Zoom Experiment.

[Paul]

Tried a little experiment tonight.

Two photos taken at the top end of the Sigma 150-500 zoom lens. No optical stabilisation used, tripod mounted, live view, manual focus, remote release, used on both images.

The first is at 500mm, the second at 500mm plus Sigma's 1.4x EX extender.

Both these were taken at night, at ISO 500 in AV mode, giving a 4 second and a 6 second exposure, at f/6.3 and f/9 (I should have done the extender shot first and matched apertures really, but I didn't think of it).

Interesting to see the sharpness using the live view and my eyes on each, and also the difference in sharpness at different apertures (i.e. caused by the 1.4x) on the brickwork of the gate post.

The focal point I used was the number 18 on the door of the house.

On each image, no noise reduction and no sharpening has been used, the only adjustments were to try and get the whites similar, because they were different, though I failed! (I assume due to the glass in the extender having an effect in some way).

Effective focal length - 800mm:



Effective focal length with extender - 1120mm (I think):



I did it because I wanted to try something - no science involved, just curiosity...


Paul.

[Terry]

Interesting Paul, out of curiosity what exposure metering where you using? I bought a cheapish (£80.00) Jesspos 2 x converter to use with my Tamron 70/300 zoom but have hardly used it. Hope to use it more this year for my wildlife pics but concerned about the image quality

[Paul]

Hi Terry.

I was using evaluative metering.

As Robin will confirm, the Jessops x2 are made to a budget (I was a manager for 2 of their stores) and are good to get starting out with, but if you find you like having the extra distance you'll upgrade in time. I got the Sigma EX 1.4x which is decent. Not in the league of a Canon extender of course, but close to the quality of Kenko Pro's.

[Terry]

Thanks Paul, Robin did point out at the time they were a budget converter but I'll need to see if its worth up grading depending on the use I get out of the one I have. To date its only been on the camera a couple of times.