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MINOX DC-6311




Office computers have been looking alike since the very beginning. Those who enter texts to computers hardly feel the difference between the two boxes, which differ practically only in brands. Computers, assembled in unified PC cases from unified components. It does not matter where and who assembled them. The higher is the unification, the larger is the circulation. The larger is the circulation, the lower is the price. Individual character of a device used for standard tasks will hardly have a positive effect on its functionality. Standard devices are used by millions of people, and the chances to miss mistakes and fail to correct them are very low. While exclusive samples exist in solitary numbers, and no matter how thorough their development is, the chances to miss a mistake are considerably higher.

Initially all digital cameras were individual and differed much from each other. Now we are entering the epoch when cameras as well as computers differ only by titles on their boxes. They are absolutely the same in appearance and in contents. A new model differs from a previous one in insignificant design modifications and some changes in the stuffing, which have little effect on the final result, as in case of office computers used for entering texts. Admit it, if you type texts on a computer with a 200 MHz processor or 2 GHz processor, the difference is hardly noticeable. And if these processors are installed into identical cases, perhaps you will feel no difference at all.

When you look at this camera, you notice right away its genetic similarity with the previous model MINOX DC-5211. As in the previous case, there exist several dozens of cameras which are actually different only in their names on the housing. Claiming no completeness, I'll give you a list of cameras, which appearance hints at their immediate relationship.

Ai-6330, BENQ DC C60, Genius G-Shot P633 ,Premier DC 6330, Rekam Presto-T60Rollei Prego dp6300 , RoverShot RS-Z60 , ...

One can practically say that there appeared an industrial standard for a digital point-and-shoot camera. According to unofficial data, the ancestor of this standard is Premier Image Technology Corporation. Interestingly, there is no 6 Mp camera DC-6330 on their web site, it features DC-S6 instead. But the design probably depends much on componentry, and the caprioles of fancy of engineers were considerably restricted. It's highly probable that another group of designers would construct the same camera from those elements.

Not to repeat ourselves, let's review the main differences of this model from the previous one.

They are practically identical from the front, differing only in a decorative plate. The same lens, view finder, flash. Considering that decorative elements differ even in the same cameras from different manufacturers, one can say that the camera experienced no changes en face. If you turn on the camera, you will notice that the color of autofocus assist light has changed from red to green. The power on time has changed a little, which indicates that the innards have also suffered modifications.




The time from power on to the first shot is 5 sec. The moment the camera was switched on, the second hand was pointing at the upper mark of the clock dial.

The main changes were introduced to the rear panel.




The display grew to a 2-inch one, in this connection engineers had to modify the location of buttons. If you examine the camera closer, you will see that the side panels in these models are very similar but not identical. So you cannot say that the elements of the previous model are used to assemble this camera.












The camera menu was also modified. Firstly, there appeared a histogram, which can be displayed in camera mode as well as in the playback mode, and the ISO sensitivity range is changed. The new camera offers 50, 100 and 200 ISO.













   

CCD area remained the same, while the number of pixels is increased from 5 to 6 Mp. You will hardly notice the difference on 10x15 or 13x18 photos, especially considering that, as in the previous model, the spreading determined by lens adjustment is quite considerable among different cameras of the same consignment. That is we can easily find a 5Mp camera with a better resolution than 6Mp, and vice versa. Anyway, all cameras meet the requirements set to digital point-and-shoot cameras.

Sensor area change is about 15%. So one can assume that the previous model had its real sensitivity a tad overestimated. If you compare it to large 6Mp matrices, 20x15 mm in reflex cameras, you will notice practically no differences with sufficient illumination. If the illumination is not enough, the 9 times as small sensor area will immediately has its effect. As you can see in the table below, the same noise level in a larger matrix is demonstrated at 400 ISO. These figures may vary depending on the illumination spectrum. However, there is nothing to be done, the noise level is in inverse proportion to the sensor area.




