Zoom confusion

2007-02-24

in Geek stuff, Photography

A quick question for fellow photographers:

I have never found my Canon Powershot A510 to be any good in the telephoto range. Even photos with shutter speeds suggesting they should be impervious to camera shake (say, 1/1000th of a second) nonetheless come out far from sharp. Is some other phenomenon at work here? One of the very few reasons I consider using my Elan 7N these days, with all the costs inherent to shooting film in England, is that I can be confident that shots taken at the long end of my 28-105mm f/3.5-4.5 lens will have that nice flattened portrait effect. Why does nothing similar seem to happen at the long end of my A510 zoom?

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{ 26 comments… read them below or add one }

Tristan Laing February 24, 2007 at 7:29 am

I’m a bit confused, but there are a few factors to consider.

1) Autofocus, irrelavent at wide angle, can show up its errors in the telephoto range
2)You may just have a lens which isn’t spot on in the telephoto range.

but

3) I’ve seen excellent portraits out of your camera, taken at the long end of the zoom range with plesantly blurred backgrounds. Of course, you’ll never get the blurring of a large sensor camera.

My suggestion is to get the rebel xt as soon as possible. It, combined with your excellent zoom, will make an ultimate portrait tool.

Tristan Laing February 24, 2007 at 8:35 am

On an unrelated note, you might want to check out google’s new plugin for Iphoto that allows integrated explorting to picasso webalbum. I set it up, and in minutes created an online gallery for the original cabin feever here: http://picasaweb.google.com/tristan.laing/CabinFeever1

Not bad for free.

Milan February 24, 2007 at 9:54 am

Tristan,

The greatest trouble seems to be at maximum telephoto and a focal range of approximately infinity: buildings in the distance, for example. Even using a tripod and a very fast shutter speed, these never come out sharp.

Milan February 24, 2007 at 9:59 am

This photo demonstrates the tendency we are discussing. I took five of them, several bracing against a tree and all in excellent light. None came out any sharper than this. (And, yes, the autofocus was set to the tower, not the branches.)

Milan February 24, 2007 at 10:04 am

This shot was 1/640th of a second at f/4. This is the JPG straight from the camera, with EXIF data included.

It is by no means the worst example of the sharpness problem, but it is the most recent photo for which I recall being annoyed about it. Perhaps I will be able to find an image that better demonstrates the problem, but I use the maximum zoom extremely rarely, and would likely have already deleted images that are too soft.

Anon @ Wadh February 24, 2007 at 2:59 pm

The linked photo of Magdalen doesn’t look too bad to me.

Anonymous February 24, 2007 at 3:22 pm
Anonymous February 24, 2007 at 3:27 pm

Actually, I think the above entry is self contradictory. The A510 only has four possible apertures when fully zoomed (140mm equiv).

F5.5 / F6.3 / F7.1 / F8.0

Milan February 24, 2007 at 3:45 pm

About the aperture, you are correct. f/4 is only possible two zoom ranges away from the maximum. This tower photo isn’t really a good example of what I was describing.

Tristan,

I would love to get a Rebel XTi, but I am not sure which lens I would get to begin:

1) The kit zoom (advantage: cheap)
2) A better zoom, suited to a small sensor camera
3) A 35mm prime lens

Also, I had never seen the photos from your Russian project, though I remember the experience of taking them very well.

Mike Kushnir February 24, 2007 at 4:09 pm

i don’t know if this is the definitive answer – in fact, i wouldn’t be surprised if i were way off – but i seem to remember this from photo class…

the trouble with adjustable telephoto lenses is that, in the interests of practicality, they’re made of plastic instead of glass. at short range, the difference is pretty much nil. at maximum zoom, however, the difference is apparent.

basically, for cameras like yours and mine, there’s not really too much to do. canon’s rebel series is fantastic for users like yourself; my mum bought one years and years ago (in the dinosaur days of silver-base…yikes…) and i remember it being just amazing. even when it was about 7 years old, i was the envy of the photo class…although i remember preferring to use an old-school nikon until i got my own.

regardless of what you choose to do, the quality of the rebel kit lens will be far superior to the lens on your powershot. for your purposes, that might just do it. take a shot with it (pun not intended) and go it from there.

Tristan Laing February 24, 2007 at 6:40 pm

Ignore the article about diffraction – it is relavent only to large sensor cameras, probably not even medium format, only large format.

Whether you tried to focus on the branches or not is not the issue. The fact is, the branches are sharp and not the building. That indicates to me that the af failed to select the correct objecet OR failed to focus all together and simply picked the hyperfocal point, where the branches happened to be. Try shots again using manuel focus and see if the problem goes away.

Tristan Laing February 24, 2007 at 6:43 pm

I think in terms of lenses to get with the Rebel XT the awnser hands down is the kit lens

1) It’s cheap, very cheap when you get it with the rebel
2) It’s sharp, very sharp, because zoom lens technology has progressed a lot in the last 5 years.
3) You love wide angle, so you coudn’t live without a 28mm equivalent, and you cannot afford an 18mm fixed focal lengh af EF lens. I don’t even want to know what it costs. And if you could afford it, you ought to get the 10-22 AF instead, because apparently it has spookily low distortion.

Tristan Laing February 24, 2007 at 6:44 pm

Also, while its true that the kit lens has some bad distortion at the wide end, it mostly corrects with software. I don’t think that would be a huge inconvenience.

Milan February 24, 2007 at 6:56 pm

Mike,

the quality of the rebel kit lens will be far superior to the lens on your powershot. for your purposes, that might just do it. take a shot with it (pun not intended) and go it from there.

