I've put a 25mm extension tube and 1.4x converter on my 100mm macro. Fully
extended, this should theoretically give me an enlargement of 1.38(ext tube)
* 1.4 (converter) = 3.92.
Using the Canon ML-3 (GN11) ring flash with my EOS3 at f16, All photographs
are significantly underexposed with the subject about 6-8cm away from the
front of the lens. Now, I'm wondering:
- Is the TTL metering of my EOS3 completely fooled by this setup (25mm +
converter)
- Is the effective f-stop (works out to f47) just too small for this flash
to light up a subject 6-8cm away?
- Does the distance from lens front/flash source to film plane (about
27.5cm) play a significant role?
I know the standard GN=f*d formula, but I don't know if this takes into
account the macro situation where your film plane could be significantly
further back from the flash than the object is in front.
Has anybody here tried something simular?
Regards
Thys
---------------------------------------------------------
Thys van der Merwe
Portfolio of African Images:
http://mysite.mweb.co.za/residents/teknovis
Cell: (+27) 83-441-3108
Tel: (+27) 35-753-3766
Fax: (+27) 35-753-4489
-----------------------------------------------------------
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
