I'm sort of new at this.  I want to take a poser image I saved and open it up in photoshop.  How do I change the format of the file to a pdf?  Or is that necessary to see it in photoshop? 

Save the image in Poser as a .png file.

Then go to Photoshop and click "File" and open the .png file you saved.  It will show up in Photoshop as an image with a transparent alpha layer.  You can save it back out as a .psd file if you want or you can work on it in .png format and then save it as a .psd file when you're done so that it saves the layers etc.

Photoshop opens many image formats.
Save your render as tif for best quality and Photoshop won't have a problem opening it.

.jpg is for posting ya pictures on the web.

RorrKonn
http://www.atomic-3d.com

Poser will also export in the Photoshop native format of PSD.

Expoorting Images can be found on page 102 of the Poser 5 pdf manual.
Getting Images into Photoshop and ImageReady can be readily found in the Photoshop online Help file.  Both of these contain all the pertinant information you need to answer your question.
DPH

Save the Poser-Image as    .TIF.
Open it in Photoshop (CS2) and "Save as" in Photoshop with the Filetype PDF.

Here's a second question: why do you need to save a file from Poser as ong, jpg, or tiff when Poser will save it as a native Photoshop file? The original question was how to get a Poser image into Photoshop. The answer should be "save as a Photoshop file".

i tend to save mine as both a .png version and a .jpeg version so that i can do lots of different overlay techniques. 

if you save your scene just before you are ready to render, then you could try any one or all of these output formats suggested here and see which one suits you.

I Think, the original question was:
***How do I change the format of the file to a pdf?

*** Not PSD - he ask to Adobes PDF-File-Format

missed that bit!! once you have opened your image in photoshop, .png, .jpeg, whatever... you can save it as any file type listed in the "save as" drop down menu, which includes .psd, or .pdf.

as far as i know .psd will save in layers, so if you are painting hair, clothes, etc..... then you will be working in layers, so you will want to save progress as a .psd file. whereas .pdf files i would guess (never tried it) would save as a flattened image that would open with Adobe acrobat reader, you could make a scrollable e-zine by saving as a.pdf file, with both text and images. hope that right. and helps ya.

1. Create render in Poser.

2. Save the render as PSD, TIFF or BMP. These are loss-less compressions. 

3. Load the image into your paint programme, photoshop, paintshop pro etc.Postwork as desired.

4. In your paint programme, you literally print the image to .PDF using Adode Acrobat or other PDF creation software. Just google "Free PDF creator"..

5. Adjust compression levels accordingly in the PDF software and apply security to the PDF if needed. 

notes: 
adobe acrobat reader only reads PDF doesn't create them. 
Some free .PDF printers don't have compression or security settings. watch for spyware.  

Vince3 is correct you could easily make a scrollable e-zine by using one long image. 
Though it's best to 'print' each page seperatety and add them together as pages in something like Acrobat. It's a 10 second job.   

security - even with the right security settings most PDF's can have the images extracted if you have the right tools. Zoo publishing the makers of 3dcreative use the best security system yet. Thats unbreakable so far.   

EXPERT TIP ...
Another neat trick of Adobe 7 and higher PDF's is to embed real 3d models in them. Though the filesizes are massive.  Extracted models from PDF's are next to useless, though can be used as lowpoly background objects. If you need to show real time interactive models not renders  
Wirefusion is the best.system.