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Old Jan 28, 2006, 10:25 AM   #1
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The KM 5D body alone is $100 cheaper than the "kit" which includes the f/3.5-5.6, 28-70 mm lens. How useful will this lens be forme?I need to use the camera indoors in low light conditions for family pictures at home and to freeze wrestling action in a gym. Therefore, I was planning to get a lower f/number lens in the same zoom range, say f/2.8 28-70 mm. I expect to get a larger telephoto and a low f/number 50 mm prime also.

I will do some shooting outdoors in conditions where their will be plenty of light and I might appreciate a greater depth of field of a higher f/number lens. I'm don't have any SLR experience, so I'm not sure if the f/2.8 lens is versatile enough or would one want a higher f/number lens for general outdoor photography?

If a higher f/number lens might be a good addition for outdoors shooting, would an extra hundred or two dollars provide a meaningful upgrade over the kit lens?

What are some potential downsides to accessory lenses? Might focus time increase? Is this related to zoom range? Are there lenses that are described as compatible that might result in some lose of function or interaction with the camera?

I am still may consider the Nikon D50 because of its low noise at high ISO, so any comments that might pertain to their kit lenses would also be appreciated.

Thanks in advance,
Scott
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Old Jan 28, 2006, 10:41 AM   #2
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Your understanding of how aperture ratings work is flawed.. Lenses with larger available apertures (represented by smaller f/stop numbers) can still be used at smaller apertures. Most lenses go to around f/22 (and some to f/32 or even smaller apertures).

Lenses are rated by their largest available apertures (smaller f/stop numbers), and for most (but not all) zoom lenses, you'll see two aperture ratings... the first one is for the widest aperture at the wide end of the lens, and the second is the widest aperture at the long end of the lens. The largest available aperture will fall somewhere in between these two numbers at focal lengths in between the two extremes.

Some zoom lenses can maintain a constant aperture throughout their focal range (with f/2.8 being the most common). Of course, a brighter zoom lens is larger, heavier and more expensive. For indoor use without a flash, a lens with a constant f/2.8 aperture is preferred in a zoom (but, a brighter prime is even better, allowing faster shutter speeds and/or lower ISO speeds for the same conditions).

Aperture is a ratio, and is determined by dividing the focal length of the lens by the size of the iris opening.

The aperture scale (in one stop increments) goes f/1.0, f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8.0, f/11, f/16, f/22, etc. With each one stop move to a smaller aperture (represented by larger f/stop numbers), you will need shutter speeds twice as long for proper exposure.

So, a lens with a larger available aperture is desired to get fast enough shutter speeds to reduce motion blur (either from camera shake or subject movement) in many conditions.

Of course, the downside to using larger apertures is a shallower depth of field. This can be a pro or a con, depending on what you're shooting. But, for portraiture, you typically want a shallower depth of field (to help your subject stand out from distracting backgrounds). Again, just because a lens has larger available apertures, doesn't mean you need to shoot that way.

The lenses can also use smaller apertures than the largest available (and a lens isn't going to be as sharp at wide open apertures anyway, so "stopping down" a bit can yield sharper photos, and you've got more room to stop down with a prime starting out with larger apertures versus a zoom that may start out at f/2.8 or smaller).

Here is a handy online exposure calculator that lets you see how larger apertures impact shutter speeds, in 1/3, 1/2 or 1 stop increments (you can change this via check boxes at the bottom).

http://www.robert-barrett.com/photo/exposure_calculator.html

As for the KM kit lens, it's an 18-70mm f/3.5-5.6 (not a 28-70mm f/3.5-5.6). Big difference. 18mm is much wider, allowing you to get more of the scene in an image when you can't back up enough using longer focal lengths. But, it's not suitable for low light without a flash.

I'd suggest bright primes for existing light indoors. The 50mm f/1.7 is bright, sharp and inexpensive (but you may want something longer).



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Old Jan 28, 2006, 2:09 PM   #3
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JimC wrote:
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Your understanding of how aperture ratings work is flawed.. Lenses with larger available apertures (represented by smaller f/stop numbers) can still be used at smaller apertures. Most lenses go to around f/22 (and some to f/32 or even smaller apertures).
Thanks for setting me straight. Thatclears up a lot of questions.Thanks also for the lightening fast reply, which I caught just after you posted it.

