Filter thread: 40.5x0.5 vs 40.5x0.75

There are two main kinds of 40.5mm filter threads.

1. 40.5mm with 0.5mm pitch (40.5x0.5)

This is an old and quite popular thread in the past for rangefinder film camera lenses. I have several lenses with 40.5x0.5 filter threads: the Industar-26M, the Steinheil Quinon 50/2, the Meyer-Optik Helioplan 40/4.5, the Staeble-Lineogon 35/3.5.

2. 40.5mm with 0.75mm pitch (40.5x0.75)

This is a thread of modern compact lenses. My Olympus M.Zuiko Digital 14-42/3.5-5.6 has this filter thread.

However, if you want to buy a modern lens accessory with a 40.5mm filter thread mount, it is quite difficult to determine its thread pitch (0.5 or 0.75) in advance.

For example, there are both versions of 40.5mm-52mm filter step-up adapters. But sellers don't know the exact pitch of the adapter they sell.

These are my two 40.5mm-52mm adapters (Noname, made in China):

The left one is 40.5x0.75, the right one is 40.5x0.5. Both have no pitch information.

The 40.5x0.75 adapter is mounted on the Steinheil Quinon 50/2, only one rotation is possible due to the wrong pitch:

While the 40.5x0.5 adapter fits well on the Steinheil Quinon 50/2:

The good thing is that the 52mm filter thread has a 0.75mm pitch for old and new lenses/accessories. So with these 40.5mm-52mm adapters I can use very old and very new filters.

See also related notes:

• Carl Zeiss Jena Triotar 80/4 (M40x1): Long-focus uncoated (non-T) triplet lens (2025-08-07)

Image albums:

• Lens accessories

Viltrox AF 20/2.8: Samples [1] - FF - f/2.8

Camera: Sony a7c (FF, 24MP)

Lens: Viltrox AF 20/2.8 at f/2.8

The profiled lens (distortion/vignetting) correction is disabled.

See also related notes:

• Viltrox AF 20/2.8 (FE): Ultra wide angle autofocus lens (2024-08-31)

Image albums:

• Viltrox AF 20/2.8 FE

External optical viewfinder (35mm)

A modern external optical viewfinder (35mm FOV):

For mounting in a camera shoe.

It is made in China and quite cheap. Expect it to be all plastic. I think even the optical elements are some kind of plastic.

I tried it a little. Unfortunately, while the image is quite good, the frame limit is not clear, it depends on the position of the eye relative to the viewfinder.

Also, it is difficult to mount the viewfinder in the shoe of some old cameras. It looks like the adapter part of the viewfinder is too wide.

See also related notes:

• External optical viewfinder (35mm): Accuracy (2024-10-11)

Image albums:

• Photo

Far Manager vs Midnight Commander: Keyboard shortcuts

For many years I used file managers with two-panel (usually text-based) user interfaces. Starting with the classic Norton Commander,  then Volkov Commander, File Commander/2 (for OS/2), and even muCommander (for macOS).

And today I still use Far Manager (for Windows) and Midnight Commander (for Linux).

I have prepared a keyboard shortcut memo for frequently used actions.

Far Manager vs Midnight Commander

Find file (in tree):  Alt-F7 vs Meta-?

Find file (in panel): Alt+... vs Meta-s (or Ctrl-s)

Paste panel path: Ctrl+[ (left) Ctrl+] (right) vs Meta-a (active) Meta+A (inactive)

Paste file name: Ctrl+Enter vs Meta+Enter

Paste file path+name: Ctrl+F vs Ctrl+Shift+Enter

Previous command: Ctrl+E vs Meta-p

Next command: Ctrl+X vs vs Meta-n

Command history: Alt+F8 vs Meta-h

Directory history: Alt+F12 vs Meta+H

File attributes (chmod): Ctrl+A vs Ctrl-x c

Change another panel to the same directory: Alt-F1/F2 and select disk vs Meta-i

Reread/refresh panel: Ctrl+R vs Ctrl+r

Show directory size (short): F3 vs Ctrl+Space

Show directory size (detail): Ctrl-Q vs Ctrl+x i

Hide panels: Ctrl+O vs Ctrl+o

To enter Meta combinations, I prefer to use the Esc key instead of the Alt modifier key. 

