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crop factor confusion

Ojustabo

Established Member
Hi all. Drunk a bit too much beer and have completely confused myself over the crop factor.

have a canon 400D with a crop factor of 1.6

Looking to get a new lens (should have brought my first choice, the more I research, the less I can make my mind up :D)

Want to get a lens costing no more than £200 with IS.

On my 18-55 kit lens, after playing round with it, I am sure that for this particular holiday (family snaps at Disney world and snaps of some of the shows etc) 35mm should be about the lowest/widest I would want. Don't think I'd ever use 18mm (may be go a little lower say 30mm if it was there, but don't think I'd really miss it)

With that in mind, the Canon 28-135 EF IS caught my eye, but I think I'm right in saying that on my camera this would be 44.8 - 216 (28 x 1.6 etc). If this is the case, the lens would be no good. Have I got this right, or have I simply confused myself?

many many thanks
 

senu

Distinguished Member
Be very careful; You would need to move right back to take any meaning full "family or group people type pictures if you ignore the need for some wideangle
You will miss it
In a theme park that would be painful bordering on very painful if you got stuck with a 28mm lens on a crop sensor
All IMHO of course,
 
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Thatsnotmynaim

Distinguished Member
The Canon EF-S 17-85mm IS is the crop equivelent of that lens and should be able to be bought around your price range too. Great walk around. :)
 

Logrus

Established Member
hmm just re-reading your original post again, you played around with your 400D and the 18-55 and decided that 35mm was as wide as you would need.

So whatever lens you put on "your" camera then the smallest you would want to consider is 35mm full stop, the crop factor doesn't come into it, since you have based your decision on your camera in your hand with a certain lens.

Now if you were to place a lens at 35mm on a full frame camera it would certainly look different, but that is not the case here.
So in actuallity, when you set 35mm on your lens on your 400d and take a picture you are actually taking a picture at 56mm.

Sorry i haven't really answered your question about which lens though, the 17-85 is certainly a reasonable upgrade to the kit lens, both in range and quality, and you should be able to achieve that lens on your budget.

Hope this helps and doesn't confuse you further.
 

denno75uk

Prominent Member
I agree with Logrus. Whether you've decided 35mm is enough by remembering the focal lengths you use most often or by checking the EXIF data for your shots, it's likely no conversion factor has been taken into account. EXIF for example, simply records the focal length used for the shot. So the 28-135 IS should be fine for you. I have the 28-105 and have used that as a general walkabout lens, but decided it wasn't wide enough for me and got the Tamron 17-50. I believe the 28-105 and 28-135 are optically similar and I was always very happy with the results I got from it.
Now, if you've come to the 35mm figure by doing the conversion in your head, ie you always look at focal length and do the conversion to 35mm/full frame equivalent as a matter of course, that's a different matter. I would still say though, that you need to really think about how you came to the 35mm figure you say is wide enough. 28mm was as wide as I could go for a good while and in the end I found it really wasn't wide enough.
 

senu

Distinguished Member
I would still say though, that you need to really think about how you came to the 35mm figure you say is wide enough. 28mm was as wide as I could go for a good while and in the end I found it really wasn't wide enough.
Pretty much what I hinted in my post, especially for a holiday where you wont have the luxury of being that far off to get small grps of family members or crowded events, and shows

I used an old 18-55 ( kit) lens on a disney holiday ( a good few years ago on a 350D) and found the 55mm limiting a bit but I would have missed the 18mm a lot more if I had a 28-105
 
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Ojustabo

Established Member
I agree with Logrus. Whether you've decided 35mm is enough by remembering the focal lengths you use most often or by checking the EXIF data for your shots, it's likely no conversion factor has been taken into account. EXIF for example, simply records the focal length used for the shot. So the 28-135 IS should be fine for you. I have the 28-105 and have used that as a general walkabout lens, but decided it wasn't wide enough for me and got the Tamron 17-50. I believe the 28-105 and 28-135 are optically similar and I was always very happy with the results I got from it.
Now, if you've come to the 35mm figure by doing the conversion in your head, ie you always look at focal length and do the conversion to 35mm/full frame equivalent as a matter of course, that's a different matter. I would still say though, that you need to really think about how you came to the 35mm figure you say is wide enough. 28mm was as wide as I could go for a good while and in the end I found it really wasn't wide enough.

