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02-26-2010, 06:08 PM   #1
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K-X with AF280T . How to use it?

Hello guys,

recently I bought K-x and af280t.

really satisfied with K-x and I wanna learn how to use flash so i got af280t.

but, I recognize after got flash that it doesn't work with p-ttl.

(BTW, what is p-ttl? lol)

I'm a new at dslr so I don't know how to set up the flash.

I understand that can't use TTL mode, but how about AUTO(what is difference between

green and red? )? does AUTO work with k-x well?

please help me out!!

Thanks guys, have a wonderful weekend!

02-26-2010, 06:33 PM   #2
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Hi I have this flash unit & have used it successfully with K10D & K7, I have found best to use in manual mode (H L). The Auto green settings when using up to approx 1.5 metres & red setting when from approx 3.5 - 7 metres from subject (this is according to another manual I have from the AF200T).

P-TTL is only with the newer Flash units suited for Digital - ""P" simply refers to Pentax & "through the lens", other brands have different prefixes.

The following can be downloaded:

Pentax AF280T Flash User's Guide

Hope this helps. Just play around and you will have a few failures & wins get the hang of it to find what works.
03-03-2010, 08:02 AM   #3
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THANX!

I don't get it.. still.. but I'm working on it!!

Thanks for your help. It's really hard to use it...

I wanna be good at it like all you guys~~
03-03-2010, 08:10 AM   #4
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The K-x (and K100D) recognizes the flash and will set itself to the correct aperture and shutter speed. Put the AF280T into the TTL mode, or more reliably, one of the auto modes. Try all three and see what settings the camera picks. It won't do TTL or pTTL, but the thyristor eye on the flash unit will read the light well.

Alternately, you can go into Av and set the aperture to what the flash tells you to, in one of the auto modes. The camera should set shutter speed correctly.

Note that the camera will vary shutter speed based on ambient light, i.e. shorter in brighter light.

03-03-2010, 10:44 AM   #5
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Set the flash to the red or green auto modes. Red is what I used 99% of the time. If your subject is close, use the green to save on batteries.

In program mode the flash will set the aperture and shutter speed. If you want to use AV, set the slider on the back to the ISO you are using. The follow the red or green line (pick the line to the auto mode you selected) and use the aperture it tells you. So in red auto for ISO 200, your aperture will be set to f5.6, for ISO 400 your aperture will be set to f8.

The flash will set your shutter speed for you in AV mode
03-03-2010, 10:59 AM   #6
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With Auto mode on AF280T, the shutter speed you set on camera doesn't really matter for your object to be lighted, as long as it is not faster than your camera's sync speed. You just set the AV & ISO according to what's shown on flash. The exposure of your main object is controlled by the light sensor on AF280T - when enough exposure is achieved, it shuts off the light. This is what "Auto Mode" means.

However, the shutter speed does play a minor role in redering the background. The slower speed, the brighter background.

I find it is better to set camera to M mode when use Auto Mode on AF280T.

p.s.: TTL mode doesn't work for K-x. Manual mode works because you will be the one to calculate and control the exposure - that's part of the fun in photograpy!

Last edited by hyyz; 03-03-2010 at 11:11 AM.
03-03-2010, 11:14 AM   #7
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I find TTL does work, within limits, only the flash actually defaults to auto mode... no actual TTL going on.
03-03-2010, 11:21 AM   #8
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Yeah! That's very likely although I didn't try it. Pentax seems to hint that don't count on TTL flash functioning as TTL flash on DSLR after *ist DS. But they may have implemented it to behave just like what Nesster found out.

QuoteOriginally posted by Nesster Quote
I find TTL does work, within limits, only the flash actually defaults to auto mode... no actual TTL going on.


06-21-2010, 09:05 PM   #9
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Hi everyone,

I just picked up an AF280T to use with my K-X from ebay

However, I'm a little stumped - I've been trying to play with the Red Auto mode to take a picture in fairly low light of a white refrigerator 3 meters away from me.

The results are overexposed, and ghosted.

Perhaps someone can point out if I'm doing something wrong, or the Auto mode of the flash isn't doing what it's supposed to do

1. Flash in Auto Red mode
2. ASA slider set to 400
3. Finder A Check set to "on"
4. Head set to 0 degrees - pointing straight forward

a. K-X set to Av mode
b. ISO set to 400
c. Aperture set to 8 (this is where the thick line touches the distance/aperture scale)
d. ev set to -1/3
e. Shutter speed on camera calculated as 0.5" <===??? really?
f. Lens set to "A" for aperture

What I notice with the image is a ghosting effect and slight (1/3, 2/3) overexposure

What I also notice is that with the flash turned off or removed from the camera, the calculated shutter speed did not change

I get the feeling I'm missing something fundamental; at the same time I want to know if the flash is behaving as it should.

