Photoshop brush sizes - blurry when viewed 100%

[Melinda28795130vvrh]

I'm struggling with PS brushes and sizes.  If I design a 24x36 300 dpi piece of art using various size brushes there are times that the brushes are blurry looking when I view at 100%.  Am I to assume that even though Brushes can be resized up to 5000px that perhaps they shouldn't?  I want to make sure I get a clear image when viewing at 100%.  

[Signfeld]

A brush when it is defined does have its original 100% size. That size is for you to pick (maybe up to certain limits) or determined by who supplied them. Some are not that huge, some are. Like any pixel based thing (they are not vectors), enlarging it may become visible too much, depending on how strong it's applied, the style of image, or your (strict) requirements.

[Melinda28795130vvrh]

So I should be advised that when using brushes I should stick with the
default size that is shown when chosen?

[Signfeld]

That would render them almost useless.  For pixel based art, it's always more acceptable to size things down than up, which is why they supply a large brush usually. If your use is "artsy," sizing up should work for a while too, but there is a limit at which you may dislike enlargement artefacts. Maybe one day it will have something like Topaz Gigapixel on the fly 😉
Actually, if you need some brushes to be HUGE all the time, you might extract or sample them, enlarge with Topaz (or similar) (even PS should be fine), and redefine that as a brush. I'm not a brush expert, so can't guide that process.

[Signfeld]

You could also wonder or ask around if you really need a huge canvas. AFAIK, many color printers are perfectly fine at 150 dpi (esp. cos large work is often viewed from further away). I'm not at all an expert on printing either though... 😉

[davescm]

A few points:

1. As mentioned above, brushes when enlarged will get softer, so if you are creating a brush to use large then define it at a large size.

2. Are you aware that 100% zoom is not actual print size? It merely means 1 image pixel mapped onto 1 screen pixel. Depending on the pixel density of your screen that could be bigger or smaller than actual print size.
To view at print size, enter your screen pixel desnsity in Preferences > Units & Rulers > Screen Resolution then use View Print Size. You may find View >Actual Size does that automatically as it pickes up teh system reported screen pixel density but on some monitors and system that is picked up incorrectly.

3. 300ppi is for viewing very close e.g. a book page reading size. You don't define what the units were for '24 x 36' but if they are inches then to see the image you naturally step back and view it from around 36 inches. There is a handy formula for ppi required when printing large which is :

ppi required = 6878/Viewing Distance 

So 6878/36 = 191ppi. Anything higher is wasted as it just cannot be resolved by good human eyes at that distance.

Dave

[Melinda28795130vvrh]

Thank you for the detailed information.  I did change my Screen Resolution from 72 to 300.  I guess I should explain further what I'm attempting to do.  I'm trying to sell digital abstract art on Etsy.  I was told that if I am going to sell a piece that can be printed 24"x36" or smaller then I need to design using 7200x10800 @ 300.  To achieve the look I want then I would need very large brushes.  Correct?  My biggest fear is that I would sell a piece and the customer prints it at 24"x36" and it looks horrible.  Financially it does not make sense for me to print off every piece of art I make at 24x36 for a quality check.