Is this the right question:

[NEArcher]

What lens do I need for a Nikon D50 to be comparative to a Panasonic FZ5 ro 30 at full zoom?

I don't know enough about photograpy to know how to compare the two cameras properly.  

I am curious because I was told that the digital cameras with 12x optical zoom is like having a 400MM f2.8 lens.  With the 12x digital camera costing way less than the SLR lens by itself, never mind adding the cost of a digital body.  

Am I totaly confused.

I just want to a digital camera that will get me the closest (telephotoly) for the least amount of money, and take a decent picture during the golden hours.

Any thoughts?

[five-oh]

The 12x optical on the Panasonic is supposed to be equivalent to a 400mm lens, so on an SLR you would need to buy a 400mm zoom lens to get the 12x power of the Panasonic.

Now with that being said, all things are not equal, because even though I have a Panasonic FZ30 and love the camera, I'm not going to try and convince you that it's better than a digital SLR.  I think it does have it's place for convenience because you don't have to carry all the extra lenses, and cost is also a plus when compared to the SLR.  You can find the FZ30 for just over $500, and that's probably about how much a good 400mm zoom lens will cost for a SLR.  Plus the cost of the camera on top of that which from what I have seen for a good digital SLR will be $800 to $1000.  Guys correct me if I am way off base here.  

But where the SLR will really kick butt, is low light photography without a flash.  Most Prosumer camera's will struggle with this and that's where "noise" will start to show up in the pictures.  By "noise" I mean the grainy look that some pictures will have that are taken in low light w/o a flash.  

Both camera's have their place, and everyone's needs are different.

If you want to do more research on this go to dpreview.com.  They do a fair and honest review of practically every digital camera there is out there.

There are some guys on here who know way more than me about this, as I am sort of just getting started with my camera.  I'm sure they can add a lot more than I have, or correct me if I have totally explained it wrong.

[NEArcher]

I guess I sort of get that 12x is comperable to 400mm, but what about lens speed.  I guess thats what your getting at by noting less low light performanc, but can we quantify it?  Is the DSLR one stop faster, or several?  If I understand things correctly, its the speed that tends to make a lens expensive.  Is the 12x really f2.8?  

Maybe another way to phrase my question is, whats the least expensive way to fill the frame with a rabbit at 50 yards, at sunrise/set, with reasonable shutter speeds?

[Weasel]

If I'm correct, the 400mm equivalent on the Panasonic is equal to a 400mm on a film camera. If you put a 400mm on a Canon DSLR with the 1.6 crop factor, it's like having a 620mm.

I have a real hard time believing the 400 on the Panasonic is f2.8.  Have you ever seen a 300mm or 400mm f2.8 lens?  They are huge!

[Weasel]

I stand corrected. It is f3.7 at the 420mm end according to this:  http://www.dpreview.com/reviews/panasonicfz30/

That's pretty impressive!

[five-oh]

Here is a pic I took of a deer running.  It was midday but extremely foggy.  She was about 40 yards and running at a pretty good pace.  The camera was set on auto mode and not to action.

 http://i40.photobucket.com/albums/e217/sprintcarfan/P1000321.jpg

Most of the low-light limitation in the prosumer models comes not from the f-stop, but the sensor size.  The sensor is much larger in a digital SLR.  I'm sure there are other factors but from what I understand and have read the smaller sensor is one of the biggest reasons for this.

Weasel I believe you are right that the 12x is equivalent to a 400mm film camera.

[NEArcher]

Weasel, that sort of answers my question.  If you buy an FZ30 for less than $600, you get similar performance to a 35MM camera with a lens on costing thousands on it.  Seems too good to be true?

[Dave N./TX]

I am a little surprised no one has said anything about focus speed of digitals at lower light conditions. I have a Minolta Z1(3.2MP), a Cannon A60 (2.2MP) and a Nikon D70 (6MP). Both the Z1 and th A60 take long enough to focus at low light you can miss a shot completely. The D70 is way faster.

Any time I look at a digital now one of the main things I look at is focus time.

Dave

[Rob DiStefano]

In my earlier photo dayze, I shot quite a bit of surf images and used both a 400mm and 800mm lens with my Nikon and Olympus gear - IMO, there is no comparison between a mechanical telephoto lens and a "software telephoto" lens.  You get what you pay for ...