Do I need a telephoto lens or a macro lens?

Started 2 months ago | Discussions thread
John K Veteran Member • Posts: 8,651
Re: Do I need a telephoto lens or a macro lens?

Hossein93 wrote:

Hello,

I am spreading the metal powder particles with different spreading speeds on a flat surface; it means one blade, which has a H= 50 um gap with the surface, will spread the powder particles, which are like a powder pile in front of the blade, on the surface. Thus, the powder particles will be in a very fast motion to pass through the gap and be deposited on the surface. For having an idea of what I am referring to, please see the below picture:

  1. Chen, Q. Wei, S. Wen, Z. Li, and Y. Shi, “Flow behavior of powder particles in the layering process of selective laser melting: Numerical modeling and experimental verification based on discrete element method,” Int. J. Mach. Tools Manuf., vol. 123, pp. 146–159, Dec. 2017.

I need to take some pictures of powder particles with sizes of around 20 microns. I have an SC1 Edgertronic camera which can be found here. The location of the camera is shown in the above picture but the camera is actually connected to the side of the blade and is moving with it. Thus, the avalanches that the powder creates can be observed with the camera. An image of what I am referring to is shown below:

This is the Zoomed-in image of the above one (I know the fame # is different, but it is basically the same but at a different time).

As can be seen, the distance between the powder and the camera is large and the powder particles cannot be observed and tracked. I need a lens that is capable of getting the track of particles. As I mentioned earlier, this event is happening so fast, so I needed to use a high-speed camera like this. I do not need the features on the surface of powder particles; I only need to see how fast they are moving and what angle is the powder pile creating with the surface (the angle can be observed in the above picture).

Please answer the below questions:

1- Do you know whether I need a telephoto (zoom) lens or a macro lens? I have been searching the Internet for a while, but I 've got kind of confused. Sounds like the telephoto lenses would just get close to the subject while losing the focus; the macro lenses, however, would have a reproduction rate of at least 1:1, which would present a sharp image of small creatures. I have to mention the camera is only compatible with the F mount Nikon series lenses; so, is there any way I can convert other lenses to the F mount or somehow figure this limitation out?

I don't think that a zoom lens will give you the magnification that you need. I have a 100 to 400 F4L II Lens and at minimum focus it's just 1/3 life size. I think that 1x is the minimum mag you want to go for, and even that's a tough recommendation because I don't know the size of the blade that's pushing particles.

2- I think I need some kind of backlight illumination for these pictures to be able to see the particles in a way that they cannot be mixed up and be tracked pretty easily. Can you help me with the suggested backlight illumination for this project? Also, for backlight illumination, I need to have a light diffusion screen and non-flicker light source as well; what light diffusion screen is more recommended? What about the non-flicker lamp?

Looking at the stills I don't think that back lighting will help -it won't shine though that powder.

I think a high powered diffused LED light source would be best, especially if you're shooting video.

3- Do you know anyway or software that could count the time and place it on the pictures, just like the frame number, ISO, EXP time, and FPS as shown in the below picture?

No idea.

Since I need to have the particles in larger sizes on the camera's sensor, I was thinking I need a macro lens, but I was not sure. So I asked my question here to use the knowledge and experience of experts.

A macro lens and a crop factor sensor so that the particles will look larger in the video. So an APS-C camera (best image quality) or a micro 4/3 (larger subject size due to the bigger crop factor, lower image quality due to the smaller sensor).

I should mention I am new to photography.

Any help would be appreciated.

Thanks!

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