Help with camera terminology

[radhak]

My brother is looking to buy an entry level DSLR, and that set me thinking while buying the lens for it. (he is interested in the Canon Rebel XT).

how do i translate / compare
'28-80mm f / 3.5-5.6 Auto Focus Lens' and
'28-200mm f / 3.5-6.3 Auto Focus Lens' and
'28-200mm f / 3.5-6.3 Auto Focus Lens'?

As far as I remember, the first shows the optical zoom range? So longer zoom is always better?

And what is the 3.5-5.6 thing?

Isn't there a website that describes all this?

[nickg]

Digital Cameras

Isn't there a website that describes all this?

Probably more than you ever wanted to know These guys can explain what the lens numbers/ratings mean better than I can.

http://www.dpreview.com/learn/?/Glossary/


Good source of general information, plus reviews and comments on specific camera models. There are a few other sites like this.

I was interested in a DSLR too, but didn't want to hassle with the extra bulk. Opted for a smaller 6MP Canon which is probably 1/3 the size of the SLR (and a lot less expensive), and takes some great pictures. I'm always on the 'bleeding edge' with this kind of stuff, but I can say digital cameras in general, have gotten much better and less costly in the last several years.

Nick

[Tom Slick]

check out www.dpreview.com they have forums.
I own a rebel xt, it's a great camera. I'll gladly answer any questions you might have about it.

28-80mm is the optical zoom range, there is no digital zoom gimmick on a DLSR. the F/ number is the largest aperature opening possible with that lens.

zoom is tricky, one of the benefits of a DLSR is interchangable lenses so it isn't best to try to get a one-lens-does-it-all, there are always tradeoffs. kind of like using a combo blade on your saw, it will do it all but it might not be the best at ripping and may splinter a little when cross cutting, but its cuts are acceptable.The 18-200 that sigma makes is a decent lens. sometimes a fixed non-zoom lens is desireable

the f/ number (also called f-stop) has to balance with your exposure time for properly exposed photos. the smaller f/ the larger the aperature. the larger aperature lets more light into the camera but shrinks the area that is in focus. those photos where the subject is in focus and the background is blurred are taken with a low f/ number. if you want the entire scene to be in focus the you choose a larger f/ number. basically it's control over how much of the scene is in focus.

keep in mind that a DLSR doesn't do as much stuff automatically as a point and shoot camera does. they let you have control. most guys that start out complain that their pictures don't look nearly as good as they did with their point and shoot, 99% of the time it's because they are at the bottom of the learning curve.

[gsmittle]

There's probably a web site somewhere, but I'm too lazy to look for one just now.

The first set of numbers is indeed the zoom range. Bigger is not always better, in that often compromises have to be made to get the big zoom. Often, the clarity/sharpness will suffer at one end or the other or both.

The second set of numbers refers to the "speed" of the lens. Here's where things get interesting: the smaller the number, the "faster" the lens. IOW, the faster lens lets comparatively more light fall on the sensor. Again, faster is not necessarily better, all other things being equal. Faster lenses generally require larger glass, special glass and coatings, etc.

What it boils down to is: the "slower" lens will need more light for a given shutter speed than the "faster" lens. For example, let's say the lens has a speed of 3.5 and a particular scene requires a shutter speed of 1/500th of a second. A second lens with a speed of 1.75 (will cost you a bundle and have a front glass about the size of a car headlight) photographing the same scene will need a shutter speed of 1/1000 for the same exposure.

Don't get me started on depth of field, varifocus vs. true zoom and other stuff. Nowadays most cameras are pretty good at figuring out the optimum exposure for you, but it never hurts to understand what the camera's doing. Besides, sometimes you want to go manual, if for no other reason than you can.

I hope this helps--it's been a while since I got behind a camera. Which reminds me, I need to take my vintage Canon A-1 out for a spin...

Totally OT here--does anybody know if Canon makes a digital back for the A-series cameras?

g.

[Tom Slick]

Totally OT here--does anybody know if Canon makes a digital back for the A-series cameras?

I don't think canon makes a digital back retrofit for any cameras.

