How to update a Silver Label Contax G1 to use the 21mm and 35mm lenses

[everyXnewXday]

Contax G1 bodies come in two varieties, “silver label” and “green label”. The later green label bodies work with all the Contax lenses (except the 35-70mm zoom) but the earlier bodies with a silver label in the film loading are incompatible with the Contax 21mm and 35mm lenses... until now!

After studying the G2 repair manual (https://learncamerarepair.com/product.php?product=130&category=2&secondary=4) and doing quite a bit of experimentation I figured out how to add the 21mm and 35mm lens data to the silver label cameras and I thought I’d share it here.

It sounds complicated at first, but it’s honestly not that hard and you really can’t screw anything up. Nothing is saved in the camera firmware until you explicitly tell the camera to save your changes, so if you feel like you did something wrong just turn the camera off and start over.

Let me know if anything is unclear or you need help. Have fun!

1. Set the camera to any Drive mode other than Multiple Exposure mode.
2. With the camera back open, press and hold the film rewind button for 2 seconds.
3. While still holding the rewind button, press the shutter button.

If you did it right the shutter will not fire and the camera will now be in "Manual Adjustment Mode." You can do all sorts of things in the manual adjustment mode menus, like checking the shutter count, tweaking shutter speed timing, and calibrating the metering and autofocus. Check out the G2 service manual if you are brave and want to try to figure that stuff out.

Once you’re in Manual Adjustment Mode there are three separate “Adjusting Mode” menus, which are selected using the A.B.C. (Exposure bracketing) lever under the shutter speed dial. The lens data is entered in Adjusting Mode 2 which is activated by setting the ABC switch to +/-.5.

In Manual Adjusting Mode 2 you’ll see the lens data bank number in the frame count window. These banks are numbered 1-11 but not all of them are used. Bank 3 is for the 21mm and bank 6 is for the 35mm.

1. Use the Drive/ISO buttons to cycle through and select the lens data bank you want to edit.

2. Once the correct bank number is showing in the frame counter window, flip the power switch to AEL and then immediately back to ON. This enters the sub items menu for the lens bank that you selected. The current lens bank will still show in the frame counter window and the sub item number will be blinking in the top iso/drive/distance LCD display.

3. Use the Drive/ISO buttons to select the sub item number you need to edit.

4. Flip the power switch to AEL to enable the adjustment of the item’s value. The 2 digit value to the right of the sub item number will now be blinking. Adjust the blinking value (which will be "00" [edit: or “FF”] on a non-updated silver label camera) to the new lens data value.

5. Move the power switch from AEL back to ON and use the drive/iso buttons again to select the next sub item to edit. Again, switch to AEL to edit the value. Repeat for all the new sub item data values. (If it seems confusing remember that ON=menu navigation and AEL=data adjustment).

6. After you’ve changed all the values, make sure the power switch is set to ON and navigate to sub item number 00. Press the shutter button to write all the adjusted values to memory.

7. Turn off the camera or close the back to exit manual adjustment mode.

8. Repeat for each lens data bank you are adding data to.

Here are the sub item numbers and data values for the 21mm lens, to be entered in bank 3. Any item numbers not listed should be set to “00” [tip: go backwards from “00” to get to FC, FA, etc. Otherwise you’ll need to scroll through a ton of values.]

Bank 03 — 21mm lens data

01-FC
02-FA
03-54
05-50
06-03
07-60
08-03
09-54
10-03
11-40
12-03
14-13
19-5b
20-3E
21-CA
23-30
24-18
25-02
26-47
27-19
28-11
50-01

Here are the values for the 35mm lens, to be entered in bank 6:

Bank 06 — 35mm Lens Data Values

01-FC
02-FE
03-8C
05-E0
06-05
07-dd
08-05
09-bb
10-05
11-b0
12-05
14-3b
19-24
20-FA
21-CA
23-30
24-10
26-7d
27-22
28-11
50-01

 

[Donald Qualls]

I didn't read the title carefully -- here I was thinking you were fixing a post-War Contax IIa or IIIa to accept the protruding rear elements on the Jupiter-12/Biogon 35mm, which would have been something along the lines of a curtain transplant...

 

[mann61]

Contax G1 bodies come in two varieties, “silver label” and “green label”. The later green label bodies work with all the Contax lenses (except the 35-70mm zoom) but the earlier bodies with a silver label in the film loading are incompatible with the Contax 21mm and 35mm lenses... until now!

