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05-31-2019, 08:42 AM   #1
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55-300 PLM and 1.4x aw rear converter metering incorrect

When I turn on the KP in Program mode with HD Pentax DA AF 1.4X AW rear converter & 55-300 PLM mounted and lens extended to 300mm, the display shows exposure is wrong by blinking. If I take a picture it's totally black. With the rear converter and 55-300 PLM the readout is; shutter speed 1000, f 9.5, ISO 100. As soon as I turn the front or rear dial just a little to adjust shutter speed or aperture all the settings go into a proper exposure. The problem is repeated each time the camera is turned on. Cleaning the contacts has not fixed this.

I think the problem is a Pentax problem with the 55-300plm and converter because
• when turn on camera in P mode it meters incorrectly
• when turn on camera in any mode other than P it meters correctly
• P mode meters correctly after turning the front or rear dial
• when press the green button P mode meters incorrectly
• the converter and other lenses meter correctly in any/all modes when turn on camera

I hope someone else with the 55-300 plm & converter looks to see if the same problem exists with their equipment.

05-31-2019, 09:20 AM - 1 Like   #2
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I don't think you are supposed to use teleconverters with lenses this slow. My guess is the meter doesn't work at f9 very well, so in P it just gets confused. If you want do do that, time for faster glass, or work in Av or manual.
05-31-2019, 09:33 AM   #3
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QuoteOriginally posted by Bernie Quote
When I turn on the KP in Program mode with HD Pentax DA AF 1.4X AW rear converter & 55-300 PLM mounted and lens extended to 300mm, the display shows exposure is wrong by blinking. If I take a picture it's totally black. With the rear converter and 55-300 PLM the readout is; shutter speed 1000, f 9.5, ISO 100. As soon as I turn the front or rear dial just a little to adjust shutter speed or aperture all the settings go into a proper exposure. The problem is repeated each time the camera is turned on. Cleaning the contacts has not fixed this.

I think the problem is a Pentax problem with the 55-300plm and converter because
• when turn on camera in P mode it meters incorrectly
• when turn on camera in any mode other than P it meters correctly
• P mode meters correctly after turning the front or rear dial
• when press the green button P mode meters incorrectly
• the converter and other lenses meter correctly in any/all modes when turn on camera

I hope someone else with the 55-300 plm & converter looks to see if the same problem exists with their equipment.
I have the same setup, and I can't see any problem,. When I turn it on the way you described, everything works perfectly.
05-31-2019, 10:09 AM   #4
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I have the PLM version and converter, And I don't have the problem as you described

05-31-2019, 10:59 AM   #5
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From the in-depth specs review: “The following lenses are not supported according to Pentax; using these lenses with the converter will damage the lens or converter:
SMC Pentax-DA 15mm F4 ED AL Limited
HD Pentax-DA 15mm F4 ED AL Limited
SMC Pentax-DA 21mm F3.2 AL Limited
HD Pentax-DA 21mm F3.2 AL Limited
SMC Pentax-DA 40mm F2.8 XS

All other current lenses (as of March 2014) can be used with these caveats:
SMC Pentax-DA* 55mm F1.4: The largest usable aperture with converter is F2.4 (the same holds for the F and FA 50mm F1.4 lenses as per our tests)
MC Pentax-DA 17-70mm F4: Contrast detect AF is unreliable, use phase detect
HD Pentax-DA 560mm F5.6: phase detect autofocus may be unreliable, use contrast detect
SMC and HD Pentax-DA 55-300mm F4-5.8: phase detect autofocus may be unreliable when zoomed in, use contrast detect”

I have same lens & TC but never use them together, yet. Suggestions: check KP firmware version and update if needed. Possibly do a factory reset of default settings for “P” mode and retest.
05-31-2019, 11:01 AM   #6
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Do a camera reset. Update the firmware and see if that helps.
05-31-2019, 05:57 PM   #7
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QuoteOriginally posted by Bernie Quote
When I turn on the KP in Program mode with HD Pentax DA AF 1.4X AW rear converter & 55-300 PLM mounted and lens extended to 300mm, the display shows exposure is wrong by blinking. If I take a picture it's totally black. With the rear converter and 55-300 PLM the readout is; shutter speed 1000, f 9.5, ISO 100. As soon as I turn the front or rear dial just a little to adjust shutter speed or aperture all the settings go into a proper exposure. The problem is repeated each time the camera is turned on. Cleaning the contacts has not fixed this.

