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12-09-2011, 09:59 PM   #1
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Looking For My First Prime Lens

I am looking for my first prime lens, I am wanting one that has the same FOV as your avarage 35mm film fixed focus P&S camera.

What mm do I need to be looking for?

Just out of curiosity, do fixed focus prime lenses exist?

12-09-2011, 10:10 PM   #2
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Thank a 24mm would be close to a 35mm on a film camera.Check out the lens database for both Pentax and third party makers lens and you will find quite a few to fit Pentax including the older manual focus lens.
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12-09-2011, 10:12 PM   #3
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Some are going to just offer you a # and others are going to do math for you or have you do math to figure out the Prime Length that you want. I think its simplier than that - look through your camera with your current kit lens - turn it until the image is what you want in a prime and then look at those that are close to that length. Simple.
12-09-2011, 10:17 PM   #4
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A 35mm lens on a film camera has the same field of view as a 21 or 22mm lens on a Pentax DSLR (1.6 crop factor).

Pentax has the DA 21mm LTD but its quite slow at F3.2.

The last generation of Pentax primes, the FA series, aren't all available anymore. You might be able to buy the FA 20mm F2.8 or the FA* 24mm F2 on ebay or the forums here.

If you don't need auto focus there are many lenses with that focal length in the A, M and K series.

Good luck

12-09-2011, 10:52 PM   #5
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I fear your question has been misread. For 35mm film P&S cameras, the fixed lens was sometimes as short as 35mm (like the Olympus XA) but more often somewhere between 40-50mm, usually around 45mm. The 'normal' focal length would be 43mm, which is the diagonal of the frame size for 135/FF (full-frame 35mm) cameras. Our APS-C dSLRs like the Kr and K5 have sensor diagonals of 28-30mm.

We figure the FOV format-faktor as being about 1.5x. Here are the rough equivalence numbers:

135/FF . APS-C
--------------
50mm ---- 35mm
43mm ---- 28mm
35mm ---- 24mm

So the lens on APS-C that most closely corresponds to a film P&S would be around 28mm, maybe a little more. There are many good manual-focus and AF 28mm lenses available, new and used, from various makers, sometimes quite cheap. There is the superb Pentax 31Ltd, and a popular but rather large Sigma 30/1.4. Alas, these are NOT cheap.

Some people are used to using 50mm or 55mm lenses on their film cameras, and want the same FOV. They tend to use 35mm lenses on their dSLR. Again, there are a wide range of new and used options in all price ranges there. If you don't mind manual focus, you can get something quite good quite cheap.
12-10-2011, 12:37 AM   #6
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QuoteOriginally posted by heasley Quote
A 35mm lens on a film camera has the same field of view as a 21 or 22mm lens on a Pentax DSLR (1.6 crop factor).
Hmm, not quite.
1.47 crop is what I understand it to be exactly (simplified to 1.5).

1.6 is only Canon's cropped sensors.
12-10-2011, 01:48 AM   #7
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It looks like I'm going to have to go with a higher mm than what I am looking for.

Ideally this Zeiss Wide Angle 28mm f/2 Distagon T* ZK Manual Focus 1486-307 or this Pentax Wide Angle SMCP-DA 21mm f/3.2 AL Limited Series 21590 B&H matches what I am looking for but are both way out of my price range, if I were to spend that much it's going to be on a telephoto.

This is more my price range being on sale for $169.95 Pentax 35mm DA L F2.4 AL Lens 21987 B&H Photo Video
12-10-2011, 02:26 AM   #8
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I agree with RioRico that the question was more than likely misread. I just had a look at my wife's Olympus mju II and it has a 35/2.8 lens (coincedence that it matches the 35mm in your description). Note that this was already an AF camera. 35mm on film is considered the beginning of wide and it can be considered a nice compromise between (ultra) wide and standard if it's the only lens. It will translate to 24mm on APSc cameras.

What you're looking for is probably something between 28 and 35mm that can act as a standard lens; my preference would be at the wider side of that range (28mm to 31mm). Although not my preference, the plastic fantastic DA-L35/2.4 is probably the best buy for the money. Slightly wider and you can think of FA31Ltd and Sigma 30/1.4. And the beginning of that range is covered by something like the Sigma 28/1.8

Those are current lenses; plenty of options (both AF and MF) if you go second hand.

