Railfan Technology > Nikon help please

Hi all, this is my first time posting on railfan tech. I sold my D50 body not long ago it was bought in 2005. I now have a D3100 and not knowing tried to put the old 70--300
lens from the D50 on it thinking it would be compatible. And that was a big no, My question is how do I go about buying a new lens at a decent price that would work? I don't know
how to check for one that fits or not.



Thanks for any help...

Steve H.

The D50 had a focus motor built into the body. The D3100 does not. I'm assuming the 70-300 lens you have is a G model, which has no focus motor built-in to the lens, and depended on the body motor to drive it, which your 3100 does not have. Your lens is compatible with your D3100, but you have to manually focus it.

What you need for the 3100 to use auto focus are any of Nikon's DX format AF-S lenses, which have a built-in "silent wave" focus motor.

http://imaging.nikon.com/lineup/dslr/d3100/compatibility02.htm



Edited 1 time(s). Last edit at 12/07/17 16:46 by trainjunkie.

The D3100 does not have a motor, so do I need a 70-300 AF-S ?

Steve H

70-300 AF-S is fully compatible.

trainjunkie Wrote:
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> 70-300 AF-S is fully compatible.


Thank you so much Mr. trainjunkie you have helped so much. Now I just have to find a new one at a decent price...


Steve H...

There are a few versions of that lens but the best one is the Nikon - AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED Telephoto Zoom Lens. Around $300 last time I checked on ebay.

Tom Trent
Eugene, OR

You need an "AF-S" lens as others have said. DO NOT BUY the newer "AF-P" lenses -- they are not compatible with older bodies (which the D3100 is now considered to be). You can buy new from Best Buy, B&H Photo, or Adorama, or used from KEH Photo in Georgia. Otherwise, buyer beware.

Or, since many train pix are shot at infinity, just focus the lens yourself.

I, too, used to focus on infinity. That was then, however. Modern lenses for my Nikon D-750 are so precise and seem to have less tolerance in focus that infinity doesn't work anymore. Auto-focus does pretty well, but when there is a lot of subject matter in the photo the precise focus point is difficult to find in auto modes and in manual. It seems a never-ending challenge to set proper focus points. Does almost everyone rely on auto-focus these days? I take a lot of photos and have for a long time, but focus continues to challenge me.

Ed

ISO 400, f8, infinity in live view if you have it.
Or use the center point in auto focus. It's usually the most accurate. Oh, and for a return of the split image rangefinder. Stay away from the green square auto everything. It has a tendency to either miss focus or set a too slow shutter speed. You can see that on TO with numerous pix that are not sharp for a variety of reasons.

Nostalgia gets a pass. Those lenses were the best we had and are no match for modern glass.

Setting a smaller aperture can dramatically change the depth of field which will bring more of the scene into focus. Keep in mind that the smaller the aperture (or f-stop) the larger its number will be. For example f-16 is "smaller" than f-4. In other words, the diameter of the adjustable lens opening at f-16 is smaller than it is at f-4. This is easily done by either manually setting the f-stop on the lens or in the automatic mode, selecting aperture priority and then choosing the f-stop. There is a trade-off of course. Smaller f-stops require slower shutter speeds which is a consideration if the camera is being hand held or something in the scene is moving, like a train. The concept described here is a variation on hyper-focal and zone focusing. Good luck. It is easier to do than to describe.

I'm in the Zone focusing camp as well, there's something not right with how we assume the auto-focus has found the moving train and is doing the work correctly at the right moment. A lot of my older manual focus photos have that pop out of the background look which I don't get anymore. In that same way half of the depth of field is lost using auto-focus and the foreground is out of focus. So the camera limitations are defining the photo.

The closest thing I can get is using Aperture priority set around f8, crank up the ISO as needed. Also of interest is the modern lenses don't have the depth of field lines on the lens barrel.

Just a quick thought about shooting. With one exception, all my lenses are manual focus. I never had a film SLR and have had my D7100 for two years and got it because it could meter the older lenses. My most successful manual focusing technique is to determine the frame that I want to shoot and where the train will be in it and then find a focus point that puts what I want in the depth of field (obviously not for grab shots). For me this has been trial and error with a lot of error. Finding the focus point can be tricky because Nikon's focusing system uses contrast and can have trouble in situations that lack it, like midday sun or low light. I would kill for a full frame and a bigger viewfinder (not to mention the focus peaking system in the D850).

Tom Trent
Eugene, OR

Little late to this party but my Nikons have always had a green focus confirmation light when I have to manual focus.. I shoot a lot at night where focus will not work and shoot at 1.4. For a while I was using AIS manual focus lenses but now have auto lenses and put my focus point on a distant light, get focus and then set lens to MF.

My major mess ups is when I prefocus too soon and then touch the focus ring.

Bob

Auburn_Ed

I am currently shooting a D-810, with a D800, D-700, D-300, D-80, D-70 in the past. I photograph trains using auto focus generally using the Dynamic Area AF mode and Continuous Release. The problems that I have with focus are usually associated with camera shake AKA photographer error. I recommend using the center focus point for most shots and with a moving train you shouldn't need a ton of focus points activated. Shutter speed can be another factor if you are close to the train as it passes by. The closer you are the faster the shutter speed to stop the action for a sharp image. Boosting the ISO on the D-750 will, depending on the level of boost, will eventually lead to a soft, not sharp look to the image.

Just some food for thought.

Jim


Auburn_Ed Wrote:
-------------------------------------------------------
> I, too, used to focus on infinity. That was then,
> however. Modern lenses for my Nikon D-750 are so
> precise and seem to have less tolerance in focus
> that infinity doesn't work anymore. Auto-focus
> does pretty well, but when there is a lot of
> subject matter in the photo the precise focus
> point is difficult to find in auto modes and in
> manual. It seems a never-ending challenge to set
> proper focus points. Does almost everyone rely on
> auto-focus these days? I take a lot of photos and
> have for a long time, but focus continues to
> challenge me.
>
> Ed

I use auto-focus, but what works best for me is to set it on one single point — not 9, 64, or more — and then move that point around on the screen to the thing I most want in focus, like the locomotive nose, for example.

That way the camera does the work of focusing, but I still decide what to focus on.

Posted from iPhone

walstib Wrote:
-------------------------------------------------------
> I use auto-focus, but what works best for me is to
> set it on one single point — not 9, 64, or more
> — and then move that point around on the screen
> to the thing I most want in focus, like the
> locomotive nose, for example.
>
> That way the camera does the work of focusing, but
> I still decide what to focus on.
>
> Posted from iPhone


Interesting strategy. Have to check it out.