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Old May 3, 2008, 5:16 PM   #1
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So you all know I'm a newbie. When I take photos I like my subject to be the photo. I mean if I shoot a wine glass, that's all I want in my photo. Not a wine glass on a table in a room, just the glass. I think that's why my 200mm is my fav lens. I can get real nice full frame shots if I'm far enough away of course. Now the bulk of my photographs will be shooting my clothes, people in my clothes and runway shots. With that in mind which lens(es) would be my best options?
And I don't want any "consumer" lenses. Should I decide to upgrade my body one day I want my lenses to go with me.
But wait, more questions, what I would like to know is....
when choosing a lens does a lower aperature rating mean a better lens? i.e f1.4 would be better than a f3.4 yes? no? or what the hell do all these numbers mean anyway?

Thanks for the info guys,
Cheers
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Old May 3, 2008, 10:05 PM   #2
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Hi pdgirl,

Ok, I'll give it a shot, however some additional information would really help everyone here. First, the answer to your "numbers" question. The simple answer, is that there are 2 main numbers that concern lenses. The focal length - the larger the number the closer it gets you to your subject (i.e. your 200mm is the focal length), hence the larger and heavier the lens, along with a higher price. The other number is the minimum f stop the lens is capable of. The smaller the number, the more light it is capable of gathering, which usually translates to more and higher quality optical glass/lens elements in the lens, a heaver lens weight and a higher cost.

So, in general - yes a f1.4 would be a better lens than a f3.4 - IF you are trying to take a photo in a dimly lit room, with everything else being equal. However, there are additional methods to compensate. For instance using a higher ISO speed (lower is better (i.e. 100), higher is more grainey(i.e. 3200)), and/or shooting in an area with a lot of good light. This translates in to - using a good flash, or have a good lighting setup, taking pictures outdoors, etc.

Here are some questions that would assist everyone in helping you....
  • What is your current camera setup? Are you satisified with the 200mm lens? Are you able to get close enough with it? or do you need to get closer?[/*]
  • Do you need high quality images? [/*]
  • In shooting your clothes, either hanging or on models posing or on the runway, what type of lighting is available? Is it dim ambient light, or is there adequate lighting for your current camera setup? Are you using a flash?[/*]
  • Where do you do most of your work - with the clothes pre-posed, or on runways with the models walking (in motion)? If it is in a "in motion" situation, do you want to zoom in or out, in order to frame the shot?[/*]
  • Do you anticipate using a tripod?[/*]
  • About how far away will the subject be posing? On the runway?
    [/*]
Pentax is not known for their fast (low f stop) telephoto (200mm and higher) lenses, since their selection is not that large - especially over 300mm.

There is a person here on the Pentax board who is an award winning professional fashion photographer in Paris who could probably be very helpful. Right off hand I have forgotten his name and would have to scroll back - benjikam is his board name. and here is his website http://www.benjaminkanarek.com/

Also, there are a number of additional items that you need to consider. Its not just a matter of getting the absolute fastest lens (lowest f stop) - f1.2 200mm lens available (and I do not think that any one makes such a lens). But lets just use that as an example. Here is a depth of field calcuator http://www.dofmaster.com/dofjs.html

I am using a K100D camera body with a 200mm lens, f1.2 with the subject about 10 feet away, for this example. The depth of field would be 0.36 inches. So everything within 3/10 of 1 inch would be in focus (depth wise).

Going to f2.8 the depth of field would be 0.96 inches - or almost a full inch.
f4 provides a dof of 1.32 feet or 15.84 inches

Where I am going with this is, just because you may be able to get a very fast lens like a f1.2 does not mean that it may be useful to you. Think of it this way - Your going to photograph a model wearing a blouse. Focusing of a button on the front, at a f1.2 aperature, would have the button in focus with everything 3/10 of an inch of depth in focus also. However, by the time your eye rolls back to the model's sholder, which may be about 4 to 5 inches behind the button, it would all be out of focus. That would mean all of the collar detail would be fuzzy too. To bring it into focus, you would have to adjust the f stop to about f3.4 to have sufficient depth of field to have the model wearing your blouse in focus - unless your selling buttons.

So lets say you can find a 200mm f1.8 lens for $6000, and a 200mm f2.8 for $1000, would the $5000 difference actually be useful for your endeveour? Also, the f1.8 lens (all by itself) weighs 6.6 pounds (and it does not fit on a Pentax body - its a Canon lens). So lets say that the lens is 6.6 pounds with the camera body weighing in at a pound with the flash at 1/2 pound - so your at 8 pounds now.

The f2.8 lens is still 1.8 pounds (its a Pentax lens by the way and brand new and suppose to be quite good - its one of Pentax's new professional * lenses).

If the clothing is moving - the model is walking, then you will need a fairly fast shutter speed, so the motion will not blur the image. That requires good light. If the model is standing still, then you can use a slower shutter speed and less light or a larger f stop.

Same example - If the clothing is moving - the model is walking, with dim lighting, you can use a high ISO speed, like 1600, but the image takes on a grainey effect, that might mask the details of your material. Or you could slow down your shutter speed, or have the model sit in good light.

Good high quality lenses do help, however they are just one part (a very important part) of the overall set of variables you need to control for good images.

The bottom line is that there are a lot of factors that compensate of not having a lot of light - low f stop lens, slower shutter speed, higher ISO speeds, subjects not moving, and / or very good lighting. Also, the texture and color of the subject - if you want or need great images of the fine detailing, texture of the material, etc, then your problems just mount (especially if the clothes are on a model who is moving).

Also prime lens (not zoom) are usually very good, very sharp and very useful for this type of application. Zoom lenses are good if you need to quickly adjust the focal length on the fly to frame the image. I would suspect that a prime lens wouid probably be best for your application.

