Lens/speed dilemmas

[Pekka]

Hi,

I might soon face a situation that I need to buy a D30 :), that's the easy part, but the choice of lenses is not. It's the deciding factor if D30 really can deliver what I need: more speed and less noise in low light photography (indoors, no flash).

I've never owned an SLR or lenses, so bear with me.

I've heard that Canon 70-200/2.8L is one of the most used and liked concert photography lenses, but I've also learned that prime lenses will give better quality and are cheaper. Also, there is apparently this problem about getting too shallow DoF if you go to e.g. 50 or 80mm f1.4 lenses, and also that fully open aperture in all lenses is softer, and ca. 8 is the sharp point.

So my burning questions are:

1. Is a prime lens really better quality than a L-series lens, on real life (not just on paper)? Can D30 show the differences?

2. I shot with G1 1/13/f2.5, ISO 50 image http://studio-on-the.net/photography/G1/168-6844_CRW.html .
Doesn't getting a 70-200/2.8L lens + D30's ISO 100 mean that I can get that same exposure with same speed (1/13), as what I gain in more sensitive ISO I loose in lens speed? And ISO 200 gives me 1/15 speed? I really need something like 1/30 or more in those situations to make shooting more productive and not really mostly on plain luck to get sharp shots.

4. Which brings a question, why aren't the SLR zoom lenses more sensitive?

5. If you compare G1 shots to D30, what D30 ISO gives same noise level as G1's ISO 50?

6. If I go to 85mm/f1.8 or 50mm/f1.4 I'll get more speed (maybe up to 1/60 in same situation), but will the DoF get too shallow for capturing a person with an instrument? What about sharpness, is fully open aperture softer in all lenses?

7. How fast you can change a lens, and is CCD dust a common problem with people who change lenses a lot?

Thanks for all replies,

Pekka
http://studio-on-the.net/photography/G1/

[Thom]

Pekka wrote:

6. If I go to 85mm/f1.8 or 50mm/f1.4 I'll get more speed (maybe up to 1/60 in same situation), but will the DoF get too shallow for capturing a person with an instrument? What about sharpness, is fully open aperture softer in all lenses?

I'll address the DOF issue first ... some interesting results with a 3m distance film to subject:

D30 85mm f/1.8

Hyperfocal distance 174.52 m
Nearest focus 2.95 m
Furthest focus 3.05 m
Depth of field 0.10 m
Field of view at focus 0.79 m
Circle of confusion 0.023 mm


D30 50 mm f/2.0

Hyperfocal distance 54.35 m
Nearest focus 2.84 m
Furthest focus 3.18 m
Depth of field 0.33 m
Field of view at focus 1.36 m
Circle of confusion 0.023 mm

D30 50mm f/1.4

Hyperfocal distance 77.64 m
Nearest focus 2.89 m
Furthest focus 3.12 m
Depth of field 0.23 m
Field of view at focus 1.36 m
Circle of confusion 0.023 mm


G1 21mm f/2.0

Hyperfocal distance 24.83 m
Nearest focus 2.68 m
Furthest focus 3.41 m
Depth of field 0.74 m
Field of view at focus 1.26 m
Circle of confusion 0.00888 mm

You can see that your G1's small sensor size greatly enhances DOF. I picked 50 mm for the D30 as that was close enough for the G1 at max. focal length of 21mm regarding comparative field of view.

The 85mm D30 example shows how quickly DOF falls off at an aperture of 1.8 with increase in focal length. Of course magnification is higher than the 50mm lens.

D30 200mm f/2.8 at focus distance of 11m

Hyperfocal distance 621.12 m
Nearest focus 10.81 m
Furthest focus 11.20 m
Depth of field 0.39 m
Field of view at focus 1.24 m
Circle of confusion 0.023 mm

Now with a 200mm you can see that you can back off to 11m away and get similar DOF as the 50mm, but all the D30 options are about one half the DOF of your G1.

A rule of thumb regards sharpness is typically two stops closed down from max. aperture will show significant improvement in sharpness for any lens. From there it gets better as you approach f/8-f/11, then diffraction effects from the small aperture size start to soften the image again. That said, the Canon "L" glass is designed for being as sharp as possible at max. aperture. In practice, they all are very good, albeit some better than others.

You'll have to let me know if the field of view is about right? Maybe a bit too wide for landscape orientation but ok for portrait?

I'll get to your other questions a bit later.

Regards ...

[Thom]

Hi Pekka,

Item 1. There are prime and zoom lenses in both the L series and non-L series. There are USM and non-USM and there are even cheaper consumer lenses with plastic bayonet mounts. Typically, the L glass is "better" than the non-L USM consumer lenses. Better includes not only sharpness, but contrast, color, clarity, chromatic aberration, bokeh and overall image quality. They produce images with a more three dimensional appearance. It is apparent on film or the D30. However, a few non-L prime lenses are so good that they should be!

The first consideration with zooms vs primes is distortion, typically barrel at wide angles and pincushion at longer focal lengths. So if architecture is an important subject, zoom lenses, whether L or not, are less desirable than primes. Zoom lenses, even at their best are compromises that tend to show their worst at their extreme ends, typically softer at the longer end. But don't rule them out, the L series zooms are very good lenses and often the convenience of one lens is more important than the ultimate in sharpness. I currently carry six lenses from 14mm to 300mm. I use all of them in equal proportion. All my zooms are L, all the primes are non-L. The non-L primes are as sharp as the L zooms and are f/2.8 or faster. L primes are the best of the lot.

