I found a pair of beakers (600ml). They are vintage ones from East Germany (GDR/DDR).
Jenaer Glas, Rasotherm.
I already use these beakers for some tasks. But their graduation is rather imprecise.
2024-04-14
2024-04-13
Pentax DA L 18-55/3.5-5.6: Samples [1] - FF
Photos taken with the Sony a7c (FF, 24MP) and the Pentax DA L 18-55/3.5-5.6. Since the lens is designed for APS-C (crop factor 1.5x), it can only be used as a 28-55mm on FF. The aperture was fully open: f/4-5.6 depending on the focal length.
Of course, the profiled lens correction is disabled. And there are no EXIF aperture and focal length data.
See also related notes:
- Pentax DA L 18-55/3.5-5.6: Using on FF (2024-03-19)
- Pentax DA L 18-55/3.5-5.6 (K) (2024-02-15)
Image albums:
2024-04-12
EDTA-Na2: Hose clamps from Jimny
2024-04-11
"Zoom View Finder 1.08-1.60x" magnifier.
The viewfinder of the Pentax K-m is rather poor for manual focusing, especially after mirrorless cameras. I used to use magnifiers on the Pentax DSLRs, but I sold them. So I bought a cheaper alternative called "Zoom View Finder":
It is a universal thing, it includes adapters for SLRs of different manufacturers (and Pentax, of course).
The main feature of the magnifier is the zoom. It is possible to change the magnification factor from 1.08x to 1.60x, as mentioned.
I haven't tried the magnifier yet, because I rarely use the Pentax k-m.
See also related notes:
Image albums:
2024-04-10
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)
2024-04-09
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.
2024-04-08
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:
2024-04-06
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:
Image albums:
2024-04-04
SZ Viewer A1-2024-04-04 (Android)
SZ Viewer (Android) changes:
1. Target API level 34 (Android 14).
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)
2024-04-03
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)
2024-04-02
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:
2024-04-01
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:
Image albums:
2024-03-31
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:
Image albums:
2024-03-30
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.
2024-03-29
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.
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