Set Focus to Infinity - Help!

Discussion in 'Canon EOS' started by mick_brown|1, Mar 25, 2007.

  1. Hi all:

    I am an absolute newbie to my EOS 300d - just got it Friday - and my photog
    skills are at a beginners level.

    I'm into astrophotography and I've been advised, when taking certain shots, to
    set my focus to infinity.

    Is there a way to do this with my cam?

    Any help - much appreciated!

  2. Hi Mick, Actually it's done with your lens. If you put your lens in manual focus look at the distance indicator and you should see a mark at one end that looks similar to a figure "8" - that's infinity. Turn your focus ring to that. Many lenses go a little past infinity to compensate for temperature changes - it's ok to go past "infinity" if your lens does it. That's as "far out" as it'll focus. Good luck!
  3. Look at the lens. There are markings on it in a scale.. one side of the scale is in feet and the other in meters. The ring next to this one on the lens lens should have a dot or mark on it. Line the infinity symbol with the stationary ring mark.

    Check by looking thru the camera at a distant horizon which should now be in focus.

    I could add more to this, but there is a beginner tutorial on this website. Read that. You need to know how to walk before you can run (we all had to as well). :)

    Have fun!
  4. Sounds like you might need a manual for that camera:
  5. Thanks, Beau, but there doesnt seem to be a "distance indicator" on this, and nothing on that subject in the user manual, either. Am I looking in the wrong spot?
  6. What lens(es) do you have?
  7. Just turn the end of the lens counter-clockwise (counter clockwise if viewed from the behind). That'll get you to infinity focus. Just be sure to turn the switch on the lens to "mf"
  8. You probably have the "kit" lens (18-55mm EFS) and that doesn't have an infinity mark on it. To find infinity just focus the lens on something close (and in a lit area) and you'll then know that turning the front of the lens, which is where you manually focus that lens, the opposite way until it stops will be infinity. Make sure you have it on manual focus (switch on the lens).

    However, all the way to infinity on this lens will still be a bit out of focus as there is allowance, as was said above, for temperature differences. The way to compensate for that is to set the aperture of the lens to at least f/11, which will allow enough depth of field that the difference won't matter at all for star shots.
  9. Bruce C:

    The lens I'm using is an EF 28-90mm lens.
  10. Set the switch on the lens to auto-focus. Focus on the moon. Set the lens switch to manual focus, don't touch anything else on the lens from that point on.
  11. Thanks Sheldon - this sounds easy enough for me! So - just focus on the moon in auto-focus...does that mean the camera itself will adjust the lens?

    And then switch to manual.

    OK - will give it a try tonite!
  13. Thanks, Mark - coincidentally, I copied that article last nite!

    Attached is what I am getting of Jupiter, using the suggestions of Sheldon as far as the focus goes. I set ISO to 400 and that was it. The attached is about a 20 second exposure, taken using a remote control so as not to shake the tripod (in this case, my telescope, on which the cam is piggy-backed).

    Its a weird-looking Saturn! Any suggestions as to why?
  14. Its a weird-looking Saturn! Any suggestions as to why?
    It's missing its rings? ;-)
  15. No one takes pictures of the planets with 20s exposures anymore. The best images are collected with inexpensive (usually video) cameras, and stacking hundreds of carefully selected frames.

    From your description (note: your image does not bear this out!), it sounds like you have a simple case of mis-tracking. Check your polar alignment, buy a better mount, etc.

    The business about focus is a serious problem in general re: astrophotography. The referenced article above was appropriate for 1998. With a digital camera you would do much better to obtain an ASCOM motorized focus setup, with readout, and some focus software. The usual advice:

    Generally speaking, taking good pictures of the night sky is hard. Really, really, REALLY, hard. A lot of equipment to acquire, setup times are measured in hours, many things to learn and monitor while working, the slightest of mistakes, changes in environment, and so forth can flush large amounts of time down the tube. Think large format photography, but with cameras and tripods that have 10x the mass, and you have to drive 3 hours to begin to use them to their best, and it takes 90 minutes to get everything into a state where you can finally begin to work. And most of the the time you are washed out by the Moon, clouds, or the need to work at a normal job.

    Not that this should deter you. It certainly hasn't deterred me! Eventually, more likely because of luck, I'll finally get a good M31.
  16. Thanks to all who've contributed suggestions to my problem.

    I did happen upon 2 very good websites with info targeted to the EOS 300D/Rebel camera user. If you're interested they are at:

    Really good tips on using this camera for astrophotography!

  17. With a Canon EOS, without an infinity indicator mark, you could do as suggested, focus on the moon through the viewfinder, then make a fine mark on the focus ring, and lens with something like WhiteOut, or white paint. This will simplify setting up for your star photos.

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