lens – Origin of the sound / noise made by some stabilized lenses?

The sound may be produced by some form of a permanent feedback loop to allow a movable lens element to “float” in the air, but does any one know what is, precisely, the origin of the sound? And why it is permanent on Fuji lenses with OIS?

Without power, the OIS element in Fuji lenses (and some others) is free floating. The OIS element isn’t “parked” and locked when the power is removed (unlike, say, read/write heads for spinning hard drives). Thus, the OIS element has to be held “rigidly” in its optically neutral position (non-stabilizing control) at all times when the camera is powered.

As with any system with active feedback control systems, the controller is still working, even if it was commanded to just stay at a commanded point. By analogy, a Harrier VTOL jet that is asked to just hover 100 ft. above the ground is still working its control systems. The controller is always trying to compensate for error inputs, such as gusts of wind that might move the jet laterally or change its altitude.

Functionally, the only difference between enabling and disabling OIS in these types of lenses is whether or not the feedback control system is trying to filter out (i.e., compensate for) motion frequencies around 20 Hz and lower. ST Microelectronics has an interesting white paper discussing OIS controller design and implementation, that covers this in more depth.

This controller has to be almost immediately responsive to movement, so the feedback controller is operating at much higher frequencies than just the 20 Hz (and below) that needs to be filtered. It’s this controlling frequency moving the OIS element that is the source of the noise. In essence, the OIS element is acting like a speaker cone — a thin, more-or-less planar surface moving to some degree back and forth (although it’s mostly just laterally) pushes air around. Because it’s controlled by electromagnet motors, the moving OIS element is also pushing back on the lens body itself. Some of the motion is in the audible range of human hearing, which is the buzzing sound you hear.

equipment identification – What mount system is this Hanimex zoom lens?

This lens was manufactured in the Canon FD (and new FD), Nikon F, Minolta M/MD, Pentax K, Fujika FX, CONTAX/Yashica (C/Y or Y/C), Konica AR, Olympus OM, and M42 mounts. Your lens is not any of those.

It is not the Sigma SA, Contaflex, Exacta , Praktica PB, Praktina, Icarex, Ricoh XR, Leica M, or Leica R mount.

It appears to have been modified at some point to be compatible with a changeable mount system like the Tamron Adaptall or T4-TX system. But it isn’t either one of those systems, either.

The Arri PL mount for cinema cameras looks similar, but isn’t a match.

Perhaps it has a missing part?¹

Perhaps, but there are no obvious attachment points for anything behind it other than the three locking tabs and the single pin tab. No open screw holes and no threads on the protruding rear lens group. I think it has been modified to fit in an obscure 8mm or 16mm movie camera.

¹ From a comment by @Rafael

artifacts – is it normal to get significant lens flare with a 50mm f/1.8 prime lens?

What you are seeing in the photo is a specific type of lens flare known as ghosting. It is an inverted and reversed reflection of the brightest highlights of the scene. If you were to draw an x and y axis intersecting in the center of the photo, then the bright light on top of the building just left of the vertical axis is reflected the same distance below the horizontal center line and the same distance to the right (in the ball court). The greenish tint in the reflection is caused by the color of the bright light. The light itself looks white because all three color channels are fully saturated at the exposure level used to take the picture. The color of lens coatings designed to minimize reflections is also influencing the color of the reflection. The other bright lights in the scene are also being reflected the same way. Lights in the upper right will show up in the lower left and so on. The five-sided shape of the bokeh around the reflections are due to the number of aperture blades in your lens.

enter image description here

The brightest parts of the scene are most likely bouncing off the IR filter on the front of your sensor and then reflecting back off the back of elements in the lens. If you can also see the reflections through the viewfinder, then the first reflection is occurring in the lens. The EF 50mm f/1.8 II was designed in the film era. Film is less reflective than modern sensor assemblies and so reflections from the camera were less of a concern. Newer lenses have mult-coated optics on both the front and rear surfaces of most or all elements to help combat this.

My Rebel XTi with the EF 18-55mm f/3.5-5.6 II kit lens tended to do this in similar conditions as well.

Parade pic

Some things you can do to reduce such ghosting include:

  • Remove any filters screwed onto the front of your lens. The flat rear surface of the filter is perfect for creating reflections of light bouncing off elements in the lens, or even from the sensor stack itself.
  • Use a lens with better anti-reflective coatings or a camera with a less reflective sensor/filter stack.
  • Try to compose shots so that the brightest points in your scene have bright visual elements at the corresponding point in the cross quadrant to make the reflection less obvious.
  • Make a mask for the front of your lens that blocks half the field of view. Then combine two exposures, one with the mask on the left, the other with the mask on the right (or you might do the same thing with a strong graduated Neutral Density filter). The reflections would still show on the “dark side”, but you would mask them out in post processing when combining the two images.

