Keep an eye on this page, contact information will be posted later. Not sure just yet if this will be offered as a service but check back for updates on that too.
This is a word of warning; this is what I did with my own camera. I fully understood that it would void my warrantee and possibly destroy my camera. I’m not suggesting that you do the same. I am giving you a brief description of what I did And how it works. You will have to have some skill to pull this off. You will need a volt meter, soldering iron and the skills to use them. Remember this is an electronic device that has a rather large capacitor which stores power, the risk of electrical shock is there, you have been warned
My D40 is a great camera I love it, the only thing that I didn’t like was the fact that it has no manual lens metering capability. If you have certain AI-S lenses you can get then chipped but I only own one the 105 f2.5 and that one can’t be. This is how I got mine to meter with pre-AI, AI, AI-s lenses.
To make a long story short, I hard wired a chip from a lens in my camera. I purchased a 35-70 f3.8-f4.5 non-D AF lens on eBay for $30, dismantled it and removed the chip; it’s a variable aperture lens so you can jumper from f3.8-4.5, I chose f4. The next thing to do was to dismantle the camera so I popped the flash up and removed the battery. The first thing to come off was the bottom; there was one hidden screw under a rubber cover by the battery compartment. The next thing is the lens mount; there are three thin metal clips under the mount that I removed so they wouldn’t get lost. Now comes the front, there is one hidden screw at the bottom of the battery compartment and two inside the flash. When I lifted the front off, the plastic plunger that tells the camera that a lens is locked at its smallest aperture fell out, it could easily get lost. There is a ribbon cable that comes from the contacts that you see inside the lens mount and travels up towards the flash where it is soldered to another ribbon cable; this gave me a convenient and very obvious place to integrate the chip. I soldered #30 wire to this junction and ran the wires to the right towards the capacitor. I made a shield to go over the leads and the body of the capacitor out of thin plastic and this is where I set the chip, on top of the capacitor, the only place I could find. I soldered the #30 wires to the corresponding leads on the chip, shielded it in electrical tape and tucked it on top of the capacitor. There is no space inside this thing, the hardest part was trying to find space for everything and get the camera back together without interference. The key to making this thing work is you have to add a switch between the added chip and ground (-) on the cameras ribbon cable that will allow you to turn the chip on and off so leave that wire longggg. I used a normally open non- latching micro switch that I mounted externally to the camera. It is removable so that I can take it off when I use auto lenses. I also epoxy the switch that tells the camera that the aperture ring is locked to its minimum setting down (I first used heavy tape to hold it down while I was experimenting, you should to)
First, set the camera to manual mode press the added switch to turn the chip on and tap the shutter release to wake up the camera. Tell it at what f-stop you want to use to meter the scene (+/- & command dial) and match it on the lens aperture ring. Now, by using the command dial alone adjust the shutter speed to get the exposure bar to -0- . You have just metered the scene in manual mode just like you would with an auto focus lens. The exposure and shutter speed should be visible in the viewfinder. To make this work, just before you make the exposure, release the added switch. This turns off the chip and the f# in the view finder, but the camera remembers the shutter speed. And since you set the aperture on the lens to the appropriate f-stop the picture is exposed correctly. There is no delay when you turn off the chip you can expose immediately. If you were to keep the switch pressed during exposure the camera would try to stop the lens down for you and that would only work with an AI-S lens that matched the max aperture of the chip, in this case an f4. By releasing the switch and shutting the chip off the camera releases its aperture control arm during exposure to its lowest level allowing the ring on the lens that you have set to take affect. When you turn the chip back on it remembers your last settings (f# and shutter speed) Adjust the shutter speed slightly if the lighting has changed release the switch and expose another picture. If you want to shoot at f2.8 and the chip will only let you dial in a max aperture of f4, set your aperture ring on the lens to f2.8 and just dial in one stop shutter speed exposure compensation instead of -0- , it will expose correctly.
When I started this project I had no idea what would happen. Everything that I thought I new about Nikon metering, told me that it would only work with f4 lenses because that matched the chip. My main lenses that I used on film were a 200mm f4 micro and a 300mm f2.8 with a 1.4x converter and if I could only use those two, I would be happy. My 200mm worked great but my 300mm had an exposure error that got worse as you stopped the lens down. I realized that the d40 could only stop down AI-s lenses So I had to add the switch to shut the chip off before exposure and set the aperture on the lens. I tried my 55mmF1.2 set at f5.6, expecting it to have a massive exposure error, but it exposed correctly. The camera thought it was looking through an f4 lens but was actually F1.2, that’s 4 stops off, and yet metered the scene within- 2/3 of a stop (shutter speed) of what the kit lens metered the same scene at the same f-stop. I tried every MF lens that I have at various apertures and they almost all underexpose @-2/3 of a stop compared to an auto focus lens on the d40 but that is almost exactly the difference between my D40 and D70s with the same lens. The exception is my well used 80-200 f4.5, it tends to overexpose by 1 stop. When I use this lens I just dial in –1 stop instead of – 0 - on the exposure bar and it’s O.K.
It seems to me that the camera doesn’t need to know the max aperture of the lens to meter the scene with a non-D chip. The chip information is used when the camera stops the auto focus lens down, this is the only way the D40 is designed to work. The aperture arm that is inside the camera that the lens aperture lever rests on, always Starts out at the home position regardless of what max aperture the lens is and holds the lens wide open. The chip calibrates the arm by setting a value of the home position (F 2.8, F4 f5.6) if the max aperture is f2.8 and you want to shoot at f4 the camera tells the arm to move an increment of 1 stop from its home position during exposure. A variable aperture zoom has sliding contacts that change the value of the home position as the effective aperture gets smaller as you zoom out. When we shoot the hacked D40 we shut the chip off, just befor you trip the shutter, so the aperture arm drops to its lowest level and since we set the aperture on the lens and the camera remembers the shutter speed, we get correct exposure regardless of the max f-stop.
I new when I told people about this project there would be a lot of questions about its capabilities and limitations. I have spent months experimenting with this camera, using every lens I owned at different apertures and shutter speeds, in conditions that I would normally never shoot in, trying to get answers. Then I realised that no one is paying me for this and its no longer fun. If I told you that I new exactly how this camera figured out the exposure, I would be lying. Can you use a faster chip? Can you use a D-chip? Will a F5.6 max aperture lens work? What’s the life expectancy of the chip? The answers that I don’t have are endless. All I can tell you is that I have a blast with this thing when I use it, not when I test it. It has done everything that I have asked it to do, well.
Videos of how it works and such
Links to photos taken with specific lenses below. They are large so be warned if you are on dialup, clicking on them may not be the best idea.
Links to the camera opened up and with the external button mentioned in the videos
