How to use a comparator mirror.

Comparator Mirror article

OK, so you are here to see a fascinating tool, that has been around for hundreds of years, but alas, and again, not much of this is shown in your modern art schools of today.  There are schools, however, that do continue to explore and teach methods used by the masters.  (I have a few films below that show where it is taught) This article I hope will educate and inspire you to discover more.

There are a number of videos on this subject.  I have included a number of links to them within the article, and hopefully, their owners will keep them up for a long time.   Because they are You Tube links, some may drop out as time goes on.  If you find a bad link, send me a quick email so that I may try to find a similar video in future.  As for now, enjoy the videos, they will help you better understand and give you a deeper knowledge of the subject.

My interest in such matters has always been from the aspect as a picture maker, what can I do to make my ability to produce more work more efficiently, and accurately.

For those purist's that believe every work of art needs to be done free hand, well, lay your brush down now, because if you are using your brush handle as a measuring device during a session of sight sizing, well, you are cheating.

The comparator mirror is a tool.  Like the brush handle.  And if you view the reference videos, you'll see a quote by Tim Jennison that says he believes the comparator mirror is harder to use than free handing.  But, he also states it is more accurate.  This is paramount if you plan to do portraits.

I can attest to this.  As you can see in my video, the ability to match the subject being painted both in line and color matching is quite possible. 

Some folks would say this method is a cheat.  Well, again, as stated by Mike Derby, the mirror does not mix the paint, it does not create the brush stroke, and does not do the painting for you.  It is just another artist tool.  Like the brush handle in sight size drawing.

How did I get my materials.  Well, lets start with the mirror.  You will need a "first surface mirror".  A small mirror purchased from a local arts/crafts store will work, but you have to do a little something to it to make it into a "first surface mirror".  I purchased five for less than $2.  Using fingernail polish remover and a cotton swab, I removed to painted coating on the back to reveal the highly polished mirror surface.  Don't rub too hard or you can remove the mirrored surface as well.  This back side of a normal mirror now becomes your "first surface mirror"

comparator mirror creation

Why do this?  Flip the mirror over, and view its edge.  On the edge you can see the glass.  This will create a blurred line around the edge of the mirror that you don't want.  Flip the mirror over to view the "first surface" and you will see a very distinct clean edge.  In watching the films, when you have the image matched correctly in color and value, this edge literally disappears.  And that's the key to this device.  There is an instant positive reinforcement of a match when using this mirror.

The other instruments I used were a dowel in which I glued my mirror to (using a quick setting epoxy), and a machinists clamping device, which has a fairly heavy base and adjustable clamps to hold the dowel.  You can use duct tape and a brick as long as the mirror, once set over your canvas does not move. (in the photo, you see one mirror glued to a dowel in the upper part of the frame)

visual explanation or comparator mirror placement

In the film, I show how the mirror is held in place over the canvas and lined up with the image I wish to paint. 

I printed off two sheets of a graph paper about the size of my painting and set one up on the box or my viewing field.  Your viewing field can contain a photo, or an actual still life.

The purpose of the graph paper is to check mirror alignment.  If the mirror is not set at 45 degrees and 90 degrees to the picture plane, you will have some pretty bad distortions.  (check the Hockney films out, it will show you exactly how this happens and examples of masterpieces painted in the past that actually have these distortions, more proof to show optics were used in their creation)

comparator mirror alignment

Laying the graph paper down and using line of sight to make sure the edges were lined up to the graph paper taped to the box.  I then measured to be sure paper was equal distance from my corner created by the box and the table surface.  I then viewed the image of the graph on the box (through the mirror) while watching the graph on the table.  When they matched,  and I had minimum distortion, I locked my mirror in place.  I did have some distortion of the image on the outside edges near the corners.  The films (videos below) explain why this happens. (Especially the Hockney Videos)

comparator mirror setup

At this point, I am confident of being able to reproduce the image that is placed on the box with an excellent point of accuracy and no distortions that can't be compensated for.

I then select an image, in this case a beautiful single blossom rose with two buds, and I reverse the image using a photo editing program.  (like photoshop)  Why reverse the image?  well, the mirror does this, so to get a correct image, you must reverse it.  (again, refering to Hockneys film, he talks about the statistical impossibility of having so many left handed people in portraits painted during the time in question, and his very plausible explanantion is they used mirrors)

Once the image is taped to my box, I begin.  Direct alle prima onto the canvas.  Matching color and line placement went quickly for me, and the first pass was done in a matter of hours. 

Probably one of the best direct painted pictures I've ever done.  I was doing my happy dance when I stopped to take a sip of coffee and realised how nice this rose was coming out to be.

comparator mirror rose

Once the first pass was dry, I completed the work with adding a bit more to the background, adding a few highlights here and there, and a signature.

Pink Rose created using comparator mirror.

This wasn't a fluke.  Below, you can see several student artist's creating some amazing works using this simple device.

Students using a comparator mirror:

Comparator mirror being used in an art school, multiple students filmed while painting using the device.

Note this when you view the film.  The mirror is equal distance between subject and artwork, and the image on the canvas is reversed to the image in the still life box.

This is relevant when you see David Hockney's video's on "Secret Knowledge".


In this Video, a fellow artist reviews Tim's idea's concerning the comparator mirror.  It's a short but sweet film.

Using a comparator mirror and other simple optics to paint oil paintings.

This guy gets in real deep with the subject.  I think he is an engineer.  Fascinating and educational.  He shows you step by step how to set the device up.  He even paints a little bit with it.

The best evidence that early masters used optics (comparator mirror, lens, and concave shaving mirror).

These two video's by David Hockney are probably the best films to date to talk about this theory.  Seven minutes into the first film will show you something that (at least for me) convinced me beyond a shadow of a doubt the validity of the theory.  Do take time to watch these.   

David Hockney Videos talking about the device:

Part 1:
https://youtu.be/JKbFZIpNK10

Part 2:
https://youtu.be/MDIiVkoTik8


Here are some additional reference material for you to follow.  The last is a You Tube video of an interview done some time back.  Still really good stuff.

Tim Jennison's Blog
http://boingboing.net/2014/06/10/verm...

The Movie
http://www.amazon.com/s/ref=nb_sb_ss_...

Secret Knowledge by David Hockney the book
http://www.amazon.com/s/ref=nb_sb_ss_...

Vermeer's Camera by Philip Steadman
http://www.amazon.com/s/ref=nb_sb_ss_...

David Hockney Interview 



Did you enjoy, or learn something from this page?  Why not create some good Karma, and pass it on? Face book like us, Pin the images you love, or Google + and let others feel the warmth!

Care to see more of my work?  Click here to head over to my fine art site at delmusphelps.com

New! Comments

Have your say about what you just read! Leave me a comment in the box below.

Looking for something?


(opens a new window)





Related Art Articles

Sign up below for your free informative Easy Oils Blast! A news alert that keeps you informed of up-to-date changes, new demo's, and other juicy tid-bits about us here at Easy Oil Painting Techniques!

Don't worry — your e-mail address is totally secure.
I promise to use it only to send you Easy Oils BLAST!.

Still Life Instruction

learn oil painting, oil painting techniques


Flower Painting DVD
learn oil painting, oil painting techniques

Landscape Painting
oil painting demonstration



Highly Recommended

Insightful, and reinforces techniques and theories discussed here. What are you waiting for, go see for yourself! Read my complete review.

Mastering Color - Click here for more info.