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10-03-2012, 03:59 PM   #31
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Here are some answers to some questions asked and a bit more of what I am thinking...again this is based loosely on experimentation and experience and sheer trial and error.

I mainly shoot with zooms. 90% of the time its a zoom on my camera. I did this on purpose so I could get a 'feel' for the different focal lengths and so forth and have quick, easy access on the fly. My school of thinking is that if I 'think' I can learn about primes by using zooms...I just have to pay attention to details.

I bought some manual primes that are all 50mm except one and that one is 28mm A series. The 50mm ones are what I call my 'creative lenses or so I like to think...I can play with the DOF and so forth with those lenses and create effects that I can't do with a lens with a limited aperture.

Walking around though I found that for my tastes and preferences a 50mm isn't wide enough for me. Sheer personal preference. I took my 28mm and did 'street photography' so to speak with it (not real street photography because where I live is sparsely populated)...but I went into some small nearly abandoned Texas towns and actually wound up with some of my best shots ever using a lens I rarely use. Even that though wasn't wide enough for me but I actually really enjoyed myself leaving the house with only one lens and that's it.

Whoever it was that mentioned the 'way your eye sees things' or 'closest to the natural eye'... that seems to me to be right up my alley. I have to look back and see which one that is, but I think they said 21mm...

Here is further questions... my 28mm is built for a full frame camera and hence it gets 'cropped'...the real angle of view on the thing isn't really that wide on my K-5 because it gets cropped.

Now keeping that in mind, there are a bunch of these lenses that are built for crop sensors. For kicks and giggles lets have a mythical full frame 28mm lens...and a 28mm lens built for a crop camera. In theory would the angle of view be different seeing how the lens built for a crop camera is actually different dimensions and so forth? Would I realistically get a wider angle of view out of the crop designed prime vs the full frame designed prime?

Is anyone understanding my question here? I truly have no idea.

Right now my 'feeling' is my choice is between a 15mm and a 21mm...is that 'same as the natural eye' field of view mean one eye or both eyes? I would like to have a lens that is intuitive if that makes sense.

I also know that some of the wide wide ultra wide lenses have distortion on the edges...its almost like they are trying to bend the light to fit on that sensor and it bends things that should be straight or makes them slanted or whatever...

I do not have any crop designed primes. Nothing. All I have is the older manual ones which of course do their job. I don't hate my 50's....sometimes I love my 50's...it all depends on the job to be done.

I am thinking of a prime lens, with AF, where it is untutive...it needs to be wider than my A series 28mm (I have no idea what the real angle of view is on that with a crop sensor for the K-5)....I don't want it so wide that its un natural or that it has edge distortion.

After typing all this I am thinking 21mm, but that is just a guess. And since said lens will be 'free' (to me) in the form of a santa clause gift I am trying to think outside of what I already have. I really enjoyed shooting with that 28mm prime, but it wasn't wide enough...and it also didn't have AF...

All that said the 15mm would be good too...Who knows.... I am thinking this all through. Maybe they buy me one and I buy me the other...


Last edited by alamo5000; 10-03-2012 at 04:13 PM.
10-03-2012, 05:53 PM   #32
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QuoteOriginally posted by alamo5000:
Whoever it was that mentioned the 'way your eye sees things' or 'closest to the natural eye'... that seems to me to be right up my alley. I have to look back and see which one that is, but I think they said 21mm...
Yep. That would be me.
QuoteOriginally posted by Sandy Hancock Quote
I would suggest the DA21 as your first wide angle limited prime; it's smaller, faster, and not *too* wide. Its angle of view matches what I see with the naked eye very well, so it's intuitive to use. When I look at shots taken with my 16-50, I'm frequently struck by how many are taken at exactly 21mm.
As for your question about full frame vs crop sensor lenses of the same focal length you'll get pretty much identical results with an APS-C camera.
10-03-2012, 09:17 PM   #33
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QuoteOriginally posted by alamo5000 Quote
For kicks and giggles lets have a mythical full frame 28mm lens...and a 28mm lens built for a crop camera. In theory would the angle of view be different seeing how the lens built for a crop camera is actually different dimensions and so forth? Would I realistically get a wider angle of view out of the crop designed prime vs the full frame designed prime?
No, they would both give you the same AOV on a cropped sensor. A crop designed prime would just produce a smaller image circle ("cropped", if you want).