After studying the G2 repair manual (https://learncamerarepair.com/product.php?product=130&category=2&secondary=4) and doing quite a bit of experimentation I figured out how to add the 21mm and 35mm lens data to the silver label cameras and I thought I’d share it here.

It sounds complicated at first, but it’s honestly not that hard and you really can’t screw anything up. Nothing is saved in the camera firmware until you explicitly tell the camera to save your changes, so if you feel like you did something wrong just turn the camera off and start over.

Let me know if anything is unclear or you need help. Have fun!

1. Set the camera to any Drive mode other than Multiple Exposure mode.
2. With the camera back open, press and hold the film rewind button for 2 seconds.
3. While still holding the rewind button, press the shutter button.

If you did it right the shutter will not fire and the camera will now be in "Manual Adjustment Mode." You can do all sorts of things in the manual adjustment mode menus, like checking the shutter count, tweaking shutter speed timing, and calibrating the metering and autofocus. Check out the G2 service manual if you are brave and want to try to figure that stuff out.

Once you’re in Manual Adjustment Mode there are three separate “Adjusting Mode” menus, which are selected using the A.B.C. (Exposure bracketing) lever under the shutter speed dial. The lens data is entered in Adjusting Mode 2 which is activated by setting the ABC switch to +/-.5.

In Manual Adjusting Mode 2 you’ll see the lens data bank number in the frame count window. These banks are numbered 1-11 but not all of them are used. Bank 3 is for the 21mm and bank 6 is for the 35mm.

1. Use the Drive/ISO buttons to cycle through and select the lens data bank you want to edit.

2. Once the correct bank number is showing in the frame counter window, flip the power switch to AEL and then immediately back to ON. This enters the sub items menu for the lens bank that you selected. The current lens bank will still show in the frame counter window and the sub item number will be blinking in the top iso/drive/distance LCD display.

3. Use the Drive/ISO buttons to select the sub item number you need to edit.

4. Flip the power switch to AEL to enable the adjustment of the item’s value. The 2 digit value to the right of the sub item number will now be blinking. Adjust the blinking value (which will be "00" [edit: or “FF”] on a non-updated silver label camera) to the new lens data value.

5. Move the power switch from AEL back to ON and use the drive/iso buttons again to select the next sub item to edit. Again, switch to AEL to edit the value. Repeat for all the new sub item data values. (If it seems confusing remember that ON=menu navigation and AEL=data adjustment).

6. After you’ve changed all the values, make sure the power switch is set to ON and navigate to sub item number 00. Press the shutter button to write all the adjusted values to memory.

7. Turn off the camera or close the back to exit manual adjustment mode.

8. Repeat for each lens data bank you are adding data to.

Here are the sub item numbers and data values for the 21mm lens, to be entered in bank 3. Any item numbers not listed should be set to “00” [tip: go backwards from “00” to get to FC, FA, etc. Otherwise you’ll need to scroll through a ton of values.]

Bank 03 — 21mm lens data

01-FC
02-FA
03-54
05-50
06-03
07-60
08-03
09-54
10-03
11-40
12-03
14-13
19-5b
20-3E
21-CA
23-30
24-18
25-02
26-47
27-19
28-11
50-01

Here are the values for the 35mm lens, to be entered in bank 6:

Bank 06 — 35mm Lens Data Values

01-FC
02-FE
03-8C
05-E0
06-05
07-dd
08-05
09-bb
10-05
11-b0
12-05
14-3b
19-24
20-FA
21-CA
23-30
24-10
26-7d
27-22
28-11
50-01

 

[mann61]

Thanks so much I will try this next week when I get home. I looks a bit daunting but well worth a try : the G1 is such a nice small brother of the G2. All the years I've left the G1 at home because it couldn't take 21 or 35, I've even bought a beat up M5 to take a 7 Artisan 35/2. It sounds wrong but I prefer the G1 over the G2 and M5.

 

[narsuitus]

How long did it take for you to research, analyze, and develop this update?

You should be congratulated.

Now, if this fix would also change the label color.


White Label vs. Green Label by Narsuitus, on Flickr

 

[everyXnewXday]

How long did it take for you to research, analyze, and develop this update?

You should be congratulated.

Now, if this fix would also change the label color.


