Explain a few photo terms to me?

[Taoism]

I was doing some browsing to learn more about the Canon 10D, and I am not sure I quite understand everything (as a matter of fact I KNOW I don't understand much of photography "lingo" at all)

I was reading a few threads and they were saying that since the CMOS capture of the 10D is smaller than the normal size of 35mm film the camera it acts as a 1.6 multiplier??? So, umm, for a given photo taken with a 10D and a 35mm the 10D will be smaller but be able shoot things further away clearly??

There was also talk on one thread of "should I buy 100mm or 180mm macro" and one suggestion was to buy the 100 + extender tubes to get a feel for a 180? I assume the tubes have additional optics in them? Are they for macro photography only?

Other threads had people talking about using diopters to help shoot with (I think) zoom lenses?

There was also a thread about using rails with a macro lens while the camera is mounted on a tripod?

Also, for macro shots, have any of you used one of those flashes that screw right onto the lens? Or do you use a normal top mounted flash?

Can anyone clear a few of these things up for me?

Cheers,
Keith.

[TS]

With the 1.6x factor, yes, a lens will act like one 1.6x longer... so I 100mm will get you as close as a 160mm would on film.

extender tubes don't have any optics in them, they simply move the lens farther away from the sensor which (somehow) allows for a closer minimum focusing distance... so you can get closer with the tubes on.

Diopters are optics that help you achieve the same effect- a lens with a diopter will be able to focus froma closer distance.

A macro focusing rail is a convenience... it lets you easily slide the camera forward and backward with precision, so you can get the perfect macro shot without having to move the tripod forward and back while framing the shot.

I've heard of the macro ring flashes, haven't used one but would like to.
A canon 420ex flash unit has done the job very well for me.

[gljjr]

Travis is correct, true extension tubes are just tubes with no optics in them. If you remember your days of playing with a magnifying glass and burning ants you will remember that the farther away from the "Point" of light distance you got the larger the dot got. This is because the lens bends the light. The "Point" you got is where the light comes together before expanding back out. A camera lens does the same thing. However it has been designed such that the lens is just the right distance away to fully fill the sensor/film with the light. As you move the lens farther away from the sensor/film the wider the width of the light is. So you only get a portion of the available light caught on the sensor/film.

I hope that explains it! Kind hard to do without a picture showing how it works

[gregr]

re. the 100 vs. 180mm macro lens: i'd stay away from the 180 as it does not have a very short close focusing distance-- 1.6 feet, is very big-- 2.4 pounds. it's also very expensive-- $1200+.
for a long time i thought i wanted the 180 and it was probably going to be the next lens i bought but then i read the specs and realized it's not ideal for aquarium photography. better to stick with the 100 and use a 1.4 or 2x and or extension tubes if necessary.
any macro lens can be used for regular photography as well as close-ups. and they will produce stunningly sharp images- the Canon 100mm macro lens is among the very sharpest lenses they make.
the ring light will produce very even flat light for subjects close to the lens- not good for regular photography but very good for extreme close-ups.
greg

[TS]

Greg, good point on the 180 macro. I came to a similar conclusion about the Caonon 1x-5x macro lens. At 5x, you need to be 2cm from your subject. The working distance is so small, we'd also have to invest in an underwater housing to get the most of this lens.

A couple lingering questions for you Greg-

Have you tried extension tubes with the 28-135IS? I was really impressed with how close this lens could get to the 100mm macro. It's really tough to use at anything short of the full 135 mm, but performs quite admirably.

Also, have you combined the 500D diopter with extension tubes? Does it add that much benefit? Seems like it may just buy you a little more close-focusing distance but again to the point where you've got to be on top of your subject.

When I'm ready to invest in going bigger for macro, I'm thinking a Kenko 1.4x extender would give me the best additional magnification for the buck. Would you agree?


Thanks
Travis

[gregr]

hey Travis-
i don't have the 28-135IS but i've played with one, and i'll likely be buying one before my next trip (fall). but i've used tubes with my 80-200 and it's very good, albeit not as easy to use with tubes as a prime lens. i used to do tons of close-ups with a 300 and tubes/converters-- that' still my set-up for butterflies and dragonflies and stuff like that.
but as good (and flexible) as the 28-135 is it doesn't compare, optically speaking, to the macro lens. so whenever you're in the 80-120 range i say switch to the 100 macro.
i do have the 500D and it performs like you expect. it's also a good butterfly set-up (80-200 and 500D). there's a big pro that recommends this combo for butterflies and suchlike-- George Lepp maybe?
re. converters- i recommend the Canon. it costs more but there's a very good reason- optically it is excellent. get the newer version and you won't be sorry.
haven't tried the Kenko but this is one area i wouldn't scrimp on.
greg

[gljjr]

If you really want extreme macro go buy two cokin adapter rings. Epoxy them together and put one on your zoom and another on an a short lens. What you will end up with is a lens system that is capable of VERY macro pictures. You just have to make sure you can lock the aperature on the reversed lens wide open.

[TS]

Hey Greg, I think I got a "bad copy" of the 100mm macro, because I have just never been all that impressed with it. I actually like sharpness/contrast better with the 28-135. That being said, I've recently started using mirror lockup on my macros, perhaps I'll see a noticeable increase in sharpness with the 100mm.... it certainly is a touchy lens IMO- or Imay be really spoiled by the IS.

gljjr, I've heard of that technique before and definitely would like to play with it some time. I may PM you for more info. I know there's a reverse-lens adapter out there but it costs about $300 or so.

Travis

[gljjr]

I read about it in a book I read years ago (I think by John Shaw). I see no reason to spend $300 when all you need to do is get 2 of the Cokin filter adapters and epoxy them together. I did that several years ago for my Canon Elan. I used my 70-210 for the main lens with my 28-70 reversed. It worked quite well but I only took a few shots and to do this efectively you really need a focusing rail as the depth of field is so short and you also really need a ring light or something to light your subject as you are so close you block the light with the camera. I just didn't find that many things I could use it for as it was very hard to focus without the focusing rail.

If I can ever talk the wife into letting me get the 10d I'll probably also get a focusing rail and another extension tube. I already have one I just would like another one

[Taoism]

Hi Travis, and everyone else

Thanks for the responses. They clear things up quite a bit for me. I think I am going to do a lot more reading on the D10, but I think it will be the digital camera I buy when the time comes

Travis, I have a side question for ya. Is there a trick to getting those nice borders around your pictures? Or is it a plugin for Photoshop?

Cheers,
Keith.

[TS]

I re-size the photos to a specific size every time for web posting, then copy and paste the image onto a larger image I created that has a black background and the type. Then use the layer effect "inner glow."

HTH

T