When macro photographers wish to exceed 5X in their subjects, a great deal of time, research, creativity and experimentation is required.  Macro photography is NOT ‘plug and play.’  A tube lens such as that pictured above is great for 5X, 10X and maybe 20X for macro photography.  However, at this point in my macro experience, I do not exceed 10X due to the many complexities which arise at greater magnifications.  This lens set-up cannot be purchased, rather it must be built.  Here I’ll show you how to construct such a set-up and the issues which arise.  This is not an all encompassing explanation of tube lenses, rather a documentation of how I built mine. I’m simply documenting one method to build a tube lens for macro photography and where you can buy the parts.  There are decisions you need to make and tests to conduct.

Tube Lens Basics

Reading about tube lenses can become overly complex in a hurry.  Some sites start off with complex formulas whose purpose seems to be to confuse.  No photographer needs such formulas, nor will they improve our photographs.  So I’m ignoring them here.

Notice the small silver lens above which is 2 1/2 inches long looks very similar to a lens you may find on a microscope.  That is because it is manufactured for a microscope.  Thus, it is no longer called a lens, rather an objective.  Mine is an infinity-corrected, apochromatic (APO) objective Mityutoyo 5X, 10X or 20x.  Should you go shopping for an objective, that entire bolded phrase is important.  Nikon makes such an objective at 1/3 the cost, but it produces much chromatic aberrations and not near the quality of the Mityutoyo infinity-corrected, apochromatic APO objective.

Think of a standard microscope.  The eyepiece is about 8 inches, or 200mm or so away from the objective, which is near the subject being examined on the glass slide.  It is that tube between the microscope subject and the eyepiece we are building, but for a camera. What is being documented here is not your only option.  Instead of the solid tube above, one can actually use a standard 70-200mm camera lens.  Allan Walls shows you the steps for such a set up in this Quick Start Guide.  The Allan Walls YouTube photography channel is all about helping ordinary people get the very most out of their photography. Videos cover all kinds of photography related topics, but he spends a lot of time educating viewers about macro photography.  He is my go to guy for all things macro and I’m a Patreon supporter of his channel. Here is the link for the  Allan Walls YouTube Channel . However, unlike what Allan shows you in his ‘Quick Start Guide,’ my preference is to build a set-up made specifically for that particular function, and not use something which people say works just as well and cheaper.  The standard camera lens option is also much more bulky.

Tube Lens Confusion

In the image above note the writing on the section that says ‘THORLABS’.  That is the location of the tube lens, the ThorLabs ITL 200.  The placement of this ThorLabs lens and the distance it is from the camera sensor is critical.  The 200 in ITL200 stands for 200 millimeters, or almost 8 inches.  ThorLabs states the ITL200 should be 200mm away from the eyepiece, or in our case the camera sensor.  Mityutoyo, the manufacturer of the objective, stamps on the objective an f or focal distance = 200mm.  However, the macro world is not that simple.  Allan Walls, a successful, YouTube macro photography educator, says the Thorlabs lens should be installed at a distance of 245mm and backwards….  This is confirmed by Robert OToole of  CloseUpPhotography.  OToole clearly states: “After spending a lot of time testing the ITL200, it turns out that the THORLABS official set-up instructions are wrong if you are looking for the best image quality.”

So below I’ll provide you with both set-ups, should you wish to experiment for yourself.  I did some experimentation myself and did not come to the same conclusion.  However, there are so many variables that are difficult to control, I put little credence in my findings at this point.  Since Allan Walls is my ‘go-to guy’ for all macro instruction, I’m doing what he suggests to omit any finger pointing should I have issues down the road.

Tube Lens Assembly Basics

The concept or construction is fairly simple.  We are building a metal tube with a single lens inside, the tube lens, that will focus the image from the Mitutoyo objective onto our camera sensor.  There is a special section of the tube, sometimes called a helicoid, with outside threads from end to end.  This design allows us to make small adjustments to the length of the tube.  In the photo above, the helicoid section is just to the right of the section that says THORLABS.

The difficult part for construction of this lens is finding all of the parts with the correct threads and adapters for your camera.  Three good suppliers are:

• Edmond Optics  for the objective, part #1.
• THORLABS  for part #2-10 plus #12.
• RAF Camera   located in Belarus, for the adapter to attach to your camera, part #13.
• B&H Camera for #11, #14 & #15.

 

Reverse Build Suggested by Allan Walls & Robert OToole

Assembly Part #1)

5X Mitutoyo Plan APO Infinity Corrected Long WD Objective;

5X Mitutoyo ; $773  from Edmond Optics.

.10X Mitutoyo Plan APO Infinity Corrected Long WD Objective;

10X Mitutoyo ; $971 from Edmond Optics.

Part #2)  The objective above gets screwed into the SM1A27 below.  Note you may wish to screw in the objective into the SM1A27 as a final step to protect this delicate piece while building the rest of the tube lens.

Part #3)  Part #1 & #2 fit inside this doughnut looking part, SM2A6.

 

Part #4) SM2M30, $40.

 

Part #5) ITL200 is the tube lens made by Nikon, $470.  Thread the ITL200 lens into…

Part #6) SM2A20, the part with the big ‘Image Plane THORLABS‘ label.

