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Message |
    
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 1
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 13, 2010 - 06:06 pm: | 
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Hi!
I recently got a Yashica Electro 35 GX and I'm currently putting my first roll through it.
It's in great shape but unfortunately I've got a
problem with it (as you might have guessed by the subject-line).
If set to ISO800 the camera gives correct exposure for ISO200. This behaviour is constant over all apertures and iso-settings as far as I can tell (using the arrow-lights (1/30-1/500), set f-stop and my Canon 20Ds metering).
I'm running the camera on two fresh 1.55V silver-oxide batteries. I am aware of the higher voltage than the 2x1.35V it was designed for. Could this be the reason for the 2 stops over-exposure?
Or might it be, as I fear, the light-metering silicone chip that is dying?
Any help would be appreciated. I did try to use the search function, but couldn't find a old thread with the same subject. If you know of one, please point me to it  . |
Greyscale
Tinkerer
Username: Greyscale
Post Number: 23
Registered: 07-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 13, 2010 - 07:16 pm: |
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One suggestion would be to try a pair of 1.4 volt zinc-air hearing aid batteries and see if it still over-exposes then. You MAY need to drill a small hole in the battery cover to allow a little extra air in when using zinc-air batteries.If that works for you, either continue to use the zinc batteries, or buy a suitable Cris adapter to allow you to use the silver-oxide batteries. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 2
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 13, 2010 - 07:30 pm: |
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Thank you Greyscale, I'll try to find some cheaper way to feed the camera a lower voltage first, to see if it makes any change, before buying new batteries. |
Donnie_strickland
Tinkerer
Username: Donnie_strickland
Post Number: 95
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 14, 2010 - 08:18 pm: |
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Have you tried it with film yet? It's difficult to compare directly with another camera's meter, since the meter angle of view is not the same on the two cameras. I run my GX with two PC640A alkalines and that works just fine, since the GX can compensate for small voltage differences. I would suggest simply trying a roll of film under varying lighting conditions and see what you get. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 3
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 15, 2010 - 05:48 pm: |
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Hi Donnie and thank you for your input .
I am putting a roll of Tri-X 400 trough it right now, only a couple of frames left. I've got the meter set to 800 on the camera, wich according to my tests will exposure the film for 200 wich is what I'll develop it as. If I'm right, the film will be correctly exposed.
I'm quite sure my tests are correct, I have compared the cameras metering (center avg. on the canon and a similar focal lenght) on large (easily filling the whole frame) evenly lit surfaces, using different kinds of lightning (flourescent, sunligt, etc) always with the same 2 stop difference as a result. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 4
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 17, 2010 - 08:18 am: |
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Update: I have just finished my testroll, I'll give another update as soon as I've developed it.
I have also been in contact with yashica-guy, he tells me that there is no way the voltage differential pushes the metering two steps off (in fact, he claims that the GX is specified to 1.5V), he believes that the silicone-cell has aged and that I could compensate for this by changing a resistor in the camera. I will attempt this, but I can't say how soon.
If you have the same problem, have a look at this guide for the Yashica Lynx: http://www.yashica-guy.com/document/lynxfix.html
The procedure for the GX should be similar. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 5
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 18, 2010 - 05:12 am: |
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The testroll came out very well exposed. The lens of this camera clearly outperforms my Konica C35, it's also better than my Minolta X700 with the MD 50/2.0. Impressive.
I can also confirm that you can adjust the GX's rangefinder via a small hole under the hotshoe just as for other electro-models.
I'll try to remember updating this thread when I have tried to calibrate the cameras lightmeter.
If you feel that you have something to add, please do. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 6
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 10:45 am: |
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Since last update the over exposure warning bulb has broken down (cold winter day, about -20C). Since I was going to remove the cameras top plate to look for some possibility to adjust the lightmeter anyway, I exchanged both exposure warning bulbs for 3mm LEDs, this seems to work very well.
I did not, however, manage to find a way to adjust the light meter. The only resistors I saw was too hard to get at for it to be worth a try. At some point I'll give the lower-battery-voltage-theory a go, but I don't think that's it, so I'll just use it as a ISO 6-200 camera instead of a ISO 25-800 one.
Any ideas other than lowering the battery voltage (I'll try that later on) are very welcome. |
Br1078lum
Tinkerer
Username: Br1078lum
Post Number: 31
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 11:05 am: |
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Read a post on another forum where the owner of a recently purchased Yashica GX had to clean out the area where the meter cell sits. If this is a silicon cell, they do sometimes have the habit of growing a white fluff on the surface that will obscure the cell over time.
PF |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 7
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 16, 2011 - 03:55 am: |
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Thank you for your input Br1078lum, I removed the "faceplate" of the lens when I first discovered the exposureproblem and then removed the "aperture blind" under it, covering the lightsensor. Unfortunately it was spotless. |
Jelu1661
Tinkerer
Username: Jelu1661
Post Number: 8
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 18, 2011 - 06:51 pm: |
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Good news everyone!
It seems to improve with use, it's now about 1 1/3 stops off instead of two stops off. I.E: works great using ISO200 setting for ISO100-film. So now I can take it up to 400, wich is enough for me
Thanks to everyone who has given me input, hopefully some of this can help someone else. |
Monopix
Tinkerer
Username: Monopix
Post Number: 206
Registered: 11-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 19, 2011 - 10:05 am: |
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I've come to this thread a bit late but, the GX uses a CDS cell not a silicon cell as the Lynx does so the link you gave to the lynxfix page isn't really relevant.
Anyone have a GX repair manual? It should be pretty easy to identify the fault with the right information. Doesn't mean it's easy to fix of course... |
Br1078lum
Tinkerer
Username: Br1078lum
Post Number: 75
Registered: 11-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 21, 2011 - 10:42 am: |
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Must not have been awake yet when I posted last. I know it has a CdS cell, but aparently my brain cells need to have the fluff cleaned off of them. Anyhow, I was thinking that maybe if this camera has not been used in a long time, maybe the timing circuit capacitor had gotten 'dry', and is now rejuvenating itself. That could explain the change in metering towards the better. Only other thing I can think of is dirt in the shutter mech working it's way out, but that would give varying speeds instead of being constant. So I'm sticking with the rejuvenating capacitor theory.
PF |
