Tamron 90mm macro digital AF questions

[Kind_Karma]

Okay,
So I splurged and got one of the new Tamron 90mm macro lenses for my K10D.
I have a couple of questions since I'm a newbie.

1.)This is my first "nice" lens(other is kit lens)...I want it to last and not get messed up, should I put a lens filter on it? If so, I want high quality pics, what kind should I put on it?

2.)I tried the lens out this morning and I noticed that I still had to get pretty close to insects. What is the most cost efficient and also still have high quality way to increase my working distance? A teleconverter?

3.)If I get an old manual teleconverter, would this take away from the quality? I found myself focusing the lens manually BTW.

4.)Is it deemed acceptable in the macro photography world, to crop a picture?

Thanks and peace.

[Nesster]

1.)This is my first "nice" lens(other is kit lens)...I want it to last and not get messed up, should I put a lens filter on it? If so, I want high quality pics, what kind should I put on it?

While the purists will tell you NO FILTERS! there's little downside to using one as protection, as you can always remove it if conditions warrant. Get an UV or Haze type, the big brands are Hoya and B&W, but between us it's OK to use Tiffen or similar. I mean, we're sinning already


4.)Is it deemed acceptable in the macro photography world, to crop a picture?

No, absolutely no! The macro police will send out army ants after you and fungus spores after your lenses if you so much as touch a pixel of the sacred image!

[Nesster]

For 2 and 3, the old mf Tamron 90 can use a bbar flat-field 2x converter. I'd say, go for it, whether it's af or mf doesn't by itself affect quality - the quality of the converter itself, as a lens, is what determines ultimate iq.

I too was surprised at how close a 90 had to get for high magnification.

For your #4 question, cropping's done all the time with macros. I wouldn't worry about it. I hope I didn't offend with my joke above.

[Venturi]

The front element is recessed ~1.5" from the front of the barrel on the Tam SP 90mm which makes it feel like you are closer, and with the lens hood on it really does feel like you're right on top of the subject (and a tad difficult to strobe it).
The recessed front element is also why I do keep a Hoya HMC UV filter on the front - it's a pain to clear out pollen and other stubborn dust from inside "the cave".
I've only put my 1.5 TC on the SP90 a couple times for kicks, and not enough shots taken to form any real opinion.

As for cropping, I've got a 1:1 shot of the RAID logo I flash to the army ants if they come try and mess with my crops.