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01-11-2011, 08:55 AM   #1
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Shopping for primes : a fast lens & a landscape one...Dazed and confused...

Hi all,

this is my first post here, bought myself a K7 for Xmas, moving to pentax after playing around with a D70 for two years...Very glad i made it!

I got my K7 used with the kit 18-55 lens which i need to replace asap in order to make full use of the body. I must have spent at least 10h on this forum, reading comparing and then reading some more and the only conclusion i came to is the title of this post. I want 2 lenses, one for nightime shooting and DoF messing around and the other for landscapes.


Intially i was thinking of only buying one 28, 30 or 35mm lens to do everything but i realized that such a choice will restrict me when it comes to landscapes. So i was wondering if you people could help me choose : concerning f1.4 or 1.2 for lowlight is it possible to find old lenses equivalent to a 50mm film that open as wide and which have autofocus? I saw Cosinas but they're 55mm... On the 1.2 thread it seems most of the users use the 1.2 for close up, can someone tell me why?


The dilemma is either i spend my 500-600 euros (600-700$ US) budget on a sigma 30mm 1.4 either i manage to find a used K mount equivalent for 100-200 and buy a 10-20 or 12-4 for landscapes.

I went pentax for the wide variety of old lenses available but i didn't imagine, at the time of buying, how wide the choice was ; sorting and filtering all the lenses available, with adapter, without adapter, AF, non-AF, all the different series etc etc is truly disconcerting for a begginer...



I'm sure all of you have at some been in my shoes and i'm sure as well i'm not the first to ask for help. Sorry if this is a double post, couldn't find decisive answers with the search engine. To sum up :

  • Any recommendations on a fast 50mm-equivalent oldschool lens with AF?
  • For landscapes is zoom fundamental (10-20, 12-24) or should i just get a prime around 15/20 and deal with it ?
  • Whats a good book to learn about lenses?
Here in Andalucia, Spain we have amazing landscapes & skies, it is the primary reason i upgraded to the K7 and up to now i never considered investing in primes, hence my lens newbieness... let me be forgiven!

Thank you all in advance for your time.

01-11-2011, 09:09 AM   #2
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I have several older SMC Pentax 50mm lenses, ranging f1.4, f1.7 and f2. My favorite is the A series f1.4. Not quite as fast as a f1.2, but it does a very nice job. Any 50mm A or M series lens will do nicely, and will mount right onto the camera with no trouble. Then you have the screw mounts, which require an adapter, but some are really good too. I don't know much about the newer lenses, never used any except the 18-55 kit lens that came with my K-x. Wasn't too impressed, I did get some good shots with it but the manual 50's do better by far.

The same goes for the older K mount Pentax 28mm, nice lens, I wish i could find mine but I think it's on a ME I goofed up and let go to the pawn shop. Only because I didn't realize the 28 was on it...I got some nice landscapes on film with it. But it's not as fast, f2.8 I think, can't really remember.

Be aware though, any lens wide open will be tough to focus. At 1.4 you have no depth of field, your focus on close up subjects has to be dead on, and even for landscapes you have to focus pretty close. That said, when you do get good focus the pictures are great. I shoot my A series 1.4 wide open now and then, but not often. When I do it's really tough to ge tthe focus right, since it's usually either macro shots or close ups of insects, but it gives me a really nice shot when I peg the focus...same for the others, f1.7 and f2 all do nicely, but focus is critical when wide open.

The best advice I can give you on manual focus is to remember the three P's...

Practice, Practice, Practice.
01-11-2011, 09:17 AM   #3
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I think the Sigma 30/1.4 is your best bet for an AF/Fast/50-like lens. For landscape, your title said "shopping for primes" so I'm a bit confused that you mention the 10-20mm and 12-24mm.

I own the DA 12-24mm and it is excellent - very sharp. However, with you budget, after spending on the Sigma 30mm, and wanting primes (I think), I'd look at something in the 20mm range. Go manual focus since they'll be less expensive, and because you don't need autofocus for landscape (especially with the ability to zoom in on focus with Live View on a tripod). 20mm is an arbitrary length, as landscape can be done with any focal length, but I think its a good "in the middle" length, i.e. not so wide that it minimizes scenes, but wide enough to capture grand vistas. Options in this range would include the A 24mm, M 20mm, K 20 and 24mm. Or, if you want to stretch the budget a little, find a used DA 21mm, which renders landscapes like it was made solely for that purpose.

Happy hunting!

