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SZ Viewer A1: Google Play statistics (2022-2023)

Today's install base of SZ Viewer A1 [for Android] (the difference for the year).

Belarus: 282 (-118)
China: 8 (+7)
Eritrea: -
Iran: 9 (-11)
Mali: -
Nicaragua: 6 (-4)
Russia: 10647 (-2632)
Venezuela: 39 (0)
Zimbabwe: 2 (+1)

Other 168 countries/regions: 20094 (+3206)

All 177 countries/regions: 31087 (+449)

These are Google Play statistics: The number of active Android devices on which the app is installed. An active device is one that has been turned on at least once in the previous 30 days.


NE555 pulse generators (now 4 samples)

I already had two NE555 pulse generators to improve the work of the Suzuki Jimny's automatic transmission in the low range of the transfer case. I added two more samples.

I have not yet decided which one to use for further experiments.


Holga HL(W)-SSN 29/8: on the full-frame camera

I was playing with the Holga Holga HL(W)-SSN (29/8) toy lens on my Samsung NX cameras. I wanted to use a homemade adapter from NX to Sony FE (for my Sony a7c camera), but the adapter appeared to be too bad. Instead, I managed to mount the lens with the tail of some Sony FE extension tubes. I just fixed it with duct tape masking tape. 

But the thickness of this tail is less than required (25.5 - 18 = 7.5mm), so the Holga's focusing ring is set to the closest distance. This caused the optics to move away from the rear "sieve" aperture plate, making the vignetting more visible at infinity.

And of course the vignetting is very heavy on the full-frame sensor.

Some photos: 1.5 crop (APS-C) and full-frame images.

See also related notes:


All-wheel drive and viscous coupling unit

At one time viscous coupling units were one of the key factors in the development of all-wheel drive systems, allowing them to be introduced into on-road vehicles.

The torque (M) transmitted by the viscous coupling unit is sensitive to the difference in speeds of the input and output (Δn) and to the temperature (υ).

(some viscous coupling unit)

So the application of the coupling in all-wheel drive has been a two-way thing. In the more advanced case, it was used in conjunction with a conventional (inter-axle) differential to lock it automatically. In the more budget-friendly case, the viscous coupling was a substitute for the inter-axle differential, allowing the second axle to be engaged on-demand.

Applications in conjunction with the differential were found in both on-road and off-road vehicles. The application as a differential replacement is more the domain of relatively inexpensive, but still all-wheel-drive road cars.

It is interesting that the first generation Jeep Grand Cherokee (ZJ) had both options: first (1993-1995) the viscous coupling was used in Quadra-Trac system as automatic locking of differential, and then (1996-1998) the viscous coupling was used to engage the front axle on-demand. And it turned out to be "the complete opposite". The first version of the system was more suitable for the roads (because of the lack of manual inter-axle differential lock, viscous coupling can not ensure it), and the second one for off-road (because of the presence of a forced lock, if you do not forget to activate it by switching to 4Lo).

It is also possible to remember the four-wheel drive systems of other manufacturers as well.

There were also some odd experiments. For example, Honda INTRAC (1988-1995) used two viscous couplings in the rear axle, which both replaced the rear and inter-axle differentials.

Then it was clear that viscous couplings would become obsolete, despite their simplicity. They had many drawbacks: lack of control, slow, even unpredictable operation, a tendency to overheat, and low reliability.

There were attempts to replace the viscous coupling with an automatic hydraulic control clutch: for example, Honda Dual Pump, and Quadra-Trac II/Quadra-Drive on the second generation Jeep Grand Cherokee (WJ/WG). However, it was not further developed.

As expected the electronically controlled coupling has won. It is the basis of the majority of modern four-wheel drive systems, up to extremely exotic implementations such as Active Drive 2/Active Drive Lock on Jeep Cherokee (KL).

But the viscous coupling continues to be used in all-wheel drive systems. These are mostly cheap JDM cars where economy is important (Kei cars and so on), but the presence of all-wheel drive is significant. 

Suzuki, for example, still uses them today.

But I was more surprised that such a system of all-wheel drive is used in the current Honda Fit, including a rather advanced e:hev version. 

Although the similar (in technology) Nissan Note e-power uses a dedicated electric motor for rear-wheel drive.

But, of course, in some situations, it is better to have all-wheel drive with a viscous coupling than just two-wheel drive.


Pentax K-1 or Sony a7c for Pentax K/M lenses?

Since I have mostly Pentax K/M lenses, it makes sense to use a native Pentax K-1 [Mark II] full-frame camera instead of the Sony a7c I chose. 

But there are reasons against it.

1. Pentax K-1 is very large and twice as heavy as the Sony a7c.

I already had a negative experience with Pentax K10D. It was bigger than my previous Pentax *ist Ds, so I used it much less. And the K-1 is even bigger and heavier than K10D.

2. In practice, you can mount only Pentax K and M42x1 lenses on the K-1. And the adapter for M42x1 is awkward. While I also want to use M39x1 rangefinder lenses (too short flange focal distance for Pentax K) and Nikon F (no glassless adapter for Pentax K) lenses.

3. The Live View mode on the rear LCD screen solves manual focusing problems, but the optical viewfinder doesn't provide as much accuracy as an electronic viewfinder (with magnification of a selected focus area, and in-body image stabilization).

