Trying to take pictures in sunlight on hot and humid day: trouble focusing

[KJWangelheart]

Hello,

 I was trying to take some Macro pictures of my agates and crystals but couldn't get my camera to focus; my camera is a Canon EOS 70D with a 70mm-300mm lens. I made sure that my lens was very clean and the veiw finder was just as clean, backed up 4 ft from my subject and still couldn't get it to focus   . Here in Minnesota it is 85 degrees F and very humid today. Could that have something to do with my camera not being able to focus? 

 Thank you for your time.

 KJW

[CaliforniaDream · Accepted solution]

If your lens is the "EF 70-300mm f/4-5.6 IS USM" the closest focus distance is about 5 feet.

[KJWangelheart]

  

 Geez! Do I feel like a ding-a-ling 

 The good thing is at least I know my eyes aren't going bad