the kit 18105VR can use with kenko extension ka? u mean teleconverter?

Extension tube ... yes .. teleconverter I don't think so. Teleconverter has elements but a extension tube is hollow. A telecoverter will add 1-stop to your aperture which means if your aperture is f 3.5 it becomes f7 and if f2.8 it becomes f5.6. The AF system generally can't handle apertures smaller than f5.6. Which is why teleconverters are not used with "slower" lenses that have smaller apertures.
Anyway I've tested the Kenko 25 tube with the 18-55VR and the 18-70. AF works and it goes much closer.

TC and extension tubes cannot be compared this way. Once extends the focal length, while another decreases the focusing distance. Also, it is important to know that light loss is also associated with extension tubes, I am not sure how the light loss is computed though.

Extension tubes are primarily as an alternative for macro photography.

Again, newcomers, TC and extension tube are not interchangeable terms.

Any comment on both the Tamron 28-75 F2.8 and Tamron 17-50 F2.8?

Seems hard to find review for the 28-75 and both of it's price is almost same, wan to make a move to replace my kit lens 18-55.

You wont go wrong with any Tamron f/2.8 lenses. It just depends on the reach you need from the lens. If you find yourself needing more zoom than the 18-55 kit lens, then go for the 28-75mm lens. Otherwise, go for the more common and widely used 17-50mm f/2.8 lens.

yeah i understand now.. that's y teleconverters are used on f2.8 lenses..the big2 tele lens right?

Extension tubes decreases the MFD right? i guess it would make the subject bigger but the problem is that even if it's bigger, doing macro shots on insects get more difficult because we need to get close to them.

1. Does extension tubes decrease IQ?
2. Does ext tubes lower the light that gets into the lens?
3. What if i used ext tubes for the purpose of decreasing the MFD of 18105VR so that i can take pics of people/subjects much closer to them?

d40 still got meh?

1. Not entirely sure. But I'd say, not a lot since there are no optical conversion involved.
2. Definitely, since there is an extension, for sure there is loss of light. For more info: here and here.
3. Extension tubes are usually used with prime/fixed focal lenses. (in that sense, I think it may decrease IQ in relation to question 1)

thanks for the answers.. so it means in the case of 18105, i shouldnt use either extension tubes (for prime lens) nor teleconverters (f2.8 tele lenses)

but in the post above, project-o said he used the kenko 25 tube on 1855vr and 1870 .. guess the downsides are more than the advantages ...

I guess only photos can do justification.

I had used extension tubes (kenko 25mm) with my 50mm f/1.8 but results were bad. I ended up buying a tamron 90mm f/2.8. I don't know how good will extension tubes work with zoom lenses.

Which do you think is a better lens to cover a wedding event? Or maybe a SP AF 90mm F2.8?

For wedding I foresee more wide shots. So having 17mm would be a benefit. You can also opt for prime lens if you don't mind fixed focal.

Like say maybe the AF-S 35mm F1.8?

Let me try to find the test photos of the Kenko tube. It's just a lower cost way of shooting macro as compared to getting a dedicated macro lens but compared to a real macro lens totally no contest but is much better than those close up filters. Anyway... as for the tube...after testing I didn't buy it. There are a few lengths of tubes depending on how close you want to go to the subject.


This post has been edited by project-o: Jul 6 2009, 11:04 AM

I wouldn't stick to just one lens for a wedding. This lens would be a good addition. But I think you'd be using the wideangle most of the time.

Will need a lot of "leg zoom" if you were to use 35mm alone.

I see, maybe can recommend some lens budget around 1k+?

a suitable wedding lens imo would be any of these : 18-55VR, sigma 18-50 f2.8 HSM, tamron 17-50 f2.8, or the expensivo and big Nikon AF-S 17-55 f2.8

for me primes would suit one person shots..

yup, weddings mosly use wide lenses..

may i know where can i still buy the d40 (new unit)?

This post has been edited by beetee: Jul 6 2009, 11:59 AM