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Old Apr 21, 2006, 6:49 AM   #1
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hello all, Ive been doing event photography, mostly club work, where it I cannot rely on ambient lighting.

At first I was using the red laser AF assist on my external, hot shoe mounted pentax flash, as my ist Ds doesnt have any af assist.

Since then I have taken the external flash off camera, into my left hand, and am tiggering it optically with the built in flash of the Ds. I shoot full manual with high aperature (F8), setting the focus ring to about 1 meter, as 99% of my subjects are at that range. My photos come out well, and the faster shooting from all manual settings are great perks.

But now Im ready to invest in another dslr, and would like the option to shoot AF; and now need to know which dslr has the best on-camera AF assist illuminator or lamp.

I know the nikon D70 has a lamp, but understand it doesnt work for continuos shooting, an implemention by nikon to maximize the lamp bulb life. (I shoot 100+ pics per hour!)

I saw another event photographer using a fujifilm camera with a very strong, green colored AF assist lamp; I checked fujifilms site, and it seems like it was a non-dslr...

My pentax ist Ds rapidly fires the pop up flash for AF assist, and is basically unusable.

Does anyone have good experiences with any DSLR regarding AF assist and low light shooting? of course using an external flash with the red laser AF, like the D70/SB600 combo would solve the problem, but I really really like holding the external flash with my left hand, with a very light camera on my right, utilizing the pop up as fill.

Ive considered getting a small fill flash for the camera with AF assist, but there arent that many models, and those that do dont take advantage of the new ttl flash technologies (cullmann AF 20 is a great example - super light flash with AF assist, but doesnt work with nikon D70 ittl, and lacks manual vari power.) One idea is using the

Im pretty set on upgrading to the D70, foregoing the on camera fill flash, and using an SC29 cable with af assist to trigger an sb600 in my left hand. But it sucks not having a fill flash!

The best combo would be a DSLR with reliable AF assist, and using the onboard pop up with a hand held external flash - synced wirelessly, wired, optically, it really doesnt matter.

Ive done extensive research into this, and find it very hard to get information on on the reliability of AF assist in camera reviews. And I cant see a BH or adorama sales guy to be of any help either, sadly...

Please share your experience, or post a link to a thread thatll be of help. Ive searched and couldnt find.

thanks,

anrei d.






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Old Apr 21, 2006, 8:29 AM   #2
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What lens are you using? Are you sure that the lens isn't the reason you can't use AF?

The camera's AF sensors need to see well enough to focus. So, if your lens isn't bright enough, that could be the primary issue.

I've managed to get focus lock in lighting so low I've needed 1/4 to 1/6 second shutter speeds at ISO 3200 with my 28mm f/2 on a Maxxum 5D (although it can be tough to lock focus in candlelight).

I'm thinking about replacing it with a 30mm f/1.4 (which is twice as bright). lol

I couldn't tell you how the AF assist works (it can use the pop-up flash), as that's the first thing I turned off on my 5D (I can't stand AF assist). I'm using a non-dedicated Sunpak with it when I need a flash (no AF assist).

Hopefully, others that use AF Assist on their strobes will respond. I never have liked it. I'd go manual focus before using any kind of AF Assist.

But, my guess is that your lens is not up to the task, especially if it's a zoom, as even an f/2.8 zoom can struggle in low light. An f/2 or brighter prime is the way to go around here in candle lit clubs.

If the AF sensors are similar in the *istDs and *istD, one reviewer found the lowest light the *istD using the FA 18-35 mm f/4-5.6 would focus in was around 2.0 EV on it's wide end (18mm) where it's brightest. It would probably need twice as much light on it's long end.

The Pentax FA 28-105 mm f/3.2-f/4.5 is a bit better. On it's wide end, it could lock focus in light as low as 1.2EV at f/3.2. That's still brighter than some clubs around here.

The Pentax FA 50mm f/1.4 would focus down to 0.1EV without AF assist (flash). That's about what I can focus in using my 28mm f/2 (so the AF sensors in my KM may be a bit better).

In other words, compared to using a 50mm f/1.4 with your Pentax, you'd need 4 times as much light with the 18-35mm f/4-5.6 lens to lock focus, or more than twice the light with the 28-105mm f/3.2-4.5 (each 1 EV step represents twice as much light).

For dim clubs, I'd get a bright prime. Sigma will be shipping their new 30mm f/1.4 EX DC in Pentax mount. That would be a good one to look into. f/1.4 is 4 tiimes as bright as an f/2.8 zoom (with more difference if you're using a dimmer zoom). It's selling for around $429 in Nikon and Canon mount. So, "street prices" should be about the same for KM and Pentax mounts when dealers get them.

http://www.sigmaphoto.com/lenses/len...mp;navigator=6

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Old Apr 21, 2006, 1:20 PM   #3
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Sounds much like my minolta 5D, the popup flash works as AF assist but not that well. The external flash (sigma EF500DG Super) has a red light that works well, but dosent work when I use it wirelessly.

Perhaps using a flash cord would solve your trouble? Except for the fill flash.

Using your existing flash as a manual slave would give you the on camera flash as fill, but you still need AF assist from somewhere. Don't some cameras have it built in separate from the popup flash?