Part #6) SM2A20 $55

Part #7) Thread the image plane, part #6 into the helicoid, SM2V15.

 

Parts #8, #9)  These are two identical parts, SM2L20.  Connect these two pieces together.

PART #10)  Thread one end of Parts #8 & #9 into the longer tube part SM2L30, $41.  This forms one solid, empty 7 inch tube.

Part #11)  Three quick release plates need to be attached to the three slip rings, Part #12 below.  The brand and style of these quick release plates is not important.  Mine have no brand stamped on them.  B&H has a variety, such as the Oben QR-20 for $24 each.

Part #12)   The tube lens needs three slip rings, SM2RC, for stability.   Slide one slip ring, with the above quick release plate attached, over the very front, over the objective and lightly tighten to keep it from falling off.  Slide the remaining two slip rings over the other end of the tube making sure the tightening screws of all three slip rings face the same direction.  Do not firmly tighten the slip rings yet as we do not yet know where the top side of the tube will be.

Part #13)  Screw this 7 inch tube into your camera mount adapter from RAF Camera and attach the 7 inch tube to your camera via this adapter.

Part #14)  Attach the three quick release tightening knobs to the quick release plates.  Brands such as Oben QRA-A2 are available for $20 each at B&H.

 

Part #15)  Long quick release rail, the brand is unimportant.  Mine happens to be a Haoge 220mm, $27.  Align the three slip rings as necessary and attach them to the rail. The screws which came with the rail will need to be removed and replaced with other flush fitting nuts and bolts from the hardware store.  These new bolts need not thread through the existing holes in the rail.

Now the two slip rings closest to the camera may be tightened.  The third one, near the objective may need to be removed for the fine focusing, which comes next.

Fine Tuning the Focus

Measure 245mm, or about 9.65 inches, from you camera sensor to the word OBJECTIVE on part #6, SM2A20, that says THORLABS.  Adjust the helicoid, part #7, to lengthen or shorten the tube.  Recall that the word on this part of the tube lens will be upside down when holding the camera in the normal manner.  This is the part that is reversed per the suggestion of Allan Walls and Robert OToole.

The final step is to fine tune the focus of the set-up. Remove the objective for this job and leave it at home. Find a clear view of a tree or sign about one mile away. Attach your camera and tube tube lens to a tripod.  You are focusing by looking through the tube lens, ITL200. Using the helicoid, part #7,  turn the tube to bring the distant object into as clear of focus as you can.  Because of the very fine threads of this helicoid, this can be a tedious process.  Initially you do not know which way to turn the helicoid, not knowing if you need to make the tube longer or shorter to bring the object into focus.

When you have finally determined the best focus, turn the retaining ring tight against the helicoid, SM2V15.  Hopefully, you should now have your THORLABS tube lens set-up in focus.

Different Parts and Final Construction

Please note there are numerous ways to construct such a THORLABS tube lens. Different length tubes can be purchased and attached to get the tube lens 245mm from the sensor.  There are also cheaper means of constructing this tube.  I am simply documenting the method I happened upon.

My Results

I went to a hillside and focused on a distant sign.  I was able to get more clear photos with the manufacturer recommended distance of 200mm.  Was this my fault for not adjusting correctly, or was there more heatwaves distorting the sign I was focusing on?  For a complete test it would seem I would need to attach the objective and take some test shots at 5X.  I did not do that.  Is there really a noticeable quality difference in the final photos that is readily apparent, or is the quality difference only noticeable when pixel peeping as photographers tend to do?

My total cost of all parts was about $2,030.

Additional Steps

When mounting the tube lens on your stack shot controller from Cognysis $680 or the higher end Novoflex $3,050 (Yikes!!), try to get it mounted near the center of gravity, well balanced on the stack shot rail.

It is suggested by Robert OToole of CloseUp Photography that the interior of the tube lens get flocked to eliminate the glare inside the black tube.  He suggests the following.

Flocking material:

Protostar self-adhesive backed sheets (expensive): https://www.fpi-protostar.com/hitack.htm

Soft flocked paper sheets on amazon.com (cheap):

https://www.amazon.com/Hygloss-Products-Black-Sheets-Velour/dp/B0187Q9YNW/

 

Alternative Assembly Sequence for 200mm ITL200 set-up per THORLABS

200mm Set-Up, Order of the Parts from the objective to the camera.                            

1. 1. Mitutoyo Objective
   2. SM1A27
   3. SM2A6
   4. SM2M30
   5. SM2A20, mounted in the opposite direction as described above, part #6.  The IMAGE PLANE THORLABS wording will face the camera, right side up.
   6. ITL200, therefore, the lens will be mounted facing the camera as well.
   7. SM2V15, helicoid
   8. SM2L20
   9. SM2L30
   10. RAF Adapter for your make of camera
   11. Camera

Drawing from Robert OToole

Robert OToole shows the basic difference between the two methods of building the tube lens.

Good luck in your macro photography efforts.  Macro is not plug-and-play like landscape photography.  Much of my macro photography time and effort is spent building, redesigning, experimenting and testing…. then more building, redesigning, experimenting and testing.