Best Macro lenses for fungi and lichen

Carl_Oxford_UK

Senior Member
OK, lets see if this newbie can use some of jargon in the right order to make it sound like I have some idea of what I am on about.

I have a D7100 and am looking to purchase a macro (or micro) lens to photograph fungi and lichen. I have read several comments that suggest when taking macro shots the more mm in the focal length the better as it is possible to shoot from further away and therefore avoid scaring any insects. However, with fungi and lichen this is not an issue and sometimes I need to get really close to the subject to get around rocks and branches and other bits of the landscape that would otherwise come between me and my subject. So, does this mean that I would be better off with a shorter focal length?

The Nikon UK - NIKKOR Lenses - Auto Focus Lenses - DX Lenses - Single Focal Length - AF-S DX Micro NIKKOR 40mm f/2.8G - Digital Cameras, D-SLR, COOLPIX, NIKKOR Lenses

or Nikon UK - NIKKOR Lenses - Auto Focus Lenses - FX Lenses - Single Focal Length - AF-S Micro NIKKOR 60mm f/2.8G ED - Digital Cameras, D-SLR, COOLPIX, NIKKOR Lenses for example, rather than a 105mm or 200mm?

Further, it is my understanding that the D7100 is a DX format, so a lens with 100mm focal length will actually act as if it is ~130mm. So to achieve the same effects as a 105mm lens I would only need a 80mm lens. Is this correct?

So what about when a lens has the letters DX in the description?

I notice that the Nikkor 85mm lens Nikon UK - NIKKOR Lenses - Auto Focus Lenses - DX Lenses - Single Focal Length - AF-S DX Micro NIKKOR 85mm f/3.5G ED VR - Digital Cameras, D-SLR, COOLPIX, NIKKOR Lenses says it gives the 35mm equivalent of 127mm, so if the lens does not have DX in the name will the focal length be the actual focal length?

Thanks in advance for any comments / suggestions
 

WayneF

Senior Member
OK, lets see if this newbie can use some of jargon in the right order to make it sound like I have some idea of what I am on about.

I have a D7100 and am looking to purchase a macro (or micro) lens to photograph fungi and lichen. I have read several comments that suggest when taking macro shots the more mm in the focal length the better as it is possible to shoot from further away and therefore avoid scaring any insects. However, with fungi and lichen this is not an issue and sometimes I need to get really close to the subject to get around rocks and branches and other bits of the landscape that would otherwise come between me and my subject. So, does this mean that I would be better off with a shorter focal length?

It seems true that you would have no problem getting closer... closeness would not scare away your prey, nor allow it to reach out and bite you.

The 40 or 60mm lens would work. One issue however, sometimes with a short lens (like these), only a couple of inches from the macro subject, the lens tends to block your light, making shadows on your subject. The longer lens can stand back and offer a little advantage in that way. And this greater distance may not scare away the grasshopper as soon if using a 105 mm lens.

Now, the opposite... if you are shooting a table top scene maybe 18 inches wide, a 105 mm lens on DX probably means the camera must be about 8 feet away.... The room may not offer that much space, and you cannot reach out and rearrange your subject. The 60 mm lens will be much closer, within easy arms length.

Further, it is my understanding that the D7100 is a DX format, so a lens with 100mm focal length will actually act as if it is ~130mm. So to achieve the same effects as a 105mm lens I would only need a 80mm lens. Is this correct?

So what about when a lens has the letters DX in the description?

I notice that the Nikkor 85mm lens Nikon UK - NIKKOR Lenses - Auto Focus Lenses - DX Lenses - Single Focal Length - AF-S DX Micro NIKKOR 85mm f/3.5G ED VR - Digital Cameras, D-SLR, COOLPIX, NIKKOR Lenses says it gives the 35mm equivalent of 127mm, so if the lens does not have DX in the name will the focal length be the actual focal length?

Thanks in advance for any comments / suggestions

This part is not quite right.

