Friday, June 16, 2017

all USB connectors and USB-C thunderbolt 3 USB 3.1 gen2; speed.


MacBookPro 2016 2017 

Two or four Thunderbolt 3 (USB‑C) ports
with support for:
  • Charging
  • DisplayPort
  • Thunderbolt (up to 40 Gbps). Thunderbolt is a protocol.
  • USB 3.1 Gen 2, up to 10 Gbps (10 Gbit/s, it's exactly the max of USB 3.1 Gen 2). USB is a protocol.
USB-C is an electronic connectors not a protocol.

Sandisk 32/64Gb


Thursday, June 15, 2017

package MathWorld and path in mathematica; Get::noopen: Cannot open MathWorld

Get::noopen says that the file could not be opened, not that there was a problem with the code inside.

Is the MathWorld folder in one of the directories listed by evaluating $Path?
method of specifying the package is to provide the full path to it.
- Type in Mathematica:

  1.  place the cursor between the square brackets, 
  2.  go to Insert menu, File Path, 
  3.  in the directory dialog box that opens, trace down to the .m file and Open it (that puts the path into the Get),
  4.  evaluate the Get that now has the file path.


APS-C and full frame conversion and comparison; crop factor, focal length, depth of view, depth of field; Canon, Nikon, Sony.

Advanced Photo System type-C (APS-C) is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" negatives of "25.1×16.7 mm". All APS-C variants are considerably smaller than 35 mm standard film which measures 36×24 mm (Full Frame FF sensor)
Sensor sizes range from 20.7×13.8 mm to 28.7×19.1 mm, but are typically about 22.5×15 mm for Canon for example (crop factor=1.62× ).
For the Sony APS HD CMOS sensor of Alpha series (from alpha 100 to alpha 77 (II)), it's 23.5 x 15.6mm (also for Nikon); sensor surface=366.60mm^2, and Sensor Pixel Area = 15.28µm^2 (for 24.3MPix), and crop factor=1.55×. Then a 35mm (24x36mm)-->"35*1.55=54.25mm". 

A crop factor (sometimes referred to as a "focal length multiplier", even though the actual focal length is the same) can be used to calculate the field of view in 35 mm terms from the actual focal length.

Many companies manufacture a range of lenses "optimised" for APS-C sensors. For full frame lenses, the sensor is only in the center.
The full-frame lens is bigger, heavier (than APS lens), and uses a larger filter because it has to cover a larger sensor area.

Moreover they are also some differents designs Sony A-Mount and Sony E-Mount camera .
Shortening the flange focal distance to 18 mm (E-Mount) compared with earlier offerings from Sony which used 44.5 mm (A-mount).
Sony also produces E-mount lenses designated as "FE", which cover the entire full-frame image circle.


basis : the 5 parts

The start is the pinhole camera
No lens, only a pin-hole.
The main problem is the quantity of light due to the fact of the very small surface of the hole.
The second problem is an "infinite" depth of view" (all parts are not blurred).
Then with a lens, we have a large "hole" (diaphragm).
With the aperture, we control the depth of view".

The only problem with FF-->APS-C is the size of the sensor and then the angle of view.

Angle of view from lenses at the same focal length

The angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera (~ also this more general term field of view).
See also


The f-number

The f-number f/#  of an optical system such as a camera lens is the ratio of 2 lengths, of the system's focal length to the diameter of the entrance pupil (effective aperture). 
A 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. 
The standard f-stop scale which is an approximately geometric sequence of numbers that corresponds to the sequence of the powers of the square root of 2:   
 f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64,...
f/√2, f/(√2)^2, f/(√2)^3, ...  (2.8 is 2.828...)
Then the surface increase of 2 when you change the aperture f-number, for example 2.8->4.

When you change a full frame to an APS-C, the aperture of a lens never changes.... Only the focal length and then the f-number. It lets the same amount of light in no matter what. A 2.8 is a 2.8 ever and ever. If you have a smaller sensor doesn't use the whole image coming in.

Fundamentally, f/# is the ratio of the effective focal length (EFL) of the lens to the effective aperture diameter (DEP).

Diameter of the "first entrance lens" or pupils

Moreover remember that the diameter of the first entrance lens  (or single lens "diaphragm-like") is very important for the quantity of light and also for the resolution.

and with some effects:

This figure  shows the difference in spot sizes between a lens set at f/2.8 and a lens set at f/8.

