External auto focus assist light for mirrorless cameras is now availble

Please note that all images are clickable if you wish to see them in larger size, just click on them.

This device is solving some of the problems, especially related to using mirrorless cameras in low light conditions, such as it is common in studio conditions, or other situations where the available light might be low. The main problem is that mirrorless cameras can’t use the external AF assist light provided by some flashes because the auto focus system cannot use the red light built in the external flashes, so the users must rely on the AF assist light which is built-in the camera. Unfortunately that light is often blocked partially or fully by the user’s hand, or by the lens.

This device can be used with almost any camera which has a built-in AF assist light. The only requirement is that the light sensor, which detects the AF assist light of the camera, must be installed by the user, so if you can do that then it can be used on your camera, regardless of brand or model.

The function of this device is simple

If the camera detects a low light situation and activates the built-in AF assist light then this device will detect that light and will provide the necessary AF assist light externally so that it will not be blocked but projected fully on the subject or the model.

The exposure or the white balance will not change because the light will be turned off before the exposure starts, the light is only on during the focusing process. Auto focus will be faster with less risk for racking and hunting than if you’d not use the AF assist light.

If this sounds interesting then you can order this device now. Please note that this is a DIY product, manufactured in low volume. It contains some 3D printed parts as well, and these parts are custom designed for the purpose.

Some technical information about the device

The used battery is a 23A type, which is a small but powerful 12V battery. Battery capacity is dependent the type and brand of the battery. Maximum current use of the device is 22mA. This means that the capacity is good for about 30 minutes to 2 hours of continuous light, depending on battery. This is normally enough for quite a large number of shots, depending on the speed at which your camera and lens can acquire focus. Focusing should normally not require more than 1-2 seconds, at least not with the Nikon Z7 and the 24-70/4 S lens, so even in the worst case, one battery should last for about one thousand images or more, better quality batteries will increase the number of images several times.

The LED which is used for the light is a high intensity (min. 18 000mcd) green LED, providing a range of about 8-10 meters, depending on the camera. The sensor which detects the camera’s built-in AF assist light is a high speed photo transistor. The delay introduced by the electronics is less than 2us, so it will not be noticeable during use and can be ignored. The size of the box is (L) 63 x (W) 25 x (H) 15 mm. 

It is important to attach the light sensor head in such way that maximum light from the camera's AF assist light hits the sensor when it is activated. This ensures maximum intensity of the AF assist light beam. Intensity is reduced if the sensor is incorrectly placed. Make sure also that the actual light beam emitted by the device is as centred with the lens centre as possible so that the light is covering the area where you want to get accurate focus. The adhesive putty supplied with the device allows installation almost anywhere on the camera body and also allows removal and reattachment if needed.

The light sensor head is 3D printed from PLA, which is environment friendly during the printing process as well as during use. If you wish you can use a different type of adhesive putty as long as it works together with PLA as well.

The universal sensor head is (L) 16 x (W) 10 x (H) 8 mm  so if you can fit that over the AF assist LED of your camera then you can use this device. The light sensor head is fixed to the main unit with a wire which is approximately 270 mm long. If you wish to have a longer one that can be arranged, just let me know. 

The AF assist light sensor and the main unit is attached to the camera and/or the flash using adhesive putty. The putty does not need any treatment, should not be mixed with oil or water or any other liquid. It is non-toxic and will not cause damage to the surface of the cameras, the flashes or other devices. It does not leave stain and can be easily removed. When stored, it can be put between two plastic sheets or a small plastic bag to protect it from dust.

The exposure and the white balance are not affected by the AF assist beam extender, assuming your camera works as expected. Tests of the device are carried out on two Nikon cameras only, the Nikon Z7 and the Nikon 1 V1.

Price and payment

The price for each unit is 62 EUR or 65 USD, depending on if you live in EU or outside EU. Shipping and handling costs will be added. At this moment this is 13 EUR in EU or 15 USD for shipments outside EU. I accept payments in EUR or USD only, no other currency will be accepted, orders paid in any other currency will be rejected.

Payments must be made through PayPal, no direct money transfer, checks or any other means are accepted. Prices and the terms are non-negotiable; if you think this is not acceptable for you or you think the price is too high, please don't buy it.

Note that due to transport regulations and restrictions, no battery will be included in the shipment. You have to buy the necessary 23A type battery locally.

How to order

If you are interested, please send me a mail using the contact information below. Please don't pay in advance before I confirmed that I have a device reserved for you.

After I received payment, I will need one work day to pack it and to ship it to you, using registered, traceable post. 