If the lens is marked, say 60 mm,then the focal length is 60 mm, no matter what. The lens does not change simply because you put it on a DX body. A DX lens probably does not have a wide enough viewing angle to cover a FX sensor, but no matter if lens says DX, no matter if camera is DX or FX, no matter what, the lens focal length is what the lens says it is.

The DX and FX camera sensors are different sizes, and the FX sees a larger area of the lens projection, and the smaller DX crops away some of what it sees. So it sees a smaller area, which when enlarged, appears magnified, as if using a longer lens. But all that is different is the 'angle of view" of the lens.

See FX - DX Lens Crop Factor for more detail.

There are two aspects (one for macro).

1. For normal use, standing back at 10 feet with a FX camera, will will see the same view that at DX camera will see standing back 1.5x, or at 15 feet, with the SAME lens on a DX camera. That is an "effective" focal length, but it is always what it is.
Or the two cameras could stand in same place, and the DX camera would see the same view as the FX if the FX used a lens 1.5x longer focal length. This would be the "effective focal length" (on DX, simply being the view compared to a longer lens on FX), but the focal length cannot change. It is what it is. All that changes is the sensor size, which for DX, offers only a cropped view of the full FX field.

The lens is what the lens is, but the angle of view projected onto the smaller DX sensor is smaller. This is the only difference.

2. For macro.

To get 1:1 enlargement factor, this 1:1 will be true for DX or FX when all else is the same. They both have to stand at the same place (at maybe at 2 inches) to get 1:1. The DX sensor will see a smaller cropped viewing area, but the size of the objects will be the same, 1:1.
 

Carl_Oxford_UK

Senior Member
Thanks Wayne, so it seems like a 60mm lens may let me get closer than a 105mm but not so close as required by a 40mm lens, thus avoiding casting shadow on the subject. And the 60mm lens on my DX body will give an effective focal length of 90mm that will give me good results for more general use (lots of people seem to use a 105mm lens for everything from portraits to landscapes)?
 

WayneF

Senior Member
Well, focal length of a lens (and sensor size) determines its angle of view. The numbers are not a convenient working tool, but still the numbers are:

Speaking of horizonal width angle of view:

DX camera: 60mm lens has 22 degree view, 120 mm (double) has 11 degrees (half). 105mm has 13 degrees.
FX camera: 60mm lens has 33 degree view, 120 mm (double) has 17 degrees (half). 105mm has 20 degrees.

This angle is simple "similar triangles" = 2 arc tan(radius / distance). The angle is same in front of lens (subject distance and subject dimension) as it is in back of lens (focal length and sensor size). At 1:1, the distance in front of lens is same as distance behind it. Two complications, the focal length increases as the lens is racked out forward to do 1:1. And we really do not know the point inside the lens where this is measured from - but it is all ballpark true.

FX is 1.5x DX. So, to get the same viewing angle, the numbers show we must stand 1.5x closer with FX than with DX, if using same lens. The same lens is the same lens, so the only reason FX has wider view is simply because the FX sensor is bigger, it captures a wider view, but the DX sensor crops that view smaller.

All these macro lenses will give a 1:1 size view. 1:1 size would be (for example), when a picture of a small coin would be the same actual size ON THE FILM as the coin is in real life. Means that for digital too, but we cannot remove the digital sensor and look at it, so it seems more clear about film. Same thing though.

I don't know if 1:1 (extreme closeup) would be important to you or not. But they will all do 1:1. However, in doing it, the 60 mm might be within 2 inches of the subject, where the 105 mm might be back 6 or 7 inches from subject. We feel more comfortable working back at a few inches, the camera does not block the light for one thing.

But if larger work than 1:1, if for example we want to include a subject area of maybe 18 inches in the view... then the 105 mm is a strong telephoto (160mm "view" on DX), which means it must stand back maybe 8 feet, which becomes inconvenient. 60 mm would be more like 3 or 4 feet, more friendly working.
 
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