I know, I know. I shouldn’t be buying more gear but rather taking more photos with the existing equipment.
Get out there.
But I think I got a good excuse – for the second time, I will be going next week to a nature photography workshop in the German national park Bavarian Forest. The first workshop I attended in winter 2008 when I was still using my Tokina 300 mm f/4 lens, and the experience from using the fixed focal length made me change soon after to the wonderful Sigma 100-300 mm f/4 zoom for more flexibility.
Now, a second experience I had made back then was that even with the 1.5x crop factor of the D70 (and the D300 has the same), the resulting 450 mm are not enough in many situations. I did have the Kenko 1.4x tele converter allowing me to get to real 420 mm (so 630 mm full-frame equivalent). I used this extension a lot, not to say on some days all the time! But the pictures taken by those participants who hauled 300 mm f/2.8 with 2x tele converters proved to me that the difference between my 630 mm and their Canon-powered (1.6x crop) 960 mm was absolutely surprising.
So I thought I could enter the game with buying the Sigma 2.0x EX DG converter. Theoretically, this gives me the chance to do either a 200-600 mm f/8 for a full frame max length of 900 mm, or even stack the teleconverters for a 280-840 mm f/11 monster with a 1260 mm equivalent length. Question was of course, does this work, and how much image quality (if any) remains? The question e.g. is discussed (sorry, German only) at the blog of nature photography school Foto Campus, and their verdict is: Forget tele-converters.
Having read and investigated other opinions out in the net over the use and quality of 2x tele converters, I had decided to give it a try anyway – despite the warnings about the images being degraded in quality to uselessness, I saw and still see no real alternative that doesn’t blow the budget completely. So I did the purchase, and tested it last Wednesday – from the balcony of my appartment.
[svgallery name="teleconverters"]
The four images show the top floors of the mildly famous Hypo-Hochhaus building in Munich. (Did you know it is the 41st highest building in Germany? Well…) :
- The whole frame with 600 mm – image taken wide open at f/8 effective aperture, and 1/125s exposure time at ISO 200.
- The corner of the same frame showing some cables and antennae. This is the part I had focused on using live view. Click on “show image in full size” to get the real 100% pixel view.
- The whole frame later that evening taken with stacked teleconverters, this is at 1260 mm equivalent length. Image taken not stopped down at f/11 effective with 1/1.3s exposure time at ISO 200.
- The corner of the second frame with the same cables and antennae.
Lessons learned:
- Ups, no autofocus at f/8? From my research I had thought only the Canons to turn off the AF, but the D300 did as well. There are tricks on how to use taping pins to get AF back, but I stuck with MF for these tests. And I can remember from my last visit in the Bavarian Forest even non-moving animals, with Lynx being cat after all… So this might not be such a big problem.
- Live View in tripod mode allows you to zoom in to 100%, and allows for really nice manual focus.
- Mirror lock-up is suddenly absolutely required. The images without mirror lock-up were unusable.
- At these focal lengths, the atmospheric disturbance by the air becomes visible (comparing two images of the building with it’s regular grid of windows made this very obvious).
- My tries to stop down to get sharper pictures failed – mostly I guess because of the low light situation and the fact that the exposure times were already reaching 1 second. All images with even longer exposures could be thrown away, maybe too many vibrations on my balcony?
- Stacking the TCs (the 1.4x must mount to the camera body, so the 2x sits between the 1.4x and the lens) reenabled the AF again (obviously the software couldn’t cope with both TCs connected, and reverted to detecting the f/4 lens only). But in the by then low light the AF was only hunting and did not acquire lock.
Resulting image quality? I am not disappointed, but there are many things that need to be done correctly. Looking forward to give it a try next week!
Photoblogs.com