Hmmmm.... I've been using my Nikon 1.7X with both the 200-400mm and the 500mm a lot lately, and it is REAL sharp. Just as sharp as with no Teleconverter. If your photos are sharp without the TC seems like it must be the problem.
Posted by Steve Foss on January 1, 2009 at 9:39 PM
A bad copy is always a possibility. I have clients who report good results with the 1.7 on the 200-400 and supertele primes.
One thing to consider is that if a TC is used to pull in a distant subject and the subject remains fairly small in the frame and significant cropping is needed for the final interpretation of the image, a TC is not at its best. Also, assessment of acceptable IQ varies from photographer to photographer.
There are simply so many factors that go into capturing sharp images at extreme focal lengths that we don't know enough information to diagnose the problem in this case. It's always a good idea to post an unsharpened sample image with this kind of inquiry so there's something concrete to go on. Otherwise people are just shooting blind with a scattergun, listing all the possible problems with no real sense of direction.
Posted by Brad Hill on January 1, 2009 at 11:44 PM
Hi Ed,
If you're clueless, then so am I - I've had similar results as you. Like with any teleconverter, you'll find that the performance of the 1.7x TC varies with the lens it's paired with. About the only lens that I'll use the 1.7x TC with is the 200 f2 VR - that lens is so sharp you could put a pop-bottle bottom in front of it and still get good results. But with every other lens I've tested the 1.7x TC with (including the 300 f2.8 VR, 200-400 f4 VR, 600 mm f4 VR) the degradation in image quality has been very noticeable (so noticeable that I WON'T use the 1.7x TC with them). Of course, you'll get better results if you stop down, but never as good as if you shot the lens without a TC. The 2.0x TC is worse again - mine has become little more than a paperweight (anyone looking for a killer deal on a TC-20EII 2.0x TC?) - I can't in good faith recommend it to anyone.
One final comment: You'll get a huge variation of opinions on this issue. The primary reason is the huge variation in what different photographers consider acceptable image quality. And, photographers who are VERY careful about technique (including stopping down the TC's and shooting off of rock solid supports) will do better at squeezing the most out of the TC's. But, I highly doubt that you have a "bad copy" of the TC - while it is possible, I'm willing to bet that if you tried 20 copies of the 1.7x TC you find the same thing - the results won't please you. I've now tried 3 copies of the 1.7x TC with identical (and with most lenses, unacceptable) results.
There's a reason why a TC costs about $375 and a quality super-telephoto costs thousands.
Feel free to contact me if you want more info on my experiences about all 3 of Nikon's TC's with various Nikon lenses.
Same subject with teleconverter. 100% crop unsharpened.
Posted by Mark Hamblin on January 2, 2009 at 4:41 AM
I certainly found the 1.7TC very poor when used wide open on a 200-400mm Nikon lens but improved significantly to a level I found acceptable for publication when stopped down 1 stop or more. I wouldn't use it wide open on any lens. The camera / lens combo must also be rock solid when shooting with teleconvertors especially with a crop sensor camera as the magnification is so great that any camera shake will be amplified. Mark
Posted by Basil Greber on January 2, 2009 at 4:59 AM
Yikes! The sample looks horrid indeed. Did you check for AF accuracy? Maybe your TC/lens combo suffers from back- or front focus.
Basil
Posted by Steve Foss on January 2, 2009 at 8:02 AM
Mark makes an excellent point. Even adding a 1.4 to a 400mm, which I occasionally do, makes a big difference in demanding increased steadying technique. Considering that neither the branches in front or behind the bird are sharp, I don't think back or front focusing is an issue.
It could be a bad TC or needing an improved steadying technique after seeing these images. Have you tried a similar experiment with a 1.4 TC to gauge IQ between the two TCs?
It could also be, given the shaded bird and bright BG, that the lens/TC combo was hunting for focus and the shutter tripped before focus was achieved. I'm a Canon shooter, not Nikon, but in Ai servo mode (continual autoadjust to focus when shutter held half way down), the shutter will trip if you depress it all the way whether focus is achieved or not.
You might do some testing with a rock solid tripod and a soda can to eliminate that last possibility and get the most reliable comparison for IQ purposes.
Posted by Ed Cooley on January 2, 2009 at 11:13 AM
I am pretty sure the focus is good and this is stopped down to f8. I use a heavy gitzo tripod, gimbal head and strong downward pressure on the lens which usually yields good results.
