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02-07-2014, 10:40 AM   #1
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Is a prime lens (50 mm 1.8) and high ISO (3200) worth it?

I was thinking about getting that "budget" DA 50 mm 1.8 for my new K-50 to shoot a lot of indoor sports. Flash is not an option, so I need to use available light.

I mostly have to shoot around 3200 at f4.5 or so with my K-x kit lens 18-55.

At 3200 iso or higher, is the supposed increased sharpness of a 50 prime even worth it?

Or, is it needed to compensate some for the high iso?


Last edited by ziscwg; 02-07-2014 at 11:20 AM.
02-07-2014, 10:46 AM   #2
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With the faster lens you could decrease the ISO since it allows in more light.
02-07-2014, 10:51 AM   #3
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QuoteOriginally posted by ziscwg Quote
At 3200 iso or higher, is the supposed increased sharpness of a 50 prime even worth it?
For me it is. Plus like was mentioned you can probably reduce your ISO if shooting at a wider aperture.
The 50/1.8 is really an amazing value IMO. Very sharp, pretty fast, small and light.
02-07-2014, 11:12 AM   #4
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There are two important things to remember here, an f/1.8 lens, shot at 1.8 will bring your ISO down to 600, so if you're bothered by noise at 3200, that's a plus. But, f/1.8 will give you a very thin depth of field, and lenses tend to be soft when shot wide open. I don't own the DA 50 f/1.8, so I can't comment on how that particular lens behaves. A 1.8 lens shot at f/4.5 though will not give you significantly more light than you're getting now (there might be a little more because it's a prime), though it should give you a noticeable boost in sharpness.

So if you're planning on shooting it wide open, you might a) look at some sample photos taken at that aperture setting from that lens, and b) find a depth of field calculator, and work out if you'll have enough DoF to capture the subjects that you've been shooting.

02-07-2014, 11:28 AM   #5
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QuoteOriginally posted by maxfield_photo Quote
There are two important things to remember here, an f/1.8 lens, shot at 1.8 will bring your ISO down to 600, so if you're bothered by noise at 3200, that's a plus. But, f/1.8 will give you a very thin depth of field, and lenses tend to be soft when shot wide open. I don't own the DA 50 f/1.8, so I can't comment on how that particular lens behaves. A 1.8 lens shot at f/4.5 though will not give you significantly more light than you're getting now (there might be a little more because it's a prime), though it should give you a noticeable boost in sharpness.

So if you're planning on shooting it wide open, you might a) look at some sample photos taken at that aperture setting from that lens, and b) find a depth of field calculator, and work out if you'll have enough DoF to capture the subjects that you've been shooting.
Thanks for in detailed reply

I did not think I could shoot at 1.8 because the DOF would be too small. My subject is indoor volleyball. The DOF is a person hitting mostly. So, 2 to 3 feet IIRC. I found f4.5 or so gets it done at the distance I'm at normally.

If I had a faster lens, I'd go down to 1600 and bump the shutter spd up for better freeze action.
02-07-2014, 11:40 AM   #6
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Yes!

Hello ziscwg, welcome to the forum!
Yes, faster primes are great for low-light or indoor work, because they offer choices. Faster zooms too, for that matter.
For example, your kit lens probably isn't f/4.5 at 50mm, it's likely f/5.6. The f/stop range is f3.5 (at 18mm) to f/5.6 (at 55mm), so the higher the focal length, the higher the f/stop.
Say you had a photo taken at 50mm, 1/250s, f/5.6 and ISO 3200, OK? With the DA 50, you could shoot at f/2.8 (which is still stopped down 1-1/3 stops from wide-open), so the sharpness, resolution and clarity would be better, same shutter speed and use the extra 2 stops (between the f/5.6 of the kit and the f/2.8 of the DA 50) to lower the ISO to 800.
This photo would have slightly less depth of field (normal for low-light), much better sharpness, less noise, more saturation and better edge quality (since it's stopped down from wide-open).
If your lens only opens to f/4.5 or f/5.6, you don't have this choice. You could also use the 'extra' f/stops for a faster shutter speed or a combination of the two.
Fast glass gives you more choices, that's why LBA rules! Well, it's one reason.
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02-07-2014, 11:57 AM   #7
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It has all been said, really, but I just want to reiterate that it's very hard to beat the 50/1.8 on value. The only competitor I can see for value is the 35/2.4 but that one's not relevant in this context.
02-07-2014, 12:04 PM   #8
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It is 1000% worth it. My advice: buy used on the forum, sell it along of you don't love it. Or buy new from B&H, use it for a couple of days, send it back if you don't love it. It is practically free to try out lenses.

02-07-2014, 12:15 PM   #9
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QuoteOriginally posted by ziscwg Quote
I was thinking about getting that "budget" DA 50 mm 1.8 for my new K-50 to shoot a lot of indoor sports. Flash is not an option, so I need to use available light.