Thanks in advance!

Last edited by corkboard; 06-21-2010 at 09:14 PM. Reason: additional info
06-21-2010, 09:52 PM   #10
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Easiest way to use 280 flash for me on K20 or K-7:

Set camera to M mode, with shutter at whatever speed, 180 or slower, that will render the background well. (Figure this out by experimenting. It only takes one or two exposures!)

Set camera ISO to 400. Set flash to Auto/red setting. Use slider/computer on flash to compute f/8. (note: This slider is only a computer and does nothing to the flash output!)

Set camera aperture to f/8.

Mount flash, turn it on, take photos.

That gives you dead-on flash photos.

For better-looking, more natural lighting, assuming you're shooting inside someplace with a light-colored ceiling, change the camera aperture to f/5.6 and flip the flash to point straight up. Otherwise use same settings. Tweak aperture slightly as necessary.

This works as well and as quickly as any TTL setup I have ever used.
06-22-2010, 06:24 AM   #11
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Thanks for the additional bit of info!

I retried shooting with the method you describe below, and I ended up with an image that was very over exposed

The scene is, again, a low lit room. Most objects around 2-4 meters away from me

1. Set ISO to 800
2. Set Aperture to 11 (described by slider on flash)
3. M mode; thus set shutter to 1/4 second - exposure meter indicates -1
4. Take picture

I tried again, setting the shutter to 1/40 second, leaving aperture. Exposure meter indicates -3 blinking red

Take picture, and the image is now closer to natural - brighter than the ambient light and not over exposed

I thought the flash was supposed to read the K-S's ISO and shutter speed and make adjustments to the shutter speed if both K-X and flash are set to auto mode - i.e. Av and Red Auto?

Have I forgotten to factor something in?

I'll upload pictures later
06-22-2010, 08:28 AM   #12
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After some more digging on other forums, I may have found the reason why the flash doesn't feel automatic

No M or Av - use Tv or P: Pentax SLR Talk Forum: Digital Photography Review

Apparently M or Av mode is not "available" with the flash - Tv and P are

Summary

QuoteQuote:
You can't use either one of those modes as they put you in control of the aperture (which is the only variable the flash can control). Use either Tv or P. Tv is best as P mode always selects a slower shutter speed that corresponded to the sync speed of the older film bodies. With the camera in one of those two modes, the flash will read the ISO and set the camera aperture depending on which of the two distance modes (green or red) is selected on the flash.
Credit goes to GossCTP for the information

I will try again later today and see if this holds true
06-23-2010, 08:57 AM   #13
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After trying out a few more test shots I'm still a little stumped.

Searching through the forums yields that at least on the K20D, the state of the flash (Red or Green auto, flash ready, flash not ready) affects the exposure setting on the camera

https://www.pentaxforums.com/forums/pentax-camera-field-accessories/84042-k10...tml#post853979

A follow up post indicates the same on the K-X

However, no matter what camera mode I use, and no matter what flash mode (auto red/green, manual H/L) - I see no changes to any settings on the camera.

Is my understanding/expectation incorrect? Or do I have a wonky flash unit?

Thanks for everyone's patience!
06-23-2010, 09:34 AM   #14
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Start out with this check list and see if it works for you.
  1. Mount the flash on the camera
  2. Turn it on
  3. Turn on the camera
  4. Set the camera to Av
  5. Select the aperture to match red/green
  6. Set the flash to red/green auto to match
  7. Wait until the flash ready light comes on
  8. [Fn] and enable the flash
  9. Take a picture
06-24-2010, 09:34 AM   #15
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Thanks again for the helpful list Canada_Rockies!

Here were my steps

  1. Mount the flash on the camera
    • Flash pointed straight forward
  2. Turn it on
  3. Turn on the camera
  4. Set the camera to Av
    • Camera indicated F/4 and 0.3" for overall exposure of +0
    • Camera ISO set to 100
  5. Select the aperture to match red/green
    • At ISO 100, F/4
  6. Set the flash to red/green auto to match
    • Flash mode slider set to Auto Red
  7. Wait until the flash ready light comes on
  8. [Fn] and enable the flash
    • Flash mode set to Manual Fire
  9. Take a picture
    • Scene is approximately 3-5 meters away

My overall shot is overblown - white refrigerator is over blown, brown cupboards overblown

If I set the overall exposure down to -1, it looks a little better (shutter speed sped up to 1/4)

At this point it seems like a matter of making adjustments - but should the guide settings on the back be a little more reliable?
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