Todd
01-11-2011, 09:56 AM   #4
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You can shoot landscapes with any focal length - depends on the landscape. Don't feel you need to have a 10-20 zoom or a DA15 to do landscapes, the art in photography can come from the isolating the subject of the picture or picking out a detail rather than capturing everything - very difficult to do that with a 10mm lens (hard enough to keep my feet out of the frame!).

Unfortunately you probably won't find a fast 28-35mm lens that's got autofocus and is also cheap, and you won't find any old cheap manual focus lens that'll do 10mm because they just weren't made. There are some old 15mm's but they're rare and exotic and it seems cheaper to buy a new one like the DA15 Limited.

If you were willing to try out a fast lens without autofocus, you can pick up a Pentax-A 50mm in various speeds - guess you could get the f1.7 for 60-70 and sell it for the same if you're not keen. The 1.4 and 1.2 sell for more. "A" means it'll work in all modes on your camera with automatic metering - older lenses than that will need to be used in fully manual mode.

Remember, generally speaking, old lenses are manual focus - so if you want to go that route you'll have to get used to it. Luckily it's much easier to focus old MF lenses than new AF ones. For shooting landscapes in manual focus you can generally use the hyperfocal distance rather than squinting through the viewfinder anyway.

01-11-2011, 10:54 AM   #5
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My recommendation

Hi S0l and welcome.

Unfortunately "old lens" and "auto focus" don't belong in the same sentence. You can either have an old lens (depending of course on your defination of "old") or you can have an autofocus lens but not both.
That said here are my recommendations considering your budget.
1) fast 50mm. Pentax A 50mm f/1.7. I've own(ed) a bunch of 50mm's And this is one of three I've decided to keep (the other two are the K 50mm f/1.2 and the takumar 55mm f1.8) Why the A f1.7? Relatively small and light, sharper corner to corner than the FA 50 f1.4, better bokeh (to my mind anyway) and excellent ergonomics, nice smooth focus ring with a decent throw. And considerably less money than the FA 50. But it is manual focus. link to user reviews

Landscape lens:
Look around for a used FA 20-35. This is one of Pentax's "sleeper" lenses, wonderful lens that gets overlooked a lot. But it is very sharp, even wide open and wide zoom. It's about 1/2 the size of the DA 12-24, and to my mind easily as sharp. Excellent color rendition, good bokeh, and it close focuses! What more could you ask? It's only problem is that it's f/4.0 and is prone to CA in high contrast areas. But outside of that a beaut of a lens. I got mine for under 300USD but that was a while ago, but you still should be able to find one for the 350-400 usd range. link to user reviews

NaCl(you can still get great quality glass for less than you think)H2O
01-14-2011, 09:16 AM   #6
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Original Poster
Hi all,

thanks a lot for your suggestions, i hadn't thought about the very relative necessity for AF on wide angle lenses! This is very good news for me, i am going to buy the sigma 30mm 1.4, that's for sure, then probably try to find an old manual 20 or 24mm for landscapes.

NaClH2O, thanks for the advice, I searched for the 20-35 but it is a bit over budget since i'll be getting the sigma. The 50mm are not what i'm looking for for low-light situations, tried the classic Canon 50mm 1.8 recently and though cheaper it is too narrow for my needs, hence the move to 30mm.

Timh : one question, hyperfocal distance means infinity right?

Gnatzee : thanks for the recommendations, did you personally play with each of the A 24mm, M 20mm, K 20 and 24mm? Any favourites? M stands for what? I looked on the wikipedia page for pentax mount but didn't find it in the list?

Paleo Pete: how did you find the performance of camera AF on 1.4 lenses? Do you need to go manual everytime? For instance shooting a night party or a concert at 1.4, which are quite dynamic scenes, require MF?

Has any one got experience with the K7's AF system & very fast lenses?

Thanks again for all your feedback i was right to start this thread!
01-14-2011, 09:20 AM   #7
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It's interesting that people don't like mixing 'old' and 'autofocus' in the same sentance considering AF came out for Pentax around 25 years ago!
01-14-2011, 10:06 AM   #8
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Hyperfocal distance - I'd have to word it quite carefully in order to avoid being shouted down as wrong in some slight technical way, so instead I'll just give you a link.

QuoteOriginally posted by keyser Quote
It's interesting that people don't like mixing 'old' and 'autofocus' in the same sentance considering AF came out for Pentax around 25 years ago!
Could be because 'old' AF lenses are still rather expensive for second- or third-hand items (at least the good ones).

