Well, I always teach that anyone who shoots in bulb mode yet have a shutter speed that's odd number, clearly doesnt know anything about bulb mode....
Last edited by Mythmaker; 2nd July 2015 at 11:42 PM.
Can use the chart on this site for your reference.
but in case u are lazy and wants to be spoonfed.
2nd those who asked why you will need 5 minute exposure.
There are many possibilities. One question I have is the compatibility of your holder and the filters you used. Gaskets provided by the filters may not match your holder if they did not come from the same source. I also seen some sellers in the market didn't even apply gaskets to 10 stop filters!
Could you let us know more specifics about the lens you use, the filter holder you have too?
If not, work with the shop that you got this from? If they are selling you these filters, I have to assume that they should be cluey enough to help you out.
Looks like lens flare to me, turned into a hotspot because of the long exposure. Pointing into the sun will often do that to a greater or lesser extent, depending on your lens.