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04-04-2009, 05:18 PM   #1
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Portrait Lens questions

I am thinking of adding either the Pentax 50mm or 55mm lens. I am somewhat new to this dlsr stuff, but pretty ok on basic optical theory and Photoshop.

I have read a bunch of helpful information on here and elsewhere about whether the 50mm primes are really true 75-80mm primes due to the crop factor. I originally figured the crop did not affect the telephoto compression and narrowing effect of telephoto lenses and I know there is a lot of discussion on this topic. Most of what I read supported this. I read something today, though, in Popular Photography which muddied the water a bit. Maybe the source is a problem. Nonetheless, it seemed reasonably based.

I guess what I really am asking is whether those that have the 50mm, or perhaps the new 55mm, really use it as much as you had anticipated for portrait work at 1.4 through the low f/2s for the shallow depth of field effects or whether you tend to use true telephoto zooms. I have the 16-50 and 50-135 and really like the 50-135. At 2.8 it is very good for portrait work in terms of clarity, but I wonder about the utility of having a 1.4 lens.

I know there is a big price difference between the 50mm and new 55mm, but the few reviews of the 55mm which I have read all say it is excellent and a wonderful lens (except for the slow auto focusing).

So, I was just looking for feedback from people who do portrait work as to whether the 50mm or 55mm is used by them and whether you feel these are still slightly too wide and can prove unflattering for portrait work. There is not much out there in the 85mm range, except for an Opteka 85mm 1.4. My sense is that it only would be mediocre in quality, but there is not much info on it.

Thanx so much in advance.

Gregg

04-04-2009, 05:27 PM   #2
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The few portraits I have taken, I used the 50-135. I think what Pop Photo was trying to say was that with the crop factor, you will have to be further from the subject to get him/her in the frame, by the same 50%. Perspective is affected solely by the distance from the subject, not by th focal length, so in a sense PP is correct. The additional distance is what will affect the perspective.
04-04-2009, 06:27 PM   #3
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I guess to me, the DA* 50-135 is my favorite portrait lens. I have the Fa 50 as well. I happen not to like the style of portraiture where most of the suject is out of focus. If you were to take a photo with f1.4, your depth of field is so narrow that only part of your subject is sharp. An aperture of 2.8 seems to be adaquate to give good separation from the background without having the subject be a blur as well.

I know people say to zoom with your feet, but in particular with kids, having a zoom on your camera sure comes in handy.
04-04-2009, 10:00 PM   #4
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if you are asking about focal length for portrait

I have the Fa 50 and my 55m helios-44 and the 85mm jupiter 9

I like the 55 a little better than the 50 for face shots, and I like the 85 mm for head and shoulder shots... =

If it is for indoor shots where room size is an issue the FA 35 is a good lens too

My most used lens for portraits until very recently was my Tamron 28-75... and I found most of my shot were at the long end 75mm...
I just picked up two MF 135 2.8 lenses that are pretty nice portrait shooters if you have the room.


But between the two you are asking about... tough choice. The FA 50 is a nice portrait lens and the ability to drop down to 1.4 or F2 comes in very handy sometimes. The DA 55 is really sharp and may not be the most flattering to some skin types but it looks to be a great little macro shooter too...
Tough choice...

But if I had the money or was just starting out... The DA 50-135 is the lens that would be in my bag in a heartbeat.

04-05-2009, 06:42 AM   #5
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Not being a zoom lover, but being on the perpetual search for the ultimate portrait lens....
I have just about every 50mm lens Pentax has ever made, as well as the new 55/1.4 and also the Voigtlander 58/1.4.
In theory, these are all giving more or less the same field of view on the small format DSLR as an ~85mm lens would on 35mm film.
Interstingly, I find them all quite a bit too short, even though on 35mm I found the 85mm to be almost perfect.
Go figure.
The DA55/1.4 is as sharp a lens as a person could hope for, and it is sharp from f/1.4 right through the range.
I haven't compared it directly to the FA50/1.4, so I don't know if it is sharper/contrastier, or by how much.
My feeling is that it is somewhat sharper at wider apertures.
One thing with the 55 is, as mentioned, the AF is very lazy, but to it's credit, it doesn't hunt.
Havin said that, it's slow enough that manual focus is a viable option.
I think that right now, of all the lenses I use for portraiture, the A*85/1.4 is still my overall favourite, but it is rather long for full length pictures.
If you have money to burn, then look at the DA*55/1.4. It is a pretty incredible piece of glass.
If you are on a bit of a budget, then look at the FA50/1.4 while it is still available, or the Voigtlander 58/1.4.
Of the two, I'd go with the Voigtlander unless AF is more important to you.
Another lens that has served me very well in the studio is the 70mm f/2.4.
It is quite a bit nicer for close in head shots than the shorter lenses in the 50mm range, and is still short enough for half length and full length providing you have a reasonably deep studio.

