Selling 2 Nikkor to get one - help me think thru this please

<p>My equipment:<br />D300<br />Nikkor AF 50mm f1.4<br />Nikkor AF 85mm f1.8<br />Nikkor AF 80-200mm f2.8<br />Tamron AF 10-20mm<br />Nikkor 18-200mm f3.5-5.6</p>

<p>Since my daughter is graduating HS and no longer in sports per se, and since I am shooing more and more 5K and other distance races that don;t have the extreme zoom needs of soccer, for example, that the 80-200 is good for....I am thinking of selling my 85mm f1.8 and 80-200mm f2.8 and getting perhaps a Nikkor 24-120 f4<br />I use the 50mm f1.4 for portraits and it has been over a year that I have actually really needed the 85mm f1.8 so... since the 24-120 f4 is over a $1000, I'm thinking selling those other two lenses would get me close to the cost of the 24-120mm<br />Wanted to see what people thought about the focal length of the 24-120 on a DX body in distance races and gneral use and why in the world I should not make this move. Is the depth of field good enough for isolating runners? I usually use f2.8 at 80mm on the big lens but it's almost too much zoom for the use.</p>

<p>Your thoughts?</p>

<p> </p>

<p>Wade, does the 18-200 not meet your needs already? I'd think <em>very </em>carefully before getting rid of something as nice as the AF 80-200 f/2.8, because if you want to replace it in future it'll probably cost you a lot more than you'll get for it now. One good thing about lenses is that they don't eat anything or take up a lot of space. So as a confirmed hoarder, my advice would be to hang on to them and make full use of the kit you've already got.</p>

DOF is a function of aperture diameter.

 

A 24mm at F/4 is 6mm.

 

A 50mm at F/8 is approximately 6mm.

<blockquote>

<p>DOF is a function of aperture diameter.</p>

</blockquote>

<p>Uhm no, it's a function of subject magnification. Subject distance plays a huge role in the amount of DoF, so it's not just a function of aperture diameter.</p>

<p>What Joe said makes sense; maybe for one race see with the 18-200 how things work out (and accept that it's no sports-lens for the sake of learning the range you need), and afterwards decide which range you need? Another option is trying with the 50 f/1.4. Less flexible, but if 80 f/2.8 is too long, I'd just give that one a try. It's a next logical step, I think.</p>

<p>If it where me I would sell the 18-200, keep the 80-200 as it would be a much better lens to shoot most any kind of sporting event with.</p>

<p>A 24mm lens focused at 15 feet shot at f/4 gives you just under 28 feet of DOF. A 50mm lens focused at the same distance will give you just over 4 feet of DOF at 80 mm it is around 1.6 feet.<br />To me if you want separation from the background a wide slowish lens is not the way to go</p>

<p>I have used the 18-200 in the past for some 5K races but the DOF seems too big... I want to see more softness in the background and most of the time I am shooting at around 50-75mm...so I am thinking the aperture is probably in the f4.5 range.<br />I suppose I should just do a test. take the 80-200 and shoot runners at different apertures and see if f4 is a low enough DOF.</p>

<p>I've never shot any kind of people/motorsports sports so I can't can't address that issue. I have shot street fairs with my 17-55 f/2.8 with great results. I have a D300 also. For me, the ability to go to 2.8 when needed far outweighs what I lose over 55mm. My other main lens is the 70-200 f/2.8 VR1. 70mm is just too long when I'm near the action.</p>

<p>If you are entertaining any thoughts of going to FF please discount the above.</p>

 

<p>If you're mostly around 50-75mm, you could also consider saving up a bit longer for the 24-70 f/2.8 (which probably will also be faster to AF). The D300 gives some room to crop, so it may be long enough and all in all, the 24-70 has the right specs for what you seem to seek (the f/4 lens, well, f/4 isn't that fast).<br>

Or maybe consider a lens like the Sigma 50-150 f/2.8 HSM, depends on how much you need below 50mm?</p>

Wouter,

 

What is the magnification of a pinhole "lens"? I know what the DOF for one is.

 

 

I'm going to have to look it up again. But I'm pretty sure that the DOF for a 25mm f/4 is going to be pretty close to that

of 50mm f/8. Having the same aperture diameter. Not trying to argue, if I'm wrong I need to get it right anyway.

