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Old Jun 3, 2005, 5:49 PM   #1
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Sigma Zoom Super Wide Angle 18-50mm f/3.5-5.6 DC Autofocus Lens

Vivitar Zoom Super Wide Angle 19-35mm f/3.5-4.5 Series 1 Autofocus Lens

I am considering these two lenses. Any opinions on which is better as far as quality goes? And what is the significance of 3.5-5.6 as opposed to 3.5-4.5. Is it the longer zoom capability?

I already have 28-80 and 70-300 lenses, so either will do as far as coverage goes.





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Old Jun 3, 2005, 10:50 PM   #2
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OK -- I'll take a stab at this since nobody else has answered.

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Sigma Zoom Super Wide Angle 18-50mm f/3.5-5.6 DC Autofocus Lens

Vivitar Zoom Super Wide Angle 19-35mm f/3.5-4.5 Series 1 Autofocus Lens

I am considering these two lenses. Any opinions on which is better as far as quality goes?
Photodo rates the Vivitar as a 2.9 (on a scale of 1 to 5 with 5 being the best). Here is an MTF chart on it:

http://www.photodo.com/prod/lens/det...5-45-865.shtml

But, I don't know of anyone that's used it. So, things like color, contrast, flare, AF speed, etc., are unknown to me. I did find a few older comments on it searching around on the internet (and one user did mention that it is somewhat prone to flare). But, overall, the general consensus is that it's not a bad lensconsidering the price, and sharpens up nicely when you stop the aperture down to around f/8

As for the Sigma.... The use of DC type lenses on the 7D is controversial. These lenses are designed for use with sensors smaller than 35mm film. Since the 7D moves the CCD for the Anti-Shake process, it could theoritically cause more vignetting if the CCD falls outside of the image circle being projected by the lens.

But, opinions vary. Some KM owners seem to think that this lens is designed to cover a larger sensor (1.3x crop factors) compared to the sensor used in the 7D, and that CCD movement is miminal at shorter focal lengths where vignetting is likely to occur.

The general consensus from Canon owners is that this lens is probably as good or better compared to Canon's 18-55mm kit lens from an optical quality perspective(but well short of the quality of an L lens).

I do not know of any KM 7D owners that have tried this lens on a 7D.

Quote:
And what is the significance of 3.5-5.6 as opposed to 3.5-4.5. Is it the longer zoom capability?
You're looking at the brightness of the lens. The numbers you see represent the largest available apertures at the wide angle and zoom ends of the lenses.

Larger Apertures (represented by smaller f/stop numbers) let in more light. The first number you see represents the largest available aperture at a lens' wide angle position. The second number you see represents the largest available aperture at the lens full zoom position (longest focal length).

Chances are, these two lenses are very close to having identical brightness at the same focal lengths (since the Sigma goes to a longer focal length compared to the Vivitar it's lens is stopping to smaller apertures).

See this thread for a more thorough explanation of aperture ratings and what some of the benefits are if you have a higher quality lens with larger available apertures:

http://www.stevesforums.com/forums/v...mp;forum_id=28


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Old Jun 3, 2005, 11:03 PM   #3
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Thanks, JimC. Since the Sigma is a wider angle, will the Anti-Shake come into play all that much? I would think it would be in effect much more with longer focal lengths, so would the fact that it is probably going to be used less at wider angles indicate that the possible vignetting issue would be less likely to occur? I am new to a lot of this, so please forgive if the question is a little strange.

Thanks
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Old Jun 3, 2005, 11:09 PM   #4
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I'm no expert on it. But, I've seen it explained like this in relation to this Sigmalens:

Quote:
The 7D sensor can move pretty much to the limits of the 35mm frame, vertically or horizontally, but the diagonal movement is constrained (you can't get 5mmH + 5mmV, just an overall diagonal shift of 5mm. This would indeed hit the vignetting of the Sigma DC 18-50mm at 18mm. However, the movement of the sensor is linked to lens focal length. With an 18mm wide angle you get very small movements. You only start getting large movements with longer lenses and slow shake (like travelling on a vehicle or a boat).

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Old Jun 3, 2005, 11:18 PM   #5
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I see listings for "Aspherical" lenses. My web research seems to indicate that this is superior lens type, but the costs are often lower than other non-aspherical lenses of the same focal length and aperture range. Can you explain what aspherical is and if it is indeed better?
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Old Jun 3, 2005, 11:27 PM   #6
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Jacqueaux wrote:
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I see listings for "Aspherical" lenses. My web research seems to indicate that this is superior lens type, but the costs are often lower than other non-aspherical lenses of the same focal length and aperture range. Can you explain what aspherical is and if it is indeed better?
Here is a good explanation of it on Canon's web site:

http://www.canon.com/technology/deta...uct_tech/mold/

You'll see all sorts of designations used for the types of glass, elements, lens coatings, etc. for various lens. But, you really need to take each lens on a case by case basis. Don't assume that one lens is better because of the types of lens elements used.


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Old Jun 4, 2005, 12:28 AM   #7
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Looking at Phoenix 19-35 lenses. One says for Minolta, one for Minolta MD for $20 more. What does the MD designate, and, do you have an opinion on Phoenix lenses?
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Old Jun 4, 2005, 9:53 AM   #8
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That Phoenix Lens*appears* to be the same lens as the Vivitar you're looking at, being sold under a different brand name (although there could be a difference between glass quality/lens coatings). Chances are,they're identical.

