AF 280T Flash Question

Discussion in 'Pentax' started by jordan2240, Dec 13, 2014.

  1. Hello all,
    I have a recently-acquired AF280T flash, and am trying to learn how to use it. The manual indicates that for the auto-modes of red and green, the red is the more powerful. However, in testing from the same distances, the green is generating the greater amount of light. Also, if I have the flash on the green mode, and the camera aperture reads 5.6, when I change it to the red mode, the aperture changes to 2.8. Wouldn't that indicate the red is giving less light, thus needing the larger aperture to get the same exposure as the green at 5.6?
  2. Should have mentioned I'm using a K-5ii. Also, even at close range, the red mode seems to create less (and the correct) light, and the manual specifically recommends green for close-ups.
  3. Maybe the manual (I never had one) is not well written. Red mode uses wider f-stop to grant more reach, in case you might need it. Thats all.
  4. Note that the TTL feature of the AF-280T won't work with the K-5ii, you'll just have to use the flash in auto mode with it's own sensor. But, since you can "chimp", you can fine tune the exposure.
  5. bill i have a manual. pm me if you would like a pdf
  6. Thanks for the offer David. I did download one, but for the life of me, the results I'm getting don't seem to correspond to what the manual is saying. Either that, or I'm misreading it. Funny thing is, I also have a Pentax AF200T, and it gives me the same results on the red and green auto modes as the 280t (ie the green is providing stronger light). I can get the flash to work nicely when I shoot and 'chimp,' but I wish I actually knew what it was doing. Changing the flash ISO doesn't seem to do anything either, so not sure if that typically works with digital or if the flash is just not functioning properly.
  7. The manual's not real specific though there may be some actual difference. It says (summarizing a bit):
    • GREEN setting is used for low flash output
    • RED setting for high flash output
    • for distance 1m-3.5m (3.2'-11.5') green can save batteries (or RED can be used when smaller aperture is desired)
    • Overexposure results when red setting is used for subjects closer than 1m
    • Underexposure results if green is used for subjects beyond 3.5m
    These statements suggest that there may be some difference in power between the settings.

    It sounds like you're trying to use P or Tv and have aperture set automatically, probably the flash's dedicated features are telling the camera what to set the aperture to. I'm not sure that's the right way to go. I would probably use M with the aperture, shutter, and ISO set as I want, set the ISO on the flash to match. In either auto mode, the flash will cut output when it believes (from the front-mounted sensor which according to the manual has surprisingly narrow 20 degree coverage, a field of view similar to a short telephoto like 80mm on a DSLR) sufficient exposure has occurred. You can then adjust output to taste by changing ISO (without changing flash ISO) or aperture on the camera body.
    If you don't have shutter, aperture, and ISO fixed (M or X modes) then you're not isolating the effects of the red and green modes because the flash will cut exposure when it thinks it's provided enough. And even then, exposure might not be different if you're in the middle of the effective distance range.
  8. Andrew, I probably should have mentioned that I've tried various modes on the camera, including full manual, with the same result. The green always seems to put out more light. You can even tell by the sound of the flash recycling afterward. I specifically shot some close-up macro shots, and the red gave better results than the green, which over-exposed the subject. Testing from across the room (approx. 20 feet), the green gave the greater illumination. Can't recall exactly, but I think I was at f/8 and sync speed. Ah well, I'll just use it the way it works best and not worry about it - or maybe do some more testing to verify results. Thanks for responding.
  9. Thanks to you, I just purchased one from KEH ($30)because I wanted a compact flash with tilt and swivel features. As far as I can tell, the green puts out less power than the red, so it must be your flash. I tested my flash with a subject about 18ft away. ISO 200; f5.6; 1/80 sec. When I took the picture at these settings, with the flash set to Red-auto the picture came out slightly over exposed by about 1 stop. When I switched to Green-auto with the same settings, the picture came out properly exposed ?
  10. Then again Bill, at close range it seems the green mode put out more power and the red mode less power. I'm still investigating...
  11. Harry,
    Will be curious to know what you find out. What camera are you shooting with? I also have an AF200T, and it seems to react the same way as far as the red and green are concerned. Haven't been able to find any info on the web regarding this, so I guess most just find the setting they like and go with it. That's what I'll do as well, but I'm curious about how the thing is actually supposed to work. Of course, it wasn't designed for digital, so might be totally different with film.
    What I've basically found with mine is that the red auto setting seems to give the most consistent properly-exposed result.
  12. Bill, the Manual states that for 3 feet or less you should use the Green setting. For 3.5 feet or more you should use the Red setting. That's if your camera is set to 'P' mode, (not sure what camera you are using), but I'm using the K-5 II, then the flash will automatically sets the shutter to 1/60 and the aperture to f11 for Green and f5.6 for Red.
    Which means the flash is putting out more light(not power) because of the increased aperture. However let's say you wanted to bounce the light of a wall or ceiling then you would have to open the aperture by one or two stops to get the proper exposure, either that or increase the ISO. So this is what's got me baffled because you can change the aperture regardless whether you chose the Green or Red mode ?
    I gave up trying to understand what the manual means. Maybe on the next rainy day I'll try to figure it out...

