[ckusnierek]

So I got my camera a few weeks ago (k-m) I absolutly Love it!
I have spend the last few weeks shooting in all manual mode while going back and forth with MF/AF. I did this to better learn exposure/aperture and ISO settings. Over the past few weeks I have seen much improvement in my pics.
Currently I have the stock DAL 18-55 which does not seem to take very good pics at all. I also have a Quantaray (Tamaron clone) 70-300/5.7. I love this lens but in close situations I'm restricted by the 70mm focal length.

I was thinking about a 50mm prime. Actually a 50/1.7, nifty fifty as I have read on the net. All reviews say this is a "must have lens".

So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?

And why do they not seem to make a zoom with aperture below 4?

If I go with a 50/1.7? which brand/model?

Thanks!

[sterretje]

So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?

Zoom lenses are always compromises. It's far easier to optimise a prime lens for IQ than a zoom.

And why do they not seem to make a zoom with aperture below 4?

There are. Pentax has 16-50/2.8 and 50-135/2.8; and there are others as well. Before you start asking why not below 2.8, search this forum for that question.

If I go with a 50/1.7? which brand/model?

Check Pentax Lens Review and Specification Database - Main Index and PentaxForums.com Third-Party Lens Review Database - Main Index and search the net for other reviews.

[Ari]

You have a choice of the FA 50 or DA*55 for a 1.4 lens (at least among the Pentax models).
That wide aperture will give you better shooting in low light and give you a very shallow depth of field. It also produces very nice out of focus backgrounds (bokeh). I only carry one prime with me (DA*55) and I think one fast prime lens is an essential part of everyone's kit.
Because you are one of those fortunate to shoot with a Pentax system, you have access to using the world's best family of prime lenses. You should also look at some of the FA ltds. Different focal lenghts, of course, but the 77 is a great portrait length and the 31 is close to 50mm with your sensor's crop factor.

[BethC]

I bought a 50 mm F 1.4 lens and love it! couldn't believe how much sharper the pictures where as compared to the kit lens.

as far as a zoom with a f stop lower than 4...I recently got a Sigma 28-70 mm F 2.8 lens. It's very heavy. I assume a larger focal length would be just too heavy. Although for all I know, they may make them.

OH, should add, my 50 is a Pentax. I really love that lens

[seacapt]

OK first you'll need to decide if 50mm focal lenght works for you. Secondly examine budget. Third decide how comfortable you are manual focussing.
Now the fun stuff. There are a ton of MF 50'ish lenses from various manufacturers at reasonable prices on the used market.
"Nifty Fifty" and "Fast Fifty" are interchangeable terms. These lenses were designed to give a "normal " field of view on a full frame /35mm camera. What makes them cool is the fact that they open up to f1.7 , f1.4 or even f1.2
I own a few old MF fiftyish lenses 50mm-58mm and use them for specific situations , for example I have an old screw mount 55/1.4 that I love for shooting indoors wher flash is not acceptable but in bright sun it has a tendency for blue fringing. Another is a touch on the soft side which makes it ideal for a short portrait lens on a Pentax digital.
Remember if you get an A series (auto appeture) lens you will still have all the metering functions just no auto focus but if you go with the older non A bayonet or screw mounts you'll be pushing "the green button" alot.
All that being said , My personal recomendation for you would be a Pentax A 50/f1.7 or a Pentax A50/f1.4. A nice 1.7 usually sells for around $50 and the 1.4 around $100 on the used market.
Hope this was helpful.
If you are not comfortable with manual focus there were fast 50' made in Pentax's F & FA series.
As far as a fast zoom you might consider the Tamron 17-50mm /f2.8

[hcc]

I was thinking about a 50mm prime. Actually a 50/1.7, nifty fifty as I have read on the net. All reviews say this is a "must have lens".
So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?
And why do they not seem to make a zoom with aperture below 4?
If I go with a 50/1.7? which brand/model?
Thanks!

You already received a lot of good advice. I simply add some comments that may be relevant to your situation.

You cannot compare a zoom lens (eg 18-55 mm) and a prime lens (eg 50 mm). A zoom lens has to compromise between image quality, distortion, .. for the entire focal range. A prime lens is optimised for one focal length and it will give you a much better quality.