I shot probably 100 shots with and without the TC and this is the best image of the lot.
I switched from Canon to Nikon this year (1DmkIII autofocus and D3 were the reasons) and using the Canon 2X was softer but usable the 1.4 was hardly noticeable and much better than cropping a non-tc image. Even with the 2X the extra reach provided more detail than cropping.
With the 1.7 it is so soft that upressing the 600mm image is substantially better than a full res 600+1.7 which pretty much negates the whole purpose of the TC.
Attached is the 600mm image processed and sharpened. With the 1.7 the eagle almost fills the frame so cropping is not an issue here.
Posted by Jerry Greer on January 2, 2009 at 11:35 AM
Hey Ed,
Maybe you should've stayed with Canon! Just kidding! This is a real big problem with Nikon, according to my friends that still use the system. As good as their cameras and lenses are the extenders suck. As for your sample, it looks like a focusing issue and not movement of the camera. Do you know anyone that has another you can try? You can always buy another and return it if it's soft.
All that being said.... mine is sharp as can be. I have the 1.4x and the 1.7x, used with the 200-400mm, the 500mm VR, and the 600mm. I posted this a few days ago. These birds were probably 30 meters out.
Posted by Ed Cooley on January 2, 2009 at 12:25 PM
That looks pretty good but at that resolution it is hard to compare. Can you post a 100% unsharpened crop of one of the heads to compare. Here is the 600+1.7 processed image at a similar size and as you can see it is difficult to see much difference when downsizing for web.
I think at the end of the day you just won't be happy with Nikon's 1.7x TC. Simply put, it's not a good product. Although you will on occasion be able to squeeze acceptable quality out of it, the images will never match those shot without this TC. Besides softness, I've found the 1.7x TC reduces AF accuracy (I almost always have to manually over-ride it) and both colour and contrast suffer when the TC is used. If you spend a ton of time testing numerous copies of all Nikon's TC's (which I have done), I think you'll end up finding that the only one worth owning is the 1.4x. And, even with the 1.4x TC I would keep it away from ANY zoom, including the excellent 200-400 VR.
I would suggest reading Bjorn Rorslett's views on Nikon TC's (formed after consderable testing) here:
Nikon is doing a LOT of things very well right now, but producing good quality TC's isn't among them. And I'm still trying to figure out why they have ceased making extension tubes!
Cheers...
Brad
Posted by Dan Borzynski on January 2, 2009 at 2:19 PM
I'd try the soda can test (mentioned above), using manual focus and autofocus.
Also, what tripod are you using? It is strong enough to support both of these lenses, isn't it? Same question about the ball head/gimbal head. If there is *any* doubt, repeat the test, but take the lens off the tripod and lay it on a strong table. Maybe a little bit of duct tape as well... Actually, doing this probably would be a bad idea anyway, just to eliminate the tripod, ball head and your long lens technique from the equation.
And when testing, be sure to use mirror lockup, a remote and any time delay. Last, rerun everything with and without VR.
Especially with lenses this long and the results that you are getting, you will need to be sure that you are not contributing to the problems. That is probably not the case, but there is definitely a need to eliminate everything not camera related from the equation.
Posted by David Sparks on January 2, 2009 at 11:51 PM
I've been using a 1.7 tc with a 300mm f/4 on a D80 and for a very short time on a D300. This is the combination I've used for 90% of my bird shots for the past year. Perhaps it is because I've never used a longer prime, but I think the 1.7tc performs pretty well with the 300mm lens. I'm attaching a 100% crop of a shot taken with the D80, no sharpening or other processing except using the ACR 4.4 profile (obsolete now) when opening the image in Lightroom. ISO 400 (accounts for the noise) f/6.7 (wide open) at 1/640sec using a tripod, but not a cable release or time delay. I get better results when I use the cable release or time delay.
I don't know if you find this acceptable, but it is typical of the results I get when I use a tripod and really lock everything down so that I minimize movement of the camera and lens.
David Sparks
Posted by David Sparks on January 3, 2009 at 12:46 PM
I took a look at Bjorn Rorslett's review of teleconverters mentioned by Brad Hill in his condemnation of the 1.7tc.
Bjorn gives the 1.7tc a rating of 4 - Very good, quality results can be expected. Such lenses can safely be applied to professional photography.