Maybe a better lens? I cant manually focus in dim light, as my several attempts have shown.
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Old Apr 21, 2006, 3:16 PM   #4
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better lens probably would give me better AF ability in low light. Im thinking of sticking a tokina 12-24mm or an 18mm prime on a D70. Currently Im using a stock 18-55 on my ist Ds.

But ya, using the popup for fill and holding the external gives excellent results. Great lighting and mobliity with no hand/arm cramps.
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Old Apr 21, 2006, 3:34 PM   #5
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Wide lenses aren't going to help. They're not the brightest around either.

I don't know what your experience level is, so I may be preaching to the choir.

The aperture scale in one stop increments goes f/1.0 (theoritically larger apertures are availalbe, too), f/1.4, f/2.0, f/2.8, f/4.0, f/5.6, f/8, f/11, f/16, f/22, etc.

With each one stop move to a smaller aperture (represented by higher f/stop numbers), you will need shutter speeds twice as long for proper exposure, given the same lighting and ISO speed.

That also means that with each one stop move to a smaller aperture (higher f/stop number), you lose half the light getting through the lens to the AF sensors and viewfinder. So, a brighter lens can mean a dramatic difference in low light Autofocus ability.

Your kit lens is *very* dim. That's not the kind of lens you want to use in low light.

If you're at the full wide angle lens position, you'll have f/3.5 (not too bad, except for dim clubs). An f/1.4 lens would be about 5 times as bright. Using much zoom, your lens stops down to f/5.6. Then, an f/1.4 lens would be 16 times as bright (not a typo).
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Old Apr 21, 2006, 3:49 PM   #6
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Why do you have to use popup for fill and hold the external?

Are you shooting groups or one person at a time? You need a fast prime, f1.8 atleast. Though DOF would be problem for the group. Use some diffuser on your external flash and mountthe flashusing a nice flash bracket.
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Old Apr 21, 2006, 4:00 PM   #7
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bobbyz wrote:
Quote:
[snip]You need a fast prime, f1.8 atleast. Though DOF would be problem for the group. Use some diffuser on your external flash and mountthe flashusing a nice flash bracket.
[/quote]

If he's using flash, then he can set the aperture to anything he wants to for Depth of Field purposes. Just because a lens has larger available apertures, doesn't mean that you have to use them at wide open apertures.

But, since an AF lens always focuses at wide open apertures (then stops down to the desired aperture for shooting), AF is usually *much* better in low light with a brighter lens, even if you're shooting with it stopped down some.


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Old Apr 22, 2006, 4:40 AM   #8
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JimC wrote

But, since an AF lens always focuses at wide open apertures (then stops down to the desired aperture for shooting), AF is usually *much* better in low light with a brighter lens, even if you're shooting with it stopped down some.


- this is very good news - so I can shoot at F5.6 and up, and the focusing will be done at wide open! I need to look into this a little more.

especially with smaller groups, I find the 2 flash method works well. Ive attached an example - you can see the flash reflecting off the wall on the upper right (from the handheld flash in my left hand providing most of the light) - without the pop up fill flash the shadows on the faces of the 3 main people would be too drastic. Shot at 1/6, F8, 18mm (on a chinsy 18-55). Its also done at manual focus, so if you look closely, you can tell its not that sharp.

Im leaning towards shifting between AF and MF, depending on circumstances, for the above example, I would have liked to done it in AF, since I had time for them to pose. I dont have the bucks for F1.4 lenses. I think the best I can do is F3.5, as I cant afford anything more than 500. But I definitly have something to look foward to in the future!





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Old Apr 22, 2006, 4:51 AM   #9
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At the party I took the above photo, I met the photographer for lastnightsparty.com, a high profile party photo website.

He was shooting fast as hell - not bothering with the viewfinder - just point and shoot really fast. He was using a canon digital rebel, and from the photo I took of him, the switch on the side of the lens was set to AF... how does he do it!!

One thing Ive done in the past is separate the shutter and AF, using the AE lock button as AF, and having the shutter button just trigger the shutter. That way I was able to point, hit AF and then hit shutter, to minimize any camera computer lags.

Maybe this is merlin broques' secret?

Im pretty set on the D70 with tokina 12-24, which is F3.5, or a sigma 18mm lens at the same aperture, both AF. This will let me switch between the AF and MF.

As for fill and external, Im going to have to experiment with:
no pop up, and external with sc29 cable (with AF assist)
pop up tiggering the external optically (or with commander mode)
and the standard external on hotshoe method.
I dont like brackets as it just adds weight and is too bulky for tight spaces. Plus it looks way too serious!






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Old Apr 22, 2006, 7:26 AM   #10
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That's up to you. I wouldn't try shooting in low light with a lens that dim. f/3.5 is barely adequate for AF in some home interiors at night, much less a darker club. But, if you want to use a flash with AF assist, that may be a solution.

I'd go with a prime. My favorite low light lens for my KM 5D is the Minolta 28mm f/2 (but I may end up replacing it with the Sigma 30mm f/1.4); and my 5D will probably lock focus with an f/2 in light you'd need f/1.4 with the Pentax.

As for the D70, make sure to try out the viewfinder. Your Pentax viewfinder is much better, and the D70 may be challenging to use if you ever need Manual Focus.



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