The original image is zoomed 2 times.
  MINOX DC-6311 Canon D60
ISO
Sun
Incandescent light
Sun
Incandescent light
50
114
1,5
109
1,1
103
2,8
113
2,2
116
2,0
111
1,6
129
2,8
89
4,1
100
115
1,9
118
1,6
110
0,8
106
0,7
105
4,4
122
2,9
111
1,7
118
1,1
118
2,5
119
2,4
110
1,1
105
0,9
131
4,3
98
5,9
104
1,3
80
1,7
200
116
2,7
117
2,2
112
1,2
106
1,3
106
5,7
121
3,7
112
1,9
118
1,8
118
3,8
118
3,3
112
1,2
105
1,6
132
5,4
98
8,3
106
1,6
79
2,3
400
111
1,9
110
2,1
111
3,0
121
2,6
112
2,0
109
2,4
106
2,5
85
3,6
800
111
3,3
106
3,7
111
4,7
117
4,6
112
3,5
106
4,3
107
4,2
80
6,3

To my mind, the default settings provide excessive contrast and brightness, which highlight defects instead of enhancing the image. The cameras I tested provided better results when I set contrast and sharpness to minimum in the menu.

The camera is controlled by two dials. The mode dial is located on top, which allows so set a completely automatic mode, Program AE, Aperture and Shutter Priority, Manual. We should note an interesting peculiarity here. ISO is selected individually for each mode. While modifications in other parameters are applied to all modes. Besides, the upper dial allows selecting "scene" modes: portrait, sports, night-time. The same dial sets the video recording mode. Unfortunately, you can change the focal distance only before the recording is started.

The upper dial can also be used to set the camera to playback mode, settings mode, and the transfer mode. Exposure and aperture are selected with a small dial on the side panel. This dial selects exposure and aperture, as well as expocorrection. To switch from exposure control to aperture control, you should press the left arrow on the mini joystick. The up arrow of the mini joystick allows to control the shooting distance: 1m, 3m and infinity, which significantly reduces the interval between the shots and allows not to scare people with your autofocus assist light in case of insufficient illumination.

Manual focus is the only thing, except for the lens, which distinguishes this camera from older and more expensive models. Like film cameras, digital photography has two approaches to focusing. Focusing by the range scale using a tape-measure or a range-finder and focusing based on image sharpness evaluation. One cannot say that the former method is cheaper to implement in digital cameras. By analogy with film cameras, only expensive digital cameras are equipped with visual evaluation systems. Indeed, it's more expensive to use only both methods. There is no need in lens adjustments when evaluating image sharpness on a matrix using hardware (autofocus) as well as visual methods. The only requirement is that lens must move to a distance less than the focal distance, in this case you can accurately focus at infinity objects looking at the display. Of course you will need a magnifier to provide accurate focus, but as the cameras are all equipped with digital zoom anyway, implementation of this feature is up to software and it will not affect the production price of a sample. Focusing by the range scale implies accurate adjustments of lens in each camera to infinity focus. Each camera has to be installed on a testbed and regulated by adjusting screws or by recording the lens position to the camera firmware. The second method is cheaper, but it requires pecking motors, which only have to remember the number of impulses necessary to move the lens to the given position. Autofocus exchangeable lenses for reflex cameras use pecking motors as well as regular ones. While I have never seen an analog motor in a digital point-and-shoot camera. Skilled hands are more expensive than any mass-production device, and their use for only one adjustment procedure is economically unjustified. Though the focusing approach used in this camera requires adjustments, it seems to me that this procedure is ignored. Engineers hope that the technologies will adhere to all assigned tolerances and that absolutely identical cameras will be produced. Let's evaluate the required precision of lens installation.

Depth of field or depth of lens focus is called a distance along the optical axis in the image space, within which limits a given plane retains sharpness. Depth of field characterizes the limits of matrix movements relative to the focal plane of the lens, which do not damage image sharpness. Depth of field in the image space depends only on the aperture ratio of the lens (inversely proportional). That is the complete depth of field of the image is equal to doubled product of the f number by the diameter of the admissible circle of confusion. In our case 2*2,8*6 µm = 34 µm. That is this precision is beyond a slide gauge and so it requires a micrometer calliper.