I came to the 35mm by the very unprofessional way of getting my family together, standing a few feet away from them, composing a few shots I was happy with, then looking at what the numbers on the lens was pointing to.

So I hadn't done any conversion when I got to this figure.

What I've decided on (and have now done) is to order the 18 - 55 IS kit lens as I've taken on board what senu etc have said. It's one thing me getting my family in the frame, but what about Pluto and Donald Duck :D

That gives me a better lens than I currently have and a better ability to use it in places where flash isn't allowed.

I'll see how I get on with it, I also have a Tamron 70 - 300, but haven't had much luck with it zoomed out due to camera shake. I'll see how my holiday progresses, can always nip into a photography shop in the USA :D

many thanks
 

chrisw

Prominent Member
I have the 28-135 as my main walkabout... I went from the 18-55 to this, and don't really notice not having a really wide end - I notice more at the other end of the range much more. I'm using a 40D and it's performing really well and am very pleased.

I tried the 17-85 but wasn't 100% convinced about the IQ and sharpness of the lens.
 

senu

Distinguished Member
I thnk its the potential use ( in a holiday theme park siuation)rather than general walkabout that makes little more wide angle desireable. In most other everyday situations, one just learns to live with the lens one has and eventually doesnt miss what isnt there
The 17-85 seems to be a bit of like it or hate it.
Although I have the 17-55 IS f 2.8, I still dont find the 17-85 awful , even if it wouldnt get top marks for sharpness
 

Triggaaar

Distinguished Member
I came to the 35mm by the very unprofessional way of getting my family together, standing a few feet away from them, composing a few shots I was happy with, then looking at what the numbers on the lens was pointing to.
Sounds like a fair way of deciding to me. But as others have said, and you have acknowledged, there will be other times when you want the wide angle.

So I hadn't done any conversion when I got to this figure.
You shouldn't need to worry about conversions. The only time you'd need to think about it is if you were changing camera, or looking at a point and shoot (as they would state the full frame equivelant focal length).

I also have a Tamron 70 - 300, but haven't had much luck with it zoomed out due to camera shake.
Get your body in a good position to hold the camera steady (eg, tuck your elbows into your body) and make sure you have a fast shutter speed, say 1/500th sec or faster.
 

Thatsnotmynaim

Distinguished Member
I easily get carried away buying lens and so currently have :-

EF-S 10-22, 17-55 f/2.8 IS, 18-200 IS (it came with the 50d) :D
EF 24-105 L IS, 70-200 L F/4 IS + Extender 1.4x
Primes, Sigma 30 f/1.4, Canon EF 50 f/1.8 & 85 f/1.8

I have also have had two 17-85 IS, one that came with my old 40d and another I bought again after I sold it for a 24-105 as I simply found I was lost in some occasions without it.

My absolute favourite and most used lens is 24-105 by a long way, what I do find is that even though most shots are within 24-50, in many occasions I need to put on the 17-55 or 18-200 as it is just not wide enough, things line a recent childrens birthday party.

In my opinion on the times when I have the wrong lens on, if it is a lack of zoom, I can always crop (obviously loose IQ) if need be to get me by and I get the shot, problem is if the lens isn't wide enough, you are stuffed and the only thing that will fix it is a 17 or 18mm wide or even sometimes my lovely 10-22.

Forget the fact that my 18-200 IS is not as good image quality as my 24-105, the fact is with the 18-200 I can get the shot, with the 24-105 I'd have missed it simple as that.

Don't get hung up on IQ and don't substitute IQ for range. The most important thing here is just taking some photos. At the end of the day if you absolutely know the range and if you main priority is IQ then get a prime or primes. If IQ is not your 100% factor and you want to make sure you get the picture of your family get a zoom in the range you need, but add a little extra on te wide end if your budget can allow as nothing can get you out of a lens not being wide enough situation other than either you or your family moving backwards! :)

Problem is in most situations the lens you choose will always be a compromise between range, IQ & speed and there is not a magic perfect lens. Different people's priorities are more over one of these factors. I'm still waiting for that magic 10-500mm f/1.4 L IS that weighs only 300g! :)
 

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