4. Pentax K/M series lenses (i.e. without the "A" position of the aperture ring) work only with the fully open aperture in Av mode of K-1. To close the aperture (via the lens diaphragm actuator) while shooting you need M mode, where you have to do manual metering by pressing the "green" button (without AutoISO, while TAv mode is not available as far as I know). Whereas a Pentax K pre-set like adapter (with aperture control ring) in Av mode of Sony a7c (with AutoISO if desired) is more convenient for me.

5. Pentax K-1 [Mark II] is more expensive than Sony a7c. It's reasonable, but it doesn't satisfy me.

I like the K-1's sensor movement capabilities: Pixel Shift, Composition Adjustment, ASTROTRACER.

Still, I chose the Sony a7c as a compact and, importantly for me, mirrorless (short flange focal distance, EVF) camera.


Nokia mobile phones (August 2006, in Russian)

The catalog of Nokia mobile phones (in Russian language), August 2006.


SD Memory Card Formatter

I did not know that there is an official utility to format SD/SDHC/SDXC cards: SD Memory Card Formatter

There are no more details on how this formatting is better than formatting with OS or a mobile device. At least the cluster size is chosen automatically. In earlier versions there was the "format size adjustment" option. In the latest version it is enabled by default.

The "CHS Format Size Adjustment" option is available in the Windows version only. And only for cards with the user capacity not exceeding 8422686720 bytes (255 heads x 63 sectors per track x 1024 cylinders x 512 bytes per sector).

Image albums:


My Pentax lenses (+Takumar)

All my Pentax (K Mount) lenses and one Takumar (M42x1). 

1. 28-55mm range (wide and normal prime lenses).

From left to right: Pentax K 28/3.5, K 30/2.8, K 35/3.5, K 50/1.4, A 50/1.7, M 50/4 Macro, K 55/1.8.

These are my preferred lenses, inexpensive, good, and quite compact.

The Pentax K 30/2.8 wasn't particularly interesting for me on a APS-C (x1.5 crop) frame sensor. But on the full-frame sensor it shows its traits.

Also I was looking for a replacement for Индустар-61Л/З (Industar-61L/Z) 50/2.8. I looked at Волна-9 (Volna-9) 50/2.8, but accidentally chose Pentax M 50/4 Macro. And I have no regrets about it, I really like this Tessar-like lens (on full-frame).

2. 100-200mm range (long-focus prime lenses).

From left to right: Pentax M 100/4 Macro, Takumar (Pre-set II) 105/2.8, Pentax M 135/3.5, M 200/4.

Because of the long focal length, I rarely use them.

Pentax M 100/4 M is not as good as modern macro lenses. However, it does have an interesting Heliar optical design. The other three lenses aren't bad either.

3. Takumar 105/2.8 is the oldest, from the early 1960s. Pentax A 50/1.7 is the newest, from the 1980s. The others (K/M series) are from the 1970s. Most of the lenses were bought in 2005-2007. They were waiting for a digital full-frame camera and they got it.

Image albums:


Спрут-9000 (Sprut-9000) history

The Спрут-9000 (Sprut-9000) winch was installed on УАЗ-31512 (UAZ-31512) in 2007. It is kind of like a conventional winch, not an early "home-made" one with a starter motor and an open transmission.

The so-called "big control unit" contained Taiwanese contactors, so it did not cause any problems. But it was really big and looked odd on the front of the car. It was moved under the hood.

I didn't know much about winches at the time, so I chose this option because, firstly, they were available in the shops, and secondly, it was also possible to buy a ready-to-install mounting plate.

(The bottom roller is removed to use a crank "starting" handle)

I can't say it's a terrible winch. But it is very slow. Then I compared it to T-Max 6500 (on Jimny), which was clearly more powerful and much faster. Most likely, this Sprut-9000 has a low power motor, so the claimed force is achieved through the high gear ratio. But because of this and the fact that the current is not very high, even the low output original UAZ alternator was enough (then changed to a more powerful one).

(A more powerful alternator installed with the pulley change)

When I sold the UAZ, I was too lazy to worry about selling the Sprut-9000 separately, and I did not need this winch. So it was sold together with the UAZ (in those days there was no punishment for modifying cars).

And the kept documentation. A winch like this was:

A control unit:

Different types of winch mounting plates:


"Shuttering methods and the artifacts they produce"

I've already mentioned artifacts caused by the electronic front-curtain shutter (EFCS) mode (sometimes called simply e-shutter, although it's not quite correct). And here is an article briefly describing shutter artifacts: "Shuttering methods and the artifacts they produce" (pdf available).

When exposure times were measured in minutes, the opening and closing of the shutter was essentially instantaneous. As more sensitive films and brighter optics became available, exposure times decreased, the travel time of the shutter mechanism became increasingly significant, and artifacts became visible. Perhaps the best-known shutter artifacts are the spatio-temporal distortions associated with photographing moving subjects using a focal-plane shutter or sequential electronic sampling of pixels (electronic rolling shutter). However, the shutter mechanism also can cause banding with flickering light sources and strange artifacts in out-of-focus regions (bokeh); it can even impact resolution. This paper experimentally evaluates and discusses the artifacts caused by leaf, focal plane, electronic first curtain, and fully electronic sequential-readout shuttering.


Moscow, Bryusov Lane (December 2006)

Moscow, Bryusov Lane (11), December 2006.

Pentax *ist Ds DSLR + Pentax DA 14/2.8 lens @ f/5.6

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