Ever since I started using the D800, I've been excited by the prospect of usable autofocus at f/8. However, as most of you know I've used the 400mm f/2.8 VR with a 2x TC as my long lens combo for a while. While this combination delivered outstanding sharpness and accuracy, there was simply no way to go longer than 800mm even if I could afford to use an aperture smaller than f/5.6.
      I recently bought the Nikon 600mm f/4 VR II lens, mainly with the intent of shooting it with the 1.7X and 2X teleconverters to gauge how usable it is. I did some field testing to assess performance (albeit VERY unscientific!) and thought I'd share the results with you. Hopefully this will help those trying to choose between these two lenses and trying to figure out how effective the teleconverters are with the 600.
      I shot all three combinations (bare lens, TC-17EII, TC-20EIII) from a tripod with a shutter speed fast enough to eliminate any camera movement, and the light was good enough to keep ISO's down too. All shots were taken on the D800, at a fixed exposure and within minutes of each other.The files were processed identically in LightRoom 4 - the only change was a sharpening value of +62 and then an output to JPEG. The 100% crops were taken from the center of the image.

Full image with the bare 600mm lens @ f/5.6 (click on the image for full size)


100% crop with bare 600mm lens @ f/5.6

The bare 600mm is pretty darn sharp - the detail on the fence post is captured pretty well. No surprises here then...


Full image with the TC-17EII Teleconverter mounted on the 600mm lens@ f/8 (click on the image for full size)


100% crop with the TC-17EII Teleconverter mounted on the 600mm lens@ f/8

In the past, I've seen the TC-17 deliver a bigger image without necessarily resolving more detail than the bare lens at the same distance, especially on the 70-200mm f/2.8 VR (version 1). No such complaints here - the quality of the glass on the 600 shines through and really delivers a sharp, usable image. The compromise in aperture hasn't been a big deal for me YET - the D800 seems to take it in stride and focuses swiftly and surely. However, busy backgrounds can still throw it off so you need to give focus a manual tweak every now and then. 


Full image with the TC-20EIII Teleconverter mounted on the 600mm lens @ f/10 (click on the image for full size)

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100% with the TC-20EIII Teleconverter mounted on the 600mm lens @ f/10

With the TC-20, the image in the viewfinder and on the sensor is certainly bigger, but it looks to be like the detailed resolved is similar to the TC-17. Contrast also seems to take a slight hit. Overall, a decent performance but it loses you more light than the TC-17, slows down AF a little and doesn't really resolve any more detail.

The Verdict
I'm pretty happy with the results the 600mm and TC-17 provide, and can safely say that I'll use this combo whenever I need the reach and don't need the AF speed. I wouldn't say that the AF is speed is bad, but I'm not sure it'll be up to handling birds in flight.
      I've always sworn by the performance of the TC-20EIII teleconverter on the 400/2.8, but it looks like the 600 doesn't work as well with this teleconverter. The results are certainly usable, but doesn't provide enough of an advantage over the TC-17 to recommend it. The allure of 1200mm is still too much to resist though, so I'll continue doing more field testing before I discount this combo.
What do you think? Any thoughts and comments are welcome!

I've had the D800 for a while now and have had the chance to shoot with it in less than ideal lighting - mostly between 6 and 7am when bird activity is at it's highest. One thing that has constantly surprised me is the great high ISO capability of this camera as I bought it resigning myself to dealing with significant noise. After a couple of months of shooting, I find myself comfortably shooting into the ISO 3,200 range when the light calls for it, and switching to my D3S only beyond that. The next question to me was - how does it compare against the venerable D3S that was until recently (and some say still) the king of low light / high ISO shooting?
My test included shooting both cameras in controlled lighting (the light from a single incandescent bulb) and set up on a tripod. All images were taken with the Nikon 16-35mm f/4 lens with VR switched off. The pictures were shot in RAW, viewed side by side in Adobe Lightroom 4 at 1:1 ratio (hence the much larger images from the D800), and a screen capture was taken. 
Please note that this test is ONLY intended to show noise and not resolution - from looking at the samples I can see that the D800 was out-resolving the printing capabilities of this seed manufacturer (the subject is a packet of seeds)!

Here are the results of my testing:

ISO 100-400 The images look pretty much the same, save the D800 delivering demonstrably more resolution with a hint more noise. 

D800 ISO 400


D3S ISO 400

ISO 800 I can see a little luminance noise in the D800 image, but nothing that would bother me. The D3S file looks clean.

D800 ISO 800


D3S ISO 800

ISO 1600 A little more luminance noise in the D800, but still very well controlled and perfectly acceptable, even for very large prints. The D3S is showing some noise, but it's so minute that you need to stick your face in the monitor to see it!

