What is focal distance?
1628198
when one uses any type of magnifying device--from a reading magnifying glass to a microscope--one has to adjust the closeness of it to the object being examined. With a reading magnifying glass one moves it closer or further away from the object until it is in focus. This distance is the "focal distance".
1628199
as per any microscope, it has a fixed plane of focus. This one being a reflective microscope and not a transmission microscope--thus it looks at surfaces. So it is best at looking at flat surfaces although if the object being viewed is not flat than one can adjust the focus up and down to look at different surfaces. For example if one was looking at a large insect one could focus on the top of the head and then re-focus on the lower jaws. The stage can be moved up and down to accommodate different sizes of specimens. The closet one can get to the lens is one cm.
1312202
Closest usable focus distance is about 5.5 inches from the lens. What that means in practice is that an item one-half of an inch across will fill about half the frame (at least on my 50D).
466968
No, it's a fixed magnification. You can adjust the focus by getting closer or farther away from the object you're magnifying.
65263
Same focal length, but cropped. Here is a similar discussion: http://photo.net/digital-camera-forum/00Y6zf
2217648
IS will not matter at this focal distance. Only start worrying about IS (or VR as Nikon refers to the technology) past about 70mm
797773
So this is a major concession in comparison with much less expensive cameras' focusing distances of one to two inches. Anyone with ideas as to why this is so. I used a Nikkormat with a Nikon macro lens for many years and have considered a Nikon digital body to allow continued use of the lens. Anyone with any thoughts on marrying such different technologies?
2219800
Each of the focal lengths for the 4 lenses are listed below:1.5x Lens: 19.7 inches2.0x Lens: 9.8 inches2.5x Lens: 6.6 inches3.0x Lens: 4.9 inchesPlease note that the focal length does not mean that you must hold the magnifier that far away from the object. It just means that's about the distance where the magnifier has its highest magnifying power.
2236258
According to the spec the minimum focus distance is .82 ft. Of course with close up filters you can easily go closer. That is what I do.
572073
It has a 4mm focal length, with a 54 degree viewing angle. The lens and camera were exactly what I wanted. The night vision was great. The software was a nightmare.
1391756
Up to 8 feet away and then you have a focus lever on the camera that you can adjust for clarity.
1712124
It's a fixed-focus camera. But for less than $30, it's inexpensive to experiment with. Some folks are doing really interesting things with the Pi Camera Module, including modifying it to mount other lenses (which might get you to your focal distance goals). See this page, for example: http://www.truetex.com/raspberrypi
52209
Focal Length (mm)The focal length (measured in "mm") of a lens determines how far the camera can see. The most common focal length on security cameras is 3.6mm, which will allow for roughly a 72 degree field of view (FOV described below). This particular focal length works well for residential or small office surveillance applications.If you can only learn one thing about security camera lenses, you should learn that the bigger the focal length, the farther away it can focus. The smaller the focal length, the wider the field of view.- See more at: http://www.2mcctv.com/blog/2012_07_18-cctv-lens-guide-choosing-a-security-camera-lens/#sthash.XunzUGW5.dpuf Focal Length (mm)The focal length (measured in "mm") of a lens determines how far the camera can see. The most common focal length on security cameras is 3.6mm, which will allow for roughly a 72 degree field of view (FOV described below). This particular focal length works well for residential or small office surveillance applications.If you can only learn one thing about security camera lenses, you should learn that the bigger the focal length, the farther away it can focus. The smaller the focal length, the wider the field of view.- See more at:... » Read More Focal Length (mm)The focal length (measured in "mm") of a lens determines how far the camera can see. The most common focal length on security cameras is 3.6mm, which will allow for roughly a 72 degree field of view (FOV described below). This particular focal length works well for residential or small office surveillance applications.If you can only learn one thing about security camera lenses, you should learn that the bigger the focal length, the farther away it can focus. The smaller the focal length, the wider the field of view.- See more at: http://www.2mcctv.com/blog/2012_07_18-cctv-lens-guide-choosing-a-security-camera-lens/#sthash.XunzUGW5.dpuf « Show Less
464946
Hi John,The close focus distance of the MiniMight Monocular is about 10 feet.If you have any other questions or concerns, please contact our customer service department at 631-963-5000 or by email at info@carson.com
2217647
The focal length is only 35 max, you don't need IS at this point. The further the focal length goes, the more you need IS. Don't worry.
452516
If you want 1/2 to life size extreme close-up capability this is not the lens. The focus ring scales indicate focusing upon a subject as close as .82 ft. At the 18mm setting that will capture a horizontal field of view of about 8 inches wide with the lens about 4 to 5 inches from the subject. At 55mm the horizontal field of view is about 5 inches wide with the lens about 8 or 9 inches from the subject.
905913
To avoid blurry images use the reciprocal rule.. Focal length of 25mm(2x crop = 50mm) - be sure to use a shutter speed of 1/50s or faster.Blurry images <> mean objects or people moving in your image.
1460461
Looks like focus down to 4 to 5 feet. Has diopter adjustment. I can focus without my glasses on if i adjust diopterveyepiece. That said, i would not buy that model again. Prefer the green screened nightvision. IR works but not at great distance. Price is good, though.