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01-23-2011, 04:55 AM   #16
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FA 50/1.4 performs remarkably well in terms of autofocus speed, particularly in low-light conditions, bokeh and sharpness after f/2. Since the FA 77 ltd hasn't yet been mentioned I thought it too should be considered as a fantastic portraiture option, only it can be a little long and require a decent working distance. Nevertheless, it ticks all the boxes except for affordability.

What may be within your price range is the FA 43 ltd - OK it's 'only' f/1.9 but it is a remarkable performer in every facet, even in autofocus IMO. Be tempted here: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/116799-ive-bee...-43mm-ltd.html

With a lower budget, you probably couldn't get better than an FA 50/1.4 or 1.7 - so a number of choices there, of which I don't think you'll go wrong.

01-23-2011, 05:44 AM   #17
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Autofocus may not help as much as you think for low light portraits, etc.

A full-face portrait with a 50mm lens (ie. the frame is 1.5' high) requires that you be 3.33' from the subject. At this distance and f:1.7 the depth of field is 1". See: Online Depth of Field Calculator

Unless your camera automatically selects eyes to focus on, you'll get a variety of focus locations and most will appear to be out of focus.

Besides, 50mm is a little short for tight portraits; think 70-100mm Here's an out-of-the-camera jpeg low light example at f:1.4 taken with a $250 manual focus Rokinon 85:1.4 (with a 100% crop to show detail).


The photo was taken at a Dining Room table using a K100D with an ebay split-prism finder.

Dave

PS an alternative for low-light photography is to buy a new camera body so you can crank up the ISO to avoid too-shallow DOF's (each doubling of ISO is equivalent to one f-stop.)

Last edited by newarts; 01-23-2011 at 05:59 AM.
01-23-2011, 09:02 AM   #18
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Metalwizards, you already have a near-perfect portrait lens: the M 1:1.7/50...

As Mike pointed out, you do not need autofocus, you need the right focusing screen.
Besides, autofocus won't help your portraits... ok, if you miss focus with the M50, the portrait is ruined. Clearly ruined. With an AF lens you might get a sharp picture, but... no good picture. Focus in portraits is commonly set on the eyes (though there are georgeous pictures in which this ruke has been violated, but then it has been done so willingly and purposefully). AF will focus on anything suitable - an in most cases, this will NOT be the eyes.
So AF might reduce the number of "junk" pictures, but will not improve the number of "good" ones.

I am still hestitating to buy the KatzEye, as I am eager to upgrade the camera... I think I will be able to somehow cope with the k200s catastrophic viewfinder until I will eventually be able to afford a k5. :-)

Last edited by turboseize; 01-25-2011 at 12:42 PM.
01-23-2011, 11:19 AM - 5 Likes   #19
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QuoteOriginally posted by Metalwizards Quote
What lens would you choose if you were me? .............
Steve Eastwood posted a suberb series that shows the effect of focal length on portrait perspective for a full frame camera: see Stephen Eastwood|Beauty and Fashion Photographer | Tutorials



The above were taken with a full-frame camera, to have the same perspective you should be at the same distance from the subject; this implies dividing by the crop factor for your camera (or multiplying by 2/3 for a Pentax; ie your uncropped 67mm portrait's perspective will look like Eastwood's uncropped 100mm portrait's perspective.)

Dave


Last edited by newarts; 01-23-2011 at 11:40 AM.
01-23-2011, 11:49 AM   #20
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QuoteOriginally posted by newarts Quote
The above were taken with a full-frame camera, to have the same perspective you should be at the same distance from the subject; this implies dividing by the crop factor for your camera (or multiplying by 2/3 for a Pentax.)
That's an excellent reference (and I hit your rep for it) and it's fairly applicable to APS-C cams. The formatfaktor changes the angle of view, but not the perspective, which is solely a function of lens-to-subject distance. If I wasn't so lazy, I'd shoot a similar series with a DA18-250 on my K20D. Is anybody here energetic enough for this?

