Hair looks thinner under flash lighting. Does this mean my hair is thinning or not? (Photo)

I believe what you are seeing is the natural law of physics.  If you turn off the lights, things are dark.  If you turn on the lights you see more detail.  Flash lighting and thinner hair does not mean you are losing hair.

Thinning Hair -- Rogaine, Propecia, Viviscal, Progesterone, PRPIf you have thinning hair you really need an evaluation to see if it is genetic or from another cause like stress or autoimmune. If it is determined to be genetic there are many options and traditional treatments like rogaine foam and propecia pills can be used. I have great success in my practice using injectable progesterone and prp to the scalp. Postmenopausal women also benefit from spironolactone. I suggest seeing a dermatologist with expertise in hair loss. Best, Dr. Emer.

Any good photographer can explain how light can show detail or hide it. Bright direct light will mask cellulite and facial folds and wrinkles while removing the shadows that hide the scalp under hair. Medical photography is generally most accurate with oblique lighting and a fixed macro lens. A good hair restoration surgeon can photograph you hair over time and provide density information. Generally, speaking, letting your primary care physician know that you have possibly noticed thinning hair is a good idea though I suspect your apparent thinning hair is lighting artifact.

All hair looks thinner under flash lighting. You are correct that patients often first become aware of hair thinning when they see themselves in different lighting conditions. However it doesn't necessarily mean hair loss. I always advise individuals who think they are loosing hair to take a photo and then see a hair specialist (in that order). Your photos will be a helpful guide over time as to what might be happening to your hair - if in  fact there is anything. 

hair loss is progressive and it will increase over time. If you are concerned about your hair, it is best to see a specialist for advise and perhaps start on a medical regiment routine to slow it down.

Your
biggest enemy is the progressive balding that you might have in the next 10+ or
so years. To find out, there is no substitute for making a diagnosis by going to a competent hair doctor. Whatever the cost of this, imagine the cost of losing your hair. The degree of balding that you are may be showing would suggest that you try the drug finasteride for one year. A doctor can do this and he can give you
Bulk Measurements of your hair to determine the degree of the progression of your hair loss or if
you successfully stopped or reversed it because you need to get insights into
your immediate and long term future. You and your doctor need to develop a MASTER PLAN for your future hair loss needs, if that is the case.