Pentax K 50/1.4: Samples [1] - FF - f/1.4

Photos taken with the Sony a7c (FF, 24MP) and the Pentax K 50/1.4 at f/1.4.

(I'm not sure if it's f/1.4)

Image albums:

• Pentax K 50/1.4

My "boss key" utility [DOS, 1994-1995]

In the winter of 1994-1995 I wrote a small utility to implement a universal "boss key" for [MS]-DOS.

After execution the utility terminates and stays resident (TSR). But you can press F12 at any time to quickly display the black screen and pause the current process. Then pressing F11 resumes the process and returns its screen. The purpose, of course, was to play DOS games on a public PC.

Sounds like a simple task, but it required some know-how on my part.

Normally, the INT 09h (IRQ 1, keyboard) handler should be installed to process pressed keys. But there are some DOS games that block this possibility: they set their own INT 09h handler and don't call the previous one, so the utility doesn't know about pressed keys.

So in version 1.0 (1994-12-23) I tried a workaround, instead of INT 09h the utility handles INT 10h (video services). To scan the keyboard, the utility reads port 60h (keyboard) in the handler.

But this was not enough to get a fast and stable response to the F12 key. In version 1.1 (1995-01-28) the utility mainly handles INT 08h (IRQ 0, hardware timer) and scans the keyboard port in this handler. This worked well for many games.

(the utility written in assembler)

The next task was to hide the process screen. I chose a simple but effective solution. When the F12 key is pressed, the utility sets (via INT 10h) all 256 DAC color registers to black (0, 0, 0) level. This means that the displayed data remains on the screen, but because of this black palette, it looks like the black screen. This required only 256*3 bytes to store the previous palette instead of storing all screen data in RAM.

The utility also mutes the PC speaker (61h port) and then waits in a loop for the F11 key to be pressed. This pauses the current process. When the F11 key is pressed, the values of the DAC color registers are restored to display the screen and the handler terminates to resume the current process.

This utility was very useful until Windows OS (95 and so on) came along.

Image albums:

• History

EDTA-Na2: Bolts from Jimny body

There are two bolts from the body of my Suzuki Jimny Sierra. Both were in the same state of rust.

One of the bolts (on the left) I cleaned only with some petroleum solvent. The other one (on the right) I cleaned with EDTA-Na2 solution.

Looks like there is some bluing (black oxide) on the bolt after EDTA-Na2. I hope this will protect the bolt from rust (red oxide).

See also related notes:

• Replacing the fuel filler neck [Jimny] (2024-04-18)
• EDTA-Na2: Hose clamps from Jimny (2024-04-12)

Image albums:

• Suzuki Jimny

Samsung NX 10/3.5 Fisheye: Samples [1] - APS-C

Photos taken with the Samsung NX20 (1.5x crop factor, 20MP), the Samsung NX500 (1.5x crop factor, 28MP), and the Samsung NX 10/3.5 Fisheye at f/3.5. The profiled lens (distortion) correction is disabled.

(NX20)

(NX20)

(NX20)

(NX20)

(NX500)

(NX500)

(NX500)

See also related notes:

• 10-16-20-30: объективы Samsung NX, новый NX 10/3.5 FE (2014-02-06)

Image albums:

• Samsung NX 10/3.5 Fisheye

SZ Viewer A1-2024-04-04 (Android)

SZ Viewer (Android) changes:

1. Target API level 34 (Android 14).

See also related notes:

• Nokia 5.3 (2025-01) (2025-01-29)
• Nokia 5.3 (in 2024) (2024-04-26)
• SZ Viewer: общая информация (2014-02-15)

Low ISO emulation through image averaging

In my opinion, the global shutter of a full-frame sensor is a great innovation for consumer digital cameras. I would like to see the next big step towards low ISO support.

Digital cameras already emulate low ISO with hidden positive exposure compensation, but it is rather useless because of possible highlight blowouts.

My reasons for using low ISO:

1. With very fast lenses.

2. For motion blur.

3. To increase the signal-to-noise ratio.

What are possible solutions?

Sony a9 III shortest shutter speed is 1/80000. According to the Sunny 16 rule, this is enough for f/1.0 and slightly faster lenses even at native ISO250 ( (1/250 * 1/((16/1)^2) = 1/64000, calculated shutter speed for ISO250 and f/1.0). Practically, I think 1/80000 is enough even at f/0.7.

For two other purposes, I would like to see low ISO emulation through image averaging. In this mode, the photographer chooses the emulated shutter speed. This speed is the sum of several cycles with a shorter shutter speed (of the global shutter). The number of cycles depends on the native ISO and the emulated ISO ratio. For example, ISO25 is emulated by 10 cycles at ISO250, so the shortest emulated shutter speed is 1/80000 * 1/10 = 1/8000.

The captured images are averaged to produce the final image. This increases the signal-to-noise ratio and can create the desired motion blur effect. When shooting in raw, the number of bits per sample can also be increased.

Obviously, the delay between cycles should be as short as possible in order to use this emulation without intermediate image alignment and transformation. And also as stable as possible to get an adequate motion blur effect.