Based upon your experience, a 50mm fast prime would be a good choice. A "fast prime" lens has a large aperture (small f) and it can operate well in low-light conditions without a flash. It is also capable of nive pictures at larger f values (smaller aperture). Remember that a good lens is worth it and I encourage you to get the best lens.

There have been a number of discussions on 50mm lenses, including a recent poll at Pentaxforums.com (https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/98436-50mm-ish-portrait-lens.html). A number of Pentaxian experiences have highlighted 4 prime lenses that I would recommend you:
- the Pentax 50mm f1.7,
- the Pentax FA50mm f1.4,
- the Voigtlander Nokton 58mm f1.4, and
- the Carl Zeiss 50mm f1.4.

All 4 lenses are available in Pentax mount, and I enclose below some comments including the URLs of lens reviews at Pentaxforums.com and Photozone.de.

*Pentax 50mm f1.7
An older MF lens, highly regarded. It can be purchased second hand at very reasonable prices. Worth to consider for a small budget.
Pentax Lens Review and Specification Database - SMC Pentax-FA 50mm F1.7

*FA50mm f1.4
A nice AF lens, reasonably priced and well regarded.
Pentax SMC-FA 50mm f/1.4 - Review / Lab Test Report
Pentax Lens Review and Specification Database - SMC Pentax-FA 50mm F1.4

*Voigtlander Nokton 58mm f1.4
A MF lens with a super image quality and superb built quality. Very well priced (same price as FA50mm), very solid and ideal for outdoor shooiting.
Voigtlander Nokton 58mm f/1.4 SL II - Review / Test Report
PentaxForums.com Third-Party Lens Review Database - Voigtlander 58mm f1.4

*Carl Zeiss 50mm f1.4
A MF lens, the Rolls-Royce of the 50mm. Expensive but the reference.
Zeiss Planar ZF T* 50mm f/1.4 - Review / Lab Test Report


Lastly I believe that you will learn a lot of with a MF lens. I would strongly recommend the Pentax 50 mm f1.7 and the Voigtlander 58mm f1.4 that are the best value for money, 2nd hand and new respectively.

Hope that the comments will help....

[northcoastgreg]

So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?

The quality of the glass. Any Pentax 50mm 1.7 lens will produce much sharper images with better color rendition and contrast than the inglorious 18-55. And if you go for one of the older, manual focus 50 1.7's, you can get such lens for less than $70. The great advantage of the so-called "nifty-fifties" is that they constitute the least expensive introduction to high-end glass that you're likely to find. The Pentax 50 1.7's are among the best 50's ever made and are well worth getting to know.

[ckusnierek]

Thanks for all the great info everyone!
I love this forum!

[Marc Sabatella]

I was thinking about a 50mm prime. Actually a 50/1.7, nifty fifty as I have read on the net. All reviews say this is a "must have lens".

50mm lenses used to be must haves, on film cameras, before zooms were invented. They were still one of the first lenses you'd get in addition to a zoom on film, because the focal length was close to "normal" on that format (a complicated subject, but basically, pictures taken at that focal length on film look "normal' when printed at common print sizes and viewed at typical distances for those print sizes.

On digital (APS-C format), 50mm is no longer normal (33mm is), so it's not necessarily still the "must have" it used to be. But since 50mm tend to be the cheapest prime lenses on most systems, it's still a common recommendation. And 50mm is still a potentially useful focal length on APS-C - although for different purposes than it would have been on film.

Rather rely on what someone else tells you is useful to the, use your zoom to tell you what focal lengths are most useful to *you*.

So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?

Maximum aperture is the big, huge, gigantic advantage. Should be sharper too, but that won't matter in practice nearly as much.

And why do they not seem to make a zoom with aperture below 4?

Sure they do. Quite a few f/2.8 zooms out there, from Pentax, Tamron, and Sigma, in a variety of different focallength ranges.

If I go with a 50/1.7? which brand/model

On the assumption that you'd be getting it just because it's the cheapest prime you can get and not because it's actually ll that useful a focal length for you, I'd keep it cheap by going manual focus - the "M" or "A" series 50/1.7. See the many other threads on 50mm lenses in this forum and the lens forum for discussions of the tradeoffs, but basically, "A" lenses give you full autoexposure whereas "M" lenses require "M" exposure mode.

