Adapter Ring Pentax

Adapter Ring Pentax
which is the best ring flash?

there are 3 on amazon i am looking at. i would appreciate if you guys could tell me which would be the best for a canon 5d mk ii with either of t hese two lenses (i will mainly be using my macro) 100mm macro L, 24-70 f2.8 L.
Thanks

http://www.amazon.co.uk/lenses-thread-adapters-popular-compatible/dp/B0031AQ302/ref=wl_it_dp_o?ie=UTF8&coliid=IL019DQ245CK1&colid=3M2XVH0QTQPYG

http://www.amazon.co.uk/iShoot-Olympus-Pentax-Tamron-Adapter/dp/B0032LSHE0/ref=wl_it_dp_o?ie=UTF8&coliid=IIQG2JRT5H6SF&colid=3M2XVH0QTQPYG

http://www.amazon.co.uk/Marumi-DRF14-Canon-Ring-Flash/dp/B0012MGQ62/ref=wl_it_dp_o?ie=UTF8&coliid=I11B2QYXJ3RSES&colid=3M2XVH0QTQPYG

Of those three I would definitely go with the Marumi. Another good and inexpensive ring flash alternative is the Orbis. I’ve messed around with one before, and it delivers performance very close to the Canon ring flash at over half the cost.

http://www.bhphotovideo.com/c/product/627715-REG/Orbis_ENLORB1A_Orbis_Ring_Flash_Diffusing.html#reviews

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