See also related notes:

• Sony a9 III: Full-frame with global shutter (2023-11-13)
• Камера Nokia 5.3 и уменьшение шумов слабых матриц (2022-05-09)

Auto-Takumar 105/2.8 (M42x1): 4/4 generation

There are two generations of the Takumar 105/2.8. The first generation consists of 4 elements in 4 groups and the second generation (and also the Pentax 105/2.8) consists of 5 elements in 4 groups (with the rear two elements cemented).

I already have the Takumar 105/2.8 (Pre-Set II), which is the second (5/4) generation. And recently I bought the Auto-Takumar 105/2.8.

This is a lens from 1959-1961 (or, maybe, 1959-1963). As far as I know, earlier versions were marked as "1:2.8 f=105mm", so this one ("1:2.8/105") is later.

The Auto-Takumar 105/2.8 is optically the same as the Takumar 105/2.8 (Pre-Set I):

So its optical design is 4 elements in 4 groups (without cemented elements).

The filter thread size is 49mm (while the Pre-Set Takumar has 46mm).

The aperture has 8 blades.

This lens is called Auto-Takumar because of its special aperture control. Under normal conditions, the aperture is controlled directly by the aperture ring (with click stops at f/2.8, f/3.3, f/4, f/4.8, f/5.6, f/6.7, f/8, f/9.5, f/11, f/16, f/22).

However, the aperture mechanism can be manually cocked with the lever on the lens to fully open the aperture (for easier focusing).

During shooting, if the camera supports it, the small (stop-down) pin is pressed to close the aperture to the set value.

Then cock the lens lever again to repeat the cycle.

Despite the name Auto, this is semi-automatic, as opposed to the later fully automatic aperture control lenses called Super-Takumars and so on.

This semi-automatic aperture control is completely useless in modern use with an M42x1 adapter. If an adapter keeps the small pin pressed, it is impossible to cock the lever. If an adapter doesn't push the small pin, you can cock the lever, but the lens should be removed to manually push the small pin to close the aperture. So the only way is to control the aperture directly with the ring without using the lever. Of course, the pre-set versions (both generations) are much more convenient to use with an adapter.

So, now I have two generations of the Takumar 105/2.8:

(The Auto-Takumar and the Pre-Set Takumar)

And I can compare 4/4 and 5/4 optical designs of 105/2.8!

See also related notes:

• Auto-Takumar 105/2.8: Samples [1] - FF - f/2.8 (2024-08-05)
• Takumar 105/2.8 series: 4/4 vs 5/4 designs [1] (2024-05-18)

Image albums:

• Auto-Takumar 105/2.8
• Takumar 105/2.8 (II)

Staeble-Telexon 135/3.8: Samples [1] - FF

Photos taken with the Sony a7c (FF, 24MP) and the Staeble-Telexon 135/3.8 at f/3.8.

See also related notes:

• Staeble-Telexon 135/3.8 (M39x1/44): The lens for the Braun Super Paxette II (2024-03-26)

Image albums:

• Staeble-Telexon 135/3.8

Ibanez active bass guitar: Power consumption

For a test I have an Ibanez active bass at my disposal. This bass guitar is powered by a PP3 (9 Volt, 6F22) battery. 

I wanted to measure the current draw under different conditions, so I connected an ammeter between the guitar and the battery.

When the audio jack is plugged into the guitar, the current is about 1.3 mA in standby mode. Hmmm, I expected a lower value. Turning any knob doesn't change that. During playing the current increases to 1.4-1.5 mA.

There is no explicit power switch. The only way to reduce the current to zero is to unplug the audio jack from the bass. I have heard this before and it is true, there is an internal power switch in the guitar jack socket. When the audio jack is unplugged, the current is 0.

Conclusions:

1. There is not much difference in power consumption between playing and standby.

2. Turning down the volume doesn't help reduce standby power.

3. Unplug the audio jack from the bass to conserve battery power.

See also related notes:

• Greenlee DM-210A - малоизвестная модель мультиметра семейства Brymen BM25x (2018-03-26)

Image albums:

• Electronics

Ricoh GR III HDF and Ricoh GR IIIx HDF

New Ricoh GR III HDF (with 28mm equivalent lens) and Ricoh GR IIIx HDF (with 40mm equivalent lens) are announced.

(Ricoh GR III HDF)

(Ricoh GR IIIx)

This is a minor update to the GR III/GR IIIx. The main difference is the replacement of the built-in Neutral Density (ND) filter with the built-in Highlight Diffusion Filter (HDF).

Like the ND filter before it, the new HDF can be activated very quickly with the push of a button.

How HDF works:

(without HDF, source)

(with HDF, source)

It is nice and unusual, but I prefer another kind of update. I would like to see a more dust-proof design, since dust on the sensor is the main problem with the GR series cameras.

See also related notes:

• From Ricoh GR to Ricoh GR III? (2023-08-02)

Image albums:

• Ricoh GR

Wiper/washer lever for my Jimny Sierra

Above is the stock wiper/washer lever from my Suzuki Jimny Sierra (2005, JDM, see also about location of levers on a steering column) that is part of the combination switch 37400-76J20. Below is a used wiper/washer lever from a Toyota Corolla Runx NZE12x (2004, JDM, bought for $1 some time ago).