I am searching for more info on lens in the Digitial SLR KM forum.

Scott
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Old Jan 28, 2006, 7:23 PM   #4
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Scott:

The kit lens isn't bad for what it's going for (only adds about $100 to the price of the camera).

It's got very good focal range (18-70mm, which gives you roughly the same angle of view as a 27-105mm lens would on a 35mm camera). It's also small and light.

It's just not a lens I'd use indoors without a flash. Is it worth the extra $100? Sure, and it's a low cost way to get something wider than you'll usually find in brighter zoom lenses.

Buying lenses is compromise (size, weight, focal range, brightness, optical quality, build quality, cost, etc.). If you get a brighter zoom, size, weight and cost increase.

You may just want to get the kit lens (since it's so inexpensive), and get something like a 50mm f/1.7 to go with it for existing light use indoors (it's small, light, bright, sharp and inexpensive)..

Then, once you've used the camera for a while, you'll have a better idea of your true needs (and you could always sell the 18-70mm kit lens on Ebay if you decide you need something different).

If you're rather have a brighter zoom to begin with, the Minolta 28-75mm f/2.8 is a well liked lens (but, it doesn't start out as wide as the kit lens, and it's larger and heavier).


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Old Feb 1, 2006, 1:11 AM   #5
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Jim:

Thank you for your replies and thank you and others for the many informative posts on these forums.

I purchased a KM 5D with a Tamron SP AF 28-75mm F/2.8 xr Di lens before your second post to me, so I didn't have the benefit of your last specific recommendations before hitting the store.

Is the difference between the Tamron and the Minolta 28-75mm f/2.8 significant? I paid $390 with tax and rebate. I have another week to decide on any exchanges.

I noticed the ratings for these lens at:

http://www.photozone.de

[edited by moderator] That URL doesn't work right here (as you've probably noticed). I've tried it more than once myself. LOL Something in the URL is fooling the code tags here. So, I shorted it to the sites' main URL. For anyone wanting to see it, go to http://www.photozone.de, and find the "User Performance Surveys"
[end edit by moderator]

This Tamron is rated: Good (3.36), with "significant" wide zoom distortion and slow AF speed.

The Minolta AF 28-75mm f/2.8 D (APS-C) is rated: good-very good (3.93), with slightly warm color balance, and ok AF speed.

Also, Minolta AF 28-70mm f/2.8 G is rated: Excellent (4.77), slow AF speed.

How much practical difference would be there be between the Tamron's "slow" AF and Minolta's 28-75mm "ok" AF speed?

It is not clear to me looking at various sources of lens information as to whether some lenses might result in a loss of some DSLR camera functions. I've read Minolta footnotes (e.g. the D spec = distance data is provided to the camera), but these notes often don't indicate what if any useful features might be missing. Do either of these Minolta lenses or the Tamron result in the loss of any functions on the KM 5D?

Thanks again,
Scott

Edit:After I completed this post,I noticed you mentionedthat this Tamron is well liked in the KM forum: http://www.stevesforums.com/forums/v...mp;forum_id=84
Sorry that I seem to have posted in the wrong forum.
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Old Feb 1, 2006, 7:49 AM   #6
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The Tamron 28-75mm f/2.8 XR di and the KM 28-75mm f/2.8 are the same lens optically (both are made by Tamron). Rumour has it that the KM version of the lens has different coatings and electronics (but that may just be an "urban legend"). ;-)

What you are looking at when you see ratings at http://www.photozone.de are user surveys (opinions). So, it's not unusual to see some inconsistency in the ratings. Also, you find users of both 35mm and DSLR models responding to the surveys (and a lens can work differently on one versus the other because of the sensor size).

On the plus side, with a DSLR, you're using the "sweet spot" of a lens designed to work on both camera types (since the CCD sensor is smaller than 35mm film, you don't use the entire image circle). On the negative side, a CCD is more reflective compared to film (so flare resistance can be a bigger issue with a DSLR).

