New DSLR camera

[woodbe]

That will give us a good idea of the resolving power of the lens and sensor.

Here's why you should never discuss this stuff on the innernet

But Studley, I thought a lot of lenses didn't perform at their best at the extremes of their zoom ranges? Also, at 55mm F5.6 is wide open on that lens, the results might not be the best it can deliver

How are you processing your RAW files Studley? I've been trying out the Lightroom beta, and I have to say I'm pretty happy with where it's headed. Not really impressed with the Canon software, but previously using CaptureOne LE which I like, but I'm finding Lightroom superior for organising images, and some of the tools are unique in this sort of program and quite handy.

woodbe.

[woodbe]

Also, this is a good read (that is, if you would rather sitting down reading instead of going out taking photos) It's aimed at Canon EOS and the Pro's but lots of good info inside:

(Warning, it's 7.6mb if you are on dialup)

http://www.photoworkshop.com/canon/e...ook/index.html

woodbe.

[Studley 2436]

Lenses will show greatest distortion at either end of their zooming range. There should be a sweet spot somewhere in the middle but lets ignore that and see what is happening at the ends. Likely it will balloon at the short end and pincushion at the long end but that is up to the test to see.

The other thing is that you can look at the image of your newsprint and see if it is darkening or Vignetting in the corners and also you can see the sharpness in the middle of the frame and how much sharpness is lost going to the corners.

This is the resolving power Harry. Imagine you had a four pixel camera. The best it could do with the sheet of newsprint would be four grey pixels! you might even get a couple of the pixels being more white or black than the others. Of course having ten million pixels is a whole different thing, so looking at your blown up image of newsprint mainly is a lens test to see if the lines are going straight or not. You will get an idea though if there are funny sensor things going on. Chances are with the sensor you have it just won't be an issue. It's likely that the sensor outresolves the lens. That is the sensor could record more information but the lens is not able to reproduce the scene as accurately as the sensor.

MMMM enough bleating

Studley

[Harry72]

Thanks for the help Stevo, must go buy a newspaper!


Is there any sites I could visit that just gives the "general rule's of thumb" explained in laymens terms?
Most I've visited seem to think you know all these terms off by heart, or they expect you to read for 3hrs to understand something so simple!(you know what I mean... like a lot of subjects on the net a "procrastinated explanation", just look at some audio forums and you'll see what I mean!)

[Grunt]

Harry,

You should visit www.dslrusers.com. It's an Australian photography forum. Plenty of information and honest feedback on your photos.

I'd do a google on basic photography.
http://photography.about.com/od/basics/


Chris

[Studley 2436]

photodo is a great website. They have ratings of lots of lenses there although it is old. I am not sure what they are like there on new lenses. they do give a good explanation of MTF's (modulation transfer function) and what then mean and how to read them.

Kenrockwell is a highly opinionated Nikon site but he has good explanations of things like Bokeh in addition to a nice gallery. From memory he explains somewhere about lens performance and the way lenses work at different apertures.

This is stuff I looked at about 3 years ago when I was buying some lenses and was trying really hard to make sure I got a good one. I couldn't afford to make a bad decision.

So far as aperture the wider you go the more deterioration in quality you get. You really see this when you get wider than f2. The cheap Nikon 50 f1.8 for instance outshoots the Nikon 50 f1.4 but isn't as wide. Well 2/3 of a stop slower. Fast lenses are great.

Any lens will typically perform at it's best when it is stopped down a bit from it's maximum. There is usually a clear difference between wide open and 2/3 of a stop stopped down. Typically a lens will perform best at f5.6 to f8 regarding sharpness. Closed down more than f16 you get diffraction so there is a fall off in image quality ie it loses sharpness.

This is not a brand thing it is what happens to light when it passes through an aperture. Physically things happen that can't be alltered only designed around.

There are zoom lenses that perform and even outperform fixed length lenses but they are typically high end pro lenses. I suppose Canon has some "L" zooms on this level and Nikon has the 17-35 f2.8 and 70-200 f2.8 which are on this level. Expensive puppies allow $2500 for the 17-35 and I think it is something over $3000 for the 70-200

Mind you in Nikon if you really want some really really sharp images the 400 f2.8 gives almost perfect about 0.95 out of 1 all the way from the centre of the sensor to the outside corner. It is like a flat line all the way across teh sensor where you expect to see it losing resolution towards the corners.

To see something about all this check here

18-55 MTF is here

75-300 is here


Something to be wary of is that Canon don't actually measure their lenses they do a calculation based on what they believe it should do and graph that. The other thing I notice is that the 18-55 is graphed out to 13mm or so because it is intended for digital sensors and the 75-300 goes out to 22mm so will cover a full 35mm frame. So where the long lens is falling away and losing image quality is way out past the edges of your sensor and doesn't matter

Studley

[Grunt]

My advice is to wait on getting an expensive lens. The kit lens will take great photos. I've got a Nikon D50 with th 18-55 kit lens. It's an OK lens but I've managed to take some great sharp shots with it.

You can take really fine photos at F22 or F4.5 with the kit lens. Sure, the more expensive lens' are sharper, faster and less distorted but most of the time you won't notice unless you print to A4 size and look at it with a magnifying glass.

I Cannon have an excellent 50mm 1.8 at less than $200. This would be a great portrait lens. It's very sharp and plenty fast. Here is a review

Before you go and part with $2k for a good lens, get to know your camera and concentrate on framing your subject.

This is a photo taken with the D50 with the kit lens.



Chris

[Studley 2436]

Grunt looking at the MTF's the lenses that Harry has got will give a pretty good result. I hope I didn't sound like I was saying that you have to get "Pro" lenses because I didn't mean that.

I like to shoot portraits with my 50 f1.8 which is a really good lens stopped down. Wide open it at minimum focus it goes pretty soft around the sides in particular on the left hand edge possible a touch out of allignment but this is a really good effect for portraits.

I think it is more important to know your gear and what it will do. Then you can use these failings and strengths to your advantage

Studley

[woodbe]

Agree regarding the 50/1.8 I bought one with my first DSLR because it was so cheap and had good reviews. I take it with me anywhere I need a small, light lens that I wouldn't get too upset about damaging. (Eg. the snow, I packed the camera in a beltpack.)



woodbe

[Honest Gaza]

That is also my understanding, and a good plan. I've been surprised how negotiable the price is down at Teds... Bear in mind that you are likely to have to cough up GST upon your return to Australia if your purchases are above a certain amount (they always are for me).

There's a good reference for current HK lens prices here: http://www.ygdragon.net/ Just click on "Lens Price Reference List 鏡頭價目表" on that page. This is not a shop, it's a list of recent sales per lens. The prices shown are generally very competitive, but it's up to you to negotiate.

woodbe.

Change of plans.

Got a quote back from a Hong Kong site on the Canon 400D Body + Tamron 17-50mm f/2.8 Lens for approx $1,500 AUS.

Camera House gave me a price of $2,049 for the same combination. That saving of $550 (if purchased in HK) will go a long way towards my second lens of choice - Canon 70-300mm IS USM. I'll make sure I use the camera in HK so any obvious faults are noticed before I come back to Aus.