Techart TA-GA3 Contax G adapter not working?????

Started 3 months ago | Discussions
JW PHOTO Veteran Member • Posts: 3,083
Techart TA-GA3 Contax G adapter not working?????
1

Well, I broke down and bought a Techart TA-GA3 so I could use my Contax G lenses on my Sony A7RII and was really liking it until the camera wouldn't register the aperture at which the lens was set.  When I got the adapter it worked great and I loved it, but after about a month aperture-preferred setting  stopped  working.  The camera then constant;y over-exposed by at least three stops.  I clean all contacts and checked settings, but nothing yet has worked.  Has anyone had the same problem or know what's wrong with my Techart????  I really miss using this,

Thanks, JHW

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ProfHankD
ProfHankD Veteran Member • Posts: 8,090
Re: Techart TA-GA3 Contax G adapter not working?????

JW PHOTO wrote:

Well, I broke down and bought a Techart TA-GA3 so I could use my Contax G lenses on my Sony A7RII and was really liking it until the camera wouldn't register the aperture at which the lens was set. When I got the adapter it worked great and I loved it, but after about a month aperture-preferred setting stopped working. The camera then constant;y over-exposed by at least three stops. I clean all contacts and checked settings, but nothing yet has worked. Has anyone had the same problem or know what's wrong with my Techart???? I really miss using this,

No experience with that adapter in particular... but that might be a lens problem.

Do you see the exact same behavior on multiple different Contax lenses? Otherwise, it sounds to me like the problem could simply be sticky aperture blades -- a problem every heavy user of old lenses is uncomfortably familiar with. 

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Rol Lei Nut Veteran Member • Posts: 5,637
Re: Techart TA-GA3 Contax G adapter not working?????
1

With the Techart Pro, you have to set the camera's aperture to f/2.0, otherwise the pictures will be overexposed. Possibly the same with yours.

Lightshow
Lightshow Veteran Member • Posts: 7,618
Re: Techart TA-GA3 Contax G adapter not working?????

Contact Techart.

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OP JW PHOTO Veteran Member • Posts: 3,083
Re: Techart TA-GA3 Contax G adapter not working?????
1

I'm at home right now and my other lenses are at my cottage.  I'm heading up to the cottage tomorrow afternoon and will check the other lenses out when I get there.  I'll report my findings tomorrow evening.  I have also did some searching and found that the adapters contacts might need adjusting, but will wait on doing that until after trying the 90mm and the 28mm.

Thanks for the help,

JohnW

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OP JW PHOTO Veteran Member • Posts: 3,083
Re: Techart TA-GA3 Contax G adapter not working?????

I think I’m getting to the bottom of this!  I’ll finish with my test in the morning when I have sUnsightly and will let you know the findings.

JHW

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OP JW PHOTO Veteran Member • Posts: 3,083
Re: Techart TA-GA3 Contax G adapter not working?????

Well, here’s the findings. I tried the 90mm G lens and my 50mm Sony just to see how things compared to the 45mm G lens. The Sony worked fine as expected. The 90mm G focused fine and metering was spot on when set at f2.8 wide open, but the minute I starting stopping down it began to overexpose. It was exactly the same with the 45mm G lens. Used wide open both work perfect. It tells me it’s the adapter and nothing else is wrong with my A7rII. I bought this adapter second hand so I guess I’m stuck with it. I sure did like it when it worked well, but now I think I’ll go back to using my old, brainless Kippon adapter unless anyone here has a way to get the A7rII to read the aperture of the Contax lenses via the Techart adapter.

JHW

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iTrax
iTrax Contributing Member • Posts: 906
Re: Techart TA-GA3 Contax G adapter not working?????

Is Techart the same thing as MEGADAP?

They look very similar.

I just ordered MEGADAP PK to LM to Nikon Z adapter , I decided to revive my large old Pentax prime collection.

The firmware is very crucial for the correct operation.

Perhaps it is corrupted?

Do you have a data / communication port on your adapter?

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OP JW PHOTO Veteran Member • Posts: 3,083
Update

No data port on my adapter, but I think you’re on to something with the corrupt firmware guess.  I’m going to have to research “firmware updates” for the Techart TA-GA3 and see what I find.  No time right now, but this evening for sure.

JHW

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Rol Lei Nut Veteran Member • Posts: 5,637
Re: Update

JW PHOTO wrote:

No data port on my adapter, but I think you’re on to something with the corrupt firmware guess. I’m going to have to research “firmware updates” for the Techart TA-GA3 and see what I find. No time right now, but this evening for sure.

JHW

Did you try setting the aperture to f/2.0 using the camera?

OP JW PHOTO Veteran Member • Posts: 3,083
Re: Update

F2 or wide open on both the 90mm and 45mm work perfect and exposure is spot on. Wide open is the only aperture that doesn’t overexpose.  I’ve set f2 on the camera and f2 on the lens in different combos, but no help.   Might be a bad contact on the pin and tab blocks, could need shimming? I’ve tried all the simple/most likely tricks, but still stuck. I’m checking more into the firmware thing. The camera and lens aren’t exchanging aperture information and I have to figure out why.

JHW

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iTrax
iTrax Contributing Member • Posts: 906
Re: Techart TA-GA3 Contax G adapter not working?????

https://techartpro.com/

perhaps contact them

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iTrax
iTrax Contributing Member • Posts: 906
Re: Techart TA-GA3 Contax G adapter not working?????

It looks like firmware update is done via Bluetooth and smartphone.

【Techart 】TA-GA3

  • With TA-GA3 adapter.The real time aperture value cannot be displayed on screen.The camera body and the lens are nor couple.The aperture shown on the camera body is just for reference and the EXIF data would not affect metering.When you shooting,the aperture should remain the maximum state to accurate exposure.
  • It is highly recommended to switch off the camera before you change the lens.
  • If you want to change the lens, you don't have to shave the fins,but you must notice the installation sequence.(Especially G21mm G/2.8).First ,the lens adapter mounted on the camera body and then.lense mounted on the lens adapter.

Warning:This adapter can only use on the camera which is Phase Detection Auto Focus(PDAF)at present.So for sony,you can only use on A9,A7II,A7RII,a6300,a6500.
Details:

  • Brand: TECHART
  • Lens: Contax G lens
  • Camera Body: Sony A9,A7MII,A7RII,a6300,a6500
  • Aperture: Manual

Features:

  • High quality aviation aluminum.The best balance among weight,mechanical behavior and precision.
  • The more powerful CPU and the speed of focus upgrade 50%
  • The bluetooth 4.0 which in low power consumption.Support firmware upgrade mode on IOS and Andriod.

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OP JW PHOTO Veteran Member • Posts: 3,083
Bingo!!!! Happy as a pig in a mud puddle...............

Before I attempted to do a firmware check/update I thought I'd try loosening the contact block screws on the lens hoping to possibly allow a little more thickness.  I tweaked the screws out just a hair and then tried it on the camera.  Presto, it worked like it was supposed to.  I then thought about shimming the contact plates out, but instead I just tightened the screws backup and by golly the thing still worked.  I sure like problems that pretty much fix themselves.  Most of the time I'm not that lucky.  Thanks to everyone for trying to help.

JHW

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