D800 ISO 1,600


D3S ISO 1,600

ISO 3200 The D3S is just warming up, while the D800 is noisier. The noise though is limited to luminance and isn't that hard to get rid of in post processing. On the D800, this ISO is about as high as I would comfortably go for wildlife photography.

D800 ISO 3,200


D3S ISO 3,200

ISO 6400 The D800 gets noisier and some of the fine detail is being blurred at this point. The D3S is humming a tune and picking its nails while still taking incredible pictures in near darkness. Now that's style!

D800 ISO 6,400


D3S ISO 6,400

ISO 12800 The D800 is breathing hard now, with lots of noise, loss of dynamic range and loss of more fine detail. The D3S on the other hand just realized that it's actually in a comparison test! It shows some noise but nothing that can't be cleaned up in post.

D800 ISO 12,800


D3S ISO 12,800

ISO 25600 The D800 is well out of its depth by 25,600 ISO - it's noisy, fine details are all but gone and colors, contrast and dynamic range are suffering visibly. It looks rather like a poorly executed Pointilist painting! The D3S is showing significant luminance noise, precluding this sensitivity for any critical work that'll be printed at large sizes.


D800 ISO 25,600


D3S ISO 25,600

Summary The D800 is perfectly usable for wildlife photography up to ISO 3,200. WHAT? ISO 3200? YES. It's that good! Incredible performance from a camera that many people say is only for use on tripods in controlled lighting circumstances. The D3S maintains fantastic quality right up a little over ISO 6,400, but I'd stop short of using 12,800 for critical work. As the ISO's climb over 3,200, I'd say the D3S is a 1-1.5 stops better than the D800. What was surprising about both cameras was that most of the noise was luminance noise, which to me is not as objectionable as the considerably more difficult to remove chroma noise (those ugly red, blue and green splotches).
This whole test has been based on a pixel level noise comparison, but we're ignoring one key factor here - the D800 has THREE times as many pixels as the D3S!!! To conduct an apples to apples comparison, I resized the D800 image to 12MP, and applied some sharpening and noise reduction to both images. Take a look at the results:

D800 ISO 12,800 - noise reduction & sharpening applied via Lightroom 4


D3S ISO 12,800 - noise reduction & sharpening applied via Lightroom 4

Can you tell a difference? I certainly think they're pretty comparable in terms of noise. So what I see is that the D800 has identical ISO performance to the D3S at ISO 12,800 IF you're willing to spend 15 seconds in Lightroom dragging the noise slider! On top of that, even downsized to 12MP you can see that the D800 is resolving a little more detail. Amazing!

Overall recommendation (based purely on ISO performance) If you shoot a LOT of images in low light and don't want to spend hours in post processing, the D3S is the clear winner here. However, if you shoot in both good and bad light and don't mind spending a little time working on your low light images, the sheer flexibility of the D800 will serve you better. I hope this review has been useful to you, and please feel free to leave comments or ask questions.

Affectionately referred to as the 'Sigmonster' because of its size, the Sigma 300-800mm is the second largest DSLR zoom lens currently being sold today at any price (incidentally the largest is also manufactured by Sigma - the 200-500mm f/2.8).
Weighing in at almost 13 pounds, the 300-800 is no welterweight. It has 18 elements in 16 groups, and is an internal focusing design meaning that the front element of the lens doesn't move as the lens is focused.

Build Quality & Handling
As befitting a lens of this price, the build quality is excellent. As you'll find if you read some of my other articles here, I'm not a fan of the finish Sigma applies to their lenses - the dark furry finish seems to magnetically attract scratches and rub marks. However, the body of the lens feels like a solid, professional tool in your hand (or more likely on your tripod).
Kudos to Sigma on the design of their lens foot (Nikon take note here) - the foot is a low profile, solid hunk of rubber-covered metal and fulfills its purpose perfectly. The finger indents on the top means it doubles as a very effective carrying handle. Compare this to the tripod feet on Nikon's large lenses - the Nikon tripod feet are skinny, overly tall, wobbly pieces of deadwood that most photographers replace immediately upon buying the lens.
The zoom ring and focus ring are a little too stiff for my taste, but not a big deal. The single piece lens hood is well made and seems sturdy enough too. 

Autofocus
The HSM motor in the seems pretty fast especially for such a long lens. It's a hair slower than a Nikon 400mm f/2.8 with a 2X teleconverter, but the difference isn't significant. The low light conditions I normally shoot in cause almost any long lens to hunt, but the Sigma didnt seem any worse than other big lenses I've used.
Image Quality
You'll know by now that I'm a big fan of the Nikon 400mm f/2.8 lens, which coupled with a 2X teleconverter has been my primary long lens for a few years now. I shot the lenses side by side and the images below are 100% crops from the center of the image.





