Sunday, November 8, 2009

Setting up the Tago Pentax K to EOS Adapter

First off, welcome. I've been meaning to create this blog for quite some time, to help others avoid some of the pain that I encountered.

I have an old Asahi Pentax-M 1:1.7 50mm K-mount that was mounted to my old Pentax ME-Super in decades gone by. When I got my Canon 50D, I opted for just the body and have been buying L glass for it, but I never bought a 50mm lens to complement my kit. Thus the idea of buying an adapter to mount it on my EOS body was born.

After doing research on my options, I ended up searching eBay for such an adapter. I opted for one with an auto-focus confirm feature from DVDTechnik. The item I received was in good order, and the box had no English names on it, but the English instruction manual in pdf form that they emailed me was titled "Tago", and it mentioned that this had a generation IV AF emulator chip. In order to program it to work with my 50D's auto-focus indicator beep, I had to program the adapter using a difficult process that eventually swallowed 6 hours of my time.

If you are hoping to follow in my footsteps, my own instructions should help you program your adapter much quicker. Although their instructions were fairly complete, there were some steps that were not as clear as I had hoped which tripped me up. Bear with my detailed instructions, as they do repeat a lot of the Tago manual, but include more tips. This assumes you have a moderate level of experience as well as can make the necessary adjustments for a different camera body and lens combination.

Check Existing Adapter Settings

Put the adapter on the lens, then put the unit onto your camera. Turn the camera to Av (aperature) mode. The factory default aperture that the adapter is set to will appear on your camera's display setting. To show the focal length, on my 50D I go to Menu, Custom Fn.III, Autofocus/Drive, item #7 AF microadjustment, item #3 Adjust By Lens, the press the Info button (on the back) to view and edit this setting. In the upper middle of your LCD screen you will see the current settings as a focal length range, ie "55 - 55mm."

Cold Reboot

I will make mention now of a process I call a "cold reboot". If you mess up or need to start anew, just refer back to this section for instructions:

- turn the camera off
- detach the adapter from camera
- re-attach adapter to camera
- turn camera on

Set Program Mode

1. Set EV Step to 1/3 (not 1/2).
2. Set Auto Power Off to 15 minutes, to give you plenty of time to perform the functions.
3. Set exposure mode to M.
4. Mount your camera on a tripod pointing at a well-lit subject.
5. Set the camera to a 2-second delay to prevent camera shake if you want.
6. Point and focus to the subject to get an auto-focus beep.
7. After getting your focus confirmation beep, hands off the camera. The camera should be on.
8. Now press the lens lock and turn the adapter ring fully as if to detach it from the camera, and you will see that the camera's display will show an aperture of 0.0.
9. Half-press the shutter release button and turn the adapter back on until it clicks into place.
10. Within 3 seconds of still holding the shutter release half-way down, press it all the way to take a photo.
11. The manual states that the camera display will show an aperature of 5.0 but mine didn't (it was 8.0), but it still worked.

You should now be in Program Mode.

Note: I tried using AI Servo mode for focusing on my 50D like the manual suggested, but for some reason my shutter wouldn't release so I kept it at normal one shot mode.
Note: I also tried using the DOF Preview button to do data input as the manual suggests, but it did not work for me. I had to use the shutter button.

Cmd & Data Input

Now that we've set the adapter to Program Mode, it will stay in that mode until (1) power off, (2) it is disconnected from the camera, or (3) until the Cmd & Data Input is correctly set. However, I discovered that on occasion it does not leave Program Mode correctly, or the Cmd & Data Input didn't work right, so I had to do a Cold Reboot.

Note: You can only do one command at a time. Each time you want to set a new command, you should do a cold boot and start again at the Set Program Mode section.
Note: To set a command, the manual says to take a shot at a certain aperture. Be aware that this means setting it on the camera, not on the lens!

1. Now that you are in Program Mode, set the camera to Av mode, and we'll be ready to do Cmd & Data Input.

A hint that you are actually ready to do Cmd & Data Input is that now you've switched the camera dial to Av mode, under normal circumstances for your particular lens it will not change from the given or default aperture that the adapter is set to. In other words, in normal use if you set it to Av mode and the adapter is set to f4.0, you will not be able to change the aperture from 4.0 on the display. However, in Cmd & Data Input mode, you'll be able to change this value at will, because it relates to a Cmd, not the aperature setting. Clear as mud?

Set the Aperture

1. You should be in Program Mode, with the camera set to Av.
2. Using the camera's dial control, change the aperture to F4.0, then make a shot. If you didn't get a confirmation beep, adjust the focus slightly until you do.
3. Now set the actual aperture that you want this lens to be registered to this adapter as, the values being between 1 and 64. Note that you can only use whole numbers, so if your lens is an f1.7, you'll have to choose f2.
4. Take your shot, Program Mode will be completed, and your camera should now register that lens at the aperture you picked.
5. To confirm, do a cold boot, and no matter what mode you choose, the display will show the new aperture you just set.

Set Focal Length

1. You should have done a cold boot, set the camera into Program Mode, and the dial to Av mode.
2. Change the aperture to f5.6 with the camera's dial control (not on the lens), and take a shot.
3. You are now required to set the focal length in mm, and you must use 5 digits for this. For example, a 50mm lens will be 00050, and a 400mm lens will be 00400.
4. Follow the table in the instructions to take the 5 photos which will set the focal length. So in my example of my 50mm lens, I would take shots at f4, f4, f4, f7.1, f4.
5. Once all 5 photos have been taken, it should exit Program Mode automatically.
6. Confirm by going to the section Check Existing Adapter Settings. It should appear in the LCD display as a range of what you set it to, in my case "50 - 50mm." Primes will appear as a range of the same number, while a zoom should appear as an actual range, ie "75 - 200mm."
7. If it did not work, do a Cold Boot and restart the process again.


I hope this helps you get your lens registered in the adapter relatively error-free. I recommend one adapter for each lens, as you would not want to do this each time you switched glass! Were the end results worth it? Well I could have bought a Canon EF 50mm f1.8 II for just over $100, and it would have had auto-focus. Instead I spent less than half that along with 6+ hours of setting up the adapter, plus no auto-focus, only auto-focus confirmation beeps, but only to discover that my photos were coming out blurry! Hell yeah it was still worth it, but only from a DIY nerdy point of view! Fixing the blur by properly configuring the auto-focus settings is the subject for my next article.


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