If you want to sample the best optics made by Pentax, try the FA Limiteds. The FA 31 is arguably the best lens Pentax has produced. Others may swear on the FA 77 or the FA 43.

If you want a specific focal length, then your choices will become simpler because Pentax doesn't have much redundancy in their lineup.
10-03-2012, 11:36 PM   #34
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QuoteOriginally posted by alamo5000 Quote
Would I realistically get a wider angle of view out of the crop designed prime vs the full frame designed prime?
No, as others have said, the focal length is the focal length whatever the age or design of the lens. If you were to compare the AOV of the new DA 50 1.8 vs. one of your old manual 50s, it would be identical.
Now, as for your choice between both lenses: both are Limited, great lenses. If you want to get a sense of what 21mm will give you, stick some tape on your Tamron 17-50 at 21mm and use it exclusively like this for a day or week (I'm serious, I did this before)... Now for the 15mm it's trickier, you're gonna have to 'imagine' that your 17mm is a little bit wider (don't try to replicate the FL with your fisheye zoom though, since it's a fisheye it won't deliver the same FOV). Also, go browse some pictures (here or on the PPG) and see which one give you the effects you like!
Also,
QuoteOriginally posted by Just1MoreDave Quote
I wouldn't get both the DA15/4 and DA21/3.2 at the same time. I would be caught up in the choice between them rather than getting comfortable with one focal length
I agree with that. Leave yourself a feww weeks (or months) between each purchase to really get comfortable with your new toys

10-04-2012, 01:42 PM   #35
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QuoteOriginally posted by Sandy Hancock Quote
Now pick my daughter and which role she plays
She's the blonde in the middle of the front row with her hair down.
10-04-2012, 02:56 PM   #36
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I find the DA Ltds (I have the 15, 21, 40) to be somewhat sterile but very accurate. Same with the DFA100. The FA31 (the only FA that I have) seems to convey more emotion, which may or may not be real or even important. It is certainly expensive. DA*55 is one of my favorites but you already have the 50.

The thing is, all the DA Ltds and FA Ltds have their own "personality" so it is difficult to recommend one type versus another.

But since you seem to be leaning towards the DA21, I can go along with that. It is a very versatile focal length. It isn't especially fast at f/3.2, but usually fast enough. The lens cap and lens hood makes for a compact, fun, neat little package. ( <-- That is not a snide remark, anyone who has the 21 would agree, and once you get one you will agree too.)
10-04-2012, 04:50 PM   #37
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QuoteOriginally posted by DSims Quote
She's the blonde in the middle of the front row with her hair down.
Bzzzzz! Thanks for playing.
Redhead. Towards the rear, in the middle. Eponine.
10-04-2012, 05:17 PM   #38
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QuoteOriginally posted by Sandy Hancock Quote
Bzzzzz! Thanks for playing.
Redhead. Towards the rear, in the middle. Eponine.
One row farther back than I even looked, but she does look comfortable with the photographer. Is she the one singing Little he knows... ?

10-04-2012, 05:41 PM   #39
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QuoteOriginally posted by alamo5000 Quote
I am thinking of a prime lens, with AF, where it is untutive...it needs to be wider than my A series 28mm (I have no idea what the real angle of view is on that with a crop sensor for the K-5)....I don't want it so wide that its un natural or that it has edge distortion.

After typing all this I am thinking 21mm, but that is just a guess. And since said lens will be 'free' (to me) in the form of a santa clause gift I am trying to think outside of what I already have. I really enjoyed shooting with that 28mm prime, but it wasn't wide enough...and it also didn't have AF...

All that said the 15mm would be good too...Who knows.... I am thinking this all through. Maybe they buy me one and I buy me the other...
You should go out one day with only your kit lens set on 21mm. Then you'll see if you are happy the focal length, or if you need wider.
10-04-2012, 06:22 PM - 1 Like   #40
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QuoteOriginally posted by DSims Quote
Is she the one singing Little he knows... ?
Yes. And, more importantly, "On My Own" and "Little Fall Of Rain".

Now back to our regular programming
10-04-2012, 06:25 PM   #41
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QuoteOriginally posted by alamo5000 Quote
Now keeping that in mind, there are a bunch of these lenses that are built for crop sensors. For kicks and giggles lets have a mythical full frame 28mm lens...and a 28mm lens built for a crop camera. In theory would the angle of view be different seeing how the lens built for a crop camera is actually different dimensions and so forth?
As mentioned, no. 28mm is 28mm. All 28mm lenses produce the same AOV. The "crop factor" is a function of the *camera*, not of the lens.

