Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-14-2011, 11:14 PM   #1
Senior Member
trishytee's Avatar

Join Date: Jan 2009
Location: Mandurah Perth
Photos: Gallery | Albums
Posts: 221
Using the flash

I am a total moron when it comes to using the flash so does anyone know of a good book? I find that if I am on, say f8 outside late evening, my shutter speed will read at, say, 15 seconds. Then I use the flash and get 'white out'. I really stuff up heaps of pics this way. Again if I use P the settings are for low light and using the flash still over exposes. If I pick up my crappy little digital and use that everything is just right. I have been using an onboard flash head both on and off, but just can't get it right. So any books you think I could use please let me know.
thanks

09-14-2011, 11:23 PM   #2
Veteran Member




Join Date: Apr 2011
Location: San Diego
Photos: Gallery
Posts: 883
why go buy a book when there are plenty of websites out there on the subject? Adorama has a nice series on how to use a camera and has some episodes on flash usage. Strobist is one of the more popular sites out there on flash photography. I'm sure a quick search on youtube will turn up dozens of videos on exactly what you're looking for.

one of the best things you can do for yourself though is just learning how to shoot in manual.
09-15-2011, 12:55 AM   #3
Senior Member
trishytee's Avatar

Join Date: Jan 2009
Location: Mandurah Perth
Photos: Gallery | Albums
Posts: 221
Original Poster
I prefer a book so I can have it in bed!! Plus I do seem to do ok in manual, I just mess up with the flash. Plus i seem to need something that shows what not to do.
09-15-2011, 03:06 AM   #4
New Member
FlashGordon's Avatar

Join Date: Aug 2010
Location: Espergaerde, Denmark
Photos: Gallery | Albums
Posts: 14
If I should pick one of the many books about the subject, I will go for "Speedliter's Handbook" by Syl Arena. The book is dedicated to Canon's Speedlite system, but if you ignore the system specific instructions it is great for other brands and general flash techniques.

09-15-2011, 04:25 AM   #5
Site Supporter




Join Date: Oct 2006
Location: Dayton, OH
Photos: Gallery
Posts: 4,155
It sounds like the camera isn't recognizing that you are using a flash. Are you using the built in flash or a flash mounted on your hot shoe? If an external flash, what is the brand/model?

Tim
09-15-2011, 05:41 AM   #6
Senior Member
trishytee's Avatar

Join Date: Jan 2009
Location: Mandurah Perth
Photos: Gallery | Albums
Posts: 221
Original Poster
HI, Tim I am using a mounted flash. Pentax 3 ... (sorry about to go to work and don't have time to get the correct number) I also used the combi wireless unit as well.
09-15-2011, 05:48 AM   #7
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
Aside from the questions people have posted, like is your flash compatible with the camera etc, there are a few other things to consider.

first of all, you need to know how flashes are rated.

THis is using a rating called a guide number, which is usually expressed in either feet or meters, and an ISO rating of 100.

Tge guide number gives you the distance in feet or meters (depending on reference), from the subject, to the camera for a camera mounted flash, at an aperture of F1

in general GN = distance x F Number x SQRT (ISO /100) and therefore for your flash if you know the GN the maximum distance you can shoot at is

Distance = GN / (Fnumber x SQRT(ISO/100))

For ISO 100 the last part of the equation disappears, and

distance = GN / Fnumber

If you change your ISO the Guide number increases, or conversly the distance you can shoot at increases.

You can use this equation to set your flash manually,

You will also note that shutter speed is not mentioned here. The flash duration is typically so short, that assuming the natural lighting situation is well below the balanced exposure, 100% of the lighting is from the flash.

With the issue you are discussing, subject over exposed and background black , and assuming all else is correct (i.e. flash is compatible) then you have an issue with composition and metering, where the camera may be trying to meter off the background which is further away from you than the subject.

Remember, and SLR is not a crappy little P&S, it can in most cases outperform the P&S but it requires some user input.
09-15-2011, 09:58 AM   #8
Site Supporter




Join Date: Oct 2006
Location: Dayton, OH
Photos: Gallery
Posts: 4,155
QuoteOriginally posted by trishytee Quote
HI, Tim I am using a mounted flash. Pentax 3 ... (sorry about to go to work and don't have time to get the correct number) I also used the combi wireless unit as well.
With off camera flash, you will probably need to shoot in manual. With the camera mounted flash, you might have a PTTL compatibility issue but we won't be able to tell until you provide the model number.

