When is F/1.4 better F2.8 + IS

[fractalgfx]

I was thinking that the Sigma 30mm 1.4, might be nice to for dark restaurants and night photography. At the time I was forgetting that my 17-55 2.8 IS gives me at least an extra 1.5-2.5 stops. In this case, I think the only possible benefit of a prime would be less image distortion.

[coldrain]

What is "night photography"?
To me it does not mean a small depthg of field, but longer exposure times... longer than IS can give me, so support being needed.

IS will allow slower shutter speeds, bigger aperture will mean faster speeds but shallow depth of field.

So, they are for different circumstances. It is upto the photographer to choose the tools he wants/needs.
I do not think the 30mm sigma will have less distortion than the 17-55 f2.8 IS at 30mm.

[Nickcanada]

I don't think there is a great deal of IQ difference between the 30mm 1.4 and your 17-55mm 2.8 IS. The 17-55mm lens is fantastic.

The real difference will be depth of field issues but also stopping motion in low light.


Rebel XT with 35mm 1.4L, SS 1/100, F 1.8, ISO 1600
http://i91.photobucket.com/albums/k320/livelifelivepics/Arm%20Your%20Desires/IMG_2583.jpg

Here To freeze the guy mid jump I needed a fast SS, IS would not have helped in this situation.

This is an extreme case and most of the time when shooting people in low light conditions a good flash is your best friend.

So unless you need the very narrow DOF or you need to freeze fast action in lowlight your 17-55 should be more then you need.

Your 430 EX is probably the best solution for low light restaurant stuff, or if you are interested in experimenting with fast primes you could pick up a 50mm 1.8 for very cheep.

Hope this helps. :)

[chardog]

use flash?

IS is not a replacement for f-stops.

I find that in low light situations, I can get away with my popup flash pretty well if I'm not TOO far away. Drop your shutter to around 25-50, iso 400-1600, and let the flash do the rest of the work! The picture wont look too flashed and better to have the shot than not!

example:

http://i212.photobucket.com/albums/cc38/chardog78/halloween/_MG_1473.jpg

popup flash

abient is still there and focus is on the subject.

[Gintaras]

forgive me for asking a dumb question but I do not grasp how IS can give me wider F optically speaking? I understand that IS would give me a faster shutter speed at the same F but .... :confused:

[DonSchap]

Cripes, is this confusing.

Let's break down IS ... and go from there.

You got a shot that meters in at 1/15 sec ... at ISO 1600 (the best your camera can shoot) at your lens' widest (maximum) aperture of f/4.

You know darn well that without a tripod, this is going to look quite lame at 1/15th, handheld. IS to the rescue, tight? Maybe. You turn on the lens' IS-equipped capability and yes, 1/15 sec is kind of doable. You get a good metered shot ... not too much noise (it is at iso-1600, at all) and somewhat decent saturation (it is ISO-1600, after all).

Lets admit that f/2.8 would have allowed for an ISO-800 shot ... all things left the same ... or taking the speed to 1/30 sec ... stabilizing it a little better at ISO-1600. (Only a magnification peek will reveal which is better looking.)

But, if you had a f/1.4 lens (OMG) ... you could have forgotten IS altogether ... set the the ISO-1600, speed to 1/60, and the aperture to f/1.4 and gotten a very tightly focused image. And I do mean tight ... about one-inch front to back of the focused subject.

So, wide lens ... tough focus problem. IS ... extended slower speed, with reduced handshake evident, but not much else ... ISO-expansion (say to 6400) ... a lower overall saturation of the shot, but in low light, color is rarely of a quality that is sharp. Noise goes up and can ruin well-focused detail.

Obviously, more light is your best best ... find a way to augment it ... "fill flash", redirection (through a reflective means) and even adding light, if possible. Shooting f/4 @ 1/15th sec @ ISO-1600 is just dragging your images through the mud.

Optimally, you best-looking shots, indoors, will hover at f/5.6 @ 1/60 sec. @ ISO-400 ... with only a small amount of exposure adjustment either way. Make sure your White Balance is correct for the type of lighting you are shooting with. If you can get close to this, you should get a decent series,

if the meter says: -3..2..1..|..1..2..3+ . :)

"My gosh, Don ... those are standard flash settings!" http://i76.photobucket.com/albums/j17/AWDstaff/Smileys/index.gif

Now, you have it! :D The alternative ... is a tabletop tripod.