QuoteQuote:
Right now my 'feeling' is my choice is between a 15mm and a 21mm...is that 'same as the natural eye' field of view mean one eye or both eyes?
You can check this yourself with your existing zoom. What you'll find is that even at the very widest end, your two eyes together can easily see a wider field of view. One eye alone - I don't know, that might be around 21mm. Again, you can check this yourself. Just don't make the mistake of judging by the *size* of objects in the viewfinder. People looking at your pictures won't be looking through your viewfinder - the size of object in the viewfinder is irrelevant. It's all about angle of view. 15mm actually is pretty close to the angle of view of human vision, at least if you allow for peripheral vision.

QuoteQuote:
I would like to have a lens that is intuitive if that makes sense
That's a *totally* different question. We're good at ignoring a good chunk of what we see with our eyes. In a photograph, not so much. So while there is something "natural" about the angle of view of a 15mm lens, it may be *far* wider than what you personally find "intuitive". Again, you already own a zoom; you can decide for yourself what angles of view appeal to you.

QuoteQuote:
I also know that some of the wide wide ultra wide lenses have distortion on the edges...its almost like they are trying to bend the light to fit on that sensor and it bends things that should be straight or makes them slanted or whatever...
No. It has nothing to do with bending light. It's quite simple you are taking something wider than the piece of paper you are printing on and trying to squeeze it onto a sheet of paper that is too narrow, This creates an optical illusion we perceive as distortion. happens just as surely if you draw the scene with a pencil as with any photographic lens. If you want to look natural when printed, that's yet another question. In that case, it all comes down to how large you plan on printing and from how far away you plan on viewing it. But FWIW, somewhere around 28mm gives this effect - again, doesn't matter if it is designed for a crop body or not.
10-04-2012, 07:03 PM   #42
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Look up Thomas Bojer Eltorp, user name Duplo both here and on dpreview.com. Although he shoots a lot of other lenses and I believe FF Nikon professionally, the DA21 is one of his favorite lenses and I like his shots from it. If I ever get that lens, it'll be because of him.
10-04-2012, 08:18 PM   #43
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So let's keep this relatively simple. The Pentax APS-C crop factor compared to 35mm film is 1.53x.

So for example, your 50mm on your K-5 has an angle of view similar to a 77mm lens on film. This is a short-ish portrait length.

Your 28mm is equivalent to a 43mm lens on film. This is a short-ish normal length.

For something noticeably wider I'd go for anything in the 15-24mm range. Some choices:

Pentax DA 15/4 Limited
Tokina AT-X 17/3.5
Sigma EX 20/1.8 macro
Pentax FA 20/2.8
Pentax DA 21/3.2 Limited
Sigma EX 24/1.8 macro
Pentax FA* 24/2
Sigma 24/2.8 Super Wide II

They're all in the reviews database. The ones that I think stand out are:

SMC Pentax-DA 15mm F4 ED AL Limited Reviews - DA Prime Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-FA 20mm F2.8 Reviews - FA Prime Lenses - Pentax Lens Reviews & Lens Database
SMC Pentax-DA 21mm F3.2 Limited Reviews - DA Prime Lenses - Pentax Lens Reviews & Lens Database
Sigma 24mm f/2.8 AF Super Wide II Lens Reviews - Sigma Lenses - Pentax Lens Review Database
10-05-2012, 01:03 AM   #44
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I highly recommend the 21mm it is a great wide angle street shooter, and a great start point for getting into primes.

It was for me anyway, and now after obtaining a slew of other good quality prime lenses the 21 is still my go to lens that lives on my camera until I require something else
10-06-2012, 05:23 AM   #45
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QuoteOriginally posted by GnipGnop Quote
You're mistaken on the kit lens. It's actually a great performer, especially given the price. Don't confuse prestige with great picture recording ability.
I'll second this. The Pentax kit zoom is just too good for its price and the materials from which a person knows the internals are fashioned. It even has a nice feel about it.

One thought for the OP is why not just take a rain check here by not buying any lenses right now. I have a couple of lenses I purchased with good intentions only to ask later what I was thinking. Not that there is anything wrong with that but the best lens purchase is the lens you're absolutely certain you need and want. Don't overlook other possibilities such as a high quality tripod if you should need one or a set of multicoated filters. A graduated ND filter is a beautiful thing.
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