The Tamron you've got is a well liked lens by KM DSLR owners. I personally wouldn't worry about whether I got the KM or Tamron version of it (and the Tamron comes with a 6 year warranty). ;-)

P.S. The Tamron you bought is an ADI compatible lens (it's sends distance information to the camera, just like a KM "D" lens would).



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Old Feb 4, 2006, 12:55 AM   #7
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JimC wrote:
Quote:
[edited by moderator] That URL doesn't work right here (as you've probably noticed). I've tried it more than once myself. LOL Something in the URL is fooling the code tags here. So, I shorted it to the sites' main URL. For anyone wanting to see it, go to http://www.photozone.de, and find the "User Performance Surveys"
[end edit by moderator]


Sorry, I didn't test the link I posted for the reviews oflenses for KM. I found that link here on Steve's KM DSLR forum, and it still works at this thread: "Reviews of lenses for Maxxum 5D", last post Dec 30, 2005.
http://www.stevesforums.com/forums/v...mp;forum_id=84


A question about Tamron -- what is their reputation for quality today?A former professional photographer told me that many (20-25?) years ago, Tamron was considered to a low end lense mfg.; what a person would buy if they couldn't afford a big name, likeMinolta lenses. (No diss intended.) I presume that since Tamron is now a supplier to KM, that KM approves of their quality. Yet some reviews of Tamron lenses are not so favorable. Is the situation, that Tamron has upgraded their capabilities for producing better lenses, but still makes budget lenses?

The discussion came up because I had to exchange my Tamron f/2.8, 28-75, because an uneven focus across the field of view.

Inanyevent, thanks much for all the good info.

Scott
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Old Feb 4, 2006, 8:39 AM   #8
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Tamron is a 3rd party manufacturer that makes lenses for Nikon, Canon and Minolta to name a few. Just like the camera manufacturers, they make some very good, expensive lenses, and some poorer less expensive lenses. The saying you get what you pay for applies here.
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Old Feb 4, 2006, 9:23 AM   #9
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Yep..

You'll find good and not so good (an understatement) lenses from all of the major manufacturers.

Tamron's best lenses will have SP in their name..

Sigma's best line will have EX in their name.

Canon's best line will have L in their description (for example, 50mm f/1.2L).

Minolta's best will have a G (for example, 80-200mm f/2.8G).

etc.

Now, that's not to say that you can't find a good lens that's not a manufacturer's better line (and sometimes, a lens that is in a manfacturer's better line can be bested by some less expensive lenses).

Build quality also varies quite a bit. The higher end lines usually have much better build quality. Some lenses are pretty much junk from a build quality perspective (from most manufacturers). But, that doesnt' mean that they can't do the job optically (some lower cost lenses can be just fine).

But, you really need to take each lens on a case by case basis (ergonomics, build quality, optical quality, brightness, resistance to flare, AF speed, etc.).

Quality is subjective, too (and not everyone needs an expensive and bright lens). There are tradeoffs (quality, size, weight, cost).

You may not want the best lens around in a given focal range, if for no other reason than size and weight, even if cost is not a consideration. There are a lot of variables (what you intend to shoot, what conditions you'll be in, what use you'll have for the images, etc. ;-)


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Old Feb 5, 2006, 1:55 AM   #10
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Thanksrj and Jim,

JimC wrote:
Quote:
Tamron's best lenses will have SP in their name..

Sigma's best line will have EX in their name.

Canon's best line will have L in their description (for example, 50mm f/1.2L).

Minolta's best will have a G (for example, 80-200mm f/2.8G).

But, you really need to take each lens on a case by case basis (ergonomics, build quality, optical quality, brightness, resistance to flare, AF speed, etc.).
Looks like I too will be building alens collection for my KM. I'm not at a skill level that i can evaluate lens quickly at store for the characteristics you noted. (If that's what you meant.)The reviews look helpful for evaluating prospective bargains. Can I be pretty confident of qualitywith any SP, EX, L, and G in the brands you noted or should I consult reviews prior to any purchase?

Thanks again....Scott
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