pag 28
Prompted by Info TV and Cooke Lens and with the co-operation of Molinare, we have tested the Cooke S4 HD zoom. The criteria for the tests were the basics of digital cinematography, the pursuit of the maximum possible quality for digital or analogue projection, with the quality standards set by 35mm as referent. The images included have undergone the normal modifications after going through CMYK.

Technical information:
Sony F-900 Camera with all the options set to preset
Cooke S4 HD Zoom
Wave Monitor /Vectoscope Astro LCD
ESSER TEST CHARTS TE 105 TE 125 TE 166 TE 22 TE 223 TE 106 (Some cards are transparencies lit by an LV5 spherical format)
Resolution, grey and colour HD cards
The outdoor footage was shot at the Deboth temple in Madrid

Luminous uniformity
We tested the lens’ luminous uniformity at different focal lengths and apertures. The only notorious differences occurred when the aperture was at its greatest, F. 1.7.


Shortest lens 8mm T1.7 / 20mm Lens T1.7 / Lens 35mm T1.7 / Lens 46mm T1.7


We see a slight loss of luminosity around the edges of the image that increases with the longer lenses. This optical vignette, just like the natural vignette, is inherent to the lens and its design ( it has to do with its length and the effect of the cos4 lighting law) and it manifests itself in a loss of brightness around the edges of the image. As for the zoom, that loss goes unnoticed and can only be seen on uniform images. That decrease in the brightness of the image is normal and exists within the acceptable limits for a lens of such characteristics. In a lot of cases manufacturers tolerate a certain loss of luminosity to compensate other kinds of anomalies, improving resolution, sharpness and contrast.

We can see that at F 1.7 the luminosity along the sides of the image falls between 10 and 15% with the longer lenses. That loss is hardly relevant in lenses up to 20/25mm.





On an 18% grey card and a grey scale we have seen that at different F-stops and focal lengths the lens maintains its level of luminosity, without observing a “steep” effect. We didn’t observe changes in the size of the image with the change in focus.

Sharpness
We ascertained the absence of spherical anomalies, comma or astigmatism. We saw the excellent sharpness of the image, far superior to that of the ENG lenses although it doesn’t reach the Angenieux Optimo Zoom.



Cooke S4 HD Zoom/ Angenieux Optimo Zoom



Cooke S4 HD Zoom/ Angenieux Optimo Zoom


In the enlargement we can see the Optimo zoom's greater sharpness





In this picture we can see the sharpness of the zoom, which works properly even in foggy conditions such as we encountered the day of the test. In the enlargement we see the lens’ capacity








pag 30
Resolution
Excellent resolution, sufficient for a good theatrical projection. In the images we can see that its far superior to the ENG lens for HD, although slightly lower than the Optimo zoom.



Angenieux Optimo Zoom / Cooke S4 HD Zoom / ENG Zoom


We saw that both the sharpness and resolution characteristics remain constant with different focal lengths and apertures.





In this picture we can see the excellent outlines the lens achieves in a high contrast situation


Contrast
The lens’ response was good with a grey card at a contrast relation of 1:200. In the picture we can see how the lens works with the contrast between the sky, the building and the water’s shine. The outline turns out to be very neat.





Colour
In my opinion the best thing about this zoom is the quality of its colour reproduction, similar to the rest of the S4 lenses for 35mm. It reproduces colours with a very natural aspect, in generally warm tones and a relative contrast. Compared with the Optimo zoom, those tones and the contrast become even more apparent. Furthermore, the correction of colour anomalies on the camera’s prism is excellent, slightly better than that of the Optimo.
In this card we can see the response of the lens to primary and complementary colours. We can see an excellent correction of chromatic anomalies, which are only slightly visible on the blues.




pag 31
Chromatic anomalies are very hard to correct, specially in HD lenses, where the camera’s prism CCD block is present. There are two kinds of chromatic anomalies as we can see in the diaphragms. The lateral anomaly is the hardest to correct on HD.







In this image we can see the lateral colour anomalies characteristic of HD. In the first image we see the green/magenta lines along the very contrasted edges of the lamp. Underneath we have colour graded the same image, where we can see a significant correction of the anomaly.







View of the EBU stripes. We can see a slight tendency of the green towards yellow. The tendency towards magenta is not due to the lens.









Mechanics
The zoom has a very easy handling, as much for focusing as for aperture and focal lengths. Special mention should be made of the Back Focus, very precise and reliable. The lens easily adapts to all kinds of accessories, focus controllers, parasols, etc.

Geometry
We noticed a the appearance of barrel distortion in long lenses. The distortions remain more or less constant along the whole of the zoom's course.

Conclusions
1- Very good luminous uniformity on the image at different focal lengths and apertures. No aesthetic anomalies, comma, or specially notorious vignettes.
2- Very good resolution with excellent sharpness and contrast. The contrast is lower than with the ENG lenses, improving resolution, although the contrast is slightly higher than with the Optimo zoom.
3- Excellent colour reproduction with very good lateral chromatic anomaly correction. Colour reproduction in warm tones.
4- Notorious geometric distortions along the whole of the zoom’s range.
To conclude, I think the Cooke zoom fills in the gap in the market between the Angenieux Optimo zoom and the HD ENG zoom lenses. Given its great quality its advisable for film production for projection purposes, as well as for documentaries and advertising which need very high image quality. Whereas the zoom’s range is a bit short as a tele- (the zoom covers a range of 8-46mm at F-stop 1.7, whereas the Optimo covers 9.7-116mm at 1.6 ) it compensates by being lighter ( 6Kg opposed to Angenieux 11Kg) and shorter.

Technical information
Zoom range • 5.75:1
F-Stop • T1.7 to T16
Maximum f-stop • f 1.46
Aperture scales • Two opposite scales marked in 1/3 Stops
Focus scales • Two opposite scales: metric and feet
Mechanical Back Focus • 48mm (en aire)
Back Focus lens • Colour corrected for the prism 2/3" HD
Back Focus adjustment range • +/- 0.4mm
Closest focus from the front of the lens • 13 in /317mm
Angular rotation from the focus ring • 326 degrees
Angular rotation from the zoom ring • 126 degrees
Maximum covered screen ratio • 11 mm Diagonal
Horizontal vision angle( (16:9 ) • 62 to 12 degrees
Vertical vision angle(16:9) • 36 to 7 degrees
Frontal diameter • 150mm
Parasol size • l6.6 in x 6.6 in
Total distance from the front of the lens to the image plain • 17.05 in / 433mm
Montura • B4 Video
Weight • total 6 kg