For Rik...Dragonfly photo'ed with stacked tc's.

twebster · Post by **twebster** » Sat Jul 01, 2006 11:25 am

Hi ya' Riik,

Here is a dragonfly (Blue Dasher) that was photographed with the 1.4x and 2x tc's stacked on the 300mm f 2.8L IS lens...

This is about a 75% crop of the full frame. The dragonfly was about 15' from the shoreline. Stacking the two tc's on the 300mm lens yielded an effective focal length of 1344mm (figuring in the 1.6 crop factor of the Rebel XT, of course). Wide open, the actual f stop is f 8. I made this image wide open as there was a breeze blowing and I needed as high of a shutter speed as I could get. I ended up shooting at 1/320 sec @ f 8.

This image would have been nearly impossible without IS. I was having to constantly adjust focus as well as positioning in the frame. Even though the lens/camera was mounted on a tripod there was no way to lock the tripod in one position for the exposure under these conditions. I only got to make the one exposure before the dragonfly flew off. IS helped me get the image on the first exposure.

This is, also, further testament as to just how good are the Canon 300 f 2.8 lens and Canon teleconverters. Had I been able to stop down one more stop this image would have been even sharper. Still, this is remarkable sharpness for stacked teleconverters and maximum aperture

Best regards, as always, my friend.

Beetleman · Post by **Beetleman** » Sat Jul 01, 2006 11:37 am

That shot is fantastic Tom, Especially at that range. Can you use the 1.4x and 2x tc's with the 70-300mm zoom? I know you stated the IS would not work. Thanks.

rjlittlefield · Post by **rjlittlefield** » Sat Jul 01, 2006 12:07 pm

Tom,

I agree, this is remarkable -- and very pleasing!

Good point about not being able to lock the tripod. Let me think about this... The unlocked tripod will still prevent linear movements and also roll. So presumably the IS compensates for whatever up/down and side/side rotation happens as you handhold the framing and mess with the focus. Sounds like a perfect job for IS, and obvious it works well -- dang well!

I'm curious about the effect of those TC's on sharpness. Is there much more detail hiding in the original, or does this 800-pixel web image pretty much show all that's there? Could you have gotten the same detail with less TC and more cropping?

--Rik

twebster · Post by **twebster** » Sat Jul 01, 2006 1:11 pm

Hi ya' Doug,

Beetleman wrote:Can you use the 1.4x and 2x tc's with the 70-300mm zoom? I know you stated the IS would not work.

I wouldn't even attempt to stack teleconverters on this lens. 1) Although the 70-300mm IS lens is sharp for a consumer grade lens, very close to some L zoom lenses, this lens isn't nearly sharp enough to add stacked teleconverters. 2) Your maximum working aperture would be way too small for focusing except in the brightest of conditions. After stacking the 1.4x and 2x tc to the 70-300mm lens your maximum apertures would be about f 10 @ 70mm and f 16 @ 300mm. These maximum apertures are just too dim for practical field photography.

Hi ya' Rik,

Rik wrote:Is there much more detail hiding in the original, or does this 800-pixel web image pretty much show all that's there?

There is a lot of detail that is not shown in this jpeg compressed image. Here's a 100% pixel sample from the original raw file...

See all the little black hairs? These hairs do show up in a 13" x 19" print.

With stacked tc's on this lens I see only a minor difference in image sharpness as compared to each tc used alone. The biggest difference occurs in contrast. Images made with stacked tc's have a bit less contrast than images made with only a single tc. This, of course, can be easily taken care of in Photoshop.

Even with IS you still have to practice excellent "long lens technique". The best way to minimize vibrations when working with a tripod is to place one hand firmly on the lens directly over the tripod head and to jam the camera tightly against your face. This sounds like it should cause more vibrations but, the fact is, your hand and face adds needed additional mass to stabilize the whole setup.

Best regards as always, my friends

rjlittlefield · Post by **rjlittlefield** » Sat Jul 01, 2006 1:53 pm

Tom, thanks for the actual pixels. I'm just about as impressed as it's possible to be. From lens designer through photographer, this is excellent. A very useful calibration point -- quite different from my previous experiences with cheaper lenses and TC's.

--Rik

PS. Am I correct that this is the lens currently sold at Adorama for $3,899.95 (USA warranty)?

twebster · Post by **twebster** » Sat Jul 01, 2006 2:02 pm

Hi ya' Rik,

Rik wrote:PS. Am I correct that this is the lens currently sold at Adorama for $3,899.95 (USA warranty)?

Yup, that be the one.

twebster · Post by **twebster** » Mon Jul 03, 2006 6:24 am

One thing I should add to this topic, you can't expect stacked teleconverters to work this well on every image. Using stacked teleconverters is a last resort method. Like I stated earlier, everything has to be perfect to get good images using stacked teleconverters. I made about 200 images of birds, yesterday, and probably only 1 in 30 images turned out acceptable. Still, it's pretty amazing just how good are the Canon supertelephoto lenses and Canon teleconverters.

Best regards to all,