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04-23-2022, 05:26 AM   #1
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Use of Pentax AF 140c ring flash

Just managed to get hold of the Pentax AF 140c ring flash and tried using it on a Pentax K1 Mrk II camera. Tried various combinations using a Pentax 50mm macro plus a 1.4 convertor using TAV, Av, X synch etc but although I managed to get a correct setting using an F 45 aperture at 1/200s speed and 100ASA, I couldn't get too close to the subject although I tried reducing the aperture since the result was an overexposed picture. Tried fiddling with the F 5.6 and F22 setting and Manual setting on flash but there was limited difference in the outcome of the final result. Noticed that sometimes the flash went off after hearing the mirror go up but still the result was fine. I would appreciate if someone could help me out with settings since I plan to use the flash for close-up work.

04-23-2022, 05:40 AM   #2
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That is an old flash that probably doesn’t support P-ttl, I would imagine you can use manual mode only.
04-23-2022, 06:08 AM - 1 Like   #3
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The af140 can only be used in manual mode. Due to limited power level controls you may need to use a neutral density filter for macro work. A 3 stop one has been recommended in the past.
04-23-2022, 02:50 PM   #4

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I agree with UncleVanya. This flash only does TTL not the more "modern" P-TTL that your K-1 has programmed inside of it. Manual mode is the only option here and you may need to reduce the light getting to the camera with an ND filter.

The AF-160FC is a full P-TTL ring flash from Pentax which works wonderfully in P-TTL or manual modes. No longer produced but you can find them second hand usually for a high price.



04-24-2022, 06:04 PM   #5
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As noted above, TTL flash support on the AF 140C is limited to the original "analog" protocol TTL from the early 1980s. While the list of supporting Pentax cameras is actually fairly long*, dSLR support is limited to the *istD series** with all later dSLRs being limited to P-TTL.


* While the list bodies offering analog TTL proto only is fairly short, many AF film bodies also provide backward support for analog TTL flash.

** The *istD series bodies are part of a select club of Pentax cameras that support all form of TTL and flash dedication ever offered by the brand.

Last edited by stevebrot; 04-24-2022 at 06:11 PM. Reason: clarity
05-12-2022, 05:57 AM   #6
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It is ironic that legacy camera brand accessories can be less useful today than third party accessories of the same date, because the camera branded ones were tailored specifically to those cameras of that time. OTOH, third party brands like Vivitar, Sunpak and Metz, which were as well made if not better, went out of their way to make their accessories as versatile as possible.

WIth the AF140C, Pentax seemed to have put nearly all their eggs into the one basket of their brand specific TTL flash system of the time; this would have worked great with Pentax cameras of the time, but the full-power-only manual option seems to have been an afterthought for emergencies, letting you get a picture somehow perhaps if your main camera failed and you had to use your back-up K1000 or something. The Pentax AF080C would be better for close-up as it has the lower GN of 8 metres and can be reduced to 1/4 power as well.

Reading the ring flash reviews on PF I am puzzled why many reviewers complain of not enough power. I think they expect to use it for portraits. I do close-ups of technical subjects and tend to find there is too much power. I use an old Sunpak DX-8R that only cost me 10 onEbay and it has five manual power levels, from full all the way down to 1/16, and I use them. Incidentally, old-style AUTO (with a sensor on the flash unit) is useless for ring flash close up because the sensor is so out of line with the subject.

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