One thing I like about primes over zooms is viewfinder brightness when shooting under modelling lights. The extra couple of stops from f/1.4 to f/2.8 makes a huge difference to the brightness of the focusing screen, and even the half stop from 2.4 (the DA70) to 2.8 is noticable.
If you shoot in sunlight this probably won't be an issue.
04-05-2009, 08:07 AM   #6
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Check out this thread on the lens section: https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/54845-portrait-lens-2.html
04-05-2009, 08:43 AM   #7
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QuoteOriginally posted by lawjbm Quote
I have read a bunch of helpful information on here and elsewhere about whether the 50mm primes are really true 75-80mm primes due to the crop factor. I originally figured the crop did not affect the telephoto compression and narrowing effect of telephoto lenses and I know there is a lot of discussion on this topic.
Anything you read that led you to believe focal length has any effect whatsoever on perspective is quite simply wrong. It's a common misconception, so lots of people repeat it, but it's just wrong. The laws of physics don't change just because someone made a camera with a smaller sensor than they did before. Perspective has always been determined by distance to subject and distance to subject *only*. That was true when the effect was first sudied seriousl 500 years ago, and it remains true today.

To state it as plainly as possible: a 50mm lens on APS-C has *exactly* the same perspective as a 75mm lens on FF. If you shoot both form the same distance, there will be no difference whatsoever in the photos in terms of FOV or perspective. Only DOF might differ, depending on aperture. In fact, you could shoot with a 21mm lens from the same position, crop it in Photoshop to give the same FOV, and also not be able to tell the difference in terms of perspective - as long as distance to subject remains constant, so does perspective.

QuoteQuote:
I guess what I really am asking is whether those that have the 50mm, or perhaps the new 55mm, really use it as much as you had anticipated for portrait work at 1.4 through the low f/2s for the shallow depth of field effects or whether you tend to use true telephoto zooms.
I don't do a lot of portraits, but when I do, I find that 50mm on APS-C is still too wide for my tastes - it forces me to either take in too much of the surroundings or else get too close to the subject for my liking (in terms of both perspective and comfort level). I also have a 100mm lens I like, but it's good mostly for very tight portraits. The DA70 seems pretty much perfect to me. Of course, a zoom gives you that much more flexibility.

QuoteQuote:
There is not much out there in the 85mm range, except for an Opteka 85mm 1.4. My sense is that it only would be mediocre in quality, but there is not much info on it.
There's any number of used 85mm lenses. available. Also the DA70 and FA77 are reasonably close to tha focal length. But of course, with any of these, the FOV is far narrower than on FF, so if you're looking to recreate the effect of an 85mm lens on 35mm film, stik with the DA*55.
04-05-2009, 12:16 PM   #8
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QuoteOriginally posted by Wheatfield Quote
I have just about every 50mm lens Pentax has ever made, as well as the new 55/1.4 and also the Voigtlander 58/1.4.
With this experience I wonder if you have any feeling for the K50/1.2 compared with the DA*55/1.4. I would like the occasional use of AF and the use of Av setting, plus weather sealing is a bonus. But I'm somehow doubting any lens could be this good.

04-05-2009, 01:59 PM   #9
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I think of buying a Portrait-lens, too! Probably, it will be the DA 70/2,4 Limited. It´s quality over quantity.

André.
04-05-2009, 02:06 PM   #10
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dfa100 f2,8.although its for macro but it does agreat job in portrait,i like it in portrait more than in macro issues.
04-06-2009, 03:54 PM   #11
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Lots of good advice above. Here's my 2 cents worth.

Pride of place in the portrait field has traditionally gone to lenses in the focal length of roughly 50 to100mm. This is just a rule of thumb of course but a good one. My personal preference is to select a prime lens as they are almost always faster and sharper. Don't flame me zoom users it is just a personal preference but I digress. Many feel that these focal lengths provide enough room from the subject to put them at ease while pleasantly rendering the features. They argue in order to take appealing portraits, you want a lens that's going to represent the human face as it actually appears to the naked eye.

For that reason we are often advised to avoid wide-angle lenses (10-18mm) as they make subjects look like they're in a fishbowl. They make the nose overly large and the make the ears appear tiny. There is no reason you can’t use them for special effect portraits from time to time.

