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04-15-2007, 07:55 PM   #1
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Better lens for indoor sports - or maybe not?

Trying to figure out which of the two lenses I've got is better for shooting girls volleyball (or other indoor sports). In February and March, I was using a Tamron 28-75 f/2.8 lens for these games. I was reasonably satisfied with the results from the equipment. (There's always a lot of room for personal improvement, of course, but that's not what this thread is about.) Anyway, this weekend I shot a game using a Pentax AF 50mm f/1.4. I was hoping that the bigger aperture of the Pentax lens would more than offset the loss of the excellent zoom range I have with the Tamron 28-75.

I'm posting because I'm surprised that the results with the faster Pentax lens are not conclusively superior. I'm happy with the pictures from the Pentax 50/1.4, but as I said earlier, I was reasonably happy with the result from the Tamron f/2.8 lens. I guess I thought switching to a lens that's twice as fast would produce photos that were half as noisy, or twice as sharp. Does not seem to have done so. Perhaps I was simply expecting too much.

I keep saying "seem" because, to be honest, it's fairly hard to compare the results. The only really precise comparison would involve taking the exact same shot at the exact same moment, using two different cameras - a test I obviously can't rig up. There is one constant: the shots I took last weekend and the shots I took two weeks ago were taken in the same gym. But the lighting in the gym is spotty - some spots are a little darker or lighter than others. In both of these recent shoots, I generally used TAv mode on the K10D, with the ISO range set to 200-1600.

In the recent shoot, the Pentax 50/1.4 did give me more shots at ISO 800 - even though I was also using a somewhat faster shutter. But in the end, I don't care about numbers, I care about the photos, and I'm just not sure can see a big difference. I thought the shots with the f/1.4 lens would have less noise, but I don't find the difference in noise levels to be major. Some of the shots from the Tamron lens seem to be fairly noise-free - even some taken at ISO 1600 - while some of the shots with the Pentax lens are reasonably noisy. Clearly there is more to noise than simply the ISO setting.

Anyway, I'm trying to figure out how to compare these two lenses. The color photo here was taken two weeks ago with the Tamron 28-75 f/2.8 lens. ISO 1600, 1/180sec, f/2.8 at 28mm. Here's a link to the original if you want to enlarge it. The grayscale shot was taken yesterday with the Pentax 50 f/1.4. ISO 800, 1/350sec, f/1.4 at 50mm. Here's a link to that original if you want to enlarge it. Both were post-processed slightly in Adobe Lightroom (tiny enhancements to contrast and sharpness). I picked these two shots because the subject is so similar. But that may be misleading. If you want to get a bigger sample, here's a link to the gallery of shots taken with the Tamron lens; and here's a link to the gallery taken with the Pentax 50mm.

There isn't any question that the Pentax 50/1.4 is a wonderful lens, especially for the price (almost half the price of the Tamron lens) and there are many other kinds of shots for which the Pentax is easily preferred. I'm not trying to compare the lenses in some abstract, general way - they're both quite decent. I'm trying to figure out which lens I should continue to use for these events in the future. Any thoughts?

Will

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04-15-2007, 08:15 PM   #2
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Gut check

I Hope I can make this 'make some sense'; I've been crunching numbers all day, bear with me.

The purpose of a faster lens is to shoot at lower exposure values. For the lens pair of your testing the difference is practically nil.

Image quality testing would probably require a kit lens and an 'A' lens or an 'A' and a '*' pairing; or the big ugly: the kit vs the '*'.

And a whole bunch of other things like distance and lighting and post to be held at constant values.

But it will always come down to some final subjective judgment: yours in this case.

So what are you most comfortable using? This is going to be a gut-feeling call on your part. What feels like it is working better?
04-15-2007, 08:37 PM   #3
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You need some depth of field to compensate for errors in focusing when you're shooting at events like this. The disappointment with the 50mm could be due to lack of depth of field (and low contrast) if you used it at f/1.4 or f/2.

In my experience it's better to bump the ISO and go with a fast shutter speed and an aperture not larger than f/4.

I experienced exactly what you describe in my Canon film days where my slow f/4-5.6 zoom gave better sports photos than my 50mm!
04-15-2007, 09:09 PM   #4
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QuoteOriginally posted by jfdavis58 Quote
The purpose of a faster lens is to shoot at lower exposure values. For the lens pair of your testing the difference is practically nil.
John,

I've been pondering for a few minutes what you mean by "lower exposure values".

What I'm guessing is this: that you're saying that the advantage I get going from f/2.8 to f/1.4 is being offset by the fact that I'm upping the shutter speed. So in terms of noise, the result is a wash. Is this what you were getting at? Whether that was your point or not, it makes obvious sense now. I guess what I need to do is shoot another game with the f/1.4 lens, and try to keep those shutter speeds down in the 1/200sec range that I was using with the f/2.8 lens.

On the other hand, put that way, I would also have to say that I do see a slight general improvement in the more recent images, in that they freeze the action a bit more successfully, due to generally faster shutter speeds. I'm uploading two more pictures (same girl, by accident) for comparison. These two pictures were taken of the young lady serving - an action that she does in a very similar fashion every time. In the older (color) image, her feet and hands are quite blurred: ISO 1600, f/2.8, 1/125sec @ 63mm. In the more recent (grayscale) image, her right foot (on the left side of the photo) is rather less blurred, her serving hand shows motion blur but you can see her fingers quite distinctly: ISO 1100, f/1.4, 1/250sec @ 50mm. In the more recent photo, it seems to me that the number on her jersey is also sharper. Don't think I noticed this consciously prior to starting this thread.

Will

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04-15-2007, 09:25 PM   #5
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QuoteOriginally posted by Ole Quote
You need some depth of field to compensate for errors in focusing when you're shooting at events like this. The disappointment with the 50mm could be due to lack of depth of field (and low contrast) if you used it at f/1.4 or f/2.

In my experience it's better to bump the ISO and go with a fast shutter speed and an aperture not larger than f/4.

I experienced exactly what you describe in my Canon film days where my slow f/4-5.6 zoom gave better sports photos than my 50mm!
Ole,

Thanks for the reply.

Yeah, I wondered what effect (if any) moving from a lot of f/2.8 shots to a lot of f/1.4 shots would have on depth of field - and on focus. To be honest, it doesn't seem to me to have had a negative effect. For most of these shots, I don't need anything in focus other than the girl who's in the center of the photo. This is especially true of volleyball, where most of the plays are made by a single player. With the f/1.4 aperture, I seem to be getting enough depth of field to get that one player within the zone of acceptable sharpness. And at the same time, I'm able to use a faster shutter speed, which means that the subject is by and large captured more sharply (less motion blur).


Will
04-16-2007, 10:14 AM   #6
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imho, the 1/250sec shutter speed is still too slow... but i guess that's part of the tradeoff when the lighting is marginal.

shooting it tight, with minimal cropping, can be helpful.
04-23-2007, 03:07 AM   #7
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made many indoor sports shootings myself...
Yes, you need 1/250 sec at least to get the motions more freezed.
No, you shouldn't use the 1.4 wide opened but 1 stop down (at 2.0 you win 1 stop against the Tamron 2.8 ....)
At f 2.8 it's becoming very good - not before....
I used to underexpose (1-2 stops) and do the rest in post-processing.
Better to have a sharp and frozen image.....
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