K10D poor focus – manual or auto – with full-frame zoom lens

I’m getting very poor focus particularly at the long end of an 80-320mm tele lens that I am using with my Pentax K10D.

The lens was originally bought for my 35mm Pentax SLR (maybe an MZ5 or something, I don’t remember, and it’s at teh back of a cupboard these days), and worked very well with the film camera.

Theoretically the lens is compatible with the K10D, though obviously the different sensor sizes mean that it’s not a direct 80-320mm equivalent.

The problem has been present since I first bought the camera about 15(?) years ago, but I encountered it a couple of nights ago again and the frustration led me to post this question in case there is a solution.

The photo below shows the issue.

Out of focus image

The image was shot at the ‘320mm’ end of the tele lens and the settings are shown below.

Image information

The image is absolutely pin sharp in the veiw finder, but as you can see the resulting photo is blurred. Not only that, but the ‘in-focus’ beep and dot are on when the image appears to be in focus.

A while after gettng the camera I swapped the focus plate for a ‘Katz Eye Optics’ split prism partly to see if this led to any improvement and partly because I always loved this type of focus on my dad’s old Pentax film cameras. Sadly it made no difference so it seems that the problem was not that the image was out of focus in the VF.

I’ve read about the AF issues on the K10D, but this is when manually focussing and also when ignoring the ‘in-focus’ beep (I tried ignoring the beep years ago when I first saw the issue – long before I read about the K10D AF issue).

I haven’t seen the problem with the 28-80mm lens supplied with the K10D, but I have assumed that that is because it has a max focal length of 80mm and the problem only seems to manifest at the long end of the tele lens.

Is this problem likely to be lens incompatability, an issue that is only noticeable when shooting subjects like this at a distance, or something inherantly wrong in the body (like the AF / back focus issue)?

Edit: I forgot to mention that I also had a Circular Polarizer fitted for this shot as the moon was very very bright that night, but the same blur occurs without when shooting other subjects.

sigma – Can I add third party lens profiles to Nikon cameras or software?

If you’re willing to do an intermediate step using 16-bit TIFF files, the best way to get where you want is to:

  • Shoot .NEF, then use Nikon’s software to process your color, contrast, curves, HSL, etc. before outputting from the Nikon application to 16-bit TIFF. The color and other processing you do in the Nikon software will be “baked in” to the TIFF files. It’s just that with a 16-bit raster image you’ll have more latitude for additional adjustments in Photoshop or whatever other graphics processing software you choose to use than with an 8-bit JPEG.
  • Import your TIFFs into Photoshop (or Gimp, or Darktable, etc.) and apply correction for lens distortion, CA, etc., there.
  • If you have an image that you wish to process using multiple layers, you might need to export multiple TIFFs from Nikon’s Capture with the brightness, contrast, colors, etc. adjusted for what you desire in each layer. Then combine them using each TIFF for each layer of the image in Photoshop or other graphics processing software.
  • Another approach to such high dynamic range scenes would be to adjust everything to your liking in Nikon’s Capture, then expand the contrast to include all shades in the raw file before exporting. Sure, it will look “flat”, but all of your color adjustments will still be in there and should look very similar when you raise the black point and lower the white point to around the same levels in Photoshop.

There’s a lot to keep in mind about raw vs. TIFF:

The 12, 14, or 16-bits used to record raw data and the 16-bits (per color channel) used to record a demosaiced and gamma corrected TIFF or PSD are not used to represent the same exact thing in the same exact way, even though raw files often use containers that conform to the larger TIFF standard.

Raw files have one single, monochromatic brightness value for each photosite (a/k/a sensel or pixel well). Each sensel has a color filter over it that is one of three colors that are often referred to as “red”, “green”, and “blue. But the colors used in Bayer masks are NOT the same colors as the ‘Red’, ‘Greeen’, and ‘Blue’ colors emitted by our RGB display systems. To get any real color information out of the information contained in a raw file, the monochrome luminance values measured by each sensel are compared to the monochrome luminance values record by surrounding sensels filtered with each of the colors used in the Bayer mask and color information is interpolated from the results. This works as well as it does because the human vision system works in a remarkably similar manner. The wavelengths that the three types of cones in our eyes are most sensitive to are not ‘Red’, ‘Green’, and ‘Blue’ either!¹

What we usually mean when we say “TIFF files” are raster images that have a 16-bit number for each of the red, green, and blue channels for each pixel in the image. That’s why 16-bit TIFF files are so much larger than 14-bit raw files, even though they actually contain less total information.