In his general comments about teleconverters, he notes that "there are a few rare setups of master lens plus converter that yield high quality results. On these occations, there isn't a need to stop the master lens down either. Otherwise, the combination should be stopped down at least two stops to try to ensure better image sharpness." I don't know which lens/converters he is referring to.
He also makes the general point that for smaller format cameras that "utilise only the central part of the projected image", the quality of images may be much better than that obtained with full format cameras in the image corners.
Bjorn's review has this comment:
"Never, ever, add a converter to a zoom lens! Poor results are virtually guaranteed to occur."
Posted by Basil Greber on January 3, 2009 at 3:31 PM
After seeing what David and Charlie can get from their lens + TC-17 setups, and knowing Ronnie Gaubert's work (300/4 and 500/4 + TC-17) I'm even more convinced that there's a focus issue with Ed's setup, or the TC involved is grossly defective. I've never ever seen anything that soft, from any lens, unless it was out of focus. Sorry for insisting so much, but I don't think this represents typical performance.
You'll get a huge variation of opinions on this issue. The primary reason is the huge variation in what different photographers consider acceptable image quality. And, photographers who are VERY careful about technique (including stopping down the TC's and shooting off of rock solid supports) will do better at squeezing the most out of the TC's.
I wouldn't call this "a condemnation". But I probably shouldn't have stated that the 1.7x TC isn't a good product - what I should have said is that the product doesn't work for me, so for me it isn't a good product. I fully realize that there are many people who will be completely happy with the TC-17EII, just like there are many people who are happy with point-and-shoot cameras (please don't take this out of context - I am not implying that using the 1.7x TC is comparable to using a point and shoot - I am simply saying that different folks have different needs and image quality standards).
Interestingly, if you scan through the Fauna and Avian galleries you will almost never (note that I said ALMOST) see anyone posting pictures shot with the Nikon 1.7x TC (and you will see far more Canon TC's being used than Nikon TC's). I wonder why?
In closing - because the performance of all of Nikon's teleconverters vary dramatically with the host lens they are paired with, it is quite difficult to generalize about their performance. For this reason I have posted (on my website) my experiences with all of Nikon's current TC's with every Nikon lens I have used them with. My experience in pairing Nikon's TC's with zoom lenses parallels that of Bjorn Rorslett - I have not found a combination that produces results that please me, although I acknowledge that there may be a zoom lens/TC combination I haven't tried that works fine.
Brad
PS: If anyone is looking for an awesome deal on either a Nikon TC-17EII (1.7x) or TC-20EII (2.0x) TC, please feel free to contact me.
Posted by David Sparks on January 3, 2009 at 5:14 PM
Brad:
I'm not trying to defend the TC-17EII teleconverter. I'm using it because, at this point it time, it is the only way I can obtain sufficient reach to try my hand at bird photography. Perhaps if I had access to a long prime lens, I would be very unhappy with the images I'm currently obtaining. I'm particularly interested in this thread because I plan to acquire a longer lens soon and would like to know if teleconverters are options for the various lenses I'm considering. Because of this, I've been closely monitoring the use of teleconverters by contributors to the Avian Forum. There are a number of regular contributors who use Nikon tcs. Among them are: Richard Ditch (TC20E with the 300/2.8), Phillip Tomkinson (1.4tc with 200/2.8), and me (300/f4 with 1.7tc). Ronnie Gaubert's use of the TC17EII with 400mm f/2.8 and 300/f4 has already been mentioned.
I must say, I don't have closure on this subject. Some of the factors mentioned in this thread as possible sources of variability in results obtained by different users are: defective teleconverter (bad copy), differences in stabilization (tripod/no tripod; sturdiness of tripod, etc.), lens/teleconverter combination, differences in acceptable IQ, aperture setting, interaction with autofocus accuracy, use or lack of use of mirror lockup/remote-shutter-release/time-delay, and possible interaction with VR. Perhaps we could get Nikon to support a double-blind study in which all these factors were varied systematically.
I am definitely interested in other sources of information about the use of teleconverters with various telephoto lenses and will take a look at the information on your web site.
Just for those interested, I also have a write up using the 1.4x on the 200-400 and that can be found here.