Also, Esc followed by a number key ("1", "2"..."9", "0") works as F1-F10 in Linux. This is very useful for those awful modern notebook keyboards.

Steinheil Quinon 50/2: Samples [2] - FF - f/2

Camera: Sony a7c (FF, 24MP)

Lens: Steinheil Quinon 50/2 at f/2

See also related notes:

• Steinheil Quinon 50/2 (M39x1/44): "Planar" version (2024-05-02)

Image albums:

• Steinheil Quinon 50/2

Viltrox AF 20/2.8 (FE): Ultra wide angle autofocus lens

Without a fisheye lens, the widest lens I own for FF has a focal length of 28mm (the Pentax K 28/3.5). My experience with the Pentax DA 14/2.8 (for APS-C, 21mm equivalent) and the Samsung NX 16/2.4 (for APS-C, 24mm equivalent) has shown that I generally do not need such a wide angle. But sometimes there are tasks where an ultra wide angle lens (24mm or wider) could be useful.

I would prefer an old manual focus 20mm/24mm lens made for film cameras, but they are too expensive and the image quality is usually not very good. So I decided to buy a modern, inexpensive autofocus lens (for Sony FE). This is the Viltrox AF 20/2.8 FE.

It costs me about $110. And it is my second autofocus lens for Sony (after the Samyang AF 25/2.8).

The Viltrox AF 20/2.8 is quite compact (for 20mm) and light. The filter thread is 52mm.

The lens has 10 elements in 8 groups:

The aperture has 7 blades.

The maximum magnification is 0.17x (as mentioned, I didn't check it).

It comes with a removable hood (PL-56).

But in my opinion the hood is impractical and useless. So I removed it from the lens and don't use it at all.

Overall, it is a nice lens. It works well. The image quality is also good (as expected for a modern lens). 

See also related notes:

• Viltrox AF 20/2.8: Firmware update (V1.1.2) (2024-11-16)
• My AF lenses for Sony FE (2024-10) (2024-10-07)
• Viltrox AF 20/2.8: Samples [1] - FF - f/2.8 (2024-09-08)

Image albums:

• Viltrox AF 20/2.8 FE

Kenda 28/29x1.9-2.35 tube

After the tire (and the inner tube) got punctured, I glued the tube and bought a spare inner tube.

This time it is a rather heavy Kenda 28/29x1.9-2.35 tube. It weighs 256 grams by my measurement. While the Kenda 29x1.9/2.3 Super Lite weighs about 178-188 grams.

See also related notes:

• 29x2.1 wheels: First puncture (2024-08-07)
• Kenda 29x1.9/2.3 Super Lite tubes (2024-06-05)

Image albums:

• Bicycle

Angarsk: 4 photo cards from around 1966

A set of Angarsk photos of unknown origin from around 1966 (or later): 4 photos.  And there are also my photos of the same places (August 2024).

Disclaimer: My photographs are nothing more than a documentation of reality.

1.

This is a standard architectural project of a school of that time. There are several very similar schools, but the surrounding objects are different from the picture. The reason is simple: the picture is horizontally mirrored.

The right version:

2. 

The movie theater helps to determine the time period.  There are two movie posters:

"Девушка из джунглей": Das Mädchen aus dem Dschungel/The girl from the jungle (East Germany).

"Стряпуха": Stryapukha/The cook (USSR).

Both movies were released in the USSR in 1966. See also the set of photos from 1966 (or later).

By the way, today there is no movie theater in the building for many years.

3

. 

4.

