Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon Lenses

Reply
 
Thread Tools Search this Thread
Old May 15, 2005, 1:24 AM   #1
Senior Member
 
Join Date: Oct 2004
Posts: 182
Default

Alright, my church and another organization gave me a little over 200.00 dollars to buy a zoom lens (had to be a local purchase, no online dealers) and a bag.

Well I've got everything, and I knew it was far from the best (what 200.00 lens is for a tele-photo!!)

SO... I am the proud owner of a Promaster (Tamron built) 70-300mm f4-5.6 1:2 Macro telephoto zoom lens. It came with a lens hood, and a lifetime warrenty. The images are fine, not the sharpest out of the camera but it's no "L" lens. =o)

My question is this... I know my full zoom level on my Canon Digital Rebel is 480mm, when the crop factor is added in. At this range my DOF is very small, correct? How do I increase my DOF at full zoom? I "step the lens down" correct? Meaning I bump the F stop up, to 8-22 or something right? Meaning again that a longer shutter length would be wanted to allow enough light in.

AmI correct in my research? (I've had an ultra zoom Fuji s602z) but it was only a 357mm with telephoto conversion lens. This is a LOT more zoom. =o)


Please help me! NHL, where you at! =o) Hehhe

Talk to ya'll in the morning, and thanks for the help everyone! TELEPHOTO ROCKS!

Now I'm starting to save up for that EX f2.8 Sigma 70-200mm.

-tlmiller10
tlmiller10 is offline   Reply With Quote
Sponsored Links
Old May 15, 2005, 12:19 PM   #2
Super Moderator
 
peripatetic's Avatar
 
Join Date: Nov 2004
Posts: 3,599
Default

DOF calculator and site.

http://www.dofmaster.com/dofjs.html

Yes, stopping down will increase your DOF, but use the calculator - you may find at the distances you are using full zoom your DOF is adequate anyway. Your DOF is greater with the smaller sensor too.

If you stop down be aware that the sharpness will start to degrade due to diffraction limitations on the sensor. Most people find this starts to be noticable at around f14 and quite noticable at f22.

If you find your shutter speeds dropping too low then you may have to push up your ISO setting until you get 1/effective focal length shutter speed.
peripatetic is offline   Reply With Quote
Old May 15, 2005, 3:44 PM   #3
Senior Member
 
Join Date: Oct 2004
Posts: 182
Default

Thanks for the link and help! =o)

-tlmiller10
tlmiller10 is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 3:07 AM.