How to Increase Magnification Ratio to 1: 4 for Nikon AF-S 105 f2.8 Micro?

Normally we have 1:1 magnification ratio for Nikon AF-S 105 f2.8 Micro lens.

Any idea how to improve magnification ratio from 1:1 to 1:4 for this lens? Which extension tube are used? And which brand? I need extension tube that enable TTL and AF work.

This is an interesting question

I guess the first thing is that trying to use auto-focus in the macro mode is to say the least problematic. For that reason I always shoot using my macro lenses in the manual focus mode and use the depth of field preview to assure that what I need in focus is in focus.

The longer the lens (105 mm vs. 60 mm vs. 40 mm) the depth of field becomes shallower and that in itself can produce some issues depending upon the actual depth of filed you need for each shot.

As you go from 1:1 to 4:1, the depth of field is further reduced.

So, while you can probably find good third party electronically connected extension tubes, they will be most practical when metering your shots.

If I have my math correct, at 1:1, the focusing distance from the center of the lens to the focal plane is going to be 105 mm.

Here is the standard optical formula 1/fl=1i+1/o for determining the subject to image ratios where fl=focal length, i=image distance (total lens extension) o=object distance

I will let you do the math to determine how much more extension you will need to reach 4:1

NOTE: For clarity, the lens is calibrated at the following subject to image ratios

1:1, 1:2. 1:3 and 1:4. The last three ratios are less than a 1:1 ratio.

What you seem to be wanting to do is magnify the subject to 4x its actual size

First, a 1:1 reproduction ration is life-size so a 1:4 reproduction ration would be 1/4 life-size. I'm guessing that what you want is a 4:1 reproduction ration which would be 4 times life-size. This is going to be difficult to achieve with just extension tubes. This article is long but worth reading:

http://macro-photography.org/extension_tubes_and_amount/index.php

This article shows you how to compute the additional increase in the reproduction ratio using extension tubes: http://www.tylermerrick.com/downloads/photography/extension_tubes.pdf

As you can see, the best way to achieve the 4:1 reproduction ratio you want is to use a bellows instead of extension tubes. However, when using bellows you'll need a focusing rail that mounts on your tripod. So plan on turning the AF "OFF".

Here are two articles dedicated to using bellows:

http://www.macrobellowscom/

http://www.joshwhitephoto.com/macro-bellows/

Good luck in your pursuit of extreme macro photography.