So can you guess which picture is from the Sigma and which is from the Nikon? The first one is from the Sigma and the second one's from the Nikon. You can make your own conclusions, but to my eyes the Nikon is quite a bit sharper. This couldn't have been due to lens shake as multiple shots were taken locked down on a tripod with 1/400 sec+ shutter speeds. Ignore the lighting differences as the sun went behind some clouds as I was shooting with the Nikon.

Stopping down seemed to help make the Sigma's output a little crisper, but not by much.

I've been asked a few times why my reviews of long lenses stick to analyzing just the center of the image in a field setting. Wouldn't shots of a test chart in perfect studio lighting conditions provide a much better guide to lens sharpness? I don't doubt it. I'm almost always shooting in bad light and less than ideal conditions, so performance in a studio setting means nothing to me. Also I hardly every put anything in the corners of the image so corners sharpness doesn't mean much either for a long lens.

Size & Weight
The picture below shows the Sigma 300-800 compared to the Nikon 400 (with 2X TC). They're both big lenses, but the Sigma is a few inches longer and a few pounds heavier. It's definitely enough to feel on a day in the field.



Conclusion
The Sigmonster is a very specialized tool for a specialized application. It's calling card is the sheer flexibility of the zooming. In my experience the greatest benefit is in zooming out to 300mm, finding the subject, and quickly zooming in to 800mm. Having missed great shots in the past due to being a split second late in finding the target, I can't stress enough how important this is.
On the downside, you do trade some size and sharpness disadvantages for this flexibility - some of the name brand prime lenses are noticeably sharper and weigh less to boot. Is this lens the right one for you? If you need the zooming flexibility in a super telephoto lens and don't mind carrying around a gargantuan lens, this might be the one! 

Several people have asked me this question over the years, so I'll give you an answer that applies to ALL my photographs. I don't ever remove the backgrounds in my images using software - the soft, blurred backgrounds are the result of the lenses I shoot with and the way I position the background.

Lenses
I try to stick to lenses with either a long focal length or wide aperture as both these factor into getting a shallow depth of field. My lens of choice for bird photography is the Nikon 400mm f/2.8 VR used mostly with a 2X teleconverter, and for flight shots or very close subjects I use the Nikon 70-200mm f/2.8 VR (sometimes with a 1.7x teleconverter). Both these lenses have pretty nice Bokeh, and using the teleconverters further reduces the depth of field compared to a 'straight lens' - for example, the 400/2.8 with 2x teleconverter (effectively 800mm f/5.6) has a smaller depth of field than a straight 800mm f/5.6 lens.

Background positioning
I try to make sure the background is as far away from the subject as possible, as combined with a small depth of field this results in a blurred background. How can you change the distance of the background in wildlife photography? Simple - just reposition yourself so that there's nothing behind the subject for 10-15 feet at least.

An example of good Bokeh - the background is a blurred, soft wash of color and emphasizes the subject


Bad Bokeh - the branches in the background detract focus from the subject

The Nikon D300S has been my trusted primary camera for over two years now. This review isn't a scientific test; rather, it's a summary of my own subjective experience with this camera. I've also limited my commentary to areas of the camera I feel warrant my comments; more comprehensive reviews can be found on other sites. 

Body & Handling
I've always preferred a larger body whenever I've used a camera for any period of time. When I sold the D700 and moved to the D300S, I simply transferred the grip from the D700 over to the D300. The camera becomes a dream to use with the grip attached. I recently had a chance to use a Nikon D3, and to me the D300 had two major advantages:
1. Additional focus point selector - the D3 has one method to select the focus point, which is done by using the directional pad. Great for landscape mode, but change over to portait mode and your thumb can't quite reach it. This is a problem in real world shooting, especially for me - I need to be able to change the focus point without taking my hand off the camera. The D300S has an additional directional joystick that can be used in portrait mode.
2. The portrait grip just seems to have a little more meat to it than the D3, making it a tad more comfortable for long periods of use.

Autofocus
Autofocus is a critical part of bird photography. Low light, small subjects, an 800mm effective focal length and f/5.6 aperture would be challenging for ANY camera. I'd say the autofocus in the D300 is adequate. It's certainly better than the D200, but probably a tad slower than the D700. After using a D3 for a bit, I can say than the D3 wins hands down and just seems to lock on effortlessly. That said, focus seems to be accurate, and maybe my expectations of this camera are too high!

Frame Rate
Something I really liked moving from the D700 to the D300S was the increase in base frame rate from 5FPS to 7FPS. I feel that this frame rate is adequate for wildlife photography, though I'd jump at the chance to up this to 9-10FPS!

Crop Factor
The 1.5x crop factor is the DEFINING factor of this camera for me. Compared to a pro full-frame body like the D3 or D4, I have slower FPS, worse low light performance, slower AF and worse battery life. However, locking the D300S onto a small songbird and getting that frame filling shot because of the crop factor sometimes more than makes up for it!