To achieve the effect of not having to focus, buy a wide angle lens, set aperture to about f/8 or f/16 and distance to something like 2 or 3 meters and you will have DOF from nearby to infinity; read up on hyperfocal distance. You can find the exact numbers by using something like dofmaster.com 's Online Depth of Field Calculator

PS
you posted while was typing; be aware that the DA-L35/2.4 does not has a distance scale (to my knowledge) which will make the use of hyperfocal distance more complicated. You need to focus on something around 3 meters away, set aperture to f/11 and anything between 1.5 meters and infinity will be in perceived focus.


Last edited by sterretje; 12-10-2011 at 02:31 AM.
12-10-2011, 02:57 AM   #9
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I reckon get an FA 50mm f1.7... you'll melt inside and never go back when you see what a fast 50 does.
12-10-2011, 05:21 AM   #10
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@TechGuru,
The DAL35/2.4 is probably the most cost-effective new AF lens in the vicinity. As sterretje mentioned, it (like all DA lenses) lacks a DOF scale, so zone focus / hyperfocus are not easy. I don't know if that's important to you. The 35 has a FOV we call long-normal, good for many applications. I happen to prefer a bit wider. You might find a used AF 28mm lens in your price range. Wider than that, they start to get expensive.

But consider wider manual-focus lenses. There are 21/3.8 lenses available, often for under US$100 used, often in M42 mount, that are ideal for hyperfocus work. I set my M42 Lentar-Tokina 21/3.8 to f/11, prefocus to 2m, and have DOF from 1m to infinity. No need to refocus! This is good for from-the-hip shooting in good light.

For shooting in lower light, the Vivitar-Kiron 24/2 in PK-M mount is great, and can probably be found for around US$150. Going a little longer, the Vivitar-Komine 28/2 CF (close focus) can be found for under US$50 probably, and is my favorite manual walkaround lens. Various Vivitar and Sigma and Tamron 24mm and 28mm lenses in f/2.5 or f/2.8 are still pretty cheap; and Pentax has some good (somewhat more expensive) 24mm and 28mm manual lenses too.

But if you insist on a new AF lens, the DAL35/2.4 is probably your best bet. Good luck!
12-10-2011, 05:50 AM   #11
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If you do get a manual focus lens, I have a Vivitar 28mm f2.8 (auto aperture) here that you can have for about $70 or so.
12-10-2011, 07:04 AM   #12
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QuoteOriginally posted by RioRico Quote
So the lens on APS-C that most closely corresponds to a film P&S would be around 28mm, maybe a little more. There are many good manual-focus and AF 28mm lenses available, new and used, from various makers, sometimes quite cheap. There is the superb Pentax 31Ltd, and a popular but rather large Sigma 30/1.4. Alas, these are NOT cheap.
F 28mm f/2.8 is absolutely brilliant. And inexpensive. (Note: The FA 28mm f/2.8 is NOT the same lens).

The only thing that I view as a minus is that the bokeh can be... busy.

Easy to find, relatively inexpensive, compact and very sharp. There is something else about this lens and the way it renders that is particularly pleasing to me.

Everyone thinks you need a fast 50 in your kit. I agree. And I use my fast 50 about 1/100 as much as the SMC-F 28mm.

woof!
12-10-2011, 07:22 AM   #13
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Like I said last night - lots of guesses, opinions, and some math. Why not just use your kit lens to see what perspective it is you really like and then research lenses at that focal length?
12-10-2011, 09:38 AM   #14
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By "your average 35mm film fixed focus camera", do you those disposable jobs where you send the entire camera in for processing? Those are the only fixed focus cameras I know of that are in common use. I can't seem to find any official specs on the lenses, but the consensus seems to be the lenses are indeed around 35mm in focal length, so you'd want so ethihg around 24mm. You can get old manual 24mm lenses for $100-$200.

Or maybe you are referring to Holgas? I believe the 35mm film versmion of the Holgas typically use 50mm lenses, so a 35mm lens would be what you want for APS-C. The DA35/2.4 seems the obvious choice, or an older manual 35 like the M35/2 if you can find one. Same price ranges as the 24mm lenses.

But assuming you don't need to match the exact focal length of any given camera, a manual 28mm lens seems the obvious choice. Shouldn't need to spend more than $20. Excpet I suppose you'll want auot exposure. That pushes the price back up to $100 (and it makes 24mm lenses much more expensive, too). So I think you choices should be either the A28/2.8 or the DA35/2.4.
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