30937 <= $30

Tell your subjects to "hold still" and pop a 1/5 sec, exposure. Go even longer if you drop the ISO back to 400 for a "good saturation" shot. You'd be absolutely amazed how much illumination you can get in a 1-second exposure, and not disturb the big, bad world with an annoying flash.

[fractalgfx]

Here To freeze the guy mid jump I needed a fast SS, IS would not have helped in this situation.
The guy isn't exactly frozen, there is still a lot of motion blur. I understand the whole issue of freezing action. I was just wondering if the 1.4 would allow a fast enough shutter speed to compensate for camera shake.

It is a little easier to understand if I think of the math.

P * 2^[-(2.8-1.4)] = P/2.639.

Where P is the absolute minimum shutter speed for hand held pictures.

With my 2.8IS, P is about 1/15, or 1/10 if I'm really lucky.

(1/15) / 2.639 = 1/39.6
(1/10) / 2.639 = 1/26.4

Those speeds would be an improvement for slow moving subjects, but motion blur and camera shake will still be issues.

I'd have to be an ass to use the 430ex in a quiet dark restaurant.

[fractalgfx]

forgive me for asking a dumb question but I do not grasp how IS can give me wider F optically speaking? I understand that IS would give me a faster shutter speed at the same F but .... :confused:

Aperature and F-Stop are not the same thing, but they are frequently confused. F-Stop is a measure of the total amount of light passing through the lens. Increasing the aperture by one stop cuts the amount of light in half. Decreasing the aperture by one stop will double the amount of light.

When you calculate the total exposure you have to factor in the amount of light passing through the lens and the shutter speed. Cutting the shutter speed in half is the equivalent to stepping down the aperture by one stop.

[Nickcanada]

Whoa nelly!

I like to think real simple like. :o


Let us use that image above.

my settings were


35mm, SS 1/125, F 1.4 ISO 1600


Now lets imagine I had the 17-55mm 2.8 IS


With that amount of light this is what my settings would be to archive the same exposure.

35mm, SS 1/30, F2.8 ISO 1600


At 1/30 of a second you would not have blur due to hand shake BUT the guy would be a lot more blurry due to subject movement! You said you thought there was a lot of motion blur in the picture I posted, just imagine what it would look like if I had to shoot it at 1/30!!!

That is the difference between F2.8 IS, and F1.4.

So unless you are shooting people jumping up and down in restaurants you probably don't need the 30mm 1.4. Just tell people to sit still.

Now if you are talking still life photography like this.....

35mm, SS 1/15, F1.4, ISO 1600 (hand held, no IS)
http://i91.photobucket.com/albums/k320/livelifelivepics/IMG_0160copy.jpg

To make that shot you would need....

SS 1/4, F2.8, ISO 1600


I think some people could hand hold that shot with the 17-55mm @35mm with IS so you are dealing with about the same ability to let light in between the two lenses but the 1.4 would have a more shallow DOF then the 2.8. That can be good or bad depending on how you look at it.



One more example.

35mm, SS 1/200 F1.6 ISO 1600 the chick was moving back and forth so I needed a fast SS to freeze her.

http://i91.photobucket.com/albums/k320/livelifelivepics/The%20One%20Night%20Band/IMG_3477-Editcopy.jpg

With the 17-55mm your settings would look like this.

SS 1/60, F2.8, ISO 1600

That would not be a fast enough SS to freeze her movement.

Does that make more sense?

[Nickcanada]

I was just wondering if the 1.4 would allow a fast enough shutter speed to compensate for camera shake.



That is a loaded question. It depends on how slow a SS you can hold (w/o IS) and how much light you are dealing with. If I'm shooting people I want to have at least 1/60 -1/80 SS. At 35mm I will have no problems hand holding those SS, because on a good day I can go as low as 1/15, so if I'm shooting people I worry about freezing their movement and I know I'm gonna be able to hold it steady.

If we were talking the 50mm, 85mm, or 135mm it would be completely different because you need a faster SS to eliminate hand shake blur the longer the focal length.

