DSLR Camera questions.

Just a quick one- you were talking about low light....here's an example of an image that I took the other night without flash. It's not taken with a tripod though, so its not very clear. This is on my Canon 400d.

I cant believe the cost of the damn lenses. Mental!

Can someone explain how all the mm things work for the lense's?

Think I might have to wait a bit before I can afford this sort of thing

It doesn't have to- if you are just starting out, like I have been this year, the lens doesn't have to be the professional IS one. The 300mm I used at Donington is just £70;



It depends what you want to do with it I guess!

Hmmm, yes that sounds ok.

Might get a 400D since my mate has one so I know a bit about it. He can teach me the rest.

Might keep my eye on Ebay at that shop I linked earlier.

What sort of Zoom will a 200mm lense allow? is it 8x?

Hey Rob a good secondhand 20D would be my choice.

not that i am biased LOL (thats what i have)

the other advantage over the 400D is the frames per second ie 5 pics per sec.

anyway if ya wanna chat cameras then pm me.

Thanks Mark, and thanks for the advice. Im definitely going to start looking about, but im picking a Cokin filter system up tomorrow. Will be able to use it with other cameras

Originally Posted by ThEGr33k

Hmmm, yes that sounds ok.

Might get a 400D since my mate has one so I know a bit about it. He can teach me the rest.

Might keep my eye on Ebay at that shop I linked earlier.

What sort of Zoom will a 200mm lense allow? is it 8x?

Right here is a quick primer based on my limited knowledge of camera lenses, I am sure a someone that has been taking photos for longer/know what they are talking about will come along and correct me.

First of forget the 8x, 7x or whatever multiplier factor of zooms you want to think about, it just not very applicable to a DSLR as you can just change the lens for one a different size to reach things further away.

All the measurements on a lens now days is measured in millimetres, mm from now on. The longer the lens the further away it can zoom at. Most DSLR kits will come with a 18-55mm lens. This means when the lens is fully open, at it smallest length, it is only 18mm long. And when it is fully zoomed in it is 55mm long. I use this lens for mostly scenery shots and taking photos of people at close range. Parties, panoramas, gatherings, basically the sort of thing you might be indoor or close to the subject you want to photograph.

Another typical lens size that comes in a kit is 55-200mm, this will be your far away lens dougal, or in photographic terms your telezoom lens. Used when you can't really get close to the subject matter. Be either a race event where you can't really go on track, or you want to take some detailed photo of a building of scenery that happens to be just a few hundred metres away. In regards to your question 200mm is a very good zoom lens, it will let you get close to almost everything you will ever want to photograph. Think of something I'd say about 100m away (more suggestions here people) and it will let you photograph that with fairly good detail.

The next thing you will see on lens is something like f 3.5-5.6, this is the aperture of a lens. Which in layman terms is the size of the hole of the lens. The most important thing to remember is that apertures are reciprocals. Basically the smaller the number, the bigger the hole. Two numbers are usually given on a normal zoom lens. The first number is the size of the aperture when the lens is at shortest zoom, i.e. fully open. The second number is the aperture when the lens is at full zoom. You will pay a premium lenses which have a very large aperture, a very small f number, due to the fact that they require a lot more glass of usually higher quality to make the lens. Large apertures mean you can take photos with less light, so night shots without flash & night sky photography start becoming more Soof a possibility.

So applying this quick primer to the canon twin lens kit, it comes with a 18-55mm f3.5-4.5 & a 55-200mm f4.5-5.6 lens. The first lens is a short range lens with an aperture of 3.5 at 18mm at 4.5 at 55mm. The second lens is a lot longer than the first, it has an aperture of 4.5 at 55mm and 5.6 at 200mm.

Quick rules:
- Lens length is measured in mm, the bigger the number the further away you can photograph
- Aperture is a reciprocal. The smaller the number, the bigger the hole, the more light it will let into the camera.
- Lens diameter is also measure in mm. This is the diameter of the lens where you attach filters and hoods.

There. Damn I should have written that to begin with...

Ha ha cheers. I thought the mm thing worked like that, I was mostly wondering what the ranges were for a certain lense...

Cheers for the write up, very well written! Aparture makes sense now so nice one.

One question though. Does the f number automatically change as the length of the lense does (I.E. 100mm uses an f 0f say 4.5 and you cant change that, or can it be changed seperatly?)

So if you can get a lense that does 18-200mm it should in theory be better than having the two lense setup you mention?

Jeez.

Originally Posted by ThEGr33k

One question though. Does the f number automatically change as the length of the lense does (I.E. 100mm uses an f 0f say 4.5 and you cant change that, or can it be changed seperatly?)

The aperture/exposure is set by the camera when you take the picture (depending on settings) but the maximum aperture is usually different at different focal lengths of a zoom lens. The Canon kit lens has a max of f4.5 at 18mm and f5.6 at 55mm, iirc.

Originally Posted by ThEGr33k

So if you can get a lense that does 18-200mm it should in theory be better than having the two lense setup you mention?

Not in practice as compromises are made in the design and all sorts of other aberations are introduced (vignetting, pincushioning etc) and see comments on aperture above.

Originally Posted by ThEGr33k

Ha ha cheers. I thought the mm thing worked like that, I was mostly wondering what the ranges were for a certain lense...

Cheers for the write up, very well written! Aparture makes sense now so nice one.

One question though. Does the f number automatically change as the length of the lense does (I.E. 100mm uses an f 0f say 4.5 and you cant change that, or can it be changed seperatly?)

You can adjust the aperture of a lens through the camera. Most lenses will go down to f/16 or f/22.

Originally Posted by ThEGr33k

So if you can get a lense that does 18-200mm it should in theory be better than having the two lense setup you mention?

Not necessarily better, just more convenient.