UnderExposure w/M6 & 35 cron

[Timmyjoe]

Having an issue with exposure with my old M6 TTL and a new 35mm Summicron Asph lens. Using both new Tri-X and some left over old AgfaPan 100. No matter what I do, about half the time the images are coming out underexposed. Tried rating the Tri-X at 200, tried adding 1/2 stop more exposure to each shot, even calibrated the meter in the M6 with a gray card and my Sekonic light meter, and checked the shutter speeds on the M6, everything seems to be fine, but the images still keep coming out on the underexposed side.

Am I missing something here? Has anyone experienced this before? The only thing different is the new 35 Summicron. Do they generally underexpose? It doesn't make any sense to me.

I have never used this M6 with any lens but a 50mm Summilux, does the 35mm Summicron require a different metering style since it's wide angle?

Best.
-Tim

 

[Mr G]

hey tim, do you develop film yourself?

g

 

[Timmyjoe]

Yes, have been doing it since 1976, so I have quite a bit of experience. And looking at the negs, it's definitely an underexposure issue. Kind of a zone system guy, so I always expose for the shadows, develop for the highlights.

Best,
-Tim

 

[Todd Frederick]

When you say "...half the time..." do you mean the one whole roll is under exposed and another is not or that some of the images on the same roll are under exposed and others are not? Also, you might try some shots with one lens and the other lens on the same roll and see if it is a lens problem but since you set the aperture manually it should not be the lens. The only other thing I can think of is that you may be metering on one part of the image and moving the camera to recompose and the light may be changing after you recompose. There possibly is a shutter problem. If the shutter is erratic, that could be the cause. Take a series of exposures of the same subject at the same speed and aperture and see if the results are inconsistent. Just a few ideas to try.

 

[ferider]

Hi Tim, the Summicron should behave just like your Lux.

Hard to say what's wrong, since you checked the meter, are metering for the shadows, etc.

The only thing similar that once happened to me is using a yellow filter. My M6 meter basically ignores a yellow filter in front, the meter seems to be more sensitive to red light.

Any filters in your case ?

Really, can only be the meter, the shutter, or the aperture. The aperture you can check visually. Sounds like you did check meter and shutter. One good combined check for aperture and shutter is to take the same shot with 1/1000 f2, 1/500 f2.8, 1/250 f4, 1/125 f5.6, etc, and then compare.

Roland.

 

[Timmyjoe]

Thanks Todd & Roland. I think the test you guys are talking about are good ideas, I'll try to shoot some of that tonight. Really has me baffled and quite a bit frustrating.

Best,
-Tim

 

[Timmyjoe]

I went back and pulled the negatives I have shot in the last week, and really studied them. There's a ton of detail in the shadow areas. I'm now starting to suspect my Nikon Coolscan 9000 scanner. It's always given me really good (diffusion style enlarger) results in the past, which is why I was trusting it, but it's sure doing a lousy job on these negatives.

I am going to do one more test, shooting a scene 1000/sec-f2, 500/sec-f2.8, 250/sec-f4, etc. to make sure the shutter is okay, but I think the problem may be in the scanner.

Thanks for everyone's help.

Best,
-Tim

 

[Timmyjoe]

Hi Guys,

Just shot a test where I lit a scene and then shot it as above, 1000/sec-f2, 500/sec-f2.8, 250/sec-f4, 125/sec-f5.6, 60/sec-f8, 30/sec-f11, 15/sec-f16 with the Summicron, and then adjusted the light and shot again 1000/sec-f1.4, 500/sec-f2, 250/sec-f2.8, 125/sec-f4, 60/sec-f5.6, 30/sec-f8, 15/sec-f11, 8/sec-f16 with the Summilux. Sure enough, both images shot with a shutter speed of 1000/sec are underexposed by about a stop. Both images shot with a shutter speed of 500/sec are underexposed by about 2/3 of a stop and both images shot with a shutter speed of 250/sec are underexposed by about 1/3 of a stop. All the rest of the images have the same exposure.

Is this something that a CLA will remedy, or should I just try to compensate when I am shooting at those shutter speeds?

Thanks for any and all info on this.

Best,
-Tim

 

[rogerzilla]

Sounds like it's due a CLA. It's not right to have to use workarounds on a $1,500 camera. On the other hand, you have a Leica with a 1/2000 shutter speed!

 

[ferider]

A CLA will fix this, Tim. I'd say do it, for me 1/500 and 1/1000 are very important.

Roland.

 

[nobbylon]

Tim,
It's a common issue. The top speeds get faster. First curtain tension a little low. I'll bet that the 1/60, 1/125 and 1/250 are also running a little fast.
You can easily check the 125,250,500 and 1000 speeds using a crt tv.
Take the back off of the camera, remove the lens.
Set your tv to a channel with no station just the white fuzziness and with the camera pointed at the screen look through the film gate as you fire off a few frames.
At 1000 you should see an arc going from top and arcing down to the bottom left about 3-4mm wide. It gets wider toward the bottom. As you change to 500 the arc will broaden and again at 250 etc getting wider as shutter speed increases.
If the arc at 1000 is too thin then that's your problem.
You can very easily increase your first curtain tension one or two positions. It will probably need no more than 1/8th to 1/4 of a turn on the screw.

 

[Timmyjoe]

Tim,
You can very easily increase your first curtain tension one or two positions. It will probably need no more than 1/8th to 1/4 of a turn on the screw.

Can you tell me how to do this. I service some cameras (I service motion picture cameras for a living) and a few different SLR's and have done some work on my Leica iiif, but I have never attempted anything with the M6 TTL. I would love to be able to adjust it myself as the last Leica I sent in for service was gone for three months, and I shoot daily with this camera.

Any info you could give me on this would be greatly appreciated.

Best,
-Tim

 

[anitasanger]

I used to have this trouble a lot. I attributed mine to not being able to read the dim arrows properly.

 

[Timmyjoe]

Through in the towel and sent it in for service. Need the shutter speeds to be accurate. Thanks for everyone's help.

Best,
-Tim