White Label vs. Green Label by Narsuitus, on Flickr

Thanks man! After learning to navigate the menus and seeing the section with the lenses listed I compared the data entries for each lens between my G2 and Silver G1. I noticed that the values were all exactly the same for the 28mm, 45mm, and 90mm but that the G1 was blank in some of the slots where the G2 wasn’t. I used a hexadecimal to decimal converter to check the focal length data values to confirm that they were the correct banks for the 21 and 35mm lenses. From there it was just a matter of copying the values from the G2 over to the G1 and testing it!

I’d highly recommend exploring the manual adjustment mode menus. You can do a lot of cool stuff once you get familiar with navigating the menus and making adjustments in hexadecimal notation (I had to Google that and find a calculator). I’m still trying to successfully calibrate focus on my G2. I’m pretty sure I understand the process, but the manual is kind of ambiguous about the calibration distances and I haven’t gotten great results yet. If you or anyone else ever wants to give it a shot here’s a spreadsheet that I made to handle the necessary hexadecimal calculations. Just make sure you write down your camera’s previous values before changing them. The G1 should be simpler because there’s only one autofocus system to calibrate where the G2 has two.

https://www.dropbox.com/s/ohc8rp4m2jujpf5/Contax%20G2G1%20AF%20Calibration%20Calculator.numbers?dl=1

 

[Tsung-YI]

Can you record a video ? I can't find the Bank06....

 

[c0ntact]

Praise to the Lord, the Almighty everyXnewXday !!!

As a possesor of a 35mm, a G1, and a dead Green Label... You just made me save 350€ ( for a green label or a 7artisans 35mm )

So thank you so much for this tutorial.

Just a message, I didn't succed to go to manual adjustment mode as you said. With my g1, I had to push rewind with back closed, stay pushed on it, open the back, then press the shutter for a long time.
Going to adjusting mode was the most complex part of the convertion, so maybe it ll help someone.

The best Xmas gift I ll have this year

 

[Craig75]

Amazing post by the OP.

This didn't get enough love and respect when it was first posted.

Excellent Detective work.

 

[Sirdn]

Thanks man! After learning to navigate the menus and seeing the section with the lenses listed I compared the data entries for each lens between my G2 and Silver G1. I noticed that the values were all exactly the same for the 28mm, 45mm, and 90mm but that the G1 was blank in some of the slots where the G2 wasn’t. I used a hexadecimal to decimal converter to check the focal length data values to confirm that they were the correct banks for the 21 and 35mm lenses. From there it was just a matter of copying the values from the G2 over to the G1 and testing it!

I’d highly recommend exploring the manual adjustment mode menus. You can do a lot of cool stuff once you get familiar with navigating the menus and making adjustments in hexadecimal notation (I had to Google that and find a calculator). I’m still trying to successfully calibrate focus on my G2. I’m pretty sure I understand the process, but the manual is kind of ambiguous about the calibration distances and I haven’t gotten great results yet. If you or anyone else ever wants to give it a shot here’s a spreadsheet that I made to handle the necessary hexadecimal calculations. Just make sure you write down your camera’s previous values before changing them. The G1 should be simpler because there’s only one autofocus system to calibrate where the G2 has two.

https://www.dropbox.com/s/ohc8rp4m2jujpf5/Contax%20G2G1%20AF%20Calibration%20Calculator.numbers?dl=1

Thanks for posting this. Great work!

I have a G1 with back-focusing issues, and would like to correct this by calibrating all four focus distances mentioned in this thread. However, I can’t find the correct menu / adjustment item when I'm in the manual adjustment mode. In the G2 repair manual it lists all the item numbers (hex) in Adjusting mode I (ABC-switch to 0), and the correct Item no. to display the AF phase difference data should be 1A. My exposure counter LCD has a bad leakage, so it's not easy to see the first digit, but when going through the item numbers, I can clearly see that the order follows the menu list in G2 repair manual. The item list for the G1 though, is still shorter than the G2. I can't find 1A through 1F (and according to G2 manual I should use 1A to display the values for the focusing distances).

My questions then are:

1) Is it at all possible to calibrate the passive AF on the G1, or is this only for G2?
2) Does anyone know which item no. in Adjusting mode I it should be?
3) Does anyone have the Table of Adjusting mode I for the G1 (content of adjustment items)?