    What I do now, is place my camera in Manual mode while the flash is set to Auto(Green/Red) same technique I use with my Canon speed lights. Then I set the Aperture and Shutter speed on the camera to determine the right output. The only problem with this method is that you have to look at the lower scale to determine if the shutter/aperture setting you set on the camera is appropriate to get a properly exposed photo of your subject. This is not easy in dim lighting environments.
    The lower scale will tell you which F stop is appropriate(12ft=f11, 16ft=f8, 24ft=f5.6 etc.). Remember that the max light output for the Green setting is 16 feet and the max output for the Red Auto mode setting is 32 feet. If you want to bounce the flash off a wall or ceiling, then you might have to recalculate by opening one or two F stops.
    I'm not sure, but I think the max sync for this flash is 1/80th of a second, but I went all the way up to 1/125th with no problems.
  13. Remember that the max light output for the Green setting is 16 feet and the max output for the Red Auto mode setting is 32 feet.
    Actually this is not the case. The flash determines the ultimate aperture depending on the ISO. The ultimate aperture for ISO 100 is f8 in green mode and f4 in red mode. For ISO 200 the ultimate aperture is f11 in green mode and f5.6 in red mode.
    If you are using a wide angle filter or a telephoto filter, then the ultimate aperture increases by one stop when using a wide angle filter and decreases by one stop if you are using a telephoto filter. Let's say if you are using ISO 200, then the ultimate aperture set by the flash in green mode would be f11.
    However if you were using a wide angle filter, then the ultimate aperture would have to be adjusted to f16. If you were using a telephoto filter then the ultimate aperture would be adjusted to f8. Same thing for the red mode, but now the ultimate aperture chosen by the flash in red mode is two stops less at f5.6 at ISO 200. Using a wide angle filter you would have to adjust to f8 and using a telephoto filter you would have to adjust to f4.
    Green mode is used when your subject is from 2 feet to 3.5 feet or greater away, while red mode is used if your subject is from 3.5 feet or greater away.
    At least I think that is what is going on ?
  14. Thanks for experimenting with it Harry. I'll have to do some additional myself to see if I can fully understand what's happening. I also am shooting with the K-5 II, and have tried P mode, M mode, and X mode, as well as Av. I think M mode is the way to go with it, though frankly, I'm not sure how P mode works. I had the shutter up to 1/180 (the camera's sync speed), and all was well. Thanks again.
  15. Bill believe it or not I turned on my AF280T today and instead of the flash setting the aperture to 1/60th @ f11 for Green and 1/60th @ f5.6 for Red, it decided to choose 1/80th @ f13 for Green and 1/80 at f6.3 for Red ? However, the pictures came out properly exposed with these settings ? Now I'm totally confused !
  16. Harry,
    Yes, mine has me totally confused as well with the settings it chooses. I'm pretty sure it has automatically chosen the max sync speed at times as well. While I'm sorry to hear yours is confusing as well, I'm glad I'm not alone.
    But in the end, like you said, it's exposing correctly or can at least be set to do so, so it'll get the job done. For $30 for tilt and swivel and decent power, can't really complain!

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