Telephoto lenses (200mm +) compress space. While this is not as unappealing as the wide-angle effect it can "flatten" a face so that it's not as three-dimensional as it appears with a shorter lens. Personally I have the DA 70/2.4 and it is my go to “portrait lens.” On the other hand I often use my 200/2.5 for portraits lens when I want a different look or catch someone unawares.

I don’t think you can go far wrong starting in the 50 to 100mm range to start your portrait work. There is lots of scope for exploration here and you can branch out later if you want to. Have fun!

Tom G

Last edited by 8540tomg; 04-06-2009 at 04:20 PM. Reason: typo
04-07-2009, 03:49 AM   #12
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At the risk of seeming trite: use whatever lens(es) work for you. Different lenses work well at different distances and angles, mostly disregarding the format size.

DOF depends entirely on focal length, aperture, and distance at which the lens is focused. Period. Format is irrelevant. Shorter and/or slower lenses will always have more DOF, and longer and/or faster lenses will always have less DOF, whether they're on 110, APS-C / HF, 35mm / FF, MF, whatever.

Don't confuse FOV or crop factor with DOF. Consider a 50/1.4 lens, wide open: on a 1/1.8" PNS CCD, it's a long tele. On APS-C, it's a short tele. On 35 FF, it's 'normal'. On a 6x6 MF, it's medium-wide. On a 4x5" LF, it's ultra-wide. But it always has the same shallow DOF when focused on a subject the same distance from the lens.

So, no matter what camera it's mounted on, no matter the crop factor, a 50/2 has shallower DOF than a 35/2; an 85/2 has shallower DOF than a 58/2; a 135/2.8 has shallower DOF than a 90/2.8; et cetera, even though the FOVs of those lens pairs are just the same. Depth of field - Wikipedia, the free encyclopedia gives the exact formulae for determining DOF.

But what it comes down to is, choose the lens that has the DOF you want, and that puts you at whatever distance from the subject that you're both comfortable with.

EDIT: Oh yeah, what lenses do *I* use on my K20D? Vivitar 24/2, Pentax-M 28/2.8 for full-body; FA 50/1.4, Helios-44 58/2 for H&S; Jupiter-9 85/2, Takumar 135/2.5 for heads; Vivitar 200/3.5, Jupiter-21M 200/4 for further. Pentax-M 40-80/2.8-4, Vivitar-S1 70-200/3.5 for flexibility. Sometimes Takumar 55/1.8, Nikkor 85/2, Meyer 100/2.8, Hanimex 135/2.8, Enna 240/4.5 for difference. Whatever works.

Last edited by RioRico; 04-07-2009 at 04:25 AM. Reason: addendum
04-07-2009, 08:42 AM   #13
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Will written, RioRico. I will add one parameter to your list, however. Depth of field is also dependent on the degree of enlargement. Most DOF calculations on film were written with the 8x10 print in mind, and are based upon the size of the "circle of confusion" - the amount of blur.

So, you print at 8x10 inches, and have the depth of field that you prefer. Enlarge that same print to 16x20 and the depth of field will appear much shallower, when viewed from the same distance from the print. Viewing the 16x20 from a more distant viewpoint will return the depth of field to the preferred level.

Complicated, ain't it?
04-07-2009, 11:38 PM   #14
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QuoteOriginally posted by Canada_Rockies Quote
Complicated, ain't it?
If it was easy, everybody would do it. Ya, viewing distance and circle-of-confusion size are factors. Except for an f/64 8x10" contact print, some fuzziness will show up eventually, if an image is enlarged enough. The way around that is, print small, force viewers to close in on the image, and the c-o-c's will be nearly microscopic. I may dig up a 6x9 cm folder (I think I have an old Kodak somewhere, as well as the pano pinhole my sister gave me) and go back to contact printing, the pix to be hung in wide matted frames, just for this stealthy purpose. IMHO big prints should be behind guard rails, to prevent too-close approaches.
04-08-2009, 04:34 AM   #15
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Thanx so much

Thanx so much for your detailed responses. I have been busy with work and unable to respond. I did not want anyone to think I did not appreciate all of your help.

I have been slowly building my small home studio and have been going back and forth about getting the DA* 55mm. My sense is that I will wait a bit. I am tempted by the 85mm 1.4 Vivitar lens that is branded under several other names.

In any event my hope is to post some pictures soon with my new equipment. I would like to do some low light portrait work with my family and friends and see how all my gear performs. Like many others I am sure, work has been very busy.

Thanx so much again.

Gregg
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