[JeffJS]

So I got my camera a few weeks ago (k-m) I absolutly Love it!
I have spend the last few weeks shooting in all manual mode while going back and forth with MF/AF. I did this to better learn exposure/aperture and ISO settings. Over the past few weeks I have seen much improvement in my pics.
Currently I have the stock DAL 18-55 which does not seem to take very good pics at all. I also have a Quantaray (Tamaron clone) 70-300/5.7. I love this lens but in close situations I'm restricted by the 70mm focal length.

I was thinking about a 50mm prime. Actually a 50/1.7, nifty fifty as I have read on the net. All reviews say this is a "must have lens".

So my question is what is the advantage of a 50mm prime verses a good 18-55 other than aperture?

And why do they not seem to make a zoom with aperture below 4?

If I go with a 50/1.7? which brand/model?

Thanks!

If this is the case (highlighted), a 50mm isn't going to buy you a Whole lot of more usability in close quarters. That's with my opinion (and it is just that), of the Pentax 50mm f1.7 being one of the best lenses out there in terms of bang for the buck. Especially the A 50 f1.7. You might be better off seeking out one of the 35-40mm options. I think I saw an M35 f2.8 in the KEH catalog for some thing like $135.

[dinneenp]

I'm thinking of getting a 50mm FA 1.4 or 1.7.
Then I saw that there's Tamron 28-75 2.8 and similar (sigma 17-50 2.8 etc).

What I want the lens for is low light and bokeh/shallow dof.
Does anyone have any sample pics of differnence between 2.8 and 1.7/1.4 in low light and bokeh?
From what I know- nifty fifty- quicker, higher aperture, others have zoom range and still a high aperture.
I'd be interested to see how big the difference is. That's probably the deciding factor for me.
Cheers,
Pa.

[Marc Sabatella]

Pictures won't really show the difference - at least, not the successful pictures. The difference will be in the *unsuccessful* pictures and what caused them to be unsuccessful. At f/2.8, the problem *in some cases* will be blur from too slow of a shutter speed, or noise from too high an ISO. In other cases, though, it will work just fine. At f/1.4 or f/1.7, the problem *in some cases* will be a subject that is mostly out of focus because the DOF is too shallow. Again, in other cases it will work just fine.

There will be any number of great pictrues from either lens, if the conditions are right. So the difference won't be visible in the pictures that come out well, but in the ones that don't, and more importantly, how often and in what situations this is the case.

[dinneenp]

At f/1.4 or f/1.7, the problem *in some cases* will be a subject that is mostly out of focus because the DOF is too shallow

Can someone please explain this to me?
if the lens has auto focus and it's pointed (center) at what I want to shoot how will the subject be mostly out of focus?
I presume this only would occur with very high apertures?

[keyser]

At high apertures you're aware that the amount of the image in focus is decreased... well that means that the margin for error is much lower. If you nail the focus every time, that's not going to be a problem but AF isnt psychic so you have to be spot on with your aim.

[sterretje]

A 50mm lens, subject distance (so focused at) 100cm
aperture set to f/1.4, DOF +1.1cm and -1.1cm
aperture set to f/2.8, DOF +2.1cm and -2.2cm

A 50mm lens, subject distance (so focused at) 50cm
aperture set to f/1.4, DOF +2.6mm and -2.5mm
aperture set to f/2.8, DOF +5.1mm and -5.0mm

Note: '+' means behind subject, '-' means in front of subject

For the latter example at f/1.4: if your camera or your subject moves about 2.5mm forward or backward, the subject will be out of focus if you have focused at 50cm
Numbers were calculated with Online Depth of Field Calculator

Some other comments.

• Why are you not happy with your kit lens? Maybe post some decent sized pics (800x600 or so) and indicate what is wrong with them.
• Further a 50mm is not a 'must have'. It is (or was) the cheapest way to get a fast lens for a dSLR; however a prime has its limitations compared to a zoom. Go through your pictures and check the used focal length. If you hardly find pictures taken at 45-55mm, a 50mm is the wrong lens for you. Based on your findings, you can decide which prime or zoom is right. Alternatively, set your kit lens to 50mm and shoot for a week with it at that focal length; see if you like the limitations that you have.