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03-31-2013, 12:38 AM   #1
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First Prime Lens

I am pondering about a prime lens for K30 for general use, street photos, low light - I have the 18-135 WR only and would like something a bit faster. What is the optimal focal length, 35 or 40 or 50mm? How do you decide? I like to get the best I could afford, so a limited version. I looked at Flickr to get some idea of the focal length coverage but am no wiser. I can understand why people opt for a zoom!! Any advice is welcome.

Happy Easter to all.

Rod


Last edited by Traveler8; 03-31-2013 at 12:57 AM.
03-31-2013, 12:40 AM   #2
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The optimal focal length is 50mm, but on the K-30/APS-C that's a bit long. That's why I'd recommend getting a 35mm

Adam
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03-31-2013, 01:01 AM   #3
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QuoteOriginally posted by Adam Quote
The optimal focal length is 50mm, but on the K-30/APS-C that's a bit long. That's why I'd recommend getting a 35mm
Adam, thanks. Perhaps a dumb question but do you mean get a 20mm so that it's 35mm equivalent or get an actual 35mm focal length lens?
03-31-2013, 01:31 AM   #4
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35mm focal length is what he means. Like the FA35/2 or the DA 35/2.4 Or even the 35/2.8 Ltd, if you want it to double as a unique macro lens. 28mm is also rather nice, provides the "Normal" effect everyone likes.(Equates to just shy of 43mm on 35mm)

03-31-2013, 01:40 AM   #5
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Have a look through your pictures and see what's the most common focal length you've been using on your zoom.

Then get a fast prime to match that, it will be a length that your already familiar and comfortable with.

May your LBA begin.
03-31-2013, 03:08 AM   #6
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QuoteOriginally posted by Traveler8 Quote
What is the optimal focal length, 35 or 40 or 50mm? How do you decide?
If you look through the photos you have taken with your zoom so far, you will have a rough idea of your favourite FL. That will be the ideal prime to get.

Different people like different FL. My favourite FL is between 40-50mm (with film camera). FA31 is equivalent to that FL on my K5. It has been my primary Pentax lens for more than 12 months before i make another purchase. It is still my favourite Pentax lens.

All the best.
03-31-2013, 03:36 AM   #7
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My pick the DA 35 2.4 if you shoot abit of everything. A DA 50 1.8 or FA 50 1.4 if you love details and portraits.
All great lenses AF good in low light and affordable. The FA can be found $360 USD and below.
03-31-2013, 04:20 AM   #8
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Get the DA 35 2.4, because it's cheap, and a fantastic lens. Play around with it and see how you like the length; since it's so cheap, no real damage if you don't like it as much as you had hoped. But it really is an excellent lens. I love mine.

03-31-2013, 06:44 AM - 1 Like   #9
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Get the DA 35/2.4 and the DA 50/1.8. You can get those 2 for about what a DA 40/2.8 Ltd would cost. Add the DA 40/2.8 XS and you would still spend less than the DA 35/2.8 Ltd Macro would cost...
03-31-2013, 07:29 AM   #10
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The Sigma 30 is a superb choice as an only prime, because it is very fast. You will have to adjust autofocus, though. Also, it's really kind of mediocre at landscape, so if that is important, maybe not. My first prime was a cheap old A50 f2, which I really like, and my first limited was the 40, which I fell in love with. I also really like my Takumar 55 f2, it is superb. The truth is you won't know which prime is best for you until you jump in and start shooting. Buying a used lens from PF is a pretty safe bet, because if you don't like it, you can sell it for what you paid for it, and you are out very little. It's a great way to try many different ones until you find the one that's right for you.
03-31-2013, 07:33 AM   #11
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One of my absolute favorite lenses is my Sigma 30mm F1.4 EX DC HSM. It's a great focal length, compact size and very fast at f1.4. I used this lens as a primary lens on a recent trip to Mexico and it performed perfectly. They pop up occasionally in the marketplace but even new they aren't ridiculously expensive.
03-31-2013, 08:26 AM - 1 Like   #12
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Agree with others above that the optimal focal length for a single, versatile prime on APS-C is, for most people, in the 28-35mm range. Options in that range (some of which have been mentioned above) include:

K 28/3.5 - sharp across frame, great landscape lens, but a little slow and lacking in the bokeh department; manual focus and stop-down metering; ~$150 used

F 28/2.8 - a great versatile normal that is often overlooked (IMO); sharp, fast and accurate AF, decent bokeh and speed for this focal length, small and compact; has both autofocus and does not require stop-down (manual) metering; ~$250-300 used

variety of manual Vivitar 28mm lenses - wide array of manual lenses that can generally be had fairly inexpensively, described further in the "Great Vivitar Bestiary" thread on this site

K 30/2.8 - I don't have personal experience with it, but seems to be highly regarded, others can comment further; ~$400 or so used

Sigma 30/1.4 - again I've never used one; many folks seem to really like it; a common complaint is corner softness (making it maybe less optimal for landscapes, but nice for portraits); ~$400 used

Fa 31/1.8 limited - probably the class of all lenses for Pentax in this focal length range; fast, versatile, great bokeh, sharp and contrasty, thrives in almost all situations; I love mine, but the price reflects the quality (and some would argue it isn't better enough than the other lenses in this range to justify the premium); ~$800-900 used

Fa 35/2 - don't have any experience with it; I've heard people say it comes close to the Fa 31 for a <1/2 the cost

Da 35/2.4 - again no experience, but often mentioned as a great value in this range

Da 35/2.8 macro limited - very versatile; decent speed, sharp and contrasty, macro function is a bonus, some say a weakness is sharpness/resolution at longer focal distances/infinity; I haven't pixel-peeped enough with it to decide if I agree with that conclusion, but I do know the images that strike me most with it tend to be the macro shots; ~$450-500 used


There, that list should get you started. Others can add further options or comment more on the above (many of which I haven't owned). I would start by deciding a few basic things: 1) what is your budget? 2) do you need autofocus? auto-metering? 3) do you need something full-frame compatible? Answering those basic questions should help you narrow things down quite a bit to a manageable number of choices, and I'm sure once you've done that many folks here will be able to provide opinions about which way to go among your choices.

Good luck!
-Brandon
03-31-2013, 08:40 AM   #13
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There is no "optimal" focal length, which is why there are different ones :-) It always depends on what you are shooting and how you are shooting. Some people like to be close and wide, some further away.
03-31-2013, 09:07 AM   #14
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Great advice on this thread. Pentaxforums members are so helpful.

On a tangent, you mentioned zooms... the Tamron 17-50/2.8 is handy, very good, and cheap. Shame I just killed mine through "drop from height". Shame I also lost my FA31 through "stupidity".
03-31-2013, 09:21 AM   #15
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QuoteOriginally posted by bpv_UW Quote
K 30/2.8 - I don't have personal experience with it, but seems to be highly regarded, others can comment further; ~$400 or so used
A K 30 lens on a K 30 camera?
We need to see that!

QuoteOriginally posted by bpv_UW Quote
Da 35/2.8 macro limited - some say a weakness is sharpness/resolution at longer focal distances/infinity; I haven't pixel-peeped enough with it to decide if I agree with that conclusion
I have, and I don't.
But the lens does need to be focused.
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