Microscope adapter for 2x macro photography with Sony A, E/FE, Canon EF/EF-S, M, RF, Nikon F, Z, Fuji X, Fuji G, M4/3, Pentax M42 cameras

When the 4x microscope objective available from “Reakway” is mounted 150mm away from a camera's sensor, it works wonderfully for photography, covering a full-frame image sensor with a nice sharp image. You can find my standard 150mm-length adapter for that microscope (and other finite objectives) here:

https://www.printables.com/model/143754-microscope-adapter-for-4x-macro-photography-with-s

But it turns out that this particular objective can also be pushed down to 2x magnification by reducing the tube length to 84mm, making it useful for taking photos of larger subjects, and that's what this adapter model achieves.

Don't have a 3D-printer? I now sell 3D-printed microscope adapters on my webpage, please check it out!

On full-frame sensors a bit of sharpness is lost at the edges and corners of the image, but this is a good tradeoff for the extra field of view. I like the extra context that keeping some of the subject's surroundings brings, and the softening and vignette in the corners helps to focus attention to the subject closer to the middle of the frame.

However, if you're shooting focus stacks on a tripod in a studio, where you could expect to fill your entire frame edge-to-edge with your subject and have it all be sharp by shooting a focus stack with many photos, this corner resolution will be disappointing. For that I'd suggest using my regular 4x adapter instead.

On cropped image sensors, the image quality at 2x magnification is good throughout the image, because the smaller sensor doesn't see the full-frame's edges and corners.

Watch macro photographer Micael Widell review the adapter

Choosing the right microscope objective

My 84mm adapter has been designed specifically for the Reakway 4x objective, which you can get here:

https://www.aliexpress.com/item/32360730919.html

My adapter is unlikely to work well with any randomly-chosen objective, because it pushes the objective well outside of the mounting distance that it was designed for (e.g. with the Reakway 10x objective, the area outside of the APS-C zone is essentially just an unusuable blur)

I think that this 4x objective has also been sold by “Amscope”, but they may be changing suppliers from time to time and so are selling multiple different objectives with the same basic specs and outwards appearance. 

The model that you need looks like this (left) after unscrewing its hood (right):

There is a 4x objective on the market with an identical-looking outer casing but very different internals, and I haven't tested that one. It won't be compatible with my lens hood design and may have additional issues at the edge of the frame (like strong blur or vignetting).

Note that the threads on this objective are sharp (both the silver ones and yellow ones shown above), so don't grip it by the threads directly if you're screwing it in to the adapter. You can grab it using a kitchen rubber glove instead to protect your fingers and give you more grip on the smooth surfaces.

Printing the adapter

Print the microscope adapter that suits your camera's mount with these settings:

Material: Black PLA, PETG or ABS
Layer height: 0.1mm
Nozzle size: 0.4mm
Supports: None
Infill: 15% rectilinear
Perimeters: 3
Elephant foot compensation: Disable
Brim: Optional

Do not use PrusaSlicer's new "Arachne" perimeter generator, because I've had issues with it creating fragile thin walls in the camera mount part of the adapter.

SuperSlicer's option “Only one perimeter: On top surfaces” is highly recommended, because it creates stronger camera mounts by stitching together the three concentric perimeters at the top of the print with crosswise top infill.

I only test the adapter in eSUN ABS+ Black filament, but other filaments should work too. I print mine with filament shrink set to about 99.6% to compensate for ABS shrinkage (no compensation needed for PLA and PETG).

If you can use a matte filament, the flare performance will be improved by reducing reflections inside the tube (but shiny black does work too).

Note that the adapter looks like it prints “upside down” - the pointy end needs to be on the bed. It has been designed to print without supports in this orientation:

The lens hoods

If you're using a full-frame camera, you will need to unscrew the metal lenshood that comes with the objective and replace it with a printed version. This is because the metal lenshood will cause black corners (vignetting) in the full-frame image. 

