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20mm/1.5 c-mount SOM Berthiot

I was amazed at the sharpness and beautiful bokeh of this lens fully open.



A little beauty, and it brings only 150 grams on the scale

Here, the original full frame photo:



Ucropped 4:3 photo with heavy vignetting
1/1600 @ 1.5 - ISO=100 - Developed in RAW Therapee




Crop
 
V

Vivek

Guest
Peter, The noise at the base ISO is quite striking. Was your battery towards its end?
 

simonclivehughes

Active member
Vivek,

Are you saying that the noise gets worse as the battery depletes? That's the first time I've ever heard this. What leads you to that conclusion? I would have expected the battery interface to have at least some power regulation. Maybe on the last shot of a dying battery you might expect some funkiness, but otherwise??? :shocked:

Cheers,
 
Vivek, Simon,
I checked again if the ISO was accidentally changed when activating the MF Loupe, but no. This picture was the last I took today with the G1. It had not been touched since and the ISO was still on 100.

The white orchid flower was lit by the sun, the background was in the shade and thus underexposed. Might this explain the noise?

Cheers
Peter
 
V

Vivek

Guest
Vivek,

Are you saying that the noise gets worse as the battery depletes? That's the first time I've ever heard this. What leads you to that conclusion? I would have expected the battery interface to have at least some power regulation. Maybe on the last shot of a dying battery you might expect some funkiness, but otherwise??? :shocked:

Cheers,
Simon,

I always have trouble when the battery (the official, "special" Pana battery) goes from 3 stripes to anything lower. With one stripe, things (noise) start to go haywire.
 
V

Vivek

Guest
Vivek, Simon,
I checked again if the ISO was accidentally changed when activating the MF Loupe, but no. This picture was the last I took today with the G1. It had not been touched since and the ISO was still on 100.

The white orchid flower was lit by the sun, the background was in the shade and thus underexposed. Might this explain the noise?

Cheers
Peter
Peter, Given the lighting, it could be flare that obscured the metering. You can barely see the yellow as yellow in the Orchid.
 

simonclivehughes

Active member
Simon,

I always have trouble when the battery (the official, "special" Pana battery) goes from 3 stripes to anything lower. With one stripe, things (noise) start to go haywire.
Interesting... I haven't noticed this myself, but then I haven't been looking for it either.

Cheers,
 

pellicle

New member
I'm also seeing an ugly grid pattern in the upper right corner

I'd ditch your raw converter if that was 100iso and not drastically underexposed

my first thoughts are that to get the white not clipping (looking at the lighting) you've undertaken some application of curves or such to push up the shadows

not sure if that helps but keep having fun! :)
 
C

ChrisJ

Guest
There's some heavy vignetting with that lens, by the time you've cropped the vignette out it's not a 20mm lens anymore.

I've never heard of a low battery causing more noise, but as the voltage decreases the current has to increase (Ohms Law) so, as it's the current which causes the heat in the sensor which causes some of the noise, I suppose there may be something in it, but I've never noticed it yet.

Chris

Chris
 
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