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02-18-2013, 02:57 PM   #1
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Infinity Focus with 18-135mm lens

Hey everyone,

I recently got a Pentax K5 II, and along with it came a wonderful lens, the "smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR" (PENTAX RICOH IMAGING CANADA INC. | smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR). Last night, I was attempting some shots of the stars, and was surprised to find no "infinity" symbol present on the lens. Is there a way to properly focus to infinity on the 18-135mm, or do I simply have to look through the view finder in the day, and attempt to set it to infinity by "ear"? Oh, also the focus rings "spins" a full 360 degrees, so there is no place to indicate where it infinity focus might actually be (i.e no friction). Thanks to everyone for the help, it's my first time posting!

-yogomo

02-18-2013, 03:02 PM   #2
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QuoteOriginally posted by yogomo Quote
Hey everyone,

I recently got a Pentax K5 II, and along with it came a wonderful lens, the "smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR" (PENTAX RICOH IMAGING CANADA INC. | smc PENTAX-DA 18-135mm F3.5-5.6 ED AL[IF] DC WR). Last night, I was attempting some shots of the stars, and was surprised to find no "infinity" symbol present on the lens. Is there a way to properly focus to infinity on the 18-135mm, or do I simply have to look through the view finder in the day, and attempt to set it to infinity by "ear"? Oh, also the focus rings "spins" a full 360 degrees, so there is no place to indicate where it infinity focus might actually be (i.e no friction). Thanks to everyone for the help, it's my first time posting!

-yogomo
You have to use the viewfinder to determine when you've attained proper focus. Even if the infinity mark had been labeled, you would have needed to look through the VF, as the true infinity focus point changes with temperature. The focusing ring does produce a little bit more friction once you're at either extreme, but it's subtle.

Adam
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02-18-2013, 03:04 PM   #3
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QuoteOriginally posted by Adam Quote
You have to use the viewfinder to determine when you've attained proper focus. Even if the infinity mark had been labeled, you would have needed to look through the VF, as the true infinity focus point changes with temperature. The focusing ring does produce a little bit more friction once you're at either extreme, but it's subtle.
Awesome thanks!
02-18-2013, 03:50 PM   #4
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I had the same problem when I wanted to take pictures of star trails. It's impossible to auto focus or focus manually through viewfinder with such low light. Eventually I gave up the 18-135 lens and put on my Tamron 28-75 lens that can be manually put to infinity focus.

02-18-2013, 04:03 PM   #5
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Auto focus lenses more often then not can focus past infinity so placing it on the limit is not a good idea.
02-18-2013, 06:14 PM   #6
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I've found my K-7 will centre point auto focus on bright stars like Sirus with my 55-300.
Once in focus, a bit of removable tape holds focus in place while I recompose the shot.

Alternatives:
You can also use live view and zoom in.
You can use digital preview and adjust focus until the stars are as small as possible, use the sticky tape to hold focus between shots.
02-18-2013, 06:34 PM   #7
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QuoteOriginally posted by calsan Quote
I've found my K-7 will centre point auto focus on bright stars like Sirus with my 55-300.
Once in focus, a bit of removable tape holds focus in place while I recompose the shot.

Alternatives:
You can also use live view and zoom in.
You can use digital preview and adjust focus until the stars are as small as possible, use the sticky tape to hold focus between shots.
Sounds like an interesting way of doing it, so with the sticky tape, I hold the focus ring where it is as I recompose the shot?
02-18-2013, 07:05 PM   #8
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Yes, stars like Sirius or Canopus are so bright that even the K7 can focus on them if you use the center point. Once focused on Sirius, then all the stars will be in focus, so you can tape your lens up and switch the camera to manual focus. You won't need to focus again all night.

It's also good for making sure your zoom ring stays where you left it when taking long exposures with the lens pointed upwards.

Actually, I use masking tape - the type used by painters - I just couldn't remember what it was called. It doesn't leave any residue or gumminess.

02-13-2014, 10:37 PM   #9
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K3 18 to 135 focus problem

Hi
Not having a stop at infinity is tough on us old people. Close shots were all just fine.
Was trying to do landscape shots. tried all modes. P seemed to work the best. But I wanted all modes to work. M would be my choice. but most were out of focus just a bit.
I even tried an older lens 70 to 300 and still had problems at infinity. I am just a bit disappointed. WHERE IS MY KODACHROME?
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