I had the opportunity to further test my Leica R3 MOT with a Summicron 50mm f2. I have already related my pleasure at owning the camera and Tamron lenses. However, I was intrigued to compare how my adaptall Tamron 20-200mm stacked up against the Summicron at 50mm. I know comparisons are odious at the best of times but the opportunity arose where I could borrow the Summicron, so I did! Plus it would allow me to see if there was an issue with the aperture connection, the 3 cam, that might be causing the exposure issue I’ve had.
Trying to be logical in my approach, hard I know, I set out to take a series of four images. The first image would be taken with the Tamron at 50mm and set to automatic exposure, the second would then be taken with the Summicron 50mm also on Auto exposure. The third image would be the Tamron at 50mm but set to on Manual shutter speeds using a light meter to measure the exposure and finally the Summicron 50mm also set to manual shutter speeds.I used the same aperture on both lenses for the test. Not bad me thinks !
So here we go..
The Tamron first
Now the Summicron
With the two images above I was looking to see if there was any difference in the exposure of both lenses when they were set to automatic exposure so forgive the lack of focus. Here are the two histograms
The Tamron first
Then the Summicron
There does not appear to be much difference. Is the reason for the slightly difference in the histogram, the ability of the Summicron 50mm f 2 to gather more light when compared to the ‘slower’ f3.8/4 Tamron lens ? This was repeated throughout my images. Conclusion? Perhaps there is no problem with the ‘3 cam’ that links the aperture of the lens to the camera.
How about the sharpness?
First the Tamron
Then the Summicron
No surprises there then. The Tamron lacks the sharpness and depth of the prime Summicron.
One more example. The Tamron on Auto exposure
Now the Summicron
The Tamron on manual shutter selection
Finally the Summicron
In the first image with the Tamron you’ll notice the image is slightly darker around the edge of the far end of the table than the one taken with the Summicron. The exposure sounded ever so slightly quicker than the one when the Summicron was on the camera. You will notice that the next two images when the camera is set to manual shutter selection, which was measured to be 1/2 second, these are very similar to the exposure with the Summicron when it is set to auto. Conclusion? Maybe there is a problem with the 3 cam linkage on the Tamron?
So I’m not really any closer to finding a reason for the apparent exposure differences when the camera is set on automatic. 🤨
As regards the difference in the sharpness of the Summicron and Tamron lenses, no real surprises there. However I was surprised how close the Tamron got with the images shot indoors on a tripod and with long exposures🤔
I welcome your feedback☺️
arhphotographic 