As pixels continue to reduce in size, this effect becomes more of an issue and eventually is very difficult to overcome. The Airy Disk, or minimum spot size can be calculated using the f/# and wavelength in μm:
You can see the interest of the dimensionless number f/# .
The lambda is the wavelength of light (blue ~ 0.4µm).

f/#Airy Disk Diameter (μm) at a Wavelength of 520nm

The definition of f/# (see below) is limited in the sense that it is defined at an infinite working distance where the magnification is effectively zero. Most often, the object is located much closer to the lens than an infinite distance away, and f/# is more accurately represented by the working (f/#)w:

In the equation for working f/#,   m represents the paraxial magnification (ratio of image to object height) of the objective. Note that as m approaches zero (as the object approaches infinity), the working f/# is equal to the infinite f/#. It is especially important to keep (working f/#w) in mind at smaller working distances. For example, an f/2.8, 25mm focal length lens operating with a magnification of -0.5X will have an effective working f/# of f/4.2. This impacts image quality as well as the lens’s ability to collect light.

f/# and Numerical Aperture (NA)

It can often be easier to talk about overall light throughput in a lens in terms of the cone angle, or the numerical aperture (NA), of a lens. 
The numerical aperture of a lens is defined as the sine of the marginal ray angle in image space, and is shown in:

Visual Representation of f/#, both for a Simple Lens (a) and a Real-World System (b)

It is important to remember that f/# and NA are inversely related:

Also we must consider some aberrations for example:

Optical Depth of Field

Optical Depth of Field (DoF) Calculator for Cameras

depth of field (DOF), also called focus range or effective focus range is the distance between the nearest and farthest objects in a scene that appear "acceptably sharp" in an image. 
In fact focus is possible at only one distance and  at that distance, a point ("subpixel") object will produce a point image.
The diameter of the circle increases with distance from the point of focus; the largest circle that is indistinguishable from a point is known  as the circle of confusion

Doubling the f-number will approximately double the depth of field...


An other point is the quality of lenses:
lens transmittances of 60%–90% are typical. 
and many many bad effects as tilt, flare...


You’re admiring your work when you see an insect on the flower which you hadn’t noticed before.You have a macro lens and now you want to fill the photo with that insect.At this point, the APS-C camera might be more helpful because you won’t have to stand as close to the insect to fill the frame. While that might be nice for people who don’t like getting close to critters, being at a greater distance also means you’re less likely to scare the insect. And in macro photography, trying not to frighten off your skittish subjects is a big deal and you’ll welcome the advantage you have from being able to work at a greater distance.

But that’s not all.

Because getting enough depth of field is notoriously difficult in macro photography, you’ll probably also appreciate the slight increase in depth of field that comes from photographing your insect at the greater distance.

Depth of field increases as you move further away from your subject. 
This can give an APS-C camera an advantage when taking macro photos 
because they fill the frame with your subject from a greater distance. 
Note that this graphic is not drawn precisely to scale.

Monday, June 12, 2017

future of the Sony (Minolta) A-mount? dead or not? And Adaptators A-Mount to E-mount. GPS built-in?

The A-mount is no longer seen as a viable platform by Sony executives, because it now represents  a small % of all interchangeable camera lens sales.
So after Australia and New Zealand also Taiwan will likely no more sell any A-mount stuff.
I guess Soy’s startegy now is to sell their new A-mount cameras only in “DSLR-friendly” markets.

2017 may
Sony is the world's leading mirrorless camera brand but remains third for ILCs overall, it said in a presentation to investors (imaging product


Lists of all products
The last A-mount zooms (2015-04)
Sony α Zeiss Vario-Sonnar T* 24-70mm f/2.8 ZA SSM II
Sony α 70-300mm f/4.5-5.6 G SSM II

Example of oldies :

In french
for a sheet of all alpha A-mount:

Now (june 2017), only 3 Sony A-Mount cameras:

Comparison Alpha68 and 58:

Reasons to choose Sony SLT-A57 (2012-04) over Sony SLT-A58 (2013-04)

Reasons to choose Sony SLT-A58 over Sony SLT-A57
4 advantages
 Max Sensor Resolution 20 MP vs 16 MP --> 25% more pixels
 Battery Life 690 shotsvs 550 shots  --> 140 more frames with a single charge
 Weight 492 g vs 618 g -->126 g lighter

Reasons to choose Sony SLT-A57 over Sony SLT-A58
6 advantages
 LCD Screen Size 3″vs 2.7″ --> 0.3 inches larger display
 LCD Screen Resolution 921k dots vs 460k dots --> 100% higher resolution screen
 Continuous Shooting 12.0fps vs 8.0fps --> 4 fps faster
 Color Depth 23.4 vs 23.3 --> higher color depth
 Dynamic Range 13.0 vs 12.5 --> higher dynamic range
 Low Light ISO 785 vs 753 -->  better High ISO performance?

A57 is better than A58 
In french:


Alpha 55

(GPS built-in).
  • Slow (50 seconds) buffer clear time (RAW-mode)
  • Little control over high ISO noise reduction in JPEG mode ('auto' or 'weak')
  • Visible loss of detail at anything over ISO 400 in JPEG mode (noise reduction too strong --> blur)

Reasons to choose Sony SLT-A68 (2016-03) over Sony SLT-A65 (2011-03)

6 advantages
Flash Coverage 12.0mvs 10.0m--> 2m longer range
 Color Depth 24.1vs 23.4--> higher color depth
 Dynamic Range 13.5vs 12.6--> higher dynamic range
 Top LCD Yes vs No--> Help viewing and changing settings easily
 Smartphone_remote control Yes vs No--> Remote control your camera with a smartphone
 AF Micro Adjustment (Fine Tune) Yes vs No--> Adjust each lens for more accurate focusing

Reasons to choose Sony SLT-A65 over Sony SLT-A68

5 advantages
 GPS BuiltIn vs None track your location
 LCD Screen Size 3″vs 2.7″ 0.3 inches larger display
 LCD Screen Resolution 921k dots vs 461k dots 99% higher resolution screen
 Continuous Shooting 10.0fps vs 8.0fps 2 fps faster
 Viewfinder Resolution 2359k dot vs 1440k dot 63% higher resolution
A68 plastic mount!!!

