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Sharp focus
http://x404.co.uk/forum/viewtopic.php?f=17&t=477		 Page 1 of 2
Author:  Fogmeister [ Tue May 12, 2009 12:17 pm ]
Post subject:  Sharp focus
I went out last night with my camera to try so of the zone method stuff.

Anyway, I have a couple of lenses. A kit lens 18-?? mm that came with the canon EOS 450D and an EF lens that comes as kit with the EOS 3 (28-75mm macro IIRC).

I find that with bigger lens I can't seem to get a sharp focus on anything.

I was taking a few shots of a goose that was stood quite close to me (taking up the full picture) on one leg and was staying fairly still. I tried manual focus and auto focus with a range of aperture settings. The shutter speed never went slower than 1/10.

All of the pictures didn't seem to have a very sharp focus at all. I haven't examined them fully yet but at first glance they were all throw-away-able.

Is it that I wasn't using a tripod? I was sat down and resting the camera on my knees though. Could it be something on/in the lens? Could it be that it's an EF lens fitting?

Any ideas? When I get home I'll post some of the pictures.
Author:  nickminers [ Tue May 12, 2009 12:25 pm ]
Post subject:  Re: Sharp focus
There could be any number of reasons. It should be obvious looking at your pictures whether it's out of focus or blurred from camera shake. I suspect it may be the latter, since as a general rule (on 35mm film/ff sensors) you shouldn't use a shutter speed which is 1/focal length; so for a 28mm lens, 1/30 should be the slowest you go. With a small frame sensor, this is magnified by about 1.4x, so in your case you should be using around 1/40 at 28mm and 1/100 at 75mm. Try it with a tripod - if the results are better, then you can put it down to camera shake.

If it's a focusing issue, and you don't have the same problems with the kit lens, then the lens itself may be faulty. Do you have a polariser filter attached? I've found that unless you get a decent polariser then it can throw the AF off, and I wasted about 30 pictures finding that out!

Does your camera have live view? Most of the new Canons do - if so, try manual focussing with that feature, and a tripod.
Author:  ProfessorF [ Tue May 12, 2009 12:32 pm ]
Post subject:  Re: Sharp focus
I'd agree with Nick - I suspect hand shake could be an issue.

nickminers wrote:
If it's a focusing issue, and you don't have the same problems with the kit lens, then the lens itself may be faulty. Do you have a polariser filter attached? I've found that unless you get a decent polariser then it can throw the AF off, and I wasted about 30 pictures finding that out!

Does your camera have live view? Most of the new Canons do - if so, try manual focussing with that feature, and a tripod.


Little bit more about polarisers - if you're using one, check that it's a circular polariser filter (probably marked as CPL on it). These don't interfere with the AF.
Definitely worth trying a tripod, or at least resting the camera on something.
Do DSLRs still suffer from mirror slap or is that a thing of the past?
Author:  nickminers [ Tue May 12, 2009 12:39 pm ]
Post subject:  Re: Sharp focus
Mirror slap tends to be a problem on the longer lenses, as they exaggerate the vibration. There's not that much difference between the mechanics of a DSLR and a film one you know, Alex! All that's changed is the recordable medium! Obviously, in Live View (do you get that on your film SLRs eh Alex? Do ya? Do ya?) the mirror is already up, so it wouldn't be an issue, but try to use a cable release to minimise shake.
Author:  Fogmeister [ Tue May 12, 2009 12:49 pm ]
Post subject:  Re: Sharp focus
Thanks guys, I have a feeling it was camera shake. I didn't know about the shutter speed rule of 1/focal length. (I guess this rule only applies when using the camera hand-held?).

I'll def try with a tripod next time. Trouble is the tripod I have is a cheapo one which can barely hold the weight of my camer and tips over a lot. I'll have to get a new one :D
Author:  nickminers [ Tue May 12, 2009 1:24 pm ]
Post subject:  Re: Sharp focus
Fogmeister wrote:
Thanks guys, I have a feeling it was camera shake. I didn't know about the shutter speed rule of 1/focal length. (I guess this rule only applies when using the camera hand-held?).

Yes, only when hand-held.

Fogmeister wrote:
I'll def try with a tripod next time. Trouble is the tripod I have is a cheapo one which can barely hold the weight of my camera and tips over a lot. I'll have to get a new one :D

Always a good investment. Spend as much as you can afford, and then some!
Author:  ProfessorF [ Tue May 12, 2009 1:25 pm ]
Post subject:  Re: Sharp focus
nickminers wrote:
Obviously, in Live View (do you get that on your film SLRs eh Alex? Do ya? Do ya?)

:lol:
I just use the viewfinder like a normal person. :P
Author:  nickminers [ Tue May 12, 2009 1:35 pm ]
Post subject:  Re: Sharp focus
Weirdo.

Seriously though, for Macro work, Live View in combination with 10x on-screen magnification and the occasionally awkward camera angle is great for getting pin-sharp focus manually.
Author:  ProfessorF [ Tue May 12, 2009 1:39 pm ]
Post subject:  Re: Sharp focus
Oh I'll bet it is.
*remembers being on a cliff edge attempting something involving a rock dwelling plant*
Author:  timark_uk [ Tue May 12, 2009 1:54 pm ]
Post subject:  Re: Sharp focus
nickminers wrote:
Live View in combination with 10x on-screen magnification and the occasionally awkward camera angle is great for getting pin-sharp focus manually.
He's not wrong, y'know.

Mark
Author:  Fogmeister [ Tue May 12, 2009 2:01 pm ]
Post subject:  Re: Sharp focus
Any good website recommendations for tripods?

TVM :D
Author:  nickminers [ Tue May 12, 2009 2:10 pm ]
Post subject:  Re: Sharp focus
Some great prices on www.warehouseexpress.com
Author:  Fogmeister [ Tue May 12, 2009 5:51 pm ]
Post subject:  Re: Sharp focus
Had a quick browse through the extended photo info. The maximum focal length of my lens is 135 mm (and it's EF which would factor it up to around 215mm) and I was using 1/60 etc... shutter speeds.

Just had a listen to the Martin Bailey podcast about long exposures (Heather's thread) and I'm considering buying a tripod. Thing is though I don't really have a clue about what to go for.
If I went for something like this... CLICKY ...would I also have to buy a tripod head?

Something like this... CLICKY?

What do you guys use? What would you recommend?
Author:  HeatherKay [ Tue May 12, 2009 5:55 pm ]
Post subject:  Re: Sharp focus
After a similar request I made in the old place, I got a Giottos M9242, and subsequently a matching 3-way head.

Tripod: http://www.warehouseexpress.com/product ... ku=1017913

(Even better price than I paid. It comes with a neat carry bag, set of tools and another shoulder strap.)

Head: http://www.warehouseexpress.com/categor ... 4&brand=87

My only downer on the head is when in portrait mode you can't tilt the camera up or down. Other than that, both stonking value for money - and build quality is excellent.
Author:  ProfessorF [ Tue May 12, 2009 6:13 pm ]
Post subject:  Re: Sharp focus
I use a cheap POS from Jessops.
It's got a hook on it so I dangle my bag from it to give it a bit more weight, which has been handy on some windswept beaches.
Unfortunately the head isn't terrific, and doesn't like locking in a given position - being thermoplastic means it'll settle where it wants to, not where I tell it.
So you have to adjust for that.
I don't use it very much unless I'm doing landscapes, and even then, only if it's somewhere easily accessible and I'm not climbing about too much with a handful of tripod.
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