[havighurst]

There are a few lenses that are made for a camera with a 1.6 crop factor. Assuming that the ones you speak of are not, the Rebel has a 1.6x crop factor. Just multiply the focal length by 1.6 and you will now have your focal length for your lens. You will lose some wide angle capabilities, but will gain in zooming ability. You need to figure what you are photographing to determine your needs. As a person who freelances for a local paper and has a small photography business, I will tell you that camera bodies come and go, good glass holds its value pretty well. Aftermarket lenses (Sigma, Tamron, etc.) can take very good images, but focus a little slower than a Canon lens. Again, decide what type of photos you want to take and make your decisions accordingly.

[HarmsWay]

There is good competition in the entry level DSLR market now with the Canon XTi (XT replacement), Nikon D40, Sonly Alpha, Pentax, etc. I don't think you'd be sorry with any of them.

I think I'd disagree with Tom about them not being as automatic as point and shoot cameras. I've been using my XTi for about 6 months now. It's can be as automatic as any P&S or not - just select a more or less automatic mode.

WRT lenses, as Tom says that's a little tricky. Obviously if this is a first DSLR you probably want to start with a general purpose lens, but a decent one will cost you. If you're buying new, the camera/lens kit almost always saves you money. Some of the kit lenses are better than others according to the reviews. Not many liked the standard 18/55 lens that the XTi kit had. I ended up getting the 17/85 with mine.

If you're certain what you want to photograph then do some research and find the lens most suited to that. Odds are you'll get a deal if you buy it with the camera body.

There are sites dedicated to lens reviews like this one:

http://www.slrgear.com/reviews/showcat.php/cat/2

Bob

[LCHIEN]

the number like 28-80 or 28-280 is the focal length of the lens in mm, having a range of numbers indicates its a zoom.
The 28-80 is barely 2.6X zoom ratio (pretty short zoom range, any point-n-shoot camera has 3x zoom nowadays)
whereas 28-280 is 10X zoom range which is very good. (but the lens will be physically much larger and heavier and costlier).
Its hard to tell exactly what the range represents compared to a 50mm lens on a 35mm film camera because the wideness of the angle and telephoto-ness depends to a large extent on the film or image area it has to cover. A given range on a camera with a smaller image sensor will appear to be less wide angle and more telephoto than the same focal length range on a different maker's cameras having a larger sensor, and of course the lenses don't interchange - they're optimized for image size. Many makers will paraphrase the 35mm film camera equivalent where 50mm is a normal lens and 28mm is a pretty wide angle.

The f3.5-5.6 represents the maximum f-opening of the lens. Again, the range represents what you get with the shortest focal length zoom setting and the second number with the longest zoom setting. Technically an f number is the focal length divided by the aperature (size of the front opening) of the lens. A bigger aperature gives a smaller f-number and admits more light. and a smaller number is more desirable because generally they let you take good pictures in less light. Using flash photography, a smaller f-number wil allow you to take pictures with smaller flashes from farther away.
35mm film cameras with 50mm fixed non-zooming lenses typically were came in values like f1.4 or f2.0 but for zoom lenses f3.5 to f5.6 is about what you get. On the negative side, smaller f-numbers also make the lens larger and heavier and more expensive. As a side effect, it also makes focusing more critical. If you take pictures at midday in the sun, small f-numbers are not so important since the programmed camera exposure normally will use a larger f-number by closing the aperature with an internal iris.

just a note, when i refer to 35mm cameras, that number refers to the film width and had an image size of 24mm x 36mm. Digital cameras almost always have smaller image sensor areas resulting in some degrees of magnification if used with 35mm camera system lenses.

Final word of caution:
When buying DSLRs from a name brand manufacturer, the mfr will typically have two sets of lenses. The street names for the lenses offered only in package deals withthe camera are called "kit" lenses and they are generally cheaper and less quality than the more expensive lenses that they also will sell you as seaparte items.

As to the quality, what you get more of with the kit lenses is
barrel distortion (makes a rectangular object look like a barrel-shaped object, slightly.)
Flare (has to do with antireflection coatings and light baffling internally)
chromatic abberation (purple and green fringes around the edges of items near the edge of the picture)
Most of these defects are most visible only at high magnification and small f-numbers and at the ends of the zoom ranges. It could be said that these are only of importance to a critical pro but then again, only a critical pro should be shelling out $1000+ bucks for a camera with interchangeable lenses.

