Quick detach lenses/thermal camera optical zoom change - Page 1
Forum section: electronics / general

author: Alvarium
author_rank: Newbie
timestamp: March 03, 2025, 01:06:46 pm
content: I came upon a product which is called a macro lens for thermal cameras. I was wondering if it could be used as an optical zoom lens that is quickly detachable. On some listings there are focal lengths and lens diameters to choose but i cant figure out what opticall zooms theyll have and if focus distance will be a problem since some of them are sold as laser focusing lenses. One of those listings states it can magnify the image by 20 times just by placing it in front of already existing lens, but as i stated before im not sure if there is an effective focus range with that (its important because i plan on spotting animals from a distance). Another listing has lens size to choose from 18 to 25mm and focal length from 38.1mm to 101.6mm. If said lens would work for such application as to just magnify the image without at cost of fov without losing sensor resolution and ability to focus at distance which one should i choose? Sorry for beaing a dummy.

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2025, 12:47:47 pm
content: You need to do some Googling on telescope design and how supplemental lenses work.A single element supplemental lens can provide close up imaging as it acts like putting reading glasses on your camera. To achieve a smaller field of view and magnification is a more complex task usually requiring 2 lens elements, one positive and one negative and matched in focus distance to produce the required output to the camera. Whilst is is possible to use a single large magnification lens to project an image directly onto the microbolometer, that requires removal of the original lens and selection of a suitable lens element. That can be expensive. Telephoto supplemental lenses sometimes appear on eBay but they are often expensive. The common Fluke “Tele2” x2 telephoto supplemental lens an cost anywhere between $150 and $500 on eBay. New price is around $1500 !The high magnification factor that you see claimed by some close-up lens sellers is purely due to being able to get the camera closer to the target and not some “magic” single lens “telescope”. The closer you are able to get to the target, the more it fills the field of view.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2025, 01:03:55 pm
content: Another forum members project to create a telescope add-on to a thermal camera.https://www.eevblog.com/forum/thermal-imaging/seek-compact-pro-telescope/As you will see, 2 lenses are required. The large Trumpf lens mentioned was available from a chap selling them cheap on eBay some time ago. I have a few in stock if needed. I do not think the seller is still active though.The detailed telescope appears to be a Keplerian design, so inverts the image as it uses two positive lens elements. A non inverting telescope needs a positive and negative lens combination or a three positive lens element design with an erector lens to correct the inversion.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2025, 01:09:26 pm
content: This article is what you need to read…..https://www.instructables.com/Diy-Thermal-Camera-Telephoto-Converter/The Author is a member of this forum and I think he posted details of the design here as well.FraserThe attached images are taken from the referenced article and are the property of the Author or respective copyright owner.

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2025, 01:13:45 pm
content: More reading for youhttps://www.eevblog.com/forum/thermal-imaging/teleside-telephoto-conversion-lens-optics-question/Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 06, 2025, 01:21:12 pm
content: More….https://www.eevblog.com/forum/thermal-imaging/seek-reveal-and-reveal-pro-supplemental-lens-adapters/