It's obvious I don't have the Repair manual for G1, but I would like to ask members here first before I get one.

 

[xftyrone]

Praise to the Lord, the Almighty everyXnewXday !!!

As a possesor of a 35mm, a G1, and a dead Green Label... You just made me save 350€ ( for a green label or a 7artisans 35mm )

So thank you so much for this tutorial.

Just a message, I didn't succed to go to manual adjustment mode as you said. With my g1, I had to push rewind with back closed, stay pushed on it, open the back, then press the shutter for a long time.
Going to adjusting mode was the most complex part of the convertion, so maybe it ll help someone.

The best Xmas gift I ll have this year

Thanks, I am a newbie to the forum and is treasured to find such information for updating my G1 (silver label) to work with 28mm & 35mm lens.

I have tried both of the methods as stated trying to get into the manual adjustment mode but in vain. There wasn't any change in the LED display.

Do you guys have any update about this ? Many thanks.

 

[fra]

I just tried this and worked without problems, my 35 is now recognized (it wasn't before) and everything seems to work. Will put a roll and try it out.

Thank you so much everyXnewXday !

 

[Yashica]

Not working for myself, description is a bit fuzzy. It doesn't work, simply for my needs - no time to play with these settings, and freaking around. I want to shoot my 35/F2 Planar, and hence therefore the silver label G1 without all that tinkering doesn't work. Anyway, this is the worst ever, manual firmware update ever. Kudos to Kyocery tech guys into ca. 1996. I don't have the time, the patience and the nerves, to tinker around with these settings. I'd just buy a green label, and sell my silver label G1, other-wise i fear, i've wasted just 8 EUR for 2x new CR2 Duracell batteries.

 

[Deim]

Does anyone have the values for the 45mm f2? Would love to see if there's any difference between the G1 silver, G1 green and G2.

Thanks

 

[Yashica]

For myself, i was tired of hacking hex code values into my G1, and it didn't worked out - so some months ago, i've had just bought a green label G1, and it's perfectly fine working with my 35/F2 Planar, without any issues. Was for sure another 500 bucks, but saved me a lot of emotional stress, for peace of mind - and that is price-less...seriously. Because i couldn't deal with that cr@p.

 

[Yashica]

How long did it take for you to research, analyze, and develop this update?

You should be congratulated.

Now, if this fix would also change the label color.


White Label vs. Green Label by Narsuitus, on Flickr

It's being called silver label, and it clearly shows - i know the G1 since 1994. No hard feelings.

 

[Deim]

For myself, i was tired of hacking hex code values into my G1, and it didn't worked out - so some months ago, i've had just bought a green label G1, and it's perfectly fine working with my 35/F2 Planar, without any issues. Was for sure another 500 bucks, but saved me a lot of emotional stress, for peace of mind - and that is price-less...seriously. Because i couldn't deal with that cr@p.

I'm not that stressed about this camera. It worked ok-ish for my first roll.

I'm just curious to understand if the lens values on them are really generic, or if they're actually calibrated for each camera.

The values here are from a G2 and the OP is saying the 45f2 values are the same as the one from his G1Silver. On a YouTube video, another user is saying the values from his G1 Silver are different from his G1 Green.


The Values on the YouTube video for the 45f2 (Table Entry 07) are:

01 FC
03 B9
05 30
06 7
07 30
08 7
09 60
10 7
11 F0
12 7
14 62
19 2E
20 9C
21 CA
23 30
24 10
26 64
27 32
28 11
50 1

Any chance you could check your G1 Green values and see if they're exactly the same or somehow different?

Thanks.

 

[Yashica]

Sorry, not entering that service menu ever again. One of these night mares, which really f....d me up, therefore i got a "new" old G1. And all is written onto the web, i think G2 values might differ from G1 silver/green, because of a different (better) AF system. I keep things which are stressing me, out of my life...e Honestly, this is such a old thread, and you can find all the info, -values onto the web, i do think.

Greetings.

 

[Deim]

Thanks for your help.
I couldn't find the values anywhere else appart from that specific video but I'll search and see.

 

[limera1n]

Thanks for your help.
I couldn't find the values anywhere else appart from that specific video but I'll search and see.

It is the same across all G camera bodies.

 

[Deim]

It is the same across all G camera bodies.

It’s definitely not. The values from the silver and the green label G1 are different.