I am quite torn on this. I think it would be worth spending a few hundred bucks more to get a more serious zoom tailored to the right range.

My SLR development so far has been:

Pentax MX Super (died when I was first in London)
Canon Rebel G
Canon 50mm f/1.8 lens
Manfrotto aluminum tripod
Canon 28-105mm f/3.5-4.5 USM II lens
Canon EOS Elan 7N

From here, I am thinking:

Canon dSLR
Decent zoom lens for the same
Perhaps a 35mm prime (would be good on the film bodies, also)
Canon SpeedLite series flash and diffuser

Milan February 24, 2007 at 6:58 pm

Tristan,

Try shots again using manuel focus and see if the problem goes away.

Manual focus is extremely awkward on the A series cameras, as I am sure you know. Still, I will give it a try.

You love wide angle, so you coudn’t live without a 28mm equivalent, and you cannot afford an 18mm fixed focal lengh af EF lens.

What I am wondering is if there is a lens that is to the Rebel XTi kit lens what my 28-105 was to the kit lens for the Rebel G at the time. Basically, a stop faster, better constructed, and with USM instead of EF.

Speaking of software, I really need to get a copy of CS2. I am still using Photoshop 7.0.

Milan February 24, 2007 at 8:29 pm

Of course, I could circumvent the whole 1.6x multiplier issue in the Rebel series and just buy the Canon’s EOS-1D Mark III DSLR with live LCD. Once I rob a couple of banks, that is.

Mike Kushnir February 25, 2007 at 12:42 am

oh, no…all i’m saying is give the kit lens a go, and if you don’t like it, THEN get another one.

that is, assuming, the kit lens is included with the camera. right? and anyway, doesn’t it have an adjustable focal length?

Milan February 25, 2007 at 12:52 am

Mike,

You can buy the kit, which includes a cheap lens at a very cheap price. Alternatively, you can buy just the body.

At Adorama now, the prices are as follows:

Rebel XTi kit with 18-55mm f/3.5-5.6 Zoom Lens (US$754.95 plus tax)
Body only (US$$679.95)

Given that the implied price of the zoom is less than $100, you would be a fool not to buy it. That said, a better zoom and/or a suitable prime lens would be a very good addition to the system.

Still, I am tempted to wait for a full frame dSLR to become affordable.

. April 16, 2009 at 2:15 pm

And physics explains why you can’t take professional-quality pictures with a small camera. Big, bright, beautiful photos require big sensors and big lenses to shine on the chips. So we’re stuck with two camera categories: pocket ones that take mediocre pictures and big heavy black ones (S.L.R.’s) that take stunning photos but require a neckstrap or, ideally, a wheelbarrow.

Matt April 16, 2009 at 4:22 pm

I think a point and shoot (or a small camera) can take a picture that is professional quality. You can take excellent photos even with a pin hole camera, an SLR just makes it easy to take good photos. I’m really from the camp that it’s more the photographer than his/her equipment that makes the difference. While it’s nice to have the right tools for the job, I think some people get a bit too caught up in “look how expensive my camera is.”

Milan April 16, 2009 at 4:30 pm

Increasingly, I am coming to think that, while it is vital to know how to use your gear, there is a lot of photography that simply requires high-quality, expensive equipment.

I don’t deny for a moment that you can take great photos on a cheap disposable camera. I do think, however, that there are a lot of great photos you can take with an SLR and a good lens that are simply impossible on point and shoot equipment. Many nature and sports photos are cases in point.

Matt April 16, 2009 at 4:53 pm

I too won’t deny there are some things that nice equipment can do well, but it seems to me as if nature and sports photography is a fairly small subset of photography in general. Also, I can cite an example that a point and shoot usually does well and would require an expensive SLR lens to match it: macro photography. In my experience a kit SLR lens won’t return a macro photo as good as what you get with a newer P&S.

Of course, you’re limited with manual options with a P&S and I’m not trying to argue it’s better than an SLR. I’m just refuting the idea you can’t take a professional looking photo with one. You can get a nice big bright photo with one, as digital sensors are so good these days.

Milan April 16, 2009 at 4:58 pm

I agree.

Indeed, the photo show I am having in September will very likely involve some 8×10″ or larger prints made using files from a 3.2 megapixel P&S camera.

Milan April 16, 2009 at 5:05 pm

Now that I have a long fancy lens, I do feel a little bit tricked by the pro photographers who say that gear doesn’t matter at all. While you could spend a lifetime learning how to take photos with cheap gear, there are some options that are possible with expensive gear and impossible to replicate without it. Saying that the difference between the photos of those who have the gear and attempt such shots and those who try to do so without it is all about skill is just dishonest.

Basically, the more of these questions you answer with ‘yes,’ the more the necessary gear will cost:

  • Is the subject very small?
  • Is the subject dimly lit?
  • Is the subject far away?
  • Is the subject moving?
  • Is the subject moving quickly or erratically?
  • Will you only get one or two chances to take the photo?
  • Do you need to make super sharp prints?
  • Big ones?
  • Giant ones?
  • Are you mostly buying gear to impress colleagues, babes, or yourself?
R.K. April 16, 2009 at 5:08 pm

I need to take tack-sharp available light photos of extremely rare jungle insects in flight, after sunset, that can be enlarged to cover the side of a stadium!

Also, I am not legally allowed to touch or closely approach them.

Milan April 17, 2009 at 10:39 am

I think the photographic setup for doing that would cost about as much as the Hubble Space Telescope, if it is even physically possible.

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