Image Quality
Image quality from this camera is great, until you get into serious wildlife photography. The majority of this type of photography is done either just after sunrise or just before sunset in pretty low light levels. The ability to shoot at high ISO's with reasonable noise levels is a pretty big deal for wildlife photographers. I used to shoot this camera at a max ISO of 800 as this was as much noise as I was willing to put up with. However, I've recently started using Adobe Lightroom for noise removal and man DOES THIS FEATURE ROCK! I'm now ok with shooting upto ISO 1,000-1,250 knowing that I can get rid of the noise in Lightroom without destroying any detail.

Conclusion
The D300S has served me well over the years and it really is a fantastic camera for all-round use, and a very special camera for the bird photographer. That said, I'm eagerly awaiting the arrival of the D400(or whatever its replacements will be called. Check out my blog post on the D400 wish list for more of my thoughts! 

After my failed experiment with the 600mm f/4, I was a little tentative about the 400. While quite a bit lighter, this is also a large, intimidating lens. This time around, I made sure I had the prerequisites - the Gitzo Systematic Series 3 tripod legs and a solid gimbal head (mine's from Calumet Photo).
I can't overemphasize the importance of a good tripod/head combination to support this lens. In addition, lugging this 25-pound deadweight around requires a commitment to frequent shoulder and neck workouts! A lot of people have asked me whether the final result is really worth lugging this setup around, and after 2 years I can say that the answer is a YES! The lens seems to grow smaller every time you use it and it really isn't a big deal any more.

Build Quality & Handling
Nothing groundbreaking to report on this front - as befits a lens that costs as much as a small island, the build quality is fantastic. I did have an issue where the autofocus completely stopped working, but to Nikon's credit they fixed it for free even though my lens wasn't under warranty. Since then the lens has been a model of reliability. I almost always use this on a gimbal head or a rest, so handling isn't an issue in my opinion. I've tried handholding it, and take it from me - it's impossible. No matter how often you hit the gym.

Image Quality & Performance This lens delivers amazingly sharp pictures with good support and long lens technique. Bokeh is unbelievable and really makes the subjects pop. I coupled the lens with the Nikon TC-20EII 2X teleconverter for the first few months that I had it. The results were good but not great - I felt that the compromise in image quality was a little too much. Upgrading to the TC-20EIII teleconverter made a world of difference; I stop down by 1/3 to 2/3 stop for an effective aperture of f/7.1 and the resulting images are tack sharp. Check out the detail on the Dragonfly's wings below (this is a crop of about 10% of the original image):

Eastern Phoebe with Dragonfly

This is also probably the fastest focusing lens I have ever used - it's fast, sure and is a dream to use. However, I rarely use this lens without the 2x teleconverter, and adding the teleconverter sometimes makes the AF hunt a little in low light. However, this and the Nikon 300mm f/2.8 are probably the only lenses that can handle a 2X TC with such ease.
Here are my contributions to the big VR argument - I haven't attempted a scientific test but from what I've seen, using the VR in NORMAL mode it doesn't seem to hurt the images any! How's that for a cop-out?! Seriously, the only time I switch off VR is when I'm doing video - VR makes it sound like you're shooting from inside your local laundromat.

Conclusion
This is one serious lens - both price wise and in the commitment required to use it. However, all this pales into insignificance when  you finally snap that picture of a beautiful songbird in perfect focus with the background a soft, dreamy wash of color. For anyone who hasn't used one of Nikon's big lenses, here's my recommendation : rent one - you'll fall in love and eventually buy one!

My equipment for the Yala  drives consisted of two setups. For smaller birds and distant subjects, I used a Nikon 400mm f/2.8 VR with TC-20E teleconverter (effectively an 800mm f/5.6) mounted on a D300S body. For lower light and closer subjects, I had a Nikon 70-200mm f/2.8 mounted on a D700 body. Both setups worked well, and didn't leave me feeling like I was lacking focal lengths.

A word of advice on photographing in Yala - be ready with a shorter lens/camera combination at all times! The winding roads coupled with the dense scrub means you may come upon a leopard or bear without warning, and only have a few seconds before the animal disappears back into the bush. You often don't have time to meter or fiddle with other camera settings. I set all my cameras to Aperture Priority mode and shoot wide open, with the exposure compensation set to minus 1 stop. This works for the majority of lighting situations except where you'll have any sky in your image, in which case I change exposure compensation to 0 or +1. In my experience, keeping the exposure comp. at -1 allows me to pick up a camera and shoot quickly when I see an animal on the ground, and wherever a bird or animal is outlined against the sky I usually find I have the time to change the exposure compensation. 

I also use manual ISO, and as light changes I make sure I keep changing the ISO every 15 minutes or so to give me acceptable shutter speeds. You can do this by pointing the lens out the window at the ground while the vehicle is traveling and using the shutter button to turn on the meter and read your shutter speed.