But this does suggest the distortion from doing tight head shots with a 50mm lens. IMHO 35mm and shorter are for full-body or group shots; 50mm is great for head+torso shots; 75-90mm is about the minimum for tight head shots, with 120-135mm for a not-so-tight working distance. Longer lenses require a bigger studio, yup!
01-23-2011, 09:52 PM   #21
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IMHO, I would look into the DA-L 35mm F2.4. Or the Sigma 30mm F1.4 lens. The Sigma is a full stop faster than the 35mm DAL so keep that in mind. IQ, I just bought the 35mm today actually and haven't really gotten use to it yet but from the reviews the lens is excellent for the money. I'm guessing the 30mm is more expensive. Hence I didn't really look into it.

The 50mm that you suggested are good but in my opinion since you already have the M50 1.7. Why would you want to overlap it. You are only getting AF and newer glass benefits. The M50 1.7 is not in anyway terrible at all. Other than manual focus. And you would get 1/2 a stop more light which is negligible.

Portrait wise the 50 or longer focal length would give you the face shot for sure and upper body. The 35mm you would have to get closer to the subject for that exact same picture.

My choice was the 35mm. To give me more options. I might hazard to throw out there perhaps the 17-50 2.8 from Tamron or was it Sigma that made that lens. Not super fast but it would give you all the ranges and at 2.8 gives decent speed for portraits.
01-24-2011, 01:37 AM   #22
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K-5 Sigma 50mm f/1.4 wide open

01-24-2011, 04:43 PM   #23
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QuoteOriginally posted by creampuff Quote
K-5 Sigma 50mm f/1.4 wide open
Wow very nice shot, impressively thin DOF.

I had considered getting a split prism for manual focusing, but quite frankly I am not sure I want to replace my stock screen for a much darker one. If I ever get a second body I will most def put a split prism on the lesser body. That said while manual focus is great for those used to it, it wouldn't be very useful for me taking photos at music shows and more candid like events that I'll be shooting. I tried shooting with my M 50mm 1.7 at my little brother and sisters b-day party this weekend and I missed every shot I tried to get with it .


I am thinking that the sigma is really the best choice for me at this moment, lets hope it goes on sale or something in the next few weeks.

01-25-2011, 05:36 AM   #24
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QuoteOriginally posted by Metalwizards Quote
Wow very nice shot, impressively thin DOF.

I had considered getting a split prism for manual focusing, but quite frankly I am not sure I want to replace my stock screen for a much darker one.
Where on earth did you get the idea they're "much darker"? Have you ever used one? Or even looked through one?

QuoteQuote:
That said while manual focus is great for those used to it, it wouldn't be very useful for me taking photos at music shows and more candid like events that I'll be shooting. I tried shooting with my M 50mm 1.7 at my little brother and sisters b-day party this weekend and I missed every shot I tried to get with it .
That's like saying, "I tried eating a bowl of soup with a fork, so that's why I know it wouldn't work to eat it with a spoon." The whole point some of us have been trying to make is that the stock screen sucks for manual focus and that the problem is not your lens.

I shoot practically everything manual focus. A couple of months ago I shot a dance event and came away with about 1400 photos. Half were done with manual focus and half were done with autofocus. When I came home I sat down and weeded out the photos that had to be deleted due to missed focus. I deleted two of the manual focus shots and four of the autofocus shots.

It would be very easy to think, "That's because you're so used to manual focus."

But today was the first full day I spent with my brand-new K-5.....which is still waiting for the mailman to bring my split-prism screen, so I spent the whole day trying to manual focus with the stock screen. Know what? I totally sucked and practically every shot I took was useless due to the focus being off.

Think of that.....I went from being a guy who could nail 698 out of 700 manually focused dance shots in a dark hall to being a guy who couldn't even reliably focus on stationary objects in broad daylight. It wasn't my technique or experience that evaporated....it was all due to that godawful stock screen and how utterly useless it is for manually focusing anything.

I totally understand that buying a new lens is sexier than buying a new screen. And I can even sort of understand the thinking that autofocus is a magic bullet that is going to cure everything. It isn't my intent to try to hammer you over the head and force you into changing your screen. I'm just trying to point out that the problem you said needs solving is amply solved by a screen and want you to have the fullest information to work with when deciding what to do.
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