All that I am trying to say is that a quality lens can have a wide range of attributes. What is most important to you is that thoes attributes work for you and the uses that you apply the lens to.

Hope that helps...
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Old May 3, 2008, 10:28 PM   #3
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I hope that Daniel will chime in here - he's done some shooting of fashion shows pretty successfully and can tell you which lenses he's found useful.

As far as your questions about f stops - a lens that has a smaller number for aperture doesn't necessarily mean that it is a "better" lens. It does mean that its a "faster" lens which means you can use faster shutter speeds for low light conditions. For example, I have a couple of manual lenses - the M 50mm 1.7 and the M 50mm 1.4. The 1.7 was the lens that came with my film camera in 1980, while the 1.4 lens was bought the following year by my father. In my opinion, the 1.4 is way too soft wide open (at 1.4) to use, while the 1.7 is much sharper wide open. Both are equal when stopped down a bit. Since I mostly use the lens wide open, the 1.7 is better to me. However, the 1.4 sells for a premium, so I guess I'm in the minority (as an aside, Pentax changed the optics on their 50mm 1.4 lenses when they came out with a later version, so the current FA 1.4 is better than mine).

A faster lens has to be larger so that it can let in more light. That means it is larger and heavier, which might not be desirable for someone who's backpacking. You'll always pay a premium for a fast lens also, because it costs more to produce. A 1.8 lens can be used in more places (i.e., indoors in lower light at higher shutter speeds) than a 3.5 lens. It doesn't mean that the 1.8 lens would be sharper than the 3.5 lens - it all depends on the lens.

The advantage to a fast lens for you is that you don't have to use a 200mm lens to get that small dof that you want (where you separate the subject from the background. You can use a 50mm 1.4 or a 77mm 1.8 and be able to stand closer to the subject and still have a small DOF.
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Old May 4, 2008, 12:32 AM   #4
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Wow, thanks for the detailed information. I am familiar with Benjiman, from Montreal now living in Paris. (Lucky dog). I've seen some of his photos using both the 40mm limited, one of the more afforable lenses of the primes, and the 16-50 quite a bit pricer.
Most of my shots will be in a controlled environment wherein I can use my external flash and a tripod. I thought perhaps that the 40mm, 77mm or a 50 prime would work well for those shots. Not sure which though. Can't afford them all. On the runway where models will be in motion, its also a dimmer light situation. My 200mm (which I love) is an old lens and must be used all manually.
For that reason alone I think I'd rather have a newer Af lens that can change rapidly, but still work in low light. The ceilings are often high in that situation as well so there is limited opportunity for bounce. I just don't want to waste money on so so glass. I really do like photography and now that its digital I can afford to develop my interest further.
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Old May 4, 2008, 12:36 AM   #5
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Ah, so fast does not refer to the speed of the focus but the shutter speed. That's helpful understanding. I noticed that the lower aperature rated lenses were more costly, your information really helps clarify why. Thanks. Now I know I can get a 2.8 and get the job done with out paying a gazillion dollars on the lens.
You rock, as do your photos!
Thanks,
X
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Old May 4, 2008, 4:30 AM   #6
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Just an additional remark. The faster lenses are more expensive to manufacture, they require more glass and glass of higher quality to give acceptable results when used wide open. Thus, being more expensive, they are sold to professionals and "serious amateurs" who are prepared to pay the premium. But these buyers are also more demanding when it comes to overall quality, so the fast lenses usually have a very good build quality and durability too, making them even more expensive.

Myself I consider the lenses to be the investment, and the camera bodies to be disposableaccessories. The camera gets outdated and worn, the lenses last for a lifetime.But I've also been lucky to find some of these top quality fast lenses on the used market at very favourable prices.

Kjell


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Old May 4, 2008, 5:32 PM   #7
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I've taken a few pictures with a 77 Limited (thanks to a Pentax rep who was at my local camera store). It's a fabulous lens, I'd love to have one and I think it would be excellent for runway pictures. It might be long in confined spaces, but it's a wonderful lens and well worth the cost. As you can tell, I'm hoping that some day I'll be able to buy one.
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Old May 6, 2008, 6:05 AM   #8
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mtngal wrote:
Quote:
I hope that Daniel will chime in here - he's done some shooting of fashion shows pretty successfully and can tell you which lenses he's found useful.
interested_observer is right about the thin DoF. All my earlier fashion/portrait were mainly done with Fa135mm. I normally use F4.
No chance to give the new DA*200mmF2.8 a good workout yet. But I would guess light or the lack thereof would be an issue

Quote:

As far as your questions about f stops - a lens that has a smaller number for aperture doesn't necessarily mean that it is a "better" lens.*
In order to make a lens faster, the only option is to use better optics - a recipe for a better lens. Period. It may not take better picture which is the job of the photographer.
Yet because of the thin DoF, I would rather use F3.5 or F4 to achieve 90% of the sharpness (a trademark for all great lenses) for the subject.

But sharpness is not the only criteria. Here is a test snap shot from my daughter at 200mm and F4. Would you call the background part of a painting or a digital image?



Daniel
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Old May 7, 2008, 8:57 AM   #9
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When shooting fashion, you'll definitly need a good flash.

I'd recommend the Sigma 530 DG Super (not the ST, for fashion, go for the advanced model) or the Pentax AF540, depending on your budget.

As for a lens, either a good prime will do, or a f2.8 zoom. (I find a 28-70mm f2.8 from Sigma or Tamron very useful + it's affordable)

I always look for samples here when looking for a lens:http://pbase.com/cameras


As for your questions about the basic technicalities of photography, see this free online photography course: http://www.morguefile.com/archive/classroom.php
Lesson 2 is very helpful

Tom
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