See also related notes:

• Angarsk: Set of 10 photo cards from around 1966 (incomplete) (2024-08-08)

Image albums:

• Angarsk

My triplet lenses (2024-08)

These are triplet (3 element) lenses that I own:

From left to right:

Anastigmat Victar 50/2.9 (M40x1/44)

Staeble-Werk Choro R 35/4.5 (M39x1/44)

Staeble-Kata E 45/2.8 (M39x1/44)

ISCO Iscovitar 50/2.8 (M42x1/45.5)

See also related notes:

• Staeble-Kata E 45/2.8 (M39x1/44): Standard triplet for Braun Super Paxette II (2024-06-24)
• ISCO Iscovitar 50/2.8 (M42x1/45.5): Triplet with simple focusing mechanism (2024-05-21)
• Staeble-Werk Choro R 35/4.5 (M39x1/44): Very rare wide-angle triplet (2023-10-05)
• Anastigmat Victar 50/2.9 (M40x1): Uncoated triplet from 1940s (2023-07-24)

Image albums:

• ISCO-Göttingen Iscovitar 50/2.8
• Staeble-Werk Choro R 35/4.5
• Staeble-Kata E 45/2.8
• Victar 50/2.9

SZ Viewer A1-2024-08-26 (Android)

SZ Viewer (Android) changes:

1. Faster "Clear DTC Code" action in the "DTC" tab.

2. Support for D13A engine control module (1.3 DDiS, Suzuki Swift AZG413D).

3. Support for ABS/ESP control module 52129438AC (Jeep Cherokee/Liberty KJ).

See also related notes:

• SZ Viewer: общая информация (2014-02-15)

Pentax K 35/3.5: Samples [2] - APS-C - f/3.5

Camera: Pentax K-m (1.5x crop factor, 10MP)

Lens: Pentax K 35/3.5 at f/3.5

See also related notes:

• Pentax K 35/3.5 lens (K): Retrofocus wide-angle Tessar (2024-02-23)

Image albums:

• Pentax K 35/3.5

Samyang Remaster Slim

New Samyang Remaster Slim AF module (for Sony FE mount).

The RS AF module itself contains only electronics and mechanics for AF without optical elements.

And there are three dedicated optical modules-lenses: 21/3.5, 28/3.5, 32/2.8. The optical modules can be changed quickly on the RS AF module.

Image albums:

• Photo

"Zoom View Finder 1.08-1.60x": Using for the Pentax K-m

Finally, I attached the "Zoom View Finder" magnifier to the Pentax K-m (I bought the magnifier for this camera).

The main disadvantage is that you have to adjust the diopter after changing the zoom factor. So you cannot use the magnifier with a camera that does not have a diopter adjustment.

With the magnifier, I cannot see the Pentax K-m viewfinder at a glance. I have to move my eye to see the whole frame and viewfinder information.

The good thing is that the magnifier really helps with manual focusing, even with the Pentax K-m's rather poor viewfinder. Of course, it is not at the level of a good film camera or a modern mirrorless camera.

See also related notes:

• "Zoom View Finder 1.08-1.60x" magnifier. (2024-04-11)
• Pentax K-m: Manual focus lenses (2024-01-23)
• Pentax K-m: 10MP CCD DSLR (2023-12-23)

Image albums:

• Pentax K-m

Cheecar FF 35/1.4 II: Samples [2] - FF - f/1.4

Camera: Sony a7c (FF, 24MP)

Lens: Cheecar FF 35/1.4 II at f/1.4

See also related notes:

• Cheecar FF 35/1.4 II: Full-frame lens (2023-09-23)

Image albums:

• Cheecar FF 35/1.4 II

M39x1/45.2 film SLR cameras

Film SLR cameras with the M39x1/45.2 mount:

Зенит (Zenit/Zenith), 1952-1956

Зенит-C (Zenit/Zenith-S), 1955-1961

Зенит-3 (Zenit/Zenith-3),  1960-1962

Кристалл (Kristall/Crystal), 1961-1962

Зенит-3М (Zenit/Zenith-3M), 1962-1970

Зенит-Е (Zenit/Zenith-E), earlier versions, 1965-1967

Film SLR cameras with an M39x1/45.2 adapter available:

Старт (Start), 1958-1964

Зенит-7 (Zenit/Zenith-7), 1967-1971

See also related notes:

• Zenit-3M: M39x1/45.2 SLR (2025-08-29)
• Zenit-S: film SLR camera (2025-03-31)
• USSR film still camera mounts (2024-07-16)