It's possible to shoot with no hood attached if you can ensure that your flash lighting doesn't shine directly into the front element of the microscope (e.g. if your flash diffuser lies entirely behind the tip of the objective).

Crop-sensored cameras can continue using the stock metal hood, but you may still want to use the printed hood in order to increase your clearance with the subject (the printed version is shorter and narrower)

The 180-degree version of the hood is preferred if your flash lighting only comes from one side (e.g. only from above the lens) because you can rotate it to block stray light only from that direction, and give you more physical clearance from your subject on the other side. Otherwise use the 360 degree version. 

Printing the lens hoods

Use the same basic print settings as with the microscope adapter (0.1mm layer height, etc). 

In your printer settings, set “minimum travel after retraction” to 1mm or smaller. Otherwise you will get stringing across the slits in the sides of the model, because the filament won't retract as it travels between them.

I had to turn on the brim to successfully print the 180-degree version, the 360 degree version prints fine without it.

Make sure you're printing them in the orientation shown below. The 360-degree hood (on the left) prints tip side down, and the 180 degree version (right) is printed the other way up:

After printing the 180 degree hood, you need to snip the 4 bridges at the base of the slits in the side, e.g. with a small pair of scissors, with a craft knife, or with fingernails:

After unscrewing the lens hood from your objective (use a rubber kitchen glove to grip the threads on the objective rather than using your bare fingers, it's sharp!), you can slide the hood onto it as shown below:

Note that the hood must be held nice and vertically in order to allow it to start sliding on (it doesn't align itself):

After sliding the 180 degree hood on, you can freely rotate it to make it block the direction your lighting is coming from.

Shooting instructions

A magnification of 2x means that the field of view at the focal plane is 18x12mm on a full-frame camera and 12x8mm on a 1.5x crop camera, so choose the size of your subjects appropriately!

This objective has a nominal aperture of f/5, which is an effective aperture of f/15 at 2x magnification, and has no aperture blades so this cannot be changed.

Accordingly you will want flash lighting to get the image bright enough and to counter the effects of subject movement and camera shake.

If you're shooting with flash, on mirrorless cameras the preview image in the viewfinder may be dark (since it's showing the image that would result without flash). To fix that, set it to brighten the viewfinder image for you (on Sony cameras this is done by choosing “Setting Effect: Off”).

I shoot in M (manual) mode at my A7R's flash sync speed (1/160th), ISO 200, with my diffused flash set to 1/8th power and the diffuser placed as close to the subject as possible. This almost eliminates the contribution from natural light, so I can create my own light instead.

Most of my example photos above have been created from handheld focus stacks (you can combine together all the photos you took where you missed focus using Photoshop to extend the depth of field). 

Use Photoshop's auto-align and auto-blend layers features to merge the images. This technique also allows you to extend your field of view by shooting a “mini panorama”; change where you're pointing your camera while taking your stack of photos in order to extend the area you can see in the final merged image.

If you're shooting handheld without flash, you'll need to shoot in bright outdoor conditions and at high ISOs to eliminate camera shake and subject movement. I shot in A (aperture priority) mode at ISO 3200 to keep the shutter speed at 1/500th or faster. This is a stack of two photos taken handheld in overcast conditions:

Shooting handheld indoors without flash is essentially impossible, because room lighting is far too dim.

Micro four-thirds version

The version of the microscope adapter for Micro Four-Thirds is different from the other adapters because it is a three-piece design. You can unscrew the middle tube of the adapter to drop the magnification down to 1x. This gives you a field of view of 8.7×6.5mm with the middle tube included, and 17.3×13mm with it removed:

Configured for 2x magnification

Configured for 1x magnification

Fujifilm G version

Because Fujifilm G mount (and Fujifilm GFX cameras) are medium-format, the microscope image doesn't quite fill the frame, but you can achieve a square-cropped image. 

Use the replacement printed 4mm aperture in the rear of the microscope objective in order to improve image quality and reduce vignetting near the edges of the frame.