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Author Topic: Photo Question  (Read 11604 times)

HPsauce

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Re: Photo Question
« Reply #15 on: August 21, 2009, 10:24:07 AM »

If you are in a relatively small space, and especially if the ceiling is white, make a deflector out of white card or similar so that the flash is "bounced" off the ceiling rather than directed at the subject.
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UncleUB

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Re: Photo Question
« Reply #16 on: August 21, 2009, 10:48:26 AM »

Thank you for taking the time to reply to my queries. :)

I will certainly try the 'tissue paper' over the lens next time.


We have enough 'mugshots' here now to warrant my own filing cabinet in Scotland yard.  :D
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sevenlayermuddle

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Re: Photo Question
« Reply #17 on: August 21, 2009, 10:50:09 AM »

>>> Oh and my camera is a Sony A200 DSLR <<<
So the flash is in line with the lens..............

You may think I'm being pedantic, but from what I can see of that camera, I think the flash is not truly 'in line' with the lens, it's directly above it, and the fact that the picture is being taken 'portrait' means it is to one side of the lens, so that is the cause of the shadows.   A flash that was truly 'in-line' with the lens would need to be physically inside the lens, and I don't think that's trechnologically possible (this week, at least)?

That does mean that simply taking the picture landsape would shift the shadow to beneath the image rather than  to one side.

I also agree with all else that's been suggested, diffusing the flash with paper, and/or reflecting it off a cieling, etc.  One other suggestion,  make sure the wall behind the subject is well lit either by daylight or by pointing a spotlight at it, as that will reduce the shadow as well.

Good luck!

- 7LM

PS: Uncle, I'm deeply envious of your camera, it looks much better thyan anything I've ever owned  :)
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tuftedduck

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Re: Photo Question
« Reply #18 on: August 21, 2009, 10:58:59 AM »

@ unkyUb

>>>We have enough 'mugshots' here now to warrant my own filing cabinet in Scotland yard<<<

I think that's why they call it "Rogues Gallery"  :lol:
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UncleUB

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Re: Photo Question
« Reply #19 on: August 21, 2009, 11:47:13 AM »

Quote
PS: Uncle, I'm deeply envious of your camera, it looks much better thyan anything I've ever owned

I am really pleased with my Sony A200,it was a Christmas present to myself. :)

I decided on the Sony after much research and also with a lot of good camera knowledge and feedback from our very own camera expert...TD  :clap2:
I bought the twin lens model from Jacobs which for the price I paid at the time(£322.89 which included £30 cashback from Sony).This is my first DSLR so still finding my way around it

As you can see it is quite a bit more expensive now (£419.99 + del)

http://www.jacobsdigital.co.uk/index.php?target=products&product_id=10734
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tuftedduck

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Re: Photo Question
« Reply #20 on: August 21, 2009, 12:21:48 PM »

HP Sauce mentions "bouncing" the flash off a suitable reflector.

This is a perfectly valid and often used technique and may go a long way to sorting out shadows, as well as giving
opportunities to be " creative" and inject shadows if you want

However, with a built in flash such as on your Sony or in compacts, this bouncing can create problems.

In outdoor photography where no flash is used, correct exposure is achieved by using the correct ratio of exposure time and
aperture.

In flash photography, it is a little different in that correct exposure is a function of the ratio of aperture to flash-to-subject
distance* (* see notes below)

I assume that you shot in auto mode.......now the camera will have measured available light ( via its meter),
flash-to-subject distance (via the auto-focus function) and the set aperture and will then blip out the required amount of
flash.

Now, in order to soften the shadow, we try to bounce the flash................the available light is the same, the aperture is the
same...........but the flash-to-subject distance has changed.........the flash has to travel, instead of from the camera to the
subject, from the camera to a reflector and back to the subject.

Simple arithmetic...lets say camera to subject is five feet...bounce off a ceiling (say)....so the distance is now camera to
ceiling ( 7 feet, 10 feet...?? in TD Towers that is 14 feet) and then back down to the subject.

OK the figures are not so extreme if you are bouncing to a mirror, white sheet or whatever held to one side of the
camera....nontheless, the camera to subject distance has changed.......and the flash in the camera does not know that... and
that extra distance may be such that no or very little flash arrives at the scene of the crime, resulting in an underexposure.

