Sparky with double glass, starburst aperture, and wide/tele adapters.

This is a rambling note to myself in hopes that I remember how to use this lens. You have been warned!

Enamored of the Lensbaby Spark, I've bought accessories, including tele and wide adapters, a double glass f/2.0 optic and the aperture creative kit. I inserted this optic and a starburst aperture and performed some initial tests.

.6x wide adapter should make this a 30mm lens - the equivalent of a 45mm on my APS-C sensor. 

 The sweet spot of the Lensbaby is correspondingly smaller. One can see a bit of the starburst aperture's effect on bokeh in the upper corner of this shot - it becomes more pronounced with higher contrast. For instance:

This is purposefully unfocused to create a photo that is only bokeh - the trick to using this lense is to relegate everything to bokeh except a subject - the sharpness of the subject is created by that contrast rather than any optical clarity.

With no adapter, the 50mm (75mm eq) f/2 double glass optic allows more light than the optic that came with the Spark. With the aperture in place it seems to be an f/4. 

The "tele" attachment increases the relative size of the sweet spot. 1.6X results in a 80mm, or 120mm equivalent  focal length. Too much flexing of the Spark results in a lens vignetting.  The weight of the adapter is enough to cause this, so one has to hold the lens firmly and steadily in place.

The 53" high window shots are all taken from about 10 yards. I'm shooting in aperture priority mode using f/5.6 with a -1ev which was set to compensate for the new optic. One can see how brightness is affected by the attachments, wide gathering more light than the narrow field of the tele. Going forward I will start shooting at 0 ev, especially with the tele adapter. As I've told the camera it is a fixed aperture (there is no electronic data from the Spark) and changed it with the insert I will have to experiment with the various inserts to get good settings. f/5.6 seems to be a good starting point even though it was derived from the original optic.

Using the two adapters is an interesting proof of how "right" the 50mm focal length of the Spark's optics is. I can see the tele being useful for head shots while the wide might be good for pinpointing a subject in a field, or perhaps  a body shot where parts meld into the bokeh. More experimentation is needed.