Let's try and evaluate this limited set of distances from point of view of the depth of field provided by the lens. Let's assume that the admissible circle of confusion is 6µm, as in the previous case. We cannot expect more from this lens and matrix, though some cameras may probably produce better results. Then, if we set the focal distance of the lens to 7.2 µm and completely open the aperture F :2,8, the sharp image will be within the 0.7 – 1.5 m range. With the f number of 4 - from 0.67 to 1.96 m. If we set the distance to 3 m, then with the aperture F : 2.8 the image will be sharp from 1.5 m to infinity. Thus, in case of a wide-angle lens this set of shooting distances is enough to get a sharp image of any object, and you can estimate the distance to an object (1m, 3m or at infinity) faster than any automatics. With the maximum focal distance of 21 mm the completely opened aperture is F :4.7. In this case, when the distance is set to 1 m, we'll get a sharp image at 0.95-1.05 m. If we close the aperture to F :11, then considering the image deterioration due to diffraction, the minimum circle of confusion will be 8 µm already, the depth of field being from 0.8 to 1.24 m. If we set the distance to 3 m, the depth of field will be from 1.83 to 7.47 m. If we set the camera to infinity, the image will be sharp from 4.5 m to infinity. With the f number of 8 the image will be sharp from 8.5 m to infinity. With the f number of 5.6 – from 12 m to infinity.

Thus, in case of a wide-angle lens this set of distances is more than enough to shoot landscapes. In sunny weather and with maximum focal distance you can also leave the autofocus alone when shooting objects farther than 2 m. In macro mode or close-up portrait you will have to rely on autofocus. If you want to evaluate the depth of field for objects at a given distance on your own, you may use the program slightly adapted for this camera.

Changes in Version 1.4:

Modified initial parameters of admissible circle of confusion, focal distance, and aperture.

Added evaluation of the admissible circle of confusion by the matrix size and pixel number, or by the desirable photo size assumed that the photo is printed by a sublimation printer or on a 12 dpm photo paper. Click the question mark in the upper right corner to evaluate the admissible circle of confusion. To obtain a correct value you have to make a selection in the upper and one of the two bottom drop down menus. The upper menu sets the frame size, the next menu sets the number of pixels in a matrix, or the AgBr option which assumes an average film quality with a relatively good lens. If you set the frame size to 36x24 mm and select the AgBr option, the program will display parameters close to those on Industar type lenses. The bottom drop-down menu sets the photo size. Use this menu if your camera offers a lot of megapixels but you are not going to print large photos.

Photo

Miniature
Fragment






ISO-100; F=7 mm; F/6.7; 1/380 s. Focused at infinity.






ISO-100; F=21 mm; F/8; 1/280 s. Focused at infinity.






ISO-50; F=21 mm; F/5.6; 1/125 s.






ISO-100; F=7 mm; F/5.6; 1/175 s.






ISO-100; F=10 mm; F/4.8; 1/100 s. Focus – macro.






ISO-50; F=7 mm; F/5.6; 1 s. Focused at infinity.






ISO-100; F=21 mm; F/4.7; 1/140 s. Focused at infinity.
The last photo can be compared with the photos taken by various cameras and published in the article MICROTEK ArtixScan 120 tf

Conclusion

This camera can be considered a model of industrial standard. If you see it in the street, you will easily guess that it's a camera, but you won't know what name is written on it. Digital point-and-shoot cameras are hardly different from their film counterparts in quality and price. The largest manufacturers of photo paper mastered printing from digital sources. An increasing number of labs offer this service. If an amateur prints photos in studios on 10x15 postcards, it makes no difference what camera (digital or film) he or she owns. Paper plant capacities will not stand idle either even if all people switch to digital cameras. To my opinion, the service life of cameras of this generation will depend on their technical reliability. Obsolescence factor stops playing the deciding role. Though some companies install 8 Mp CCD into this case, the resulting cameras have no real advantages over 5 Mp cameras. Moreover, the adjustment scatter will play the determinant role, and there will be 5 Mp cameras of a better quality than 8 Mp ones. But most importantly, for printing 10x15 photos the only advantage of matrices higher than 3 Mp is that the circle of confusion covers several sensor elements with different filters. So if you convert an 8 Mp photo into 3 Mp, each point will boast of true brightness and true color. We'll get an original counterpart of cameras with Foveon matrices, which have 3 million point frames formed by 9 million sensor elements.


December 22, 2004
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