Does anyone face this problem .When you try to zoom the objects sometime the canvas also zooms and your object pixelates.
This is rare when i am sculpting a model but when i work with zsphere and try to rig the charecter this is very often.
I create a new document to solve this problem. sometimes i have to close zb and restart it. AAHalf and Actual also fixes it sometimes.
I jus want to know if there is any default setting which i can change to avoid this .
its there because zbrush has a limit on how far it can zoom
so just to compensate, it zooms the canvas when you hit that zoom limit.
Yes this is what Zoom does. If you just want to “zoom” your object use “scale” 
Remember Zbrush is 2.5d. When you “Zoom” you’re zooming in on the “pixols” in the document not on a mesh.
I think i was not clear about my doubt. I know the difference between Zoom and Scale in zbrush.
I never had a need to Zoom the canvas . But i scale the objects by using Alt+ MMB . The problem mentioned earlier happens only then.
I dont face this everytime .It jus happens randomly and after that every time i clear the screen and draw my mesh again it gets pixelated.Alt+ LMB does’nt do any good.
Only solution i found so far is to create a new document or restart zbrush again.
If you have a character on the screen, and you keep scaling in, it will eventually happen, just scale back out and it will auto-resize the canvas back down. It was ackward as heck for me at first when it started zooming automatically but I’ve really gotten used to it.
Setting Preferences > Transform > Auto Edit Doc Zoom to 1 will stop the canvas zoom when you scale in close to your model.
Got a bit of a shock when it first happened, thought there was something wrong with my eyes 
Thank You TVeyes
I think that will help.Need to test it tho
I have had a similar problem especially while working with the topology tools when I use the scale button or alt click and drag the model scales down a bit the suddenly pops back to the same size it was when a started scaling and the canvas zooms out? Very frustrating, also double clicking the scale button and alt clicking to fit the model to the screen doesn’t seem to work when I am using the topology tools? I will try TVeyes suggestion hopefully that helps.
This bit me too.
To get your doc back to normal, you can click on the ACTUAL button, under the zoom menu, or in the side bar.
I also was wondering what was going on with the auto-zoom.
Thanks TVeyes for the info…I got a question though for you.
Should that be saved under -Preferences:Config:Store Config button
or ZBrush\Zstartup\StartupDocument.zbr
So I don’t have to redo it everytime I start Z
Thanks,
Escape
Thanks for the fix TV.
I’m also wondering the same thing as Escape on what needs to be done to make that preference change permanent.
Seems like some changes stick when you store your config file, and some don’t. Same for the interface.
For example: My background color stays when I change it, but the canvas color always reverts back to black. Similarly, Auto Edit Doc Zoom always reverts back to a setting of 4.
Apparently you cannot modify the defaultzscript to set user settings, like you could in ZBrush 2. There is however another way but it involves a slightly more complicated script. I will see if I can post that here tomorrow (sorry, it has been a looong day at work and I just want to eat and sleep right now ).
The script should take care of all settings that are not currently stored in the config and set them once upon startup.
Awesome! Thanks TV