I can't hand hold a shot steady at 1/15 @50mm but I can at 35mm and that is one of the reasons I like prime lenses. I never have to worry about zooming into camera shake.... but that is off topic.

[fractalgfx]

If we were talking the 50mm, 85mm, or 135mm it would be completely different because you need a faster SS to eliminate hand shake blur the longer the focal length.

I thought it was pretty clear that I had to be talking about 30mm.

This thread really has gone in the wrong direction. When I started this thread I wasn't thinking about moving subjects, faster shutter speed is an obvious benefit of a faster lens, so lest not wast any time there.

If you look at my shutter speed calculations, it is pretty clear that I am not trying to shoot a moving subject at 1/15. In a worst case scenario there is barely enough light to get a usable picture. The point of my calculations, and the intent of this thread was to show that for still subjects, the worst case scenario would be roughly the same for either lens.

Time for Don to tell me that I can have IS at F/1.4 with a Sony.

[Nickcanada]

Off topic? Look at the title of the thread. I've been displaying the benefits of F1.4 over F2.8 IS.

Both lenses will let in about the same amount of light. The 2.8 IS will let in the light by letting you shoot at longer shutter speeds the 30mm 1.4 will open the aperture up more. If you need more light then that, buy a camera that has ISO 3200, or use your flash, or use a tripod.

If you want to measure the tinny difference between the two lenses light gathering abilities go ahead but it boils down to this, do you need to stop motion. You say no, so you do not need the sigma 30mm 1.4 IMO. Simple.

[DonSchap]

To be quite honest, I have not gone into taking lowlight moving images with the SONY α700 and the 50mm f/1.4 that I have.

Admittedly, that might be a fun test ... but I rarely put myself into such situations, these days. My nightclubbing images are way behind me.

It might be fun to try though, so in a future line up, I'll try to do some combinations with the two just to get a feel for how far you can push f/1.4, using IS with ISO-1600, ISO-3200 & ISO-6400.

But I still believe using IS to acheive images is a shaky intent (pardon the pun) to sure. It's a feature ... but not really intended to be a "constant diet" approach to photography, or you are going to be sadly served when you need to use a lens that doesn't have it.

That's simply my take on it ... (shrug) :o

[Nickcanada]

They are performing arts photographs Don. ;)






Nightclubbing..... HA! :p

[DonSchap]

I apologize for mischaracterizing these images. But, I do believe we are thinking along the same lines.

Obviously, there is a "need for speed" in these moving images, so IS or not ... I don't think it will help, because the subjects are moving ... doesn't matter two hoots what the camera is doing, unless you can pan and synchronize the camera to the moving subject. In this case, I guess the word "impossible" comes to mind since they are unpredicatably gyrating and shaking "their thing", but there have been weirder effects, to be sure.

To freeze 'em ... we're looking at the ragged edge of 1/50th, nominally, unless they are really moving ... and then, it's the killer 1/125th or worse. LOL

You could probably have a f/1.0 lens and still might be "light starved" getting these. Can you imagine, a $5000 prime, just for this?

Maybe ... just thinking , here ... what about "continuous drive"? You might just get something salvageable, catching them at the instant they are frozen between moving to and fro. I suppose that may be worth a try, once or twice. :rolleyes: (<- Andy's "looking thoughtful" icon)

[Nickcanada]

Hahaha, I was just joking around you can call it whatever you want Don! :)


It sure is a challenge sometimes! but even trying to catch a candid shot of someone laughing or even an animated talker at a dinner table can be just as challenging without using flash to freeze them, bounced flash of course! ;)

I'm always talking about the virtues of high ISO but many times it's much better and easier to just slap on the old flash gun and zap em'!

Rooz made a comment in another thread about us Canon shooters always showing off our ISO 1600 shots and not focusing on controlling light. He has a valid point, sometimes available light is just plain sucky and it needs the tender care of a light tech (that's you;) ). Although I do still think he's just a little jealous. hehe.

[DonSchap]

I have to tell ya, Nick ... the α700 does offer a variety of information and control features - on the fly.

I mean ... just look at this thing ...


30963


Talk about feedback, eh?

[Nickcanada]

That looks sweet! too many buttons for me. :D I just leave my camera on F1.4 ISO 1600 and snap away!!! :cool: