To infinity and beyond
Jul 6, 2012 12:27:24 #
A couple nights ago I was taking pictures of the moon using a tripod and self timer. I set the manual focus on infinity. In all my photos the moon was out of focus. I haven't had a chance to investigate as it's been cloudy each night since. I suspect I went "beyond infinity". Is this possible. I shoot with a D80.
Jul 6, 2012 12:30:49 #
Ha, you did go "beyond infinity". My photos are blurry too when focus is set to infinity.
Jul 6, 2012 12:55:08 #
Jul 6, 2012 13:35:14 #
Almost all AF lenses actually go past the Infinity setting, this is designed into the lens itself to prevent fast AF lenses from hitting the "brick wall" so to speak when adjusting focus. When they reach infinity the sensor will stopp the AF function, but the lens has that built-in "cushion" range just to avoid possible damage to the lenses focusing system. When a lens is brand new it is not really an issue, but as the mechanism wears there is the possibility that some play will develpo and allow for that damage so the manufacturers allow for that. Smart thinking in my opinion.
Jul 6, 2012 13:45:00 #
MT Shooter wrote:
Almost all AF lenses actually go past the Infinity... (show quote)
That is good info! I supose the reason I haven't noticed
this before is because until recently I have been shooting in the "Auto" mode. Thanks for the explanation.
Jul 6, 2012 17:27:17 #
Thanks MT. Good design on those lenses :). I just wish my lenses had the old style markings that showed me my DOF then I could focus myself :(
Jul 6, 2012 19:08:02 #
Most lens are designed to focus beyond infinity. Temperature extremes can expand or contract lens barrels and shorten or lengthen them which in turn can alter the actual focus points on the lens. The reason they focus beyond infinity is to allow for infinity focus if those changes occur. Also, infinity focus is slightly different at different focal lengths.
Jul 7, 2012 06:30:52 #
mpep05
Loc: Staten Island, NY
This could also be an issue of the image being overexposed rather than out of focus... :idea:
What were your exposure settings? Often when matrix metering a small very bright area on a dark background, the camera tries to correctly expose for the entire image, and overexposes the bright area as a result.
What were your exposure settings? Often when matrix metering a small very bright area on a dark background, the camera tries to correctly expose for the entire image, and overexposes the bright area as a result.
Jul 7, 2012 07:22:55 #
What is infinity, how would you explain it? I know, a wierd question and I am not really looking for an answer.
When ever you are focusing on an object that requires infinity to focus adjust your focus there then back off just a hair. This will normally give you a more accurate focus. When ever I photo the moon this is what I do and it seems to work well. You will probably have to set your M/A switch on the lens to manual. If you don't as soon as you push the shutter button the lens will go to infinity automatically, not what you want. You can use auto to get a starting point for your other setting, then switch to manual on the camera and lens. These setting are just going to be your starting point, I normally bracket these setting.
Jim D
When ever you are focusing on an object that requires infinity to focus adjust your focus there then back off just a hair. This will normally give you a more accurate focus. When ever I photo the moon this is what I do and it seems to work well. You will probably have to set your M/A switch on the lens to manual. If you don't as soon as you push the shutter button the lens will go to infinity automatically, not what you want. You can use auto to get a starting point for your other setting, then switch to manual on the camera and lens. These setting are just going to be your starting point, I normally bracket these setting.
Jim D
Jul 7, 2012 09:25:15 #
haroldross wrote:
Most lens are designed to focus beyond infinity. Temperature extremes can expand or contract lens barrels and shorten or lengthen them which in turn can alter the actual focus points on the lens. The reason they focus beyond infinity is to allow for infinity focus if those changes occur. Also, infinity focus is slightly different at different focal lengths.
Beyond infinity! I love it! "And exactly how far beyond infinity can you focus that lens, Bill?" We should have a Philosophy Section.
Jul 7, 2012 11:19:59 #
jerryc41 wrote:
quote=haroldross Most lens are designed to focus ... (show quote)
That does bring up a few other questions, How do the lens manufacturers determine 'infinity'? What distance are they using? Does this distance vary from manufacturer to manufacturer?
Jul 7, 2012 11:23:55 #
If you are using a lens with image stabilization turn that function off when the camera is mounted on the tripod. Many of the older lens', and some newer will continue to search for movement causing a drop in focus sharpness.
Jul 7, 2012 11:30:13 #
fthomas
Loc: Philippines
Theoretically there is nothing "Beyond Infinity". Of course I also believe the earth is flat. (Sorry, just couldn't resist!)
Jul 7, 2012 11:36:26 #
j4door wrote:
A couple nights ago I was taking pictures of the moon using a tripod and self timer. I set the manual focus on infinity. In all my photos the moon was out of focus. I haven't had a chance to investigate as it's been cloudy each night since. I suspect I went "beyond infinity". Is this possible. I shoot with a D80.
Just use auto focus on the moon or go to live view and zoom and manual focus.
Jul 7, 2012 11:49:52 #
fthomas wrote:
Theoretically there is nothing "Beyond Infinity". Of course I also believe the earth is flat. (Sorry, just couldn't resist!)
Me too! Did you know parallel lines meet and cross at infinity? My math teacher taught me that years ago. We spent a semester arguing about that. He finally showed me a Russian math book that was use at the time to teach that theory.
Jim D
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