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09-25-2014, 06:13 AM   #1
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Trouble understanding how AF280T flash works

I just picked up and AF 280T and was wondering if someone could explain how the auto modes work. I was under the impression that the flash could select an aperture for you, and while I can see that the scale is adjusted by selecting the ASA, I am confused on how to use the on board meter.

Do you really just set the ASA, set the camera to the synced shutter speed, set the aperture to the one that lines up on the back of the flash, move the head into whatever position you want, hit the test button, and then look to see if the A check light flashes? Is that really how the meter tells you the picture is properly exposed?

I may be overthinking it, but I have no experience with flash photography at all. And I'm not in DSLR kansas anymore..

Thanks

09-25-2014, 06:39 AM   #2
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Which camera are you using?
09-25-2014, 06:49 AM   #3
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I have two pentax mxs, an me super, and a k1000. I'm trying to use it on any of those.
09-25-2014, 07:12 AM   #4
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Those cameras do not support TTL flash so you must use one of the two Auto modes (green or red). These modes rely on the light sensor in the flash. You set the ASA on the flash matching the film, and you set the aperture manually on the lens per the table on the back of the camera - use the F-stop at the green or red mark, as applicable.

Only for 'A' type (and later) cameras can the flash set the aperture.

The shutter speed will automatically be set to the flash sync speed on some cameras, but not all models support this, in which case you must set it manually to 1/60s and/or 'X' as marked on the shutter speed dial.

Hitting the Check button should work as you describe it. So yes, you're on the right track.


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09-25-2014, 07:19 AM   #5
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QuoteOriginally posted by Ole Quote
Those cameras do not support TTL flash so you must use one of the two Auto modes (green or red). These modes rely on the light sensor in the flash. You set the ASA on the flash matching the film, and you set the aperture manually on the lens per the table on the back of the camera - use the F-stop at the green or red mark, as applicable.

Only for 'A' type (and later) cameras can the flash set the aperture.

The shutter speed will automatically be set to the flash sync speed on some cameras, but not all models support this, in which case you must set it manually to 1/60s and/or 'X' as marked on the shutter speed dial.


Rear panel
I know the aperture must be set on the lens manually. I also know that I can't use the TTL mode. What I don't quite understand is how I'm supposed to know if the exposure is good. I thought that was the point of the flash having its own meter.

From reading the manual I'm pretty sure that the way it works is you hit the test button, the flash takes a light reading, and then flashes the A Check light if the exposure is good. I'm looking to confirm that that is in fact the case. For some reason that's just not how I expected it to work? I'm not sure why I have a feeling that that isn't right.
09-25-2014, 07:21 AM   #6
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You have it right. Page 14 in the manual describes the use of the "A.CHECK" button.
09-25-2014, 08:59 AM   #7
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QuoteOriginally posted by Ole Quote
You have it right. Page 14 in the manual describes the use of the "A.CHECK" button.
And a nice scan of the manual can be downloaded from the Butkus site:
http://www.cameramanuals.org/flashes_meters/pentax_af_280t.pdf
If you find the manual useful, be sure and send him a few dollars via PayPal. (I have no relationship to Mr. Butkus except as a grateful user.)

As discussed above, flash support for your film cameras is limited to "red"/"green" auto, two-level manual, and manual modes. You do get flash ready display and automatic sync speed set in "red" and "green" modes with your ME Super. With the MX and K1000 you are can still use the "red" and "green" modes, but with no dedicated flash features. The manual is a little confusing regarding all this.

With a Pentax dSLR, things get a bit more interesting. I have yet to add my review of this flash to this site, have summarized the functionality on another thread:
https://www.pentaxforums.com/forums/8-pentax-film-slr-discussion/260999-me-su...ml#post2808572
Steve

---------- Post added 09-25-14 at 09:07 AM ----------

QuoteOriginally posted by cohny Quote
What I don't quite understand is how I'm supposed to know if the exposure is good.
The A check light will also light on a regular exposure if you remember to quickly check it.