I think I covered #2 fairly well in my answer to #6?

#4 Speed at the focal lengths of lenses used in 35 mm format comes at great cost in size of the glass itself. Your 7-21mm lens only requires around 8.4mm of open aperture to acheive f/2 at 21mm. An equivalent focal length and speed in 35mm format is approx. 100mm and requires a 40mm aperture. A 200 mm f/2.8 lens needs 72mm of open aperture diameter. The expense and difficulty associated with manufacturing quality glass of such size is many orders of magnitude greater than making a quality lens of less than only 1cm in diameter. Zoom lenses have even higher costs associated with maintaining quality at high speeds.

#5 I don't have experience comparing the two specifically for noise at different ISO. The D30 shows little change in noise up to ISO 400, then it becomes about as evident as film grain in scanned 800 and 1600 ISO film respectively.

#7 Changing lenses takes practice and an efficent "work-flow" which includes how you carry your gear. Ask ten people and you will get ten different answers, but it eventually just becomes automatic. Finding the perfect shoulder bag, backpack, satchel, vest or waist belt system is a life long frustration. I have a closet full :-)

Obviously, the environment in which you change a lens will have a direct effect on dust entry. I change lenses a lot, and I shoot outdoors as much as in, but I'm very careful when it is windy and avoid switching lenses in dusty conditions. So far I have no visible dust on my sensor, but others reported problems right away. I think an annual servicing by authorized Canon shop would be prudent.

Regards ...

[Pekka]

Thom,

I appreciate very much you taking time to write such a detailed answers. It really made some things clearer.

I have come now to a conclusion that I will need mostly zooms. In what I shoot (people at work) as the distance can be anything and mostly I can not just walk closer.

I found a couple of sites to help this desicion:
first was a nice set of articles in Canon Malaysia site: http://www.camera.canon.com.my/photography/index.htm . The other was Techphoto lens chart http://www.techphoto.org/urllink.epl?html=/photo/equipment/canon/lens-spec.epl which had two sets of ratings for each lens. The top picks for low light work would then be:

Rating 1 is "Chasseur 'd Images Test":
Overall performance (max 5*)/ Price vs. performance (max 5*) / "love factor" (max 5*)

Rating 2 is Japanese magazine CAPA (by GAKKEN BOOK) ratings on the EF line of lenses. :
ease of use, resolving power, resolution, cost-performance, editor's verdict (Highest rating: 5 *'s )

So I picked possible lenses I'd like to have:

20mm f/2.8 USM
(****/***/****) (4.5, 4, 4.5, 3, 4) Price USD440

EF 50mm f/1.4 USM
(***/***/****) (4.5, 4, 5, 4, 5)
(USD345)

EF 85mm f/1.8 USM
(****/****/****) (4.5, 4.5, 5, 5, 5)
USD365

EF 100mm f/2.8 Macro
(****/****/***) (4, 5, 5, 4, 4)
USD575

EF 28-70mm f/2.8L USM
(****/***/****) (5, 5, 5, 3, 4)
USD1339

EF 70-200mm f/2.8L USM
(****/***/****) (4.5, 4.5, 5, 3, 5)
USD1439

Which looks like I must first go for a EF 28-70mm f/2.8L USM and a EF 70-200mm f/2.8L USM plus possibly a EF 50mm f/1.4 USM.

I'll know the prices tomorrow. The camera is here (D30 Pro pack: D30 + battery grip + 1GB microdrive) about 26000 Finnish Markka (which http://www.oanda.com/converter/classic says it's USD4178 ). Then you add those lenses so we are talking something like FIM50 000 (USD7500). So you pay a premium to be a Finn and joy this weather :)

But I think the hobby is worth it. Let's see what my bank thinks! All this planning might go down in bankrupt....

PS. I will not sell my G1 gear - never!

[Thom]

Pekka,

Thank you for your kind words, glad I was able to help out some.

You've picked some good lenses. My current crop:

Sigma 14mm 2.8 EX USM - highly recommend, very low distortion, very sharp.

Canon 17-35L 2.8 - bought this and the above 14mm Sigma to replace a Canon 20mm 2.8 USM and Canon 20-35 3.5-4.5 USM - highly recommend. My standard walk around lens now. The D30 crops out almost all barrel distortion a 17mm.

Canon 28-70 L 2.8 - love it

Canon 50mm 1.8 - original model I, non-usm but with a metal lens mount - a classic - very sharp and fast "enough" but too noisy for discrete photos, unless your orchestra is playing :-)

Canon 100 2.8 USM macro - new model - replaced a very nice Tamron 90 mm macro - again ... love it, getting a lot of use now.

Canon 100-300L 5.6 - old non-USM lens, slow aperture, push-pull zoom (one-touch) but very sharp and focuses faster than you would think. This will be my next one to upgrade - probably get 70-200L and a 300 2.8 L prime

Oh ... you're right, hang on to that G1, not only are you good with it, there will absolutely be times when it is essential to get the shot. I will get another one, not my top priority right now, but when the price comes down a bit more, or I see a good used buy, I'm going to grab one.

Have you tried www.deltainternational.com for pricing? Very good dealer, but no clue as to international purchase.

[Super-Nicko]

hey dudes... couldnt help it - never pushed last post ever button but this is it

April 2001 wow.... and Pekka was just getting started!

i must be the original 'dead thread' starter!!