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10-12-2008, 08:40 PM   #1
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focusing in dark rooms

not sure where to post this, thought this section was good enough

i was at my cousins wedding reception this weekend and i had the nastiest time focusing in a dark room. there was literally almost no light, some spinning light thing and candles really. a lot of the images came out really badly focused, with auto focus it was taking so long to focus and manually (for me) i found it almost impossible.

any help for future events i may run into this? would really appreciate pointers

10-12-2008, 08:55 PM   #2
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What lens were you using and at what aperture?

In general, though, I would try to get as close as possible to any available light if you're not using a flash. Also, for a situation like this I would use spot metering and AF-C.
10-12-2008, 09:17 PM   #3
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My choice here would be manual focusing. If you have one of the Pentax flashes, you should be able to get a focusing grid from the infrared in the flash. I have done this with my AF500FTZ at times. It will even focus on a blank white wall. The flash need not fire if you set it up.

[Edit] - You need an external flash with the red window on the front for this. The internal flash will be more noticeable by the celebrants. In one of those places lit by table candles and disco balls, the red is completely invisible, except to the camera.

Last edited by Canada_Rockies; 10-12-2008 at 09:23 PM. Reason: See note
10-12-2008, 09:17 PM   #4
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QuoteOriginally posted by impete82 Quote
not sure where to post this, thought this section was good enough

i was at my cousins wedding reception this weekend and i had the nastiest time focusing in a dark room. there was literally almost no light, some spinning light thing and candles really. a lot of the images came out really badly focused, with auto focus it was taking so long to focus and manually (for me) i found it almost impossible.

any help for future events i may run into this? would really appreciate pointers
next time set the flash for focus assist, this will trigger small strobes of light, which will give the focusing meter something to focus on

Dave

10-12-2008, 10:35 PM   #5
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QuoteOriginally posted by MidwestMax Quote
What lens were you using and at what aperture?

In general, though, I would try to get as close as possible to any available light if you're not using a flash. Also, for a situation like this I would use spot metering and AF-C.
i was using that kit lens 18-55 :P aperture i wish i knew probably quite large now that i think about

QuoteOriginally posted by Canada_Rockies Quote
My choice here would be manual focusing. If you have one of the Pentax flashes, you should be able to get a focusing grid from the infrared in the flash. I have done this with my AF500FTZ at times. It will even focus on a blank white wall. The flash need not fire if you set it up.

[Edit] - You need an external flash with the red window on the front for this. The internal flash will be more noticeable by the celebrants. In one of those places lit by table candles and disco balls, the red is completely invisible, except to the camera.
i have that same flash, what is that focusing grid you mention? :S

QuoteOriginally posted by dafiryde Quote
next time set the flash for focus assist, this will trigger small strobes of light, which will give the focusing meter something to focus on

Dave
ok.. what?!?! there's a focus asset? lol
10-13-2008, 05:19 AM   #6
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If you use a Pentax (or Sigma ) flash, it does emit a red light beam to help the camera to focus accurately. The bad part of it is that you must remember to turn the flash off before taking the picture if you don't want it to illuminate the scene, then back on for the next "focus assist". The on board flash can be used to assist, too, but the beam is replaced by a white strobe from the flash tube, which is more noticeable.
10-13-2008, 07:50 AM   #7
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The kit lens is dismally dark at any focal length. At 55mm its best is f5.6. That means the lens isn't letting much light through to the viewfinder, so even manual focusing will be difficult. There's a reason you see so much talk about "fast" lenses, typically the FA50/1.4 or some other version of 50mm lens with 1.4 or 1.7 maximum aperture. It really does make a huge difference in low-light situations.
10-13-2008, 08:24 AM   #8
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QuoteOriginally posted by Mike Cash Quote
The kit lens is dismally dark at any focal length. At 55mm its best is f5.6. That means the lens isn't letting much light through to the viewfinder, so even manual focusing will be difficult. There's a reason you see so much talk about "fast" lenses, typically the FA50/1.4 or some other version of 50mm lens with 1.4 or 1.7 maximum aperture. It really does make a huge difference in low-light situations.
Yup. To the OP: If you're using the kit lens in very low light, it will likely struggle focusing. Even using manual focus, you won't always be able to produce a decent shot. Depending on the available light, you can try zooming out to 18mm and that does allow a good amount of light in at an aperture of 3.5. I've actually been able to shoot a concert like that without flash. But in general, you should use flash or a fast lens like the 50mm 1.4

10-13-2008, 09:55 AM   #9
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Spot Focus Beam with AF500FTZ flash

If you set the Pentax AF500FTZ synch mode to SB, only the focus aid is enabled.
10-13-2008, 11:44 AM   #10
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If there was very little light, then focus would be the least of your problems with the kit lens. Even if the lens focused quickly and accurately, the lens does not have large enough maximum aperture to guarantee you a fast enough shutter speed to avoid camera shake (even with SR) or subject motion blur. My guess is that a good chunk of what you are seeing as being out of focus is actually blur from camera shake or subject motion. Also, in order to improve shutter speeds, you need to turn the ISO up. If you didn't do that, then your shutter speeds would have been *hopeless* slow, and if you *did* turn up the ISO, you should be aware that this also tends to rob you of some sharpness.

Posting a few sample pictures (with EXIF info intact) would help. But I think you'll find you need a lens with an maximum aperture of f/2.8 or better to handle low light. And even then, you'll probably need ISO 1600 much of the time.

This is all assuming you weren't actually using your flash. If you were using flash, then things should have been fine, really - so again, posting pictures might help.
10-13-2008, 07:02 PM   #11
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as a person that shoots a lot in the dark and with flashing lights this is what i do.

the flashing lights well there is not a lot that can be dun they throw off the AF ALL the time so MF is a good way around that.

when i photo a wreck i often focice on the police cars becuse there wite and the police ect.. unforms are dark. lots of the time i hope that the deth of feild is deep enff to get what i wont. i also focice on the fierfighters cotes becuse they are refletive and make a good spot to work with.

like every one else sed fast lenes are a must, the kit is a good lens but not that fast

this is an extreme example

http://thephotograph.blogspot.com/2007/04/man-shot-in-staunton-april-22.html

the police keeped the press way far off so i had to shoot with what i had. it was all dark and i had to shoot with my Sigma 70-300 witch is SLOW, but at the time it was all i had they where shot at 1 1/2 second i braced my self agenst a telephone pole and prayed. but i used the police cares to focice on. they are not the prist photos but i was the only one to get any that night. the police where a little over 200 yards a way.

Last edited by nathancombs; 10-13-2008 at 07:18 PM.
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