Steve


Last edited by stevebrot; 09-25-2014 at 09:05 AM.
09-25-2014, 09:38 AM   #8
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The manual can also be downloaded from Pentax-Manuals.com

Pentax Manuals

Password is Pentax.
09-25-2014, 03:11 PM   #9
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The nice thing about setting the aperture manually on the lens is that you can use this to dial-in some exposure compensation. So if the red or green mode on the flash wants you to set the aperture to f/5.6, but you know your composition has some dark or light elements that would fool the electric eye (which I think is typically center-weighted, whatever), then you can compensate by tweaking the aperture a bit.

Auto mode works great for the same reason on DSLRs too -- you don't need no stinking P-TTL!
(Edit: Reading another thread, it may be that Pentax DSLR bodies recognize Pentax flashes, and automatically set the aperture on the lens. If so, that is unfortunate, since you can quickly tell if the image is over/underexposed on a DSLR. The benefit of automatically setting the aperture is so you don't waste a whole roll of film before realizing your aperture is incorrect.)

Last edited by Tanzer; 09-25-2014 at 06:40 PM.
09-25-2014, 04:44 PM   #10
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Thanks for the help everyone. I've been playing around with the flash on my mx and I've gotten the A-check light to work. I think I understand how this works now.

You use the test button to check the exposure with the flashes meter and then take the picture if it's good.

I still have a couple things that are unclear to me:

1) the flash doesn't seem to take the angle or rotation into consideration. It seems that the flash just knows I'm at f8 and the camera speed is X and that's it. If I bounce it off the ceiling or shoot it straight on am I actually going to get a good exposure? In other words, does the meter on the flash read an acceptable exposure for both of those scenarios?

2) I noticed that the mx has a relatively slow sync speed at 1/60. My me super has a sync at 1/125. If both cameras have the same film, it seems to me that the flash will "recommend" the same settings. It tells me to set the aperture at f8 when I've got 400 film and the flash set on red auto mode. That doesn't make sense to me though because the mx will take an exposure that's twice as long. There doesn't seem to be anything that takes the shutter speed into consideration.

I'm skeptical that using the information from this flash will provide me with what I need to get a proper exposure.

Also thanks again for the feedback, I'm the only one I know who's into this so I don't have anyone to help me out IRL heh
09-25-2014, 05:10 PM   #11
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In the case of a traditional flash application (where the flash is the most significant light source), the shutter speed (within reason) doesn't matter, because on "auto", most flashes will vary their duration and quench the light when enough has been supplied. The flash duration will be much shorter than 1/60th or 1/125th, or even 1/500th of a second - maybe more like 1/15,000th.

Where shutter speed matters is when you're trying to balance daylight or some other light source with the flash. The ambient light source is then typically bright enough relative to the flash that you typically control the ambient light exposure with a combination of aperture and shutter speed, and the flash exposure manually with aperture, possibly combined with a power ratio control on the flash. That's one reason why leaf shutters often work better for fill flash - they can sync up to their top speed of, typically, 1/500th for example, allowing use of a wider range of apertures while still controlling ambient exposure in a usable range.
09-26-2014, 10:23 AM   #12
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QuoteOriginally posted by cohny Quote
If I bounce it off the ceiling or shoot it straight on am I actually going to get a good exposure?
Yes, within the intensity limits of the flash. Again, the test button is your friend. Be aware that the sensor angle is 20 degrees straight ahead and that a bright white wall behind the subject may bias the exposure.

QuoteOriginally posted by cohny Quote
I noticed that the mx has a relatively slow sync speed at 1/60.
Yes, it has a traditional cloth shutter that runs in the horizontal direction. 1/60s or slower is the expected sync speed for that type of shutter. By comparison to your ME Super at 1/125s (vertical shutter) the flash exposure will be the same for a given aperture, but the ambient light contribution will be one stop different.

That is part of the mystic black arts aspect of flash photography...balancing ambient light against the strobe. In general, having a faster sync speed gives the photographer more options.


Steve
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