When lens shopping, you'll want to make sure the lenses are compatible with Minolta's Maxxum/Dynax Autofocus Cameras. More often than not, you'll see these lenses designated as Minolta AF mount.

Older MD mount manual focus lenses are not compatible withyour camera, and you often see the same optical design being used in both AF and MD lenses.

Depending on what you plan on doing with the images (and how often you'll use the wider lens), you may also want to considerhigher quality lenses compared to the ones you are considering. It would be a shame to buy a > $1k camera and put a lens on it that's not going to take advantage of the camera's potential.

If you're not going to print at larger sizes, you may not notice much difference in optical quality (although you still may prefer the ergonomics/physical design of a higher quality lens more).

If printing at larger sizes, you may notice things like corner softness, vignetting, etc., morewith a lowerquality lens -- not to mention flare, chromatic abberations/purple fringing, etc. There can also be a big difference in things like color and contrast between lenses (some lenses may be more color neutral, others may lean towards warmer colors, etc.). Bokeh/Backtround Blurcan also be impacted (is it a 6, 7, 8or 9 blade aperture -- impacting how rounded portions of the background blur appear, etc.)

The KM 17-35 f2.8-4 (D) is a popular choice (and since it's a "D" lens (supports Minolta'sADI forDistance Information), the camera's metering is using Distance Information from the lens to help makeexposure choices).

Another choice to consider would theSigma 17-35mm f/2.8-4 EX DG HSM lens. Sigma's EX designation makes this one of their better lenses. It's also compatible with ADI for Distance Information, and has a non-rotating front element (internal focus design), as well as Full Time Manual Focus.

Both of these lenses are approx. $500.00 from reputable online dealers like B&H Photo and Video.

Chances are, both of these lenses are going to be as sharp at wide open apertures, compared to the lenses you are considering stopped down to f/8 (and they'll be even sharper stopped down). But, if you're not going to be viewing/prniting at larger sizes, the difference in sharpness maynot be visible. You may not need to use a lens at large apertures either (where most lenses are softer).

Looking at MTF charts, the KM lens is probably the most consistent between sharpness at both wider and longer focal lengths. The Sigma appears to be sharpest at the wider end of the lens.

If I were you, I'd go down to a reputable camera dealer, and try out some of the lenses on your camera. Then, you'd get a better idea of how they compare from a physical design perspective (focus/zoom design, difficulty in changing between MF and AF, smoothness of zoom and focus rings, build quality, size, weight, filter size,etc.).

Also, make sure to take things like closest focus distance into consideration (as this can vary a lot between lenses).

If you're on a budget (and aren't we all - :-)), then I'd be inclined to shop the used market. That way, if you decide to upgrade to a higher quality lens later, you won't lose as much when reselling the lens.

If you are on a tight budget, I might be inclined to try the Vivitar. Most of the comments I've found for it, indicate that it's a good lens for the money (but I haven't found anyone that's used in on the D7D yet). These were comments from 35mm users, and a lens may have different optical characterics on a Digital Camera.

Often,this does go in favor of Digital (since you're only using the center portion of the image being projected because of the smaller sensor, corner softness and vignetting may not be as much of an issue). Other times, it may go against Digital (since they tend to be more prone to display chromatic aberrations and purple fringing compared to film).

At around $150.00, you may find it to befine for what you are using the camera for. But, I would make sure to try one in a store to make sure it functions OK with your camera. Sometimes, compatibility problems exist with lenses, even though they may be designed for your camera mount.For example, it'snot unusual to see camera owners needing to send older Sigmalenses back to the manufacturer for "rechipping" to make them compatible with some newer Maxxum models.

You'll also want to make sure you are comfortable with the ergonomics, etc.

After you choose a lens, please make sure to report how well it's working, so that others lens shopping have a better idea of what choices are available.


P.S.

I was hoping some more knowledgable users would respond. Trust me, I'm don't know much about lenses,and I do not own a Minolta SLR. I only responded because nobody elsehad and you wanted some answers to your questions. Because the D7D is Konica-Minolta's first entry into the DSLR market (not counting the older, discontinued Minolta Models), it will take a while before we get as many KM owners frequenting this forum.

One other thing you may want to do... Ask about your "short list"lens choices in the Nikon and Canon Lenses forums here. Most of the time,the same third party lenses are available in multiple camera mounts, so you may find some forum members that have experience with a given lens in these forums.

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Old Jun 5, 2005, 11:11 PM   #9
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Jim makes many excellent points in his reply. I think one of themost importantisgo to a reputable camera shop and spend some time looking at lenses and trying them on the camera body they will be used. There is nothing like actually using the lens to determine how it fits you. Youcould alwaysresearchoptics and determine ifthey're in the area you consider acceptable, but with digital you can actually shoot a number of shots at a shop:| and at least look at them in a preview - and don't forget the zoom. If you can borrow a memory card from a friend you can also take shots home with you to look at in detail.

I recently went through a decision on K-M 17-35mm or Sigma, Tamron, ???:angry: After going to the camera shop and trying lenses, I bought the K-M even though it was a bit more $$$! :G
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