That is why bouncing gives the best results when using a flash gun with variable power ouputs, letting you crank the power
up or down to give good, shadowless images. ( and it saves doing some aritnmetic required if you try to calculate the effect
of bouncing with a built in flash by moving the camera nearer the subject and other such hassles.)

* notes
I said above that correct exposure with flash is a function of aperture and flash to subject distance.
Shutter speed comes into the calculation only in that there is a maximum speed at which you can fire with flash, the sync
speed,............faster than that, the shutter has shut/partially shut or the image capture bespoiled by virtue of the camera
not having had time to "see" all the flash before it shuts.
The power of the flash, the "guide number" also comes into play, but with a built in job in an auto mode the camera takes care of that.
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UncleUB

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Re: Photo Question
« Reply #21 on: August 29, 2009, 06:53:00 PM »

Another question, re: night time outdoor photography.......

Am I right in saying that you don't use the flash when taking night time outdoor landscapes
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roseway

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Re: Photo Question
« Reply #22 on: August 29, 2009, 07:01:45 PM »

I'm no photographic expert, but as flash has a limited range it would only brighten up objects in the foreground, which probably isn't what you want with a landscape.
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  Eric

tuftedduck

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Re: Photo Question
« Reply #23 on: August 29, 2009, 07:36:38 PM »

Roseway is correct..........flash has a very short range and a very narrow angle...fine for close ups but not so good for wide vistas, the way to go is to allow for a very long shutter speed ( which is why you will be using your tripod), I think the Sony can go up to 30 seconds exposure. If that is not enough ( take a pic and check it on the rear screen), push the iso rating up...........moving that rating from say 100iso to say 200iso will reduce the required shutter time by 50% as by  doubling that rating you effectively double the sensitivity of the sensor.
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tuftedduck

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Re: Photo Question
« Reply #24 on: August 30, 2009, 06:42:16 AM »

Just to expand on the above.......I should have explained last night, but was a bit too  :sleep:

As an idea as to how effective is the flash built into the Sony ( and all other slrs) consider this.

I mentioned  in an earlier post that whilst correct exposure in natural light is obtained by seting the right combination of shutter speed and aperture, correct exposure for flash is a combination of aperture and flash to subject distance.
So if you know how far away from the flash is your subject you can set the aperture to suit.......and if you have decided to shoot at a particular aperture, you can calculate up to what distance the flash will be effective.

But what is the basis for this calculation, you need a starting point.
All flash units whether built in to the camera, independent and fixed on the camera hotshoe, or in the studio are rated with a "Guide Number" which is an indicator of both the power of the flash and of the resolution of the wee sum mentioned above.

The "Guide Number" on your Sony is expressed as GN12 in metres at 100 iso.

And the calculation is GN = distance in metres x f-number ( aperture)

So lets say you want to photograph an object three metres away from the flash.......the calculation would be:-

12= 3 metres x f-number...................................put another way 12 divided by 3 = 4......so you require an f-number (aperture) of f4

On the same basis as that, if you wanted to use f4 and wanted to calculate up to which distance the flash would be effective, then 12 divided by f4 = 3 metres,


As you can see from the above figures, on your Sony and using the built in flash and taking a fairly wide aperture of f4..........the flash is effective up to only 3 metres  ....no good for landscapes. And of course if you wanted to shoot at a decent landscape aperture of say f22....then 22 into GN12 gives an effective range of only about half a meter.
These figures are based on using an ISO rating of 100, if you crank that up to 200 you will get twice the effective flash range......taking the above example up to 6 metres,

Time to get the calculator out... ;D

On any of the camera auto-modes, the sum is taken care of in camera, but whoever does the sums the result is the same...small flash units can be effectively used at only short distances from the subject.
« Last Edit: August 30, 2009, 08:16:10 AM by tuftedduck »
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UncleUB

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Re: Photo Question
« Reply #25 on: August 31, 2009, 08:53:10 AM »

Thanks once again TD (and Eric) for taking the time to reply to my query. :)
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tuftedduck

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Re: Photo Question
« Reply #26 on: August 31, 2009, 08:56:48 AM »

It's a pleasure, unkyUb.. :)
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roseway

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Re: Photo Question
« Reply #27 on: August 31, 2009, 09:09:16 AM »

Always a pleasure (particularly when TD does most of the work :) )
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  Eric
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