I mostly have to shoot around 3200 at f4.5 or so with my K-x kit lens 18-55.

At 3200 iso or higher, is the supposed increased sharpness of a 50 prime even worth it?

Or, is it needed to compensate some for the high iso?
Noise is a factor of signal. If the signal is stronger or clearer, the noise is less. Shooting on a sharper lens improves (in my mind, anyways, but also in my observation of my lenses) the detail being recorded by the sensor, and therefore the signal is stronger and less ambiguous (not as likely to be smudge by noise or NR algorithms). So theoretically, a sharp prime will generate less muddy pictures at high ISO than a softer zoom.

Also, you should judge the distance and the effect it has on DOF. The further your subject, the deeper your DOF. While you have been shooting at F4.5 because your kit lens limits you to that aperture, I find that F2.8 can often have enough DOF when shooting far enough subjects. That alone can either double your shutter speed or half your ISO.

One last thing, to reduce the apparent noise, overexpose a little. Again, noise is a function of signal. Saturating your sensor with more signal will reduce the apparent noise a little. How you achieve this is up to you.
02-07-2014, 01:07 PM - 1 Like   #10
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There's one other often overlooked consideration available here and fortunately it's both free and useable with ALL lenses -- Technique.

Knowledgeable, peak-of-action shooting has accounted for some outstanding sports shots -- even in the days of flashbulbs, ASA 25-100 film and 4x5 Press Graphic cameras.
02-07-2014, 01:43 PM   #11
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QuoteOriginally posted by pacerr Quote
There's one other often overlooked consideration available here and fortunately it's both free and useable with ALL lenses -- Technique.

Knowledgeable, peak-of-action shooting has accounted for some outstanding sports shots -- even in the days of flashbulbs, ASA 25-100 film and 4x5 Press Graphic cameras.
Yes, I have worked on that peak of action technique a lot. It does help. Now if I could get them to jump in the same place everytime, I'd be set.

---------- Post added 02-07-2014 at 12:48 PM ----------

QuoteOriginally posted by JinDesu Quote
Noise is a factor of signal. If the signal is stronger or clearer, the noise is less. Shooting on a sharper lens improves (in my mind, anyways, but also in my observation of my lenses) the detail being recorded by the sensor, and therefore the signal is stronger and less ambiguous (not as likely to be smudge by noise or NR algorithms). So theoretically, a sharp prime will generate less muddy pictures at high ISO than a softer zoom.

Also, you should judge the distance and the effect it has on DOF. The further your subject, the deeper your DOF. While you have been shooting at F4.5 because your kit lens limits you to that aperture, I find that F2.8 can often have enough DOF when shooting far enough subjects. That alone can either double your shutter speed or half your ISO.

One last thing, to reduce the apparent noise, overexpose a little. Again, noise is a function of signal. Saturating your sensor with more signal will reduce the apparent noise a little. How you achieve this is up to you.

Humm, I do see your point about starting with a stronger signal yielding better results.
02-07-2014, 01:53 PM   #12
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Even if you could open up to f/4.5 with the kit lens at 50mm the IQ wouldn't be nearly as good.

The DA50/1.8 will allow you excellent IQ at f/2.8 or even wider.


You also won't know how good the images look at shallower DOF until you try it. You may find that you don't need the athlete's entire body in perfect focus anyway - it depends on the effect you want to achieve. It could be that the trade-off of having too much distracting background in focus is not worth it. But you can only decide after trying it.

I often shoot runners at f/4 on my 135mm lens, and sometimes even faster apertures on my 85mm. I'd certainly try faster than f/5 at 50mm.


But regardless of the aperture you finally choose, I'm confident you could be getting better photos than with the kit lens.
02-07-2014, 02:57 PM   #13
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This is a very interesting and helpful discussion. I have some primes but I don't think I use them enough, partly because I like the flexibility of a zoom. But I think I need to start using them more, especially in situations with less light - and with a K-3, I can crop more.
02-07-2014, 03:51 PM   #14
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Yes, it's worth it. The prime will have better IQ overall, will have better bokeh, and the f/1.8 aperture will allow you to shoot in lower light with much better results because the AF sensor is getting more light and will lock focus quicker and with more accuracy. It will also be easier to manually focus. Even if you never fire a shot wide open, I doubt you will regret the purchase. There is one exception I will mention. I don't use the 50mm focal length very often.

The DA 50/1.8 is so reasonably priced that it's hard to find a reason not to own one if you don't. I have several fast 50 and 55mm lenses. Whether you buy the DA or one of the excellent MF versions, it's still a worthwhile lens to have, even if it's not something you use every day. I don't think anything will give you more bang for the buck than a 50 or 55mm prime. You can readily find old 55/2 and 55/1.8's for under $50 and I have a couple I picked up for $10 along with other stuff in a bag.
02-07-2014, 05:59 PM   #15
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BTW, on all the earlier Pentax dslr's, and I presume on the K50, if you shoot raw there is no advantage above iso 1600.
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