Here are some of my results from my first run with this lens in the field in Greece recently. This Hyla arborea is a froglet:

A female Greek Algyroides (Algyroides moreoticus)

Balkan Whip Snake (Hierophis gemonensis)

In case that you need something "bigger" and still 1:1 macro then the best sollution is Sigma macro 150 mm or Sigma 180 mm macro (Canon has also 180mm macro but the lens is much more expensive but the quality is almost the same). 

Yes but the question is 'why' should i feel that i need that?
I guess it could be very handy for photographing Pelophylax singing from a distance, where they are not disturbed... 

If you are happy with 105 mm then is OK. 150 or 180 mm give you just more space between you and object and you still have 1:1
For green frogs, for greater distance you will need to add also a teleconverter (1.4) to get a better photo 

I use a 100 macro for 50% of my pictures (Sony A350 with , formerly Sigma 105, now Tamron 90). But don't forget other focal lenght ! I use more and more a 300/4, useful for fearful lizards...
I use too a 50/1.4 for bad luminosity or/and big snakes (with a 100 macro, you have to stay away if you want the entire snake on the picture).
And, to finish, I use a wide angle, for landscape and intersting framing !
Here is some example :
300/4 :

90/2.8 :

90/2.8 :

50/1.4 :

10-20/4-5.6 :

10-20/4-5.6 :

Of course, you need a big bag... :(...
Matt 

I use two types of cameras.
For my trousers pocket I allways have my Nikon Coolpix L5 (7.2 Megapixel) with me. For example: this Podarcis erhardii picture was made from a distance of about 80 cm with full optical zoom (5x).

Since this spring I have a Nikon D40 now too. And a SIGMA Macro zoom 70 - 300 mm (1:4 - 5.6). The following pics have been made with 250 - 300 mm and macro function

Podarcis siculus campestris, eating a diptera.

Vipera berus female, Black forest, Germany.

The SIGMA was not so expensive. About 180.-- Euro. And the test reports say, its nearly equal to the Nikon lens.
But before a few days I have tried the original Nikon AF-S VR Zoom-NIKKOR 70-300 mm 1:4,5-5,6G.
Its x-times better than the Sigma. And it is a VR (Vibration reduction), very usefull, when taking pictures with 200 - 300 mm. Price is about 460.-- Euro.
I think, its time to change!

Mario

Mario 

About the macro lenses.
When you want a 150 or 180, you will lose depth of field(DEF) compared to a 105, but this can also be a good thing to make the back of the photo "not sharp".
I used a 60mm macro,(untill my brother "borrowed" it for a 3 months trip...) now I have a 105mm macro and I really notice the difference in depht of field between the 2.
You also need shorter shutter times when the focal lenght goes up, which means making the aperture hole bigger and with this you lose DEF again.
You can go around this with using a higher ISO value, but you will lose some quality.

These are just a few things to consider when you want a bigger macro lens. 

Well in my short experience (I use almost always the 100mm 2.8 macro) the 100mm is great for portraits but is seems to me now that I'd rather have a 50mm lense instead, to fit whole snakes and lizards, or even turtles without standing too far and to save some shutter speed and iso... so my next lense will definitely be a 50/1.8 or a 60mm macro 

The 60mm macro is a very nice lens to work with, and you are able to fit the bigger things in a pic without the need to move to the back.
Before I went digital I made slides with a manual focus SLR and I had a 55mm macro lens, that one was also very nice. 

@ Gert Jan:
The focal length does have (nearly) no influence on the DOF.
As far as I get it, objects look better "cut out" (I have no idea if this is the right word, in german it would be "freigestellt") with long lenses, because with increasing focal lenght the visible section/rectangle of the background gets smaller and so also the "disturbing" parts in the background decrease.
See also
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
http://www.waynesthisandthat.com/dof.html