Personal Rant: I personally think most serious amatuers would be happy with the pseudo DSLRs selling for $500-600, the main feature is the non-removable ~10X zoom lens. I have taken a ton of pictures, I have an 35mm SLR system with 8 lenses and 4 bodies, I know most people toting around these DSLRs are incapable of using proper techniques with the very wide and very long zooms. The 10X non-removable lens cameras is plenty for them.

[jziegler]

You have a pretty good overview of the basics there. In any case for a camera with a 1.6x crop factor, you should get a lens that goes wider than 28mm (unless those are 35mm equivalent numbers). I find that I use wide angle as much or more as I use telephoto on my cameras.

Often a series of smaller zooms (or even fixed lenses) can be a better deal than one zoom to cover the whole range. As mentioned before, you make more compromises for the larger range (and all lenses are compromise designs). I disagree with faster not always being better, I'd rather have teh faster lens and the choice to use it. My wallet, of course, disagrees. I also prefer fixed lenses for the most part, but they aren't as good of a match for DSLRs as they are for film in some cases.

If you need to cover the whole range, look for a 2 lens solution, and it will cost you less and probably get better quality. The f 3.5-5.6 or 6.4 is the slowest lens that I would consider at all accptable (although a f4 would be a slight improvement). With a lens like that, indoors lowlight shots are difficult. When you zoom in, the lens gets slower, and flash becomes less effective.

A good option, especially to someone not as familiar with photography, can be one of the better "super-zoom" or "bridge" cameras. Most of the companies make them, and some are quite good. I bought a Fuji S6000fd recently, and am happy with it. It has a 28-300mm equivalent lens (better range than any you listed) that is a bit faster than those you listed. I have a film SLR that I can use (but it's big and heavy, I like old manual technology), and I use it if I need something specific. But the fuji worked well as my trip camera when I was in China a few weeks ago. Less expensive than a DSLR and does most of what a DSLR can, although if needs more mucking about in menus to do it (which I am getting pretty good at now). If is has to be a DSLR, the Canon is good, but unless there are old Canon lenses that you need compatability with, it is worth looking at the others mentioned by Bob, as well as the Olympus system.

Sorry to ramble so much, I hope that I made at least a little sense. Can I be excused since I'm tired today?

Jim

[radhak]

Thanks everybody - gives me much more than what I hoped to know, as always.

As an OT, I had done a quick google, found shopcartusa.com with amazing prices, found they pointed to expresscameras.com who were offering the camera at around $399 with lens (basic), as against $570+ elsewhere. so i quickly put my bro on it.

but - on more research, had to warn him against that site. looks like the true 'pirate' site . built on scam, that site. and i am sure there'd be more such. that $200 savings sure looked sweet. too sweet to be true. and shopcartusa.com is just like an evil twin brother to it. . aah well.

Google is more powerful than i thought - it throws up the evil sites earlier than better ones...

[Ed62]

Another thing you need to check out if you find a great deal, is if it carries a U.S. warranty. Many super low price dealers are selling those that don't. If something requires repair, you'll probably be out of luck.

Ed

[tuttlejr]

Here is an interesting site that gives you some good info on camera shops.
There are many grey market shops with questionable selling tactics.

http://www.resellerratings.com/


Some good digital SLR's to check out are the ones from Pentax. You can use older lenses with K mounts on these which can save a bunch of money. They get good reviews.

[Ed62]

Some good digital SLR's to check out are the ones from Pentax. You can use older lenses with K mounts on these which can save a bunch of money. They get good reviews.

That's good to know. I still have a K-1000 with a couple of lenses. That's a camera I really liked.

Ed

[havighurst]

The company that I have ordered online without a problem and they have low "legitimate" prices is B and H Photo. If you find a price that is lower, be sure that it has a USA warranty - not an international warranty. An international warranty will not be honored by Canon in the USA. It is gray market merchandise.




www.bhphotovideo.com

[tuttlejr]

When shopping, pick up each brand and see how they feel in your hands. Great comparisons can be made in the shops. If it does not feel good, you will never be comfortable with it. I favor the Pentax line of DSLR's myself.