The amount of light that a lens allows through to the sensor depends on how large the initial element is and the focal length. A mathematical formula eventually comes up with a specific aperture which in this case is f5.6. Now, if you place a TC in the light path, the amount of light that passes through the lens is one stop less meaning that the lens becomes an f8 lens. Basically you now have less light entering the camera and that leads to the autofocus sensor starting to fail in some circumstances.

In a way you are right that f-stop is irrelevant when it comes to autofocus. Exposures are determined with the lens wide open regardless of the f-stop you select. But this works only because the lens you are using is at least bright enough to allow enough light to pass through. If you're using an f2.8 lens there's no question you can close it down as much as you like, everything will still work since the final aperture doesn't happen until the shutter opens.

But this is a false conclusion. If you take a f8 lens and place it on the camera you'll start to have problems because the camera's focus sensors need a certain minimum amount of light and an f8 lens is not allowing enough through to enable them to calculate an accurate focus.

One other way to look at this would be in poor light. If you have a f5.6 lens that works flawlessly at high noon and you try to use it at dusk, you'll find you can't focus automatically because there isn't enough light. The answer of course is to open the lens more to allow more light in, but in this case you can't, the aperture wide open won't open more than f5.6 so you need a different solution. Well that's what happens with a TC, you have even less light and playing with the aperture doesn't change that.

When we talk about a lens losing an f-stop, we're talking about the lens TC combination reducing the amount of light through the lens by one half. If we're talking about two stops it means reducing the light passing through by one quarter. This has nothing to do with the aperture you set on the dial, it has everything to do with how much light the lens will allow through to the sensor and that measurement assumes the lens aperture is open all the way.

I hope this clarifies the issue. I know it can be confusing when you're new at this stuff.

Teleonverters are no longer like in the film days when they attached to any lens of any brand. Now they attach to only some lenses and not even to all brands. This is partly a marketing issue I bet but it's also a practical issue, some lenses just aren't designed for a TC.

That said I tend to prefer to stick to brands. I have two Sigma teleconverters for Sigma lenses only in fact for the 150-500 as well as a 150 mm and 180 mmm macro lens. They connect flawlessly and tight and they are optically lovely. At the same time I also have two Nikon TCs that I use with my Nikon lenses. These are an amazing quality and enable me to use my high end Nikon lenses to good effect. I've not tried a Sigma one on a Nikon lens or a Nikon on a Sigma lens though I expect both to work with both brands.

What is also interesting to note is that if you ask Sigma if their TCs work with Nikon they will tell you they can't comment, all they will tell you is that their TCs are designed for optimal performance on their lenses. Nikon takes the same attitude. And it's fair. Each maker designs their lenses with particular optics and so the TC is optimized for that specific design family.

There are some makers like Kenko who develop TCs apparently for all brands and all lenses. I don't buy the "all lenses" part. Some lens designs these days have lens elements going beyond the lens mount. A teleconverter could crash into those elements causing some damage. So if you use a generic TC, test it very carefully before you mount it and use it.

Recognize too that general TC designs can only approximate what's needed optically to enable a lens to perform optimally. So don't expect superior performance from something like Kenko. You won't always get it.

So this is a long winded endorsement. Use Sigma TCs with Sigma lenses, use Nikon ones with Nikons and if you decide on only one be aware that it may not work as well on the other brand. Be aware too that you can't attach them to all lenses.

Ok the only claw that looks any good is the talon on the the right foot. I made a selection of that talon with the Polygon Lasso tool. I enjoy using that that tool because your Alt Key will minus your selection and the the Shift Key to add to it. Bring your selection in pretty close to the shape you want. I cleaned up a little with the Air Brush tool, using the Alt Key to make my color selection from the area I liked and setting the Opacity to 60. This allows you to build up your color. Once that talon was to my liking I copied it with the selection.

Once copied to the clip board I pasted it, Then using the move tool to drag it over where I wanted it. I left the on it's own layer since this will allow painting the foot on the first layer easyier without any over-spray.


Select the Yellow foot with the Polygon Lasso and begin your coloring much the same way you did the talon.

Now invert the selection and clean up the feathers, this will reduce the smudging of the yellow.

You should be done, you might want to flatten the photo. or leave the layers and save as desire.

First, I don't know of any "print shop" that can print from a RAW file. You need to convert it to JPEG, or sometimes TIFF. Just ask the printer.

People often get all concerned about "can't print over "x" size with so many mp. That's crap.

Read some posts by MT shooter. I personally have had a billboard printed from a 6.1 mp camera. It all has to do with viewing distance. If you print a 30x40 print, nobody will be standing 12 inches away from it to view the whole thing. If the image is sharp, you can easily print a 30x40 print, or larger, and it will look fine. A good printer, (not Wal-Mart) will let you know before the print is made, if the resolution isn't high enough. I personally use Meridian Pro, or MPIX, or Adorama for prints, and have never had issues printing even 30x40 with my old 10mp D-200. The key is a very sharp photo to begin with.

Apparently you have the new VC version of that lens ($649). Any lens damaged beyond repair is just that, beyond repair, or the total repair cost (parts PLUS labor) exceeds the replacement cost of the lens. (The online "estimate" you first received was a good faith estimate only and actual repair needs could not be assessed until the lens had been received, disassembled, and a determination of repair parts and time was diagnosed.
Tamron is offering you a $100 discount on the replacement lens, not a bad deal really, but they also will have to keep the damaged lens to offer that discount, its simple accounting really. Personally I like the older non-VC version of that lens just as well and its only $499.

If you're just starting out in PP, this is a GREAT start!
I'd show some of my early stuff, but I think the crap police have already disposed of it! :-)

I would recommend instead of trying to remove all of the branches in post, you try to just improve the background sky by using a layer style to darken bits of it. Maybe not a blue sky, but a stormy clouds sky.
By doing it this way, you avoid the issue of soft spots on the branch the eagle is sitting on.

Again, GREAT job, and keep them coming. :-)

I will give the sky a shot with what I have but I had no luck in Lightroom. It was very blown out since I exposed for the Eagle. I guess I should have done multiple exposures and tried HDR. When you talk about trying darking different areas of the sky would that be using a pattern? I have seen tutorials on using patterns to different stuff to parts of the picture (I think using a gradient type thing) but I cant remember how to get there. Is this the type of thing you are talking about??

GT