Please note that I will only sell this unit to buyers from Australia, Canada, USA, New Zealand, countries of European Union, Norway, Switzerland, Iceland, Liechtenstein, Jersey, Guernsey, Monaco, Aland, South Africa, Namibia, Botswana, Swaziland, Lesotho and Japan. Note that I make no exceptions made from this list.

Contact information

adapting(dot)camera at gmail(dot)com

Please note: the mail address above must be modified by you. You must replace the (dot) with real dots, the spaces before and after 'at' must be removed and the word 'at' must be replaced by @ sign. This is done to prevent internet robots from sending me spam mail.

After your modification the mail address will look like: axxxxxxx.cyyyyy@gmail.com

A final note about the AF assist light extender

This is a do-it-yourself product. No warranty or refund is given, other than that I guaranty I tested the device before shipping it, and I guaranty that it is working on my Nikon Z7 and V1 cameras when I ship it. I have no possibilities to test it on any other cameras since these are the only ones I have.


Currently I am making two types of this devices, the difference between them is only the light sensor head. One is designed specifically for the Nikon Z6 and Z7, the other is a generic type. You must indicate which one you will buy when placing the order because after shipping there is no way to change the head. Both types will work with any camera, but it is easier to align on the Z6 and Z7 if you have the model designed for the Nikon Z cameras. The generic type can of course also be used on the Nikon Z6 and Z7, so if you have more than one camera model or brand, then maybe the generic type is the best way to go, but that is a decision you have to make.

The need for an external auto focus assist light

Many, if not all, cameras which are dependent on the built-in AF assist beam have the LED placed in a way which makes the light beam useless in many situations. This is typical problem especially for mirrorless cameras, which cannot use the AF assist lights built into some external flashes. These cameras are entirely dependent on the AF assist light which is built-in the camera body. The Nikon Z6 and Z7 are two such models, but that list could be made very long, and with the increase in the number of mirrorless models, that list groves heavily across every brand, not only Nikon.

The design of the cameras is a bit varying, especially across brands, and the AF assist LED can be located differently in different camera models or brands, but the number of possible locations is quite limited and I have so far not seen any camera where the LED can be placed optimally so well that it actually works without problems. The AF assist light LED is always blocked by the lens or the left/right hand holding the camera, regardless which camera we look at.

This is a problem even if the camera is on a tripod. The level of problem also depends on the subject to camera distance and the camera model. This is the case even with the lens hood removed, some lenses are just too large in diameter, or too long, so they block the light completely or partially.  Sometimes only half the AF area, or even less than that can be used, the rest is blocked by the lens. This problem severely limits the ability of image composition, and the problem can become quite serious if you want to use AF areas which end up totally out of the light beam.

Another problem with the built-in AF assist solution is that their range can be very limited, depending on camera and the age of the camera. LED technology evolved quite a lot the last years, and today we can have small and very bright LEDs with low power demands, but typically older cameras have quite weak LEDs.

The video below demonstrates both the problem and the possible solution.

The solution is fairly simple

A separate and external AF light, which turns on and off by the AF assist light of the camera. This unit can be used on almost any camera, not only the Nikon Z6 and Z7, as long as it has an AF assists LED built-in the body. The brand, size or the format of the camera does not make any difference; it can be used on small, as well as large cameras, DSLRs as well as mirrorless cameras. The light beam emitted is bright green, just like it is commonly used in mirrorless cameras.

The circular green light beam provides a bright area in a large part of the image area, allowing you to compose the image and place the focus freely in a much larger part of the image than before. The light is strong and the camera will normally focus quickly and accurately, without racking, or hunting.

The light is switched off immediately when the camera switches the internal AF assist light off. This means that the exposure is not affected by the AF assist beam extender device. The green light will be switched off before the actual exposure, so the beam will not be visible in the actual image and will not contribute with any light for the image. It will also not affect the white balance measurements.
The range is about 8-10 meters, depending on the type of battery and the level of charge. This range is measured on a Nikon Z7 with the 24-70/4 S lens on it. Other cameras and lenses may give other results. Note that the range will degrade as the battery gets used and discharged.

The used battery is a common 23A type, which is a small but powerful 12V battery. Battery capacity is dependent the type and brand of the battery. Maximum current use of the device is 22mA. This means that the capacity is good for about 30 minutes to 2 hours of continuous light, depending on battery. This will normally be enough for quite a large number of shots, depending on the speed at which your camera and lens can acquire focus. Remember that focusing normally should not require more than 1-2 seconds, at least not with the Nikon Z7 and the 24-70/4 S lens, so even in the worst case, one battery should last for about one thousand images. Of course, if you are using better quality batteries this number will increase several times.