Moreover the alpha 65 is very near of the alpha 77 (I):
  • Comparatively strong noise reduction at medium and high ISO settings
  • Very noisy raw files at high ISO settings
  • Little control over high ISO noise reduction in JPEG mode ('auto' or 'weak')
  • Limited control in 10 fps continuous shooting and movie modes
  • No live view in 8 or 10 fps continuous shooting modes makes accurate panning very difficult
  • Slightly 'laggy' menu system and UI

Converting the A65 images in Adobe Camera RAW 6.6 Beta confirms the suspicion that we had when examining the camera's JPEG output. The A65's 24MP sensor is producing significantly higher noise levels than the competition, especially towards the top of its ISO sensitivity range. At ISO 1600/3200 and above the disparity is obvious, and becomes more so as the ISO sensitivity increases.
Then bad for low light shooters!
Idem for A77

Alpha 77

Jpeg are bad after 3200 ISO.
review in french:

Alpha 99 (2013-04)

SLT-A99V with GPS.
SLT-A99 without GPS (depending on country).

Absence de sortie USB 3, Absence de Wi-Fi ; pas de flash intégré...
c'était le nouveau reflex à capteur 24x36 mm (full frame) de Sony 24 Mpx (loin du 36 Mpx du D800). Corollaire : la densité de pixels reste sous les 3 Mpx/cm², ce qui laisse présager une excellente gestion de la sensibilité.

The adapter is good quality, fits tightly to the body and the lens, and when attached you don't notice it at all. The only issue is the auto focus speed.
It's not slow, it's ridiculously slow. 

Avec un objectif sur lequel on ne peut pas régler le diaphragme mécaniquement, cet adaptateur est inutilisable car il n'y a pas de communication avec le boitier qui affiche F-- de ce fait le diaphragme reste fermé au maximum (F22) et on ne peut pas faire de photo en manuel. 


Shortening the flange focal distance to 18 mm compared with earlier offerings from Sony which used 44.5 mm.
the flange focal distance (FFD):

GPS built-in

Why GPS in cameras is going away?

super slow motion, stacking and image sensor; shoot 1000fps at 1080p; detection and tracking of objects at 1000fps

Feb and May 2017

Sony Announces 1000fps (640*470-4bits) Sensor Stacked on Top of Vision Processor
Sony announces the IMX382 high-speed vision sensor, which enables detection and tracking of objects at 1,000 fps. Sony begins sampling it in October 2017.
Sony shows off 3-layer stacked smartphone image sensor that can shoot 1000fps at 1080p and 60fps 4K.

The new 20MP 1/2.3-inch sensor minimizes the rolling shutter distortions by providing a 8.33ms-fast readout of the full 20MP of the sensor into the internal 1Gb DRAM.


XBOXOneX caractéristiques et détails techniques GPU

Xbox One X est la nouvelle console produite par Microsoft, qui sera capable d’afficher des jeux en 60 FPS/4K native sur votre téléviseur et sera capable de prendre totalement en charge la Réalité Virtuelle. La firme américaine profitera d’ailleurs de l’E3 2017 (Jun 13, 2017 – Jun 15, 2017) pour +.

60 FPS/4K signifie une définition de 3 840 × 2 160 pixels à 60image/s et 8bit/pixels.
pas le format 4K-cinéma (4 096 × 2 160 pixels) utilisé en cinéma numérique.

La console embarquera un processeur basé sur l’architecture Jaguar, avec huit coeurs cadencés à 2,3 Ghz. Elle accueillera pas moins de 12 Go de mémoire GDDR 5 : 9 Go seront alloués aux jeux, et 3 Go au système d’exploitation de la Xbox One X.

Son GPU, ou circuit graphique, se rapprochera de celui d’une Radeon RX480. Sa puissance de calcul devrait lui permettre de faire tourner les jeux actuels en 4K dans d’excellentes conditions.

Les caractéristiques techniques de la Xbox Scorpio en détails :

  • CPU à architecture Jaguar (8 coeurs cadencés à 2,3 Ghz)
  • 12 Go de mémoire vive de type GDDR 5 (6,8 Ghz, 386 bits)
  • GPU similaire à la RX 480 (1172 Mhz, 40 unités de calcul, prise en charge de DirectX 12, 6 Téraflops théoriques)
  • 320 Go/s de bande passante
  • Disque Dur 1 To (2,5 pouces)
  • 4K native
  • Lecteur Blu-Ray 4K UHD

La Xbox One X coûterait 499€ lors de sa sortie prévue le 7 novembre 2017.

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