Posted by Ed Cooley on January 6, 2009 at 12:13 PM
Richard, I have never been able to get quality like those in your blog. Can you share what technique you used to make these shots. Remote and mirror up don't seem appropriate for wildlife shooting and birds in motion/flight. I use a gimble head, heavy gitzo tripod and take multiple shots to pick the sharpest of a series.
With the 1.7x shots, one of the shots was hand held with just the tip of the lens hood resting on a ledge but the main lens and body unsupported. The other was on a beanbag (which I just noticed, I never wrote in my blog!).
I'd say if you have a body with fine tune, try playing with that but if you don't maybe the TC is a faulty one and needs replacing of adjusting at Nikon. Your example is so bad it looks more like the eagle is just outside the DOF rather than the optics are soft?! Hope you get it sorted though!!
Posted by Ed Cooley on January 6, 2009 at 12:36 PM
I suspected a focus problem as well but there is no part of the image that is in focus and even manually focusing produced similar results. I think I will take some reference shots of a resolution chart and send to nikon.
I've had a couple of people say that my examples have put them off using a 1.7x with this lens but I think they are acceptable as emergency long reach (I've seen far worst exmaples from naked long lenses from some third party manufacturers!). So I can only imagine how you must be feeling with the results from your current situation
Hope you get to the bottom of it with some testing...
Posted by Ed Cooley on January 7, 2009 at 11:15 AM
Thanks for all the great input, I found the problem with my setup. After seeing 100% crops of others images I was pretty sure I had a bad copy or seriously bad problems with my long lens technique. Even my image with just the 600mm was softer than others with their converters attached. With a trip to Florida next month to shoot birds I was freaking.
Gladly this was not the case and I have now returned to sanity.
I did some extensive testing in controlled lighting with a resolution chart. After about 10 minutes of testing (even before trying the 1.7x) it just didn't seem sturdy so I started checking everything from the tripod back to the camera. I discovered the tripod foot which mounts with 4 hex screws was slightly loose. Not enough to be obviously noticed but with my Wimberly sidekick, which mounts the foot 90 degrees to one side, it created the absolute worse conditions possible. Basically it was worse than a cheap tripod or shooting handheld for that matter. At the focal lengths involved with the D300, 600mm and 1.7x there was no hope.
Fixing that problem, the images immediately improved to what I expected. Even the 1.7X performed really well. Since I had everything setup, I did a lot of testing with the D300, 600mm, 1.7x using different apertures, techniques and shutter speeds to find the limits of acceptable performance. I'll write up a blog entry and post a followup here.
Again thanks for sharing your experiences and suggestions.
Posted by Steve Foss on January 7, 2009 at 12:22 PM
Discussion
30 repliesI have used a canon 2x with 500mm with usable results so I am wondering if I have a bad copy or if I am clueless.
Any suggestions or comments appreciated.
One thing to consider is that if a TC is used to pull in a distant subject and the subject remains fairly small in the frame and significant cropping is needed for the final interpretation of the image, a TC is not at its best. Also, assessment of acceptable IQ varies from photographer to photographer.
There are simply so many factors that go into capturing sharp images at extreme focal lengths that we don't know enough information to diagnose the problem in this case. It's always a good idea to post an unsharpened sample image with this kind of inquiry so there's something concrete to go on. Otherwise people are just shooting blind with a scattergun, listing all the possible problems with no real sense of direction.
If you're clueless, then so am I - I've had similar results as you. Like with any teleconverter, you'll find that the performance of the 1.7x TC varies with the lens it's paired with. About the only lens that I'll use the 1.7x TC with is the 200 f2 VR - that lens is so sharp you could put a pop-bottle bottom in front of it and still get good results. But with every other lens I've tested the 1.7x TC with (including the 300 f2.8 VR, 200-400 f4 VR, 600 mm f4 VR) the degradation in image quality has been very noticeable (so noticeable that I WON'T use the 1.7x TC with them). Of course, you'll get better results if you stop down, but never as good as if you shot the lens without a TC. The 2.0x TC is worse again - mine has become little more than a paperweight (anyone looking for a killer deal on a TC-20EII 2.0x TC?) - I can't in good faith recommend it to anyone.
