NZFF

There are some posts in the screenshot forum showing how to get Postimage to do what you want, including displaying a full-sized image. The 'default' here is thumbnail, which is nice for them, as it clicks through to an advertising-laden image, but not too great for the user...
Adam has posted some details on getting a full-sized image, but really the best way to use Postimage here is to upload directly to their site, bypassing the NZFF upload method. I've also posted some info on using the Postimage Windows app, which does most of the work for you. I'm aware that people are a bit wary of installing something that hacks into Windows Explorer, but really it does so much useful stuff around screenshots that I couldn't live without it now.

...Niiiccceee ads though Rob....

"...Niiiccceee ads though Rob...."
Remember your heart CP

I do use an ad blocker, but from memory those particular ads really required some sort of antibiotic shot just to view them...

I'm working on it, could take a while. there are two add image to post areas do you use the upper one or lower one ?

Both buttons do the same thing. However I don't use these, as they by default give you thumbnails linked to images with ads.
There are three ways to get a full-sized image directly into your post using Postimage.I've covered them here.
I'd recommend the second or third method. Both involve creating your own account at Postimage first.
Method 2: just login to the Postimage site and click the 'upload' button, Upload your image, copy the 'direct link' to the clipboard (there's a handy copy button), paste the link into your NZFF post, and add the image tags.
Method 3: install the Postimage Windows App, right click on your image in Windows Explorer, Send to | Postimage, it'll open a window showing the upload process, then you can choose to copy the direct link to the clipboard, paste into your post as usual.
Method 1 gives a thumbnail rather than a direct link, so you need to do some fiddly work to get the job done. Easier to control it yourself.
I do like and recommend the Windows App, it has some powerful screenshot features I use often, mainly for tutorials, like selecting part of the screen to upload/copy/edit, adding annotations, mark-up etc. You can set it up to 'hijack' the prtscn button, on my system it greys the fullscreen and I can draw a box around the area I want, then I get to choose whether to edit, copy, upload, save or print the selection. (Cntl-A Select All works as expected to get the whole screen.)
However for flightsim screenshots, using 'v', I resize them in PhotoShop, then save and upload using the right-click method in Windows Explorer.