I think the problem is a Pentax problem with the 55-300plm and converter because
• when turn on camera in P mode it meters incorrectly
• when turn on camera in any mode other than P it meters correctly
• P mode meters correctly after turning the front or rear dial
• when press the green button P mode meters incorrectly
• the converter and other lenses meter correctly in any/all modes when turn on camera

I hope someone else with the 55-300 plm & converter looks to see if the same problem exists with their equipment.
Do you get the same results in live view? The converter only officially supports lenses up to F5.6, so there might simply not be enough ambient light at the long end.

Have you also tried testing it in brighter conditions, as well as in live view?

Adam
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05-31-2019, 06:57 PM   #8
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QuoteOriginally posted by Kozlok Quote
I don't think you are supposed to use teleconverters with lenses this slow. My guess is the meter doesn't work at f9 very well, so in P it just gets confused. If you want do do that, time for faster glass, or work in Av or manual.
It meters correctly at all apertures - - - after any front or rear dial adjustment. The meter is wrong when the camera is turned on when lens is at 300mm. It always is at F9.5, auto iso is always at 100 and shutter always at 1/1000 with the shutter and aperture numbers blinking. After any front or rear dial adjustment it meters correctly.

regards, Bernie

---------- Post added 05-31-19 at 10:07 PM ----------

QuoteOriginally posted by Adam Quote
Do you get the same results in live view? The converter only officially supports lenses up to F5.6, so there might simply not be enough ambient light at the long end.

Have you also tried testing it in brighter conditions, as well as in live view?
Same thing happens in live view. The problem occurs both in bright sunlight and indoors.

I am okay not fixing this problem. The camera/ lens are fully usable and I can dial in any settings that I want after moving the front or rear dial. As soon as the front dial is moved to the next aperture (F10) or the rear dial moved to adjust shutter, metering is correct and the blinking stopped. The only thing to avoid is pressing the green button as aperture, shutter and iso go back to the same as when the camera was turned on (problematic).

thanks Bernie

05-31-2019, 07:44 PM   #9
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QuoteOriginally posted by Kozlok Quote
I don't think you are supposed to use teleconverters with lenses this slow. My guess is the meter doesn't work at f9 very well, so in P it just gets confused. If you want do do that, time for faster glass, or work in Av or manual.
Since my usual lens on my KP is the 18-135 DC lens, lately I've routinely used the 55-300 PLM with the 1.4X TC, to give me a 77-420mm lens. The PLM + TC combination worked perfectly for me last weekend, even in shaded areas where {usinging 'TAv' mode} shutter speed 1/1000 and aperture f/9.5 forced me up to ISO 4500 .... the PLM+TC combination both metered and focused just fine {100% crop below}.


Last edited by reh321; 05-31-2019 at 08:28 PM. Reason: add photo
06-01-2019, 05:51 AM   #10
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I tried the 1.4X TC with my 55-300 PLM on my K-3. It worked fine with respect to focusing and metering on my camera, but I was not happy with the results. I felt that cropping pictures without the TC were as sharp or sharper than with the TC. This may be due to needing to bump up the ISO to offset the effect of losing one stop of light. I have a DA* 300 and results with the TC are much better with that lens. I prefer to use my PLM up to about 280mm where it is still f5.6 and use the DA* for 300mm and 420mm with the TC. I also tried the TC with my DFA 100 macro WR and got good results with that combination.
06-01-2019, 07:06 AM - 1 Like   #11
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This set of images convinced me the 55-300 PLM with a TC is an emergency option only. Using my lenses (YMMV) the 55-300 resolves the 24 MP APS-c sensors, but not by enough to add a TC.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/365761-hd-...ml#post4617614

But the 55-300 without the TC is awesome.

DA 55-300 PLM @300mm


Last edited by normhead; 06-02-2019 at 06:19 PM.
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