There is an on/off switch on the device. Use it if you store the device or if you don’t intend to use it over a longer period. The current consumption is basically zero when the device is in the dark, but it is totally zero only if it is switched off, so it is better to switch it off when not in use. The light is on only for the duration the camera requires for focusing, and this is when the device actually is using the battery.

The flexible attachment solution provides a liberty to place the device on almost any other device, be that a flash, a camera or even a radio trigger. The adhesive putty supplied with the device can be used for many years over and over again, allowing the attachment and removal of the device and the sensor many times. It does not need any treatment, should not be mixed with oil or water or any other liquid. If it feels dried out it should be massaged between your fingers until it feels right. It is non-toxic and will not cause damage to the surface of the cameras, the flashes or other devices. It does not leave stain and can be easily removed. When stored, it can be put between two plastic sheets or a small plastic bag to protect it from dust.

This device will be available soon, solving some of the problems related to using mirrorless cameras in low light conditions, such as it is common in studio conditions or other situations where the available light is low. It will increase the focus speed even in situations where focus is possible, but slow due to the low light. If the camera detects such situation and activates the built-in AF light then this device will take over and will provide the necessary AF assist light.

Note that the video above shows a prototype of the device. The final product will be slightly smaller, but will have the same range, using the same battery as in the working prototype.

A final note

This device is now available. Check this post for more details:

https://adapting-camera.blogspot.com/2019/03/the-external-auto-focus-assist-light-is.html

Flash use on the Nikon Z7

Since the Z7 is a fairly new camera model, not only for me, but for every other Nikon Z7 user also, the knowledge about how well it works with different flashes and triggers is limited. I decided to test my flashes, not because I don't trust Nikon, but because I have a two non-Nikon products also and I don't know how well they work with the Z7. These two are the JY610N, which is a sort of SB-400 clone, and a Meike MK-14EXT ring flash. Both of these worked perfectly on the D800 I had before, and both showed up in the EXIF data as if they were an SB-900 flash.

There are no surprises regarding the original Nikon flashes I have, the SB-700 and the SB-900, both of them work as described in the manual of the Z7. What I need to see is how well the cloned products behave on the Z7, and here I found out a few surprises.

The image to the left was used as reference image to test the exposure to see if iTTL works as it supposed to be.


All the pictures are all clickable if you want to see a larger image.

The Nikon SB-700 and SB900

As said before, both of them work individually, or in any combination just as described in the manual of the camera. The only thing that is not working is the AF assist LED, but this is known and is as expected.

It seems also that the SB-700 and the SB-900 together with the Yongnuo YN622N kit seems to work well in all modes, iTTL and manual, single or dual flash, compensation and so on. Once again, the only thing not working is the AF assist LED which is built in the Yongnuo YN622N kit units, but again, this is as expected.

The EXIF of the image always shows that the SB-900 is used, even with the YN622N-TX.

The JY610N is not working in iTTL mode. It worked on the D800 but not the Z7. The flash fires at full power all the time, no TTL pre-flash, and the flash is not showing up in the EXIF. As a consequence, images taken with it are overexposed, unless switched to manual mode.

So, if you consider a small flash to be kept in your pocket just in case you need one, don't bother buying this one.

The Meike MK-14EXT ring flash works also only in manual mode, which I think is sad because it is my only ring flash. I don't understand what is happening, because the flash is not firing at all in iTTL mode. In manual mode it works perfectly well, so I can still use it, but it is annoying that it is not working in iTTL mode.

Using any flash in manual mode is pretty easy, but of course, many times iTTL is an advantage, especially for people who don't have a flash meter or must change shooting distance often.

How to fool the camera

The Z7 can be fooled to believe that these flashes are also SB-900 flashes if the flash is placed in the YN622N trigger and triggered with the help of the YN622N TX.

This combination works with the JY610N, just as the SB-900. The only thing is that using the flash this way is sort of pointless because it is no longer a pocket-able small flash so I might as well use the SB-700 or the SB-900. Never the less, it works well this way.

The Meike MK-14EXT ring flash can also be used in full iTTL mode if the flash is on a YN622N trigger.

This is a usable, but an inconvenient alternative because whenever I want to use it I must add also a bracket to be able to hold everything and to be able to handle the camera at the same time. This is OK, though I would prefer if it was not needed. But at least I know how to use it in TTL mode if I want to.

Of course, in all cases when the YN622N is used, the flash information in the EXIF still claims that it is an SB-900, regardless which flash it is triggering. This doesn't really matter as long as it works in iTTL mode.

My older flashes are all made for film cameras, and they work just like they worked on my old film cameras.