One final comment: You'll get a huge variation of opinions on this issue. The primary reason is the huge variation in what different photographers consider acceptable image quality. And, photographers who are VERY careful about technique (including stopping down the TC's and shooting off of rock solid supports) will do better at squeezing the most out of the TC's. But, I highly doubt that you have a "bad copy" of the TC - while it is possible, I'm willing to bet that if you tried 20 copies of the 1.7x TC you find the same thing - the results won't please you. I've now tried 3 copies of the 1.7x TC with identical (and with most lenses, unacceptable) results.
There's a reason why a TC costs about $375 and a quality super-telephoto costs thousands.
Feel free to contact me if you want more info on my experiences about all 3 of Nikon's TC's with various Nikon lenses.
Cheers...
Brad
Basil
It could be a bad TC or needing an improved steadying technique after seeing these images. Have you tried a similar experiment with a 1.4 TC to gauge IQ between the two TCs?
It could also be, given the shaded bird and bright BG, that the lens/TC combo was hunting for focus and the shutter tripped before focus was achieved. I'm a Canon shooter, not Nikon, but in Ai servo mode (continual autoadjust to focus when shutter held half way down), the shutter will trip if you depress it all the way whether focus is achieved or not.
You might do some testing with a rock solid tripod and a soda can to eliminate that last possibility and get the most reliable comparison for IQ purposes.
I shot probably 100 shots with and without the TC and this is the best image of the lot.
I switched from Canon to Nikon this year (1DmkIII autofocus and D3 were the reasons) and using the Canon 2X was softer but usable the 1.4 was hardly noticeable and much better than cropping a non-tc image. Even with the 2X the extra reach provided more detail than cropping.
With the 1.7 it is so soft that upressing the 600mm image is substantially better than a full res 600+1.7 which pretty much negates the whole purpose of the TC.
Attached is the 600mm image processed and sharpened. With the 1.7 the eagle almost fills the frame so cropping is not an issue here.
Maybe you should've stayed with Canon!
http://www.naturephotographers.net/imagecritique/ic.cgi?a=vp&pr=112392&CGISESSID=14cf6a24919defeeadfa051b6a4948a0&u=699
It is similar to my experiences with a friends 1.7 I tried before purchasing mine.
I think at the end of the day you just won't be happy with Nikon's 1.7x TC. Simply put, it's not a good product. Although you will on occasion be able to squeeze acceptable quality out of it, the images will never match those shot without this TC. Besides softness, I've found the 1.7x TC reduces AF accuracy (I almost always have to manually over-ride it) and both colour and contrast suffer when the TC is used. If you spend a ton of time testing numerous copies of all Nikon's TC's (which I have done), I think you'll end up finding that the only one worth owning is the 1.4x. And, even with the 1.4x TC I would keep it away from ANY zoom, including the excellent 200-400 VR.
I would suggest reading Bjorn Rorslett's views on Nikon TC's (formed after consderable testing) here:
http://www.naturfotograf.com/lens_converter.html#top_page.
Nikon is doing a LOT of things very well right now, but producing good quality TC's isn't among them. And I'm still trying to figure out why they have ceased making extension tubes!
Cheers...
Brad
Also, what tripod are you using? It is strong enough to support both of these lenses, isn't it? Same question about the ball head/gimbal head. If there is *any* doubt, repeat the test, but take the lens off the tripod and lay it on a strong table. Maybe a little bit of duct tape as well... Actually, doing this probably would be a bad idea anyway, just to eliminate the tripod, ball head and your long lens technique from the equation.
And when testing, be sure to use mirror lockup, a remote and any time delay. Last, rerun everything with and without VR.
Especially with lenses this long and the results that you are getting, you will need to be sure that you are not contributing to the problems. That is probably not the case, but there is definitely a need to eliminate everything not camera related from the equation.
I don't know if you find this acceptable, but it is typical of the results I get when I use a tripod and really lock everything down so that I minimize movement of the camera and lens.
David Sparks
Bjorn gives the 1.7tc a rating of 4 - Very good, quality results can be expected. Such lenses can safely be applied to professional photography.
In his general comments about teleconverters, he notes that "there are a few rare setups of master lens plus converter that yield high quality results. On these occations, there isn't a need to stop the master lens down either. Otherwise, the combination should be stopped down at least two stops to try to ensure better image sharpness." I don't know which lens/converters he is referring to.
He also makes the general point that for smaller format cameras that "utilise only the central part of the projected image", the quality of images may be much better than that obtained with full format cameras in the image corners.