For more, please see:

Why can software correct white balance more accurately for RAW files than it can with JPEGs?

RAW to TIFF or PSD 16bit loses color depth

Why are Red, Green, and Blue the primary colors of light?

1 The colors used in Bayer masks are not the same colors emitted by our RGB screens. “Red” is not even close. The “red” cones in our retinas are most sensitive to about 564nm (a lime-green color between green and yellow), the “red” filters in most Bayer masks are most transmissive to about 590-600nm (orange-yellow), while our RGB systems emit 640-650nm for ‘Red’.

If this video shows lens flare, how is it able to move erratically, passing over solid objects?

I have captured some intriguing photos and videos on my Samsung Galaxy A51 smartphone that do not seem to be consistent with typical examples of lens flare that I’ve seen. The orb appears green or blue and has been captured while I blindly pointed my camera at the sun and took pictures and videos. I was not aware of the outcome of what I captured until I reviewed the videos and photos several hour later. Can someone please explain how lens flare has the ability to bounce around and circle around moving objects. Please watch my video first for a better understanding of my question.

https://m.facebook.com/story.php?story_fbid=114242053999397&id=100062408088531
https://m.facebook.com/story.php?story_fbid=114086310681638&id=100062408088531&sfnsn=mo

focal length – Using a speedbooster on a MFT camera. Intent is to photograph and record backyard wildlife. Budget friendly lens?

Ok, upon learning that an Olympus 12-200mm with a 16.6x zoom will not be produce an equivalent or better zoom range as a Canon 70-300mm, I now pose the question:

Would it make sense technically to use an MFT to EF mount speedbooster (metabones 0.64x) on my MFT camera with an EF lens to achive the zoom I want without crushing my wallet? I could possibly go as high as 1000.00US…I know, it’s not enough.

That’s another reason I like the MFT format is because the lenses are smaller, lighter and less expensive for the most part, however if an EF lens with a speedbooster will give me more zoom I should consider those too.

Why is this so confusing for me lol? I apologize for my ignorance. I know the math seems simple to you guys but it’s hard for me to grasp anything in the beginning. Give me time and I will get it, but right now I’m still working on ‘getting it’.

I know you guys are busy, so no rush or anything.

Thanks again guys/girls:)

sunlight – Why does this particular lens produce sunstars with long spokes?

This image was shot with a Sony E 20mm f/2.8 on a Sony a7. The lens is intended for an APS-C sensor, but I removed a baffle to shoot on the full-frame body.

Sunstar shining through the branches of a tall tree

I understand the basic physics of sunstars. My question is why the sunstars from this particular lens have the giant spokes. This is not due to anything about the composition of this particular shot; the lens always produces sunstars like this.

Edit: Yes, the sensor was filthy. Other lenses used around the same time had normal sunstars. I’ve since cleaned the sensor, and this effect still appears with this lens.

If this video shows lens flare, how is ot able to move erratically, passing over solid objects?

I have captured some intriguing photos and videos on my Samsung Galaxy A51 smartphone that do not seem to be consistent with typical examples of lens flare that I’ve seen. The orb appears green or blue and has been captured while I blindly pointed my camera at the sun and took pictures and videos. I was not aware of the outcome of what I captured until I reviewed the videos and photos several hour later. Can someone please explain how lens flare has the ability to bounce around and circle around moving objects. Please watch my video first for a better understanding of my question.
https://m.facebook.com/story.php?story_fbid=114242053999397&id=100062408088531
https://m.facebook.com/story.php?story_fbid=114086310681638&id=100062408088531&sfnsn=mo

sigma – Can I add third party lens profiles to Nikon cameras?

I’m starting to shoot directly in JPG to save time, since I don’t need RAW processing most of the time.

However, my D7100 and my Z50 have no built-in lens correction profiles for my Sigma 18-50 and 50-150 lenses.

Is there a way to hack the firmware to add support for third party lenses in camera?

I could shoot RAW and batch export JPG using Lightroom, but their standard profiles are not equivalent to what Nikon offers and I like the Nikon colours better.