its in focus completely at any distance beyond about 2 and a half to 3 feet
but anywhere less than that it gets progressively more blurry as you get closer. and a half a foot its downright crap and shameful quality.
I have cleaned the lens furiously until it looks so clean it looks like it was made in a clean-room and fresh off the assembly line
Still not any better anywhere closer than a few feet
but anywhere less than that it gets progressively more blurry as you get closer. and a half a foot its downright crap and shameful quality.
I have cleaned the lens furiously until it looks so clean it looks like it was made in a clean-room and fresh off the assembly line
Still not any better anywhere closer than a few feet
Then use a close up lens.
I gave some examples (post18) of how to calculate the strength of lens you might want to use for your duty.
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> you took my message way too literally
And you are *ignoring* ours. Reading glasses. Figure what distance you want to focus. The formula/chart has been given in this trhead multiple times. The experiment is cheap. Dollar Tree has readers for $1 (they are optically fine). For zero investment, take your cellfone in the store and try it there. Or look in the couches of your older friends.
And you are *ignoring* ours. Reading glasses. Figure what distance you want to focus. The formula/chart has been given in this trhead multiple times. The experiment is cheap. Dollar Tree has readers for $1 (they are optically fine). For zero investment, take your cellfone in the store and try it there. Or look in the couches of your older friends.
post 29 is the same as post #1 - absolutely no progression from the information you have been given.
Businesses exist to make money, they don't make money by making a product to fix an issue that affects very few people.
Look at the bottom of this page:
schoolphysics ::Welcome::
You find a well-known formula there: 1/F = 1/f1 + 1/f2 - a/f1f2
If you buy two lenses and separate them by a distance "a", you can create many focal lengths. If you buy two lenses and mount them to a helical focusing mechanism that varies the distance between them, you can create a variable focus lens. You have to be smart about what you choose for f1, f2 and a.
I have a feeling you will want perhaps a 0.25 diopter lens, with a focal length of 4meters (4000mm) You will probably want one of the small lenses to have a positive focus, and the other to have a negative focus.
lets try a +50mm and a -50mm - now for some math!
1/4000=1/50-1/50-a/(-50*50)
1/4000=-a/-2500
4000=2500/a
a = 2500/4000 = 0.625mm
I did that in my head, can you believe that?
Lets say you wanted a 0.5diopter lens, with a focal length of 2000mm with the same lenses - the separation distance would then be a=2500/2000, or 1.25mm.
I have a question for you though: Is it weird that I use the capacitance meter setting on my DMM to check LED's?
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