Bjorn's review has this comment:
"Never, ever, add a converter to a zoom lens! Poor results are virtually guaranteed to occur."
Basil
If you read my first entry I state:
I wouldn't call this "a condemnation". But I probably shouldn't have stated that the 1.7x TC isn't a good product - what I should have said is that the product doesn't work for me, so for me it isn't a good product. I fully realize that there are many people who will be completely happy with the TC-17EII, just like there are many people who are happy with point-and-shoot cameras (please don't take this out of context - I am not implying that using the 1.7x TC is comparable to using a point and shoot - I am simply saying that different folks have different needs and image quality standards).
Interestingly, if you scan through the Fauna and Avian galleries you will almost never (note that I said ALMOST) see anyone posting pictures shot with the Nikon 1.7x TC (and you will see far more Canon TC's being used than Nikon TC's). I wonder why?
In closing - because the performance of all of Nikon's teleconverters vary dramatically with the host lens they are paired with, it is quite difficult to generalize about their performance. For this reason I have posted (on my website) my experiences with all of Nikon's current TC's with every Nikon lens I have used them with. My experience in pairing Nikon's TC's with zoom lenses parallels that of Bjorn Rorslett - I have not found a combination that produces results that please me, although I acknowledge that there may be a zoom lens/TC combination I haven't tried that works fine.
Brad
PS: If anyone is looking for an awesome deal on either a Nikon TC-17EII (1.7x) or TC-20EII (2.0x) TC, please feel free to contact me.
I'm not trying to defend the TC-17EII teleconverter. I'm using it because, at this point it time, it is the only way I can obtain sufficient reach to try my hand at bird photography. Perhaps if I had access to a long prime lens, I would be very unhappy with the images I'm currently obtaining. I'm particularly interested in this thread because I plan to acquire a longer lens soon and would like to know if teleconverters are options for the various lenses I'm considering. Because of this, I've been closely monitoring the use of teleconverters by contributors to the Avian Forum. There are a number of regular contributors who use Nikon tcs. Among them are: Richard Ditch (TC20E with the 300/2.8), Phillip Tomkinson (1.4tc with 200/2.8), and me (300/f4 with 1.7tc). Ronnie Gaubert's use of the TC17EII with 400mm f/2.8 and 300/f4 has already been mentioned.
I must say, I don't have closure on this subject. Some of the factors mentioned in this thread as possible sources of variability in results obtained by different users are: defective teleconverter (bad copy), differences in stabilization (tripod/no tripod; sturdiness of tripod, etc.), lens/teleconverter combination, differences in acceptable IQ, aperture setting, interaction with autofocus accuracy, use or lack of use of mirror lockup/remote-shutter-release/time-delay, and possible interaction with VR. Perhaps we could get Nikon to support a double-blind study in which all these factors were varied systematically.
I am definitely interested in other sources of information about the use of teleconverters with various telephoto lenses and will take a look at the information on your web site.
Just for those interested, I also have a write up using the 1.4x on the 200-400 and that can be found here.
I'd say if you have a body with fine tune, try playing with that but if you don't maybe the TC is a faulty one and needs replacing of adjusting at Nikon. Your example is so bad it looks more like the eagle is just outside the DOF rather than the optics are soft?! Hope you get it sorted though!!
Will advise...
Hope you get to the bottom of it with some testing...
Gladly this was not the case and I have now returned to sanity.
I did some extensive testing in controlled lighting with a resolution chart. After about 10 minutes of testing (even before trying the 1.7x) it just didn't seem sturdy so I started checking everything from the tripod back to the camera. I discovered the tripod foot which mounts with 4 hex screws was slightly loose. Not enough to be obviously noticed but with my Wimberly sidekick, which mounts the foot 90 degrees to one side, it created the absolute worse conditions possible. Basically it was worse than a cheap tripod or shooting handheld for that matter. At the focal lengths involved with the D300, 600mm and 1.7x there was no hope.
Fixing that problem, the images immediately improved to what I expected. Even the 1.7X performed really well. Since I had everything setup, I did a lot of testing with the D300, 600mm, 1.7x using different apertures, techniques and shutter speeds to find the limits of acceptable performance. I'll write up a blog entry and post a followup here.
Again thanks for sharing your experiences and suggestions.
I'm glad you found the problem with your setup. Please let me know when you write up a blog entry on the D300, 600mm, 1.7x combination.