Concerning the right focal length for macros in herping - imo handling and photographing at the same time with ~100mm (at crop sensors) is quite annoying if you want to get more than just a (small) part of the animal (like Matthieu and Ilias already said esp. for snakes or animals which move a lot). On the other hand, for in situ photographing 100mm are often insufficient or need lots of sneaking up. So I'm not sure, if the 100mm are a good or a bad tradeoff.. As far as I'm using the 105 vr from nikon and like to set the focus on in-situ-clicking, the next spending will definitely be the 300/4.0 or the 180 from sigma with an 1,4 tc..

best regards
Gerald
 

Well Gerald the focal length is actually has to do with the DOF because when you want to fit the same animal to the frame with a 50mm you have to be closer to the subject, so the dof will be smaller than that with the 100mm (you have to stand further) ;-) 

I have the feeling that I'm a bit slow on the uptake and hope we're not talking cross purposes... ;-) - what the two mentioned links say, as far as I get it, is, that if you put an object in the same frame with two different focal lengths, i.e. you have to move nearer to the object with the shorter one, the DOF is (more or less, within 0,x mm for example at 100 vs 200mm), given that you use the same aperture, still the same.
If you're not moving towards the object, I think, you have differences because of the magnification, but not by the aperture-caused DOF.
 

You can compare the dof of 2 lenses in different ways.
For example, the 60mm and the 105mm micro Nikkors.
When you want to make a photo 1:1 and both lenses at the same aperture, now the distance to the sensor is 22 cm with the 60mm and 31 cm with the 105. In this way the picture will be the same, except for the DOF, which will be a bigger part with the 60mm.
2nd way is to compare with both lenses at the same distance from the object and using the same aperture again, the photos will be different from each other because of the focal lengths,and the DOF will be bigger again with the 60mm.
In one of the links you can try it out, and when you have a crop factor you can fill in the real focal lengths. 

Meanwhile, i did some further "research"..

The first problem is, the 1:1 distance differs between lenses with the same focal length (supposably because of the lens extension during focussing):
http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/394-nikkor_60_28 and
http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/219-micro-nikkor-af-60mm-f28-d-review--test-report

If you use the 185mm nearest focus distance the dof is the same like with the 105mm VR (315mm n.f.d).

The second thing is, reduced to the formulas, (not only) according to the following page: If the reproduction scale is 1:1 or higher, there is "no" difference in the dof between different focal lengths at the same scale. Down to, lets say 1:10, it's in my opinion negligible, for example between 50 and 200mm focal length at aperture 11 there's less than 0,5mm difference at a total dof of ~80mm...

The thing I didn't know is, that at lower scales than 1:10 theres a fast growing difference of total dof.

The first column are the different reproduction scales, the "normal" formatted numbers the dof, the fat numbers the focal length. It's been taken from this site:
http://www.elmar-baumann.de/fotografie/schaerfentiefe/node19.html
Unfortunately I really didn't find any similar site in english :-(
Perhaps the one getting nearest is the part "clarification: focal length and depth of field" in the first mentioned link
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

On the other hand - the influence and right usage in the formulas of zoomable lenses, if & non-if lenses and other lens dependent factors is not really clear to me - so this is only a reduced point of view

The second way you mentioned is clear to me, but there you also change the scale.

[edit]So I would conclude (as far as i get it..) - if you want to put a lizard portrait in the frame, the difference in dof between 50 and 200mm focal length is "appreciable" (<1% of total dof). Hehe..if you want to put a whole lizard in the frame I'm not so sure about it because of the exponential growth of dof.. perhaps I'm going to calculate it for a 20cm L. agilis tomorrow ;-)[/edit]

..I hope I understood it the way it should be and I'm not talking myself into even more nonsense than I already did ;-)


 

My brother returned from far away so soon I can compare the older 60mm micro and the latest 105mm micro VR etc.
I read all the articles, you were right in a way.

What is the case most of the time when you use a bigger focall lenght, you need a shorter shutter speed to make a sharp photo, which means you need more light and most of the time you make the aperture bigger(or use a tripod)and then the DOF will become smaller........
This can also be a reason for some of the confusions... 

Hi Dan I am now using a canon eos digital with a sigma 75x300mm af that seem good for stand back photos can buy on ebay at reasonable price. keith