<p>1) it makes absolutely no sense to have both the 18-200 and 24-120.<br>

2) i agree with Rodeo Joe, i would hang on to the 80-200 and 85/1.8 simply because they are good lenses. a 24-120 would be a downgrade from an 80-200.<br>

3) IMO the 24-120 is overpriced, and makes more sense for an FX user than DX. i can think of a lot of things i'd rather do with $1000. you might get a slight improvement in IQ over the 18-200 but you lose range at both ends.<br>

4) i'd consider selling the 18-200 and getting either the 16-85 VR or a 17-50/2.8. the 17-50 would be better for action shots and subject isolation. you could also go with the tamron 28-75/2.8 for a bit more reach on the long end, which wouldn't be too bad on the wide end since you have the 10-20.<br>

5) no such thing as "too much zoom". but you do have a gap as far as not having a fast wide zoom.</p>

<p>here's a shot with the sigma 17-50/2.8 OS...</p><div></div>

<p>Richard, I am not saying that aperture plays <em>no </em>role; but a straight comparison in depth of field between 24mm and 50mm only makes sense when framing an identical photo, in which case you will be much closer with the 24mm lens. The closer subject distance would cause less depth of field again. I'm no expert at this either (did not want to imply to be one either), though, once the circle of confusion comes into play, I get confused.<br>

My main thing was most: a f/1.4 lens wide open focussed to infinity still gives quite a bit depth of field. A short lens at f/8 focussed extremely close gives a miniscule depth of field. The size of the aperture sure matters, but it's part of the equation, not the only variable.</p>

<p>Better explained: <a href="http://en.wikipedia.org/wiki/Depth_of_field">http://en.wikipedia.org/wiki/Depth_of_field</a></p>

<blockquote>

<p>For a given format size, at moderate subject distances, DOF is approximately determined by the subject <a title="Magnification" href="http://en.wikipedia.org/wiki/Magnification">magnification</a> and the lens <em>f</em>-number. For a given <em>f</em>-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF; decreasing magnification increases DOF. For a given subject magnification, increasing the <em>f</em>-number (decreasing the aperture diameter) increases the DOF; decreasing <em>f</em>-number decreases DOF.</p>

</blockquote>

<p>The wikipedia article contains a lot more info, this is just the brief opening summary.</p>

<p>I buy and sell lenses as my needs change and I have regretted it from time to time. Keep the 80-200/2.8 if you can. I too would be considering a 24-70/2.8 instead of the 24-120. I also recommend buying used to maximize value for a given budget. </p>

Wouter,

 

I'm still trying to wrap my brain around the equations on that page.

 

In their formulas it states that aperture is measured in f stops. This is counter to my intuition because I know that wide

angle lenses have more depth of field than say a normal lens at the same f stop.

 

Intuition also tells me that a pinhole "lens" has no magnification, and has virtual infinite depth of field; and this is

dependent on the size of the aperture. Field of view changes are made by changing the "focal length", which is not

really focal length but just distance to film plane.

 

I'll figure it out.

 

I was just trying to provide an experiment that the OP could try out with his existing lenses. To

estimate the depth of field for his purposes of the lens he's thinking of getting. If that's wrong, it's wrong. He could just as easily rent the lens and just test it out before he buys it.

<p>Richard, agreed it is a bit counter intuitive, and I had the same as you when I first thought of this. The point is: frame the exact same photo with say a 24mm and a 85mm lens - you will be much closer to your subject with the 24mm than you will be with the 85. With the exact same framing, same aperture, the DoF will be the same.<br>

In reality, of course, you're not likely to do that - one tends to use a wide angle different from a telelens.<br>

________________<br>

Wade, sorry for these interruptions which are quite off-topic. The idea of getting a 17-50 f/2.8 (possibly the Sigma which Eric has) instead of a 24-... lens is also a pretty good idea. 50 to 70mm is not that huge a difference, a resulting crop from the D300 should still be around 8 MP, sufficient for a quite large print. And it would give you a more useful allround lens. I'm curious to know what you'll decide in the end.</p>

<p>Rent the lens you are thinking of buying for a couple of days for some serious shooting.<br>

The decide if this is the lens for you, and if you are willing to lose 2 lenses to buy the new one.<br>

Good luck</p>

<p>Thanks for all of the feedback... really gave me some things to think about:</p>

<p>1) I might be disappointed in the aperture and resultant lack of softness of background at f4.<br>

2) I have a sweet lens in the 80-200mm f2.8 even though I am finiding I am not using it much NOW.<br>

3) The Nikkor 24-70 f2.8, even used, is too expensive for me. I might look at the Nikkor 24-85 f2.8-4 as an alternative..but might rent it first to make sure.</p>

<p>Thanks again. You guys (and ladies) are the best!</p>

<p>I am no DoF expert either but remember that a wide angle lens has a greater FoV and less magnification then a standard lens. I suggest you take two pictures, one using a wide angle vs one normal while keeping the image size the same. I think you will find the DoF is equal given the same f-stop but perspective has changed. It hurts my head a bit reading all the equations so I usually use a focal length that meets my FoV needs then determine DoF needs and go for the correct exposure.<br>

I use and like the Tamron 28-75mm f2.8 on my D700 and if that is the correct zoom range for your needs it will give better subject isolation at f2.8.</p>

<p>I actually had a copy of the Tamron 28-75 f2.8 but alas there was a sharpness problem with it and I ended up selling it as is....and I never replaced it.. had a bad taste in my mouth over that particular lens.</p>