The wider the angle of lens used the smaller the sun's image will be. A standard 50mm lens will only produce a "disc" of 1/2mm in size compared to a 2mm disc produced by a 200mm telephoto. By using a lens of 24mm or wider the sun's size is almost too small to measure and when enlarged only appears on the print (or projection screen with slides) as a very small pinprick of light.

Such point-sources of light can be enhanced by using trick filters. These range from the commonly used 4, 6 or 8-pointed Star to Diffraction filters. The latter have thousands of parallel lines engraved onto the surface which radiate colored haloes around the point light source.

Creative enhancement
Color enhancement with orange and red filters (but to a much lesser extent yellow) can create surreal effects especially with under-exposure which can produce featureless shadows or silhouettes with the right subject. If the sun is bright enough it will show through a red filter giving a glowing yellow-orange image.

For very subtle effects Series #81 and #85 amber color correction filters can be used as recommended... and for medium enhancement of natural color Cokin Sunset #1 or #2 and even Sepia filters can work well. Dawn and dusk skies can be extravagantly treated with Graduated filters ranging from (the once popular, now passé) Tobacco or Blue and more unusual Purple and Emerald... but caution is advised with these unreal colors!

When subject clarity is not desired "diffuser" filters can be used to produce unusual effects. Unlike "haze" filters which are designed to see through haze and excess UV, diffusers are more like "fog" filters which create misty effects. It's a bit of a rarity but I still have a Cokin Coloured Diffuser which was sold as a scrap crumpled cellophane with streaks of infused colors... used infrequently because it created an almost uncontrollable misty, abstract effect.