Tim

09-16-2011, 01:18 AM   #9
Senior Member
trishytee's Avatar

Join Date: Jan 2009
Location: Mandurah Perth
Photos: Gallery | Albums
Posts: 221
Original Poster
Model number is Af360fgz. I was shooting in manual and maybe that is my problem because I am never sure what setting is safe to use. Which is why IMO I need a book to study. As some of the points Lowell has made I need to digest. Plus I cannot go to 100 iso on the Kx. I think I just need to learn more. Meanwhile back to school to learn my sums!
09-16-2011, 05:56 AM   #10
Site Supporter




Join Date: Oct 2006
Location: Dayton, OH
Photos: Gallery
Posts: 4,155
Ok, your camera and flash are definitely compatible. For on-camera flash, I usually set my shutter speed and aperture manually (125-180 sec at f8 or f11) and I let the flash adjust the output to my settings. I would think this would work for your camera-flash combination as well.

However, since I have a non-PTTL and non-wireless camera (ist DS), I don't want to give any incorrect advise. I suggest you start a new post in the Flash and Lighting Technique forum. The real flash experts hang out there.

Pentax Flashes and Lighting Technique - PentaxForums.com

I would word your post something like this.....

I own a KX and an Af360fgz flash. What camera settings would work best for shooting flash on my patio at night so it doesn't 'white out' my friends? Also, I would like to use the flash off camera in the wireless mode. What settings would I need to be able to do that?

Tim
09-16-2011, 12:01 PM   #11
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
QuoteOriginally posted by trishytee Quote
Model number is Af360fgz. I was shooting in manual and maybe that is my problem because I am never sure what setting is safe to use. Which is why IMO I need a book to study. As some of the points Lowell has made I need to digest. Plus I cannot go to 100 iso on the Kx. I think I just need to learn more. Meanwhile back to school to learn my sums!
In my opinion, the best way to use flash is manual exposure mode (M) on the camera, and P-TTL on the flash, at least to start.

WHat I would recommend and this depends on whether you want full flash or fill flash, is to set the aperture of the lens aned shutter speed of the camera to give some level of exposure. For fill flash, you want this to be about -.5 to -1 stop under exposed. Then with the flash on P-TTL mode take a photo, and it should be reasonable in terms of exposure.

If you want to have the background disappear into black, you need to do 2 things, first, move the subject forward from the background, and second, set the "natural light" component of your expsoure to -2 stops or more. Also, for this mode use spot metering not matrix. This may take some trial and error to get the lighting right, but again, working with the camera in manual, and the flash in the P-TTL mode is the best approach.

WHat I have found with pentax cameras is that when used in auto mode, the camera will do everything possible within the range of acceptable available shutter speeds, apertures and ISO, to make the exposure with Natural light only, and use the flash as fill flash, taking care of the shadows only. If you leave it on full auto, you will probably get exposure right across the board, but may not get the effect you want because the camera is doing too much thinking.

As you say, you should get a book, ANY book that discusses flash, flash power and understand the basics of manual flash calculation. Yoou may not want to do the calculations often, but if you understand them, you will understand how the camera is working to a great extent, and then you can make logical selections about the automatic selections and settings you make
09-16-2011, 01:26 PM   #12
Forum Member




Join Date: Dec 2008
Location: Texas
Posts: 51
QuoteOriginally posted by trishytee Quote
I am a total moron when it comes to using the flash so does anyone know of a good book? So any books you think I could use please let me know. thanks
To answer your original question:

"Understanding Flash Photography: How to Shoot Great Photographs Using Electronic Flash" by Bryan Peterson

Bryan Peterson is the master at simplifying photo techniques. His book “Understanding Exposure” is a must-read, as well.

Amazon.com: Understanding Flash Photography: How to Shoot Great Photographs Using Electronic Flash (9780817439569): Bryan Peterson: Books

Amazon.com: Understanding Exposure, 3rd Edition: How to Shoot Great Photographs with Any Camera (9780817439392): Bryan Peterson: Books

I also agree with the Adorama TV recommendation. The host, Mark Wallace, is also very good and each installment is very informative. I recommend this to all my photog newbie friends. Their tutorials are good, too.

Adorama TV from Adorama Learning Center

And yes, David Hobby's site is a must for anyone even remotely serious about understanding flash. He’s the man.

Strobist: Welcome to Strobist.

Study up on slow and high speed sync. Slow and fast shutter speeds require different approaches with flash. The resources I linked go into it nicely so I won't rehash the subject here. I might suggest rereading your flash manual from time to time, as well. As you gain more understanding about flash, the manual will help you learn how to use your particular flash better in different situations.

Cheers,

Kazey
09-22-2011, 10:40 PM   #13
Veteran Member
sterretje's Avatar

Join Date: Dec 2008
Location: Roodepoort, South Africa
Photos: Gallery | Albums
Posts: 3,534
I think lowell covered the basics well (except for a mistake mentioned below). One note is that a flash also has a minimum distance; around 10% of the maximum flash distance. So if you're closer than that to the subject, you will get overexposure.

