> > Hi Folks, > > Despite the rest of the UK being affected by storms and other > foul weather, > here, in the N.E. Scotland, it is a fine evening and the moon is full. I > have taken the opportunity to bring out the 300 f/2.8 along with the EOS 3 > to attempt some better shots than my last efforts. > > Setup - EOS 3, 300 f/2.8, 1.4x & 2x ext. and 12mm ext tube (all Canon), > tripod for the lens and a monopod for the body. I tried all the various > combinations and a range of apertures and all shots were taken > with MLU and > a remote release on Sensia 400. > > A couple of questions I need to ask.... > > 1. What is the effective focal length of the 1.4x + 12mm + 2x + > 300? I know > I have 840 (300*1.4*2) but does the 12mm tube make any increase here? > > 2. I have read that a good moon shot should be taken with at > least a 300mm @ > 1/250 & f/8 with 100 ISO film, is this correct and what > difference will the > film I used make (Sensia 400)? > > Many Thanks for indulging me. > Bob Turner > Dundee, Scotland, U.K. > Website : www.bawbee.co.uk
Hi Bob! How goes it! If you're trying to photograph the moon itself with your combination, I think any focal length change would be minimal due to your 12mm extension tube. The way to calculate the image size of the moon on 35mm film is: approximate size=focal length/100. With an 840mm effective focal length shooting the full moon you should end up with an image on film of about 8.4mm, a pretty small for such a long lens! The moon while large is a distant subject! Do you have access to a telescope? When you couple a 35mm body to the prime focus (body only, no camera lens, no telescope eyepiece, the scope IS the camera lens), of the typical 8" Schmidt-Cassegrain telescope the effective focal length is usually about 2000mm@f/10, there are shorter, faster scopes typically 1280mm@f/6.3 but 2000mm@f/10 is by far the most common combination. Used in the prime focus the image size of the moon on 35mm film will be larger using a telescope, about 20mm, this is a more usable size but still pretty small. The beauty of this arrangement is that it's pretty inexpensive to buy the adapter to mount a 35mm body to a telescope in this fashion. I like to use eyepiece projection, it costs a little more but you can use the scope's eyepieces to increase the image size you can get on film. The camera is mounted to the scope without a camera lens BUT a telescope eyepiece is inserted between the scope and film plane. This can get you the big image size you need to capture detail on the moon surface but there is a trade off in lens speed depending on the eyepiece used (effective focal length and f/stop), and of course the adapter costs a bit more. There are other methods of using a telescope or even binoculars but they are all less popular techniques due to the rather dodgy results. The color balance of the moon is daylight, weak but still daylight, you'll have no reciprocity to worry about because you'll be shooting with pretty fast shutters. A good starting point for a full moon, high in the sky (not shooting through a lot of air as would be the case with a low lying moon), with ISO 125 film is 1/250@f/11. This is pretty convenient for shooting at the prime focus of our example 2,000mmf/10 scope, just shoot at 1/250 and the exposure for the moon will be pretty much spot on! From here on just do the math. Unless you have a bunch of spare Sensia 400 sitting around or need a transparency image or your camera support is shaky, I'd use a slower film unless you are going to try to use the eyepiece projection method on a telescope. For best results use a sharp, fine grain film (I like to use older B&W films), for the moon with your 840mm focal length combination or the enlarged/projected images will be disappointing. Good light! Regards, Chip Louie * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
