new to photography - need some help

elle_driver

elle_driver

Messages
2
Edit My Images
Yes
Hi. I'm just starting to get into photography and could do with some advice, I have purchased a canon 450d, the lens that came with it was the 18-55mm f/3.5-5.6. I have purchased another lens 55-250mm f/4.0-5.6 is II.
one of the main reasons i bought this second lens was because it said online it can be coupled with the 18-55mm to give me a 400mm., what i'm asking is how do i do this? sorry if its a silly question - i'm new at this! :)
What i really want to get into is Astrophotography but until i know my camera/lenses inside out i am going to stick to the cheaper lenses.

appreciate any advice

:D
 
Not sure who told you that, but it can't be done, I'm afraid. Both lenses work in their own right.
 
Are you sure it was'nt trying to say that by using them interchangably you get a more varied focal length?
 
Hi Elle You cannot couple the two together. But as Jamie says the two used separately will give focal lengths covering 18mm to 250mm. But not 400mm
 
Hmmm....
I reckon you may have mis-read something or been given advice that is just plain wrong.
You can't join two seperate lenses together to make longer focal length.

Where you maybe getting confused is that due the size of its sensor, your 450D is what is known as a "crop body".
That means that the image is actually cropped by a factor of 1.6 which at it its full zoom, your 55-250 gives the same angle of view as you would get with a 400mm.
It DOES NOT magically make it possible for your 55-250 to become an 88-400 (55x1.6=88, 250x1.6=400) lens or any focal length in between.
The physical properties of the lens do NOT change.
As the word "crop" suggests, all that happens is that the image is cropped from what it would be if using what is referred to as a "full frame" body.
There are a few digital full frame Canon bodies, but they are mainly at upper end.
The term full frame is essentially a throwback to the days of film where 35mm was the common type of SLR body as opposed to the multiple sensor sizes in the digital age.

You can buy what is known as tele-converter or extender - there are two types - 1.4X or 2X. They increase the magnification of the lens by either 1.4 times or 2 times.
They go between the body and the lens. However they themselves are not lenses.

As this is your first foray into photography, all you need to do is worry about what you see through the viewfinder and not worry about the terms full frame and crop factor.
Get your head around the basics first.

Edit...was typing this out whilst those above were posting....
 
Last edited:
Hi again for good advice on astro photography. Have a look in the astro forum here on TP
 
Canon's APS-C crop factor is 1.6; 250mm x 1.6 = 400mm equivalent on 35mm.

Elle, what you've read is that the 250mm end of your zoom is the equivalent to using a 400mm lens on a 35mm (or full frame) camera. Have a google on the words "canon crop factor"; here's a site as an example: sample.




ETA: Phil got in there with the same information while I was typing :)
 
philwillmedia said:
...
You can buy what is known as tele-converter or extender - there are two types - 1.4X or 2X. They increase the magnification of the lens by either 1.4 times or 2 times.
They go between the body and the lens. However they themselves are not lenses
....
Click to expand...

I doubt you will find a tele-converter for an EFs lens.
 
Technically you can couple those lenses together (reversing ring), but that's something completely different (macro). And those lenses are unlikely to be anyone's first choice for doing that.

The obvious misunderstanding is that you were told that by buying these two lenses together you've got the focal lengths covered up to 400mm equivalent (se explanation above as to why it's equivalent). You've just misheard or misunderstood what was said. Nothing to worry about.

There are a few threads on astrophotography, and when you read them you'll probably find that shorter focal lengths are better for starting out rather than longer focal lengths.
 
thanks for all the info :) your right i probably did miss-read it,I did think it sounded silly putting one lens on behind the other! :LOL:
I couldn't decide between two lenses, one was the 55-250 f/4-5.6 and the other was 100-300 f/4.5-5.6. since i have no clue whats a better lens ( I went on the f numbers lowest being better ) it took me days to decide which one to go for! I hope i have made the right choice in going for the 55-250mm.


:)
 
You must log in or register to reply here.
Back
Top