Latest or all posts or last 15, 30, 90 or 180 days.
Upgrade the memory of your 2018 Mac mini up to 64GB
877-865-7002
Today’s Deal Zone Items... Handpicked deals...
$286 $140
SAVE $146

$2699 $2199
SAVE $500

$2699 $2099
SAVE $600

$290 $203
SAVE $87

$130 $115
SAVE $15

$100 $40
SAVE $60

$3498 $3198
SAVE $300

$2347 $1897
SAVE $450

$1297 $1097
SAVE $200

$597 $497
SAVE $100

$2297 $1997
SAVE $300

$699 $499
SAVE $200

$60 $40
SAVE $20

$1699 $1199
SAVE $500

$1997 $1097
SAVE $900

$1499 $1379
SAVE $120

$372 $247
SAVE $125

$9999 $2999
SAVE $7000

$4500 $3500
SAVE $1000

$1000 $500
SAVE $500

$1398 $898
SAVE $500

$935 $549
SAVE $386

$309 $259
SAVE $49

$1300 $900
SAVE $400

$450 $280
SAVE $170

$700 $600
SAVE $100

$2000 $1270
SAVE $730

$1499 $779
SAVE $720

$450 $120
SAVE $330

$3998 $3498
SAVE $500

$150 $80
SAVE $70

$369 $175
SAVE $194

$1699 $1199
SAVE $500

$649 $449
SAVE $200

$1498 $998
SAVE $500

$999 $949
SAVE $50

$1099 $999
SAVE $100

$400 $300
SAVE $100

$7697 $4997
SAVE $2700

OWC
Blast off into savings!


DIY upgrades, computing essentials and more from OWC.

Sony FE 55mm f/1.8 Sonnar on Sony A7R Aperture Series (Red Barn) and Shutter Vibration at 55mm

Get the Sony FE 55mm f/1.8 Sonnar for A7R / A7 at B&H Photo.

Sony FE 55mm f/1.8 Sonnar for Sony A7R / A7

The Sony FE 55mm f/1.8 Sonnar shows a stunning performance wide open through f/2.8.

Sony FE 55m f/1.8 Sonnar on Sony A7R (Red Barn)

But alas, there is seen starting at f/4* a major degradation, which appears to be shutter vibration. The problem shutter speed is documented in the above series.

A confirming diagnosis comes from the same series shot with a different lens (Leica 50/2 APO) showing a similar degradation at the same shutter speed and aperture. It’s incredibly disappointing: we are talking 55mm here. Checking the problem shutter speed with previous work suggests that 35mm might not be immune.

A cross-shoot using the 24-megapixel Sony A7**, e.g. should show zero degradation at any shutter speed, which is in fact the case even at 180mm and 280mm (personally tested) and even 800mm (a NYC pro I trust for that 800mm figure). So on the A7, one can expect to see perfection across the aperture and shutter speed range.

Another confirming diagnosis is to obtain both perfect and impaired results at the same aperture at different shutter speeds; this can be done with a series of ND filters or a continuously variable lighting source (which I don’t have at present). And that is tomorrow’s project, with ND filters.

Taking the landscape orientation 180mm focal length results showing a ~1 pixel blur (e.g., camera displacement by about 5 microns), we can deduce a 55/180 fractional blur = 1/3 pixel, an idea based on some angular rotation causes by the shutter shock which of course would affect a long lens more in pixel terms. About 1/3 pixel looks to be about what I’m seeing with the 55/1.8 on the A7R at the problem speeds. It’s like a very strong anti-aliasing filter on the Red Barn scene.

UPDATE: I have confirmed a loss of sharpness under ideal (for the camera) studio conditions at f/4, varying lighting intensity, but keeping the aperture constant and the focus on manual. Field conditions cannot be better than this studio setup, only worse. Proofs will follow; I am preparing a detailed analysis to present.

See also the dolls study.

* Aperture f/4 should offer the very best performance of all, and f/5.6 nearly so.

** The Sony A7 offers a vibration-free electronic first curtain shutter.

Physics are physics

General discussion on principle; mass has its own influence and the camera system (camera + its internals + lens + mount) is far from a rigid block.

A shock acting against a mass will vector that mass. Kick your car and it moves. Kick a bus and it moves*. Not very much, but a force acting on a mass will not be denied.

* For politicians, kick the can down the road.

Sony A7R + Sony FE 55mm f/1.8 Sonnar @ f/1.8

Save the tax, we pay you back, instantly!
View all handpicked deals...

Sachtler Lightweight Audio Bag (Medium)
$286 $140
SAVE $146

diglloyd Inc. | FTC Disclosure | PRIVACY POLICY | Trademarks | Terms of Use
Contact | About Lloyd Chambers | Consulting | Photo Tours
RSS Feeds | Twitter
Copyright © 2020 diglloyd Inc, all rights reserved.