The main difference is the knob that controls the delay between cycles in the intermittent mode of the front wiper. There is no knob on the stock Jimny lever.

With a little modification it is possible to install the Toyota lever on the Jimny. As I checked, even without modifying the electrics (just changing the cover) it works well, except for the intermittent mode of the rear wiper (which is also missing on the stock Jimny wiper).

I wanted to install the Toyota lever, but I am satisfied with the stock lever and nowadays I prefer stock parts. So I changed my mind and put the stock lever back on the Jimny.

See also related notes:

• Праворульные подрулевые переключатели: JDM или UK? На примере Suzuki Jimny и Jeep Cherokee (2020-01-01)

Image albums:

• Suzuki Jimny

Vivitar 85/1.8: Samples [1] - FF

Photos taken with the Sony a7c (FF, 24MP) and the Vivitar 85/1.8 at f/1.8.

See also related notes:

• Vivitar 85/1.8: дополнительная информация (2022-05-08)

Image albums:

• Vivitar 85/1.8

Staeble-Telexon 135/3.8 (M39x1/44): The lens for the Braun Super Paxette II

I bought a broken Braun Super Paxette II BL camera, but the purpose of the purchase was the four lenses that came with the camera. One of them is the Staeble-Telexon 1:3,8/135.

This is a lens from the 1960s.

As expected, the Telexon has the M39x1 mount with the flange focal distance of 44mm, it is indeed for a Braun camera. And it has a rangefinder coupling.

The minimum focusing distance is quite long, just a bit less than 3m.

The optical design of the lens is known. It has 4 elements.

And two front elements are cemented.

The optical design is similar to the Wrayflex Lustrar 90/4:

The aperture has 10 blades:

The aperture ring has click stops at f/3.8, f/5,6, f/8, f/11, f/16, f22.

The filter thread is 52mm, it is easy to find a suitable cap. And while I am used to very compact Staeble lenses (35mm, 85mm), this Telexon is quite long.

The Telexon 135/3.8 (on the right) and the Pentax M 135/3.5 (on the left):

Unfortunately, this copy of the Telexon is not in good condition. There was fungus on the optical elements. I removed the fungus, but its imprint is still visible. Maybe the lens coating is damaged or the fungus has even etched itself into the glass. However, that doesn't stop me from using the lens.

See also related notes:

• Staeble-Telexon 135/3.8: Samples [2] - FF - f/3.8 (2025-04-09)
• Meyer-Optik Helioplan 40/4.5 (M42x1/45.5): Simple dialyte lens (2024-05-09)
• Steinheil Quinon 50/2 (M39x1/44): "Planar" version (2024-05-02)
• Staeble-Lineogon 35/3.5 (M39x1/44): Retrofocus evolution of a triplet (2024-04-27)
• Staeble-Telexon 135/3.8: Samples [1] - FF (2024-04-01)

Image albums:

• Pentax M 135/3.5
• Staeble-Telexon 135/3.8
• Staeble-Telexon E 85/5.6

K&F Concept Pro: Nikon F - Sony FE/E adapter

Fotga adapters are pretty good for the money, but the Fotga Nikon F - Sony FE/E adapter has lens play due to a poor locking mechanism. And the adapter length is too short, based on using my two Nikon F lenses, both of which focus beyond infinity.

I thought about another non-Fotga adapter, but they were too expensive. But by chance I bought a used Nikon F - Sony FE/E adapter (made by K&F Concept) for a good price.

It is a simple adapter from the "Pro" series.

The adapter has no aperture control (neither does the Fotga adapter). However, the mentioned lenses don't need it and don't provide it.

The Fotga adapter (on the left) and the K&F adapter (on the right):

The most important thing is that the length of the K&F adapter is correct. I checked the Vivitar 85/1.8 lens and now it has the hard stop focusing at infinity. This means that the KIWIFOTOS LMA-NK_NX adapter (for Samsung NX) was too long and the Fotga adapter (for Sony FE/E) was too short (as I suspected).

Meanwhile, the Mitakon [Zhongyi] Creator 85/2 still focuses beyond infinity, apparently the lens is not properly adjusted at the factory. I have tried to find a way to adjust the focus myself, but have not yet found it.

See also related notes:

• Mitakon Creator 85/2 II: Pentax K mount (2025-07-07)
• Mitakon Creator 85/2 II vs Vivitar 85/1.8 (2023-04-11)

Image albums:

• Lens accessories

Filtron OP621: Oil filter (still in use)

I still use Filtron OP621 and Blue Print ADK82102 oil filters for the M-series Suzuki engines (including the M13A in my Jimny Sierra).

But I prefer the OP621 between the two:

Simply because the oil filter wrench JTC 1114 (65mm/14) fits well.

See also related notes:

• Масляный фильтр Blue Print ADK82102 (2020-03-30)
• Масляный фильтр Filtron OP621 (2020-03-14)
• Съемник/ключ для масляного фильтра JTC 1114 (14 граней, 65 мм) (2015-03-27)

Image albums:

• Oil filter