Newbie question on focal length

[digideb]

Hi

I'm about to chuck out my old Dimage camera to get something better for indoor sports photography. So far it's looking like the Canon 20D/30D and a 85mm 1.8 lens.

As I am still very new to this, I'm having trouble understanding some of the terminology and what is means in real terms, and looking up bits & pieces around the 'net.

The lens - it's a fixed focal length ? That means I can't zoom with it ? So how do I know without buying it how close or far away from the action I need to be ? Apologies if it's a stupid question.

[coreypolis]

Yes, it doesn't zoom. Because of the size of the sensor in the cameras you are considering, it will give you the equivalent field of view to a 135mm lens on a 35mm film camera. its a mid range telephoto lens, great for portraits or gym sports.


Focal length is just something you have to learn in nature. A lens like a 17-40mm will be good for landscape and other wide angle work

a 300mm will be good for sports and wildlife.

50mm-200mm is great for portraits.

Most of us have many lenses to have many different field of views.

[lostdoggy]

The focal length of 40-70mm would be consider normal focal length in 35mm lenses. This means that a normal person w/ normal vision will see a normal view of field through the view finder w/ a lens within the 40-70mm focal length range. View of field is the angle of view if you look straight ahead from left to right or vise versa without moving your head, body or your eyeball. As you decrease wide angle)the focal length th view of field will increase and as the focal length increase (telephoto) the view of field will decrease. You will then perceive the image to be farther away (wide angle) and closer (telephoto). Now with 20D/30D you need to Multiple the focal length by 1.6 so that a 40mm will be 64mm and 70mm will be 112mm.

I would recommend buying the camera w/ the kit lens and adding more lenses as you grow. The kit lens is cheap but it will deliver good photo if you work w/ it.

[digideb]

I can really only afford 1 lens right now - I think the one I quoted is about £200. And the priority is for Sports, so it seems a good choice right now. Maybe in 2 / 3 years I can afford another :confused:

But I'm still unsure of how close I need to be to the action, since it's fixed length. I'm taking photos at Taekwondo tournaments, generally of 2 individuals sparring. If I'm 30 feet away in the stands, is this going to be too far to see anything ? If I'm allowed on the floor, and I'm 5 feet away, is this going to be too close ?

[SkipD]

I can really only afford 1 lens right now - I think the one I quoted is about £200. And the priority is for Sports, so it seems a good choice right now. Maybe in 2 / 3 years I can afford another :confused:

But I'm still unsure of how close I need to be to the action, since it's fixed length. I'm taking photos at Taekwondo tournaments, generally of 2 individuals sparring. If I'm 30 feet away in the stands, is this going to be too far to see anything ? If I'm allowed on the floor, and I'm 5 feet away, is this going to be too close ?Try going to a camera store and handling a similar camera to what you want to buy with various lenses (or a zoom lens or two) in the store. That way you can get a first-hand feel for whether or not a particular focal length will do a particular task for you. If you can handle a zoom lens, just set it for various focal lengths and you will be able to simulate the fixed-focal-length (often called "prime") lenses for test purposes.

It's difficult for someone to say that any particular focal length will work for a particular task because not only the distance has to be known, but also the size of the subject. For example, if you want to fill the frame with two people it will take one distance, while if you want to get in tight to fill the frame with only parts of the two people you will need a different distance.

If you're limited to shooting from the stands, a zoom lens makes a lot of sense but you will need a "fast" lens which equates to expensive.

[digideb]

For me, £200 IS expensive ! :oops:

Most of the time I am permitted on the floor (unofficial photographer). So basically I'm taking photos of 2 people sparring (and they can be as young as 5 and as old as 65) - and I don't need the action to fill the frame, I'm happy with cropping later in Photoshop. I just didn't want to be in the position where I'm on the floor but having to stand 15 feet back from the action in order to fit 2 people in the frame. If I have to stand that far back, then I'm in danger of walking into the mat behind me, getting in the way of other people sparring. I guess I want to know "where I stand" :lol:

I'll try to get down to Jessops, see what they have in stock for me to take a look at. I may take a gander at monopods too.

Thanks for all the assistance, everyone !

[lostdoggy]

To give you an idea how close an 85mm (136mm w/ crop factor) is at 10-12ft you would be able to take portrait (from top of head to midriff) shot of an average adult. The average length of a passenger (sedan) vehicle is 15ft/4.5M.

[digideb]

That helps, thank you.

So I need to stand further back if I'm taking portrait photos of 2 head-to-toe people sparring, I guess maybe 20 feet then, which may be ok, I have an idea of what limitations I have to work to. If I'm at the edges of the gym looking at 2 mats, thats probably good.

Now I just need the courage to go spend that much money !

[tzalman]

If you could tell me what model your Minolta is (assuming it has a zoom lens) I could tell you what setting on it would be equivalent to an 85 mm on a 20D.

[digideb]

That would be great, thanks !

It's a Dimage 7i.

[PhotosGuy]

So how do I know without buying it how close or far away from the action I need to be ? Try this: For 85mm, hold your left arm straight out, fingers together, & hand pointed to the left. Fold your thumb in. The width of your hand is about 85mm, depending on your size.

[tzalman]

This is easy for me since I once had a 7i. That camera's crop factor is 4.0 and the lens is 7mm to 50mm (28 - 200 35mm film equivalent). So the equivalent to an 85mm on a 20D would be 34mm.
Elie

[digideb]

Thanks for the reply, Elie, but have to admit, I think a big Jumbo Jet just went soaring over my head.

:confused:

That made some sense, though, Photosguy, thanks.

I've just picked up a second hand 20d on ebay with the kit lens, so I'm off to buy the fast lens, then I'm ready to go, and eager to learn how to improve.

Many thanks for all replies, it's a good forum.

[tzalman]

It's what you see on the 7i when you are zoomed 2/3 of the way toward the tele end.

[digideb]

Thanks for clarifying that, tzalman, apologies that you had to explain it twice.

I'll get there eventually, and I hope I will have the patience to explain things as you all do on this forum. :)

[Photolistic]

If your only going to have one lens for a year or more I would HIGHLY recommend buying a zoom lens!!


Honestly you should consider buying the Canon rebel XT and investing more money in lenses.