PDA

View Full Version : 70-300 + EC14 + E520 out of focus?


Tordan58
28th April 2011, 10:57 AM
Hi all

I would like to share a recent gained experience with you telezoom experts. Not sure if it should be posted in the Lens or Camera section, I put it here for now.

Background: I have for 6 months used the 70-300 in combination with EC-14. Lens has been mounted on a E520 camera body. I have been quite pleased with the results, the lens is capable of delivering sharp images given the right light conditions, even though the yield is far from 100%. However I never really excelled in capturing birds in flight, only few of the pics have met my expectation regarding sharpness. With time I came to accept it, blaming imperfections on motion blur (when it was not clearly caused by the lens slow autofocus).

Yesterday evening, I mounted the lens combo on a E-620 camera body. Sun was quite low since had to turn ISO in the range something like 1000-1600 to achieve acceptable shutter times and as anticipated image quality was quite noisy. But much to my surprise pictures were sharp. Noisy, but sharp.

Can anyone comment on this?

- I cannot believe the somewhat higher sensor resolution (12 vs 10 Mpixel, meaning 10% higher linear resolution) is a viable explanation
- Could there be there a leap quantum from the Truepic III to the Truepic III+ processor that could explain an accurate auto-focusing?
- Could it be the E-620 7 point AF point system superior to the E-520 5 pt system? (Center is the only AF point i use for birds in motion so I doubt this is a viable explanation)
- Could it be that the 70-300/EC-14 does not perform well with the E-520?
- Could it be the E-520 body specimen I have been using has a defect/bug that results in out of focus (front och back focus bias)? Is there an easy way/method to find out?

Regards
Tord

snaarman
28th April 2011, 01:36 PM
Try this:

Gat a tripod and a static target. Autofocus the camera on the target using the eyepiece. Swtich the lens to manual focus so it won't move. Now switch to live view. You can pess a button so the live view is magnified.

Is is sharp? Try moving the focus ring very very slowly to see if you can make it sharper, if you can then the camera AF is not quite right.. I figure that live view is showing you exactly what the picture will look like, so it the AF is out then live view is a quick was to see it.

Pete

Ross the fiddler
28th April 2011, 02:15 PM
Try this:

Gat a tripod and a static target. Autofocus the camera on the target using the eyepiece. Swtich the lens to manual focus so it won't move. Now switch to live view. You can pess a button so the live view is magnified.

Is is sharp? Try moving the focus ring very very slowly to see if you can make it sharper, if you can then the camera AF is not quite right.. I figure that live view is showing you exactly what the picture will look like, so it the AF is out then live view is a quick was to see it.

Pete

To add to that, use the 7 or 10 times live view magnification to be even more precise to see what is in focus.

Homer Simpson
29th April 2011, 07:41 PM
To add to that, use the 7 or 10 times live view magnification to be even more precise to see what is in focus.

:eek: I didn't know you could do that!

how?

I've just looked in the manual Ross, but you already know my problem with that :rolleyes:

Ross the fiddler
30th April 2011, 12:49 AM
:eek: I didn't know you could do that!

how?

I've just looked in the manual Ross, but you already know my problem with that :rolleyes:

You know that saying "If all else fails, read the manual". :D
On page 41 under Enlarged display operation it describes using the [INFO] key to get that function (in Live View), press the arrows keys to move the green box to desired location, turn the wheel to select 7 or 10 X magnification (the green box will change in size to match) then press the [OK] button to activate it (press [OK] to go back). With that you will see much more accurately if the focus is spot on or not.

Hope that helps.
*chr

Homer Simpson
30th April 2011, 06:38 PM
Tordan

Sorry about the hijack:o

Ross
Thanks again!
I read that section in the manual before posting but somehow it did not make any sense:rolleyes:

I've not been a fan of liveview but this bit of information was very timely as a cheapo set of lens tubes arrived this morning & I wanted to play with my legacy lenses