01-14-2011, 10:42 AM   #9
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I myself a while back was in search for a fast AF prime..the 'older' models would be fine and would not be expensive, I thought.. realizing that it still cost a fortune, I steer clear and get myself a M 50 f1.4 and never regrets

..somehow I think that AF rip the 'fun' off photography
01-14-2011, 11:30 AM - 1 Like   #10
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Hyperfocal: Some definitions are a bit misleading. The hyperfocal distance is the focus at a specific aperture on a lens that gives you a desired DOF. That DOF often (but not necessarily) extends to infinity. And this is complicated by our use of older 35mm camera lenses with DOF scales inscribed on them. Most newer lenses for APS-C dSLRs do NOT have such DOF scales.

An example: Suppose I put an old 21mm lens on my K1000 film SLR. I set the aperture to f/11. On the lens, I set the infinity mark against an f/11 mark on the DOF scale. The other f/11 mark is at 0.65m, and the central focus mark is at 1.3m. Thus, 1.3m is the hyperfocal distance, and the DOF range is 0.65m to infinity. If I put the same lens on my K20D dSLR, I must adjust my settings by one f-stop. With the aperture at f/11, I now put the infinity mark against an f/8 mark. The other f/8 mark is at 3m, the hyperfocal distance is 6m, and DOF is 3m to infinity.

Setting the hyperfocal distance is a kind of pre-focusing technique, to prepare the lens for a shot. But I may not always want DOF extending to infinity. I may want to close-focus, and to know the DOF range. With that 21mm lens at f/11 on my K20D, I set the lens so the f/8 mark is at 0.3m (12 inches). The hyperfocal is now 0.35m, and the other f/8 mark is at 0.42m (17 inches). So the hyperfocal is 0.35m and DOF is from 0.3m to 0.42m, only 0.12m / 5 inches thick. Thus if I want a subject in focus, it must be no thicker than that!
_________________________________________________________________________________________________

Landscape lenses: As mentioned, landscapes can be (are are) shot with any lens. If you look at published landscape photos, you will find that MOST are shot with lenses equivalent to 16-45mm or 18-55mm on a dSLR. Wider (ultrawide) lenses are not really suited for far 'scapes because they shrink distant objects -- that mighty mountain range becomes a line of hills, that tall city profile becomes insignificant bumps. Such a wide lens works well to show the context of a nearby subject against a diminished background.

So I use my new Tamron 10-24 to make small spaces look large. It largely replaces my 16mm and 24mm prime lenses, although I still use my Vivitar 24/2. Last year at the USA's Grand Canyon, I mostly used my Zenitar 16/2.8 and my Pentax M28/2.8. A 30mm lens would be very suitable for many undistorted 'scapes, where you want to capture what 'normal' vision sees.

Also as mentioned, autofocus is unnecessary for most landscapes; instead, use hyperfocal technique. And autofocus is often not needed with ultrawide lenses, which have immense DOF when stopped down. My Zenitar 16mm lens at f/11 and prefocused to 1m has DOF from 0.5m to infinity! But alas, older wide lenses are scarce and expensive. The Zenitar at under US$200 is the most cost-effective, but it is also a fisheye and its distortions can either be exploited, or eliminated in post-processing. Ah, but it is so dramatic, and fun!

My advice: A fast ~30mm lens will be great for low-light and 'normal' shooting. Use your kit lens to find which focal lengths you use the most, and which focal ranges you wish you had that it doesn't reach. That will help you decide how to spend your money.
01-14-2011, 12:49 PM   #11
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Sorry, I haven't used any of those. It might be a good idea to check the lens database here on the forums for others' experiences. I only have the DA 21, and I think it's a very good focal length for landscapes. Oh, and "M" is a line of manual focus lenses that were a bit smaller than the 'A' lenses. I don't know what the M stands for, maybe "mini"?
01-14-2011, 02:16 PM   #12
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For what its worth...I got back last week from 2.5 weeks in Italy, for which I took the 15mm, 43mm and 70mm Limited lenses, Sigma 30mm F1.4 and the WR 18-55 kit lens. The kit lens was great for a couple of rainy days in Venice. Other than that, well, I ran an exposure plot for fun (knowing just about what the results would be) - 80% taken with the 15mm, and I loved it. Wire portraits, scenic landscapes, great for architecture - an all around perfect travel lens. Second on the list was the 43mm, slightly wider than the usual 50mm lenses it makes for a nice half-body portrait with an interesting element in the background.

Sadly I hardly used the 70mm - its results were spectacular, I just the focal length just isn't for me (will probably be parting with it shortly). I did also enjoy the 30mm F1.4, but given the weight opted for the 15 and 43 in the bag most of the time. The sigma 30mm does provide a nice normal angle of view and hasn't disapointed yet though, and is definitely a keeper.
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