Using lowell's formula for ISO100, GN=36 and aperture 3.5, the maximum distance is about 10 meters. The minimum distance will be about 1 meter.

Also, be aware that a flash is not at infinite distance like the sun. The sun illuminates everything evenly so things nearby and far away are basically equally 'bright'. With the flash, stuff nearby will be exposed more to the flash light than stuff further away. So if you have a subject at 5 meters (GN36, ISO 100, F/7.0, flash in manual mode full power) the subject will be exposed properly. Anything in the picture further away will however be darker (up to too dark) and anything in the picture closer to the camera will be brighter (up to too bright).

A last note: check the EXIF in your overexposed images; they might reveal what is wrong (e.g. camera decided to use ISO3200)

QuoteOriginally posted by Lowell Goudge Quote
Distance = GN / (Fnumber x SQRT(ISO/100))
Higher ISO will allow for longer distance; the formula will achieve the opposite

Code:
Distance = (GN * SQRT(ISO/100)) / Fnumber
09-23-2011, 06:30 AM   #14
Veteran Member
ChrisJ's Avatar

Join Date: Nov 2008
Location: Eckington, Derbyshire UK
Photos: Gallery | Albums
Posts: 316
When using flash you are taking two exposures simultaneously, the flash component and the ambient light component.

In auto modes (A, P, S, etc.) the camera can control the pop up flash or your AF360 (or any other PTTL compatible flash) for you to balance the ambient component with the flash component. Great for 'fill in ' flash, but not a lot else.

You will get much more control over the ambient/flash balance by going into full Manual Mode, that's manual on the flash and manual mode on the camera, but now the results are down to you.

Note that with any flash shot your fastest shutter speed is 1/180th of a second, the 'X' speed for all Pentax cameras. This is because of the focal plane shutter, 1/180th is the fastest speed you can use where all the sensor is exposed and can see the flash.

It works like this

Aperture and ISO effects both the ambient and flash components.

Flash Power and flash to subject distance effects just the flash component.

Shutter speed (slower than the X speed) effects just the ambient component. This is because the flash duration will always be much faster than the shutter speed (typically less than 1/1000th of a second, it alters with flash power and can be as fast as 1/50,000th of a second with the flashgun on it's lowest power setting. The flash duration is how the flash controls the amount of light it emits).

Probably the easiest way is to set the aperture for the depth of field you want, adjust ISO and shutter speed to get a black frame (not enough light to record anything) introduce the the flash and adjust power and flash to subject distance to get a decent exposure with just the flash component, then adjust shutter speed to get the amount of ambient you want. Sounds a bit of a palava, but get's easier with practice (as does most things). As we're shooting digitally we can just 'chimp' the results and adjust setting empirically ideally a flash meter will give you a spot on aperture (accurate to 1/10th of a stop) when used from the subjects position pointing back at the camera.

Now we have full control, by adjusting the shutter speed we can get everything from a totally black background (fast shutter speed up to the X speed), to allowing that beautiful sunset (poetic license LOL) to be our backdrop with a perfect exposed subject in all the frames. We can adjust the quality of light by using soft-boxes or beauty dishes, or just bare flash, everything about the image is controllable.

The other huge benefit is that we don't need all those TTL connections on the hotshoe, we just need the sync signal, which means we can use cheap radio triggers to take our flash off camera, with all the advantages of altering the angle of light that it brings, we also don't need expensive TTL flashguns, cheap Chinese manual flashguns work just as well.

To see what advantages off camera flash can hold see this site.

Strobist

It's grown into a huge site for the basics check out the 101 Archive.

Your entering into the whole world of flash photography which is a huge subject.

Chris

Last edited by ChrisJ; 09-23-2011 at 06:53 AM. Reason: Editing for content
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
flash, pentax help
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Automated flash systems (pttl) don't begin to use flash zoom potential philbaum Flashes, Lighting, and Studio 8 06-24-2011 04:38 PM
Wireless Flash Triggers for Pentax K20D & 540FGZ Flash? veezchick Ask B&H Photo! 2 11-29-2010 04:07 PM
Sigma 530 Super flash doesn't fire multi flash, any advice? pasipasi Pentax DSLR Discussion 4 11-25-2010 02:04 AM
For Sale - Sold: Metz 48 AF-1 Flash; Pentax off-camera flash cable set (Adapter F, FG (US/UK/CA bigben91682 Sold Items 4 10-12-2010 04:23 AM
Basic Pentax K-x, hot-shoe, flash, flash bracket, wireless question MrPetkus Flashes, Lighting, and Studio 5 04-27-2010 10:57 PM



All times are GMT -7. The time now is 01:27 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top