened with the VR AF-S 200/2G, the original version was very vibration prone but the Mk II has a stiffer tripod foot so that vibration dies quickly. At least in that lens it says clearly "II" on the lens, but in the case of the 300/4 AF-S Nikon didn't say anything about the changes they made. I think a public notice about the changes would have been appropriate and helpful to users in this case.</p>

 

<p>The quality of the collar mostly affects images in the shutter speed range from roughly 1/2s to 1/100s; at fast speeds (such as 1/200s or faster) I never had any issues but some have measured vibration effects even at shutter speeds with longer lenses (400mm). At slow speeds of several seconds, the vibration from the mirror and shutter affects only a small part of the exposure so the effect if any would be slight. The applications where I find the collar to be a factor are mostly landscape photography, close-up, and other relatively static subjects, especially in the rather dark winter we have up in the North. ;-) For bird photography, you probably want to stay with fast speeds whenever possible.</p>

Art...here's the first thing to do to determine if you have a lens sharpness or "other" problem. Get outside in bright

daylight, pick a subject with contrast and shoot a couple of frames at 1/2,000 sec. at f4 and f5.6...if they are sharp, you

have an issue other than lens sharpness.

<p>All good comments above. In addition, you need to make sure your D 300's custom settings and AF selection point are set correctly for birds (in flight). There are lots of postings on this subject. <br>

Joe Smith</p>