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08-04-2016, 08:07 AM   #1
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500mm f6.3 Samyang/Walimex etc. A-Conversion

I finally got my hands on one of the infamous 500mm mirror lenses and I have to say I'm quite amazed! After all the bad press these lenses received Mine performs very good considering the price point and the difficulties of the Mirror construnction.
I use one of the User presets on my K30 with beefed up contrast and sharpness and more vivid colours. I also ordered two T2-PK adapters for comparison and one of them performed much better than the other one.

Now onto the main topic: I'm considering modifing the adapter to trick the camera into believing it's an a-mount lens to get full frame metering. Any thoughts on this and has someone already tried this?

Cheers, mf

08-04-2016, 09:04 AM   #2
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not with a lens, no. I did it with my K5 body, though. It's really pretty easy. Just unscrew the lens mount plate from the body, put a small piece of foil over the A pin, put the plate back on. The camera assumes every manual lens is an A lens. Just keep in mind that it'll screw up the exposure if you're not shooting at maximum or minimum aperture.. and if the lens doesn't have pins, it'll assume it's a 1.2-22 aperture range.
08-04-2016, 10:00 AM   #3
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QuoteOriginally posted by manufocus Quote
Now onto the main topic: I'm considering modifing the adapter to trick the camera into believing it's an a-mount lens to get full frame metering.
Jamming a small wad of foil into the "A" contact on the body (or some similar approach) will trick it into thinking an A-series lens is mounted. That should get you Av mode, assuming you dial in the lens aperture as the shooting aperture.


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08-04-2016, 10:54 AM   #4
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For a mirror lens with fixed aperture and no aperture lever I think that could be good. It would also be easy enough to create contacts to program in an f number which would be recorded in exif - tho maybe no particular point..
I would be interested to hear how you get on. Also to see some pics to get an impression of how your lens compares to the tamrons 55B/55BB (which are what I would normally recommend as tending to be better than the generic branded mirrors).

08-04-2016, 11:12 AM   #5
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From what I've seen it could be slightly better if you start pixelpeeping (which makes me unreasonably unhappy about my lenses), however it's hard to tell for certain since the lens is very very difficult to use. I decided for myself that I can accept that the pictures won't go bigger than 24" in print and am just happy to have a 500mm lens for <70.
Also I really wouldn't want to lose the f6.3 which is pretty limiting as it is. with shutter times 1/250 and downwards for handheld I'm often pushing ISO above 800 on a bright cloudy day or in shadows in Sunlight.

08-04-2016, 11:17 AM   #6
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Sample pic..
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08-04-2016, 11:35 AM - 2 Likes   #7
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QuoteOriginally posted by manufocus Quote
since the lens is very very difficult to use.
I'm curious, what makes it so difficult to use? I have the Tamron F8 55B, and find it extremely easy to use, handheld.
08-04-2016, 11:39 AM   #8
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For me, very narrow depth of field, hand-held shake and compositing. I'm not that advanced a photographer so working with the bokeh is still challenging for me.



08-04-2016, 11:56 AM   #9
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For my wildlife photos, which I primarily use the 500 for; the narrow depth of field doesn't bother me. Standing, handheld, I push my elbows into my sides firmly for added support. Experimenting with different backgrounds will give you a better understanding of the more pleasing bokeh.
08-04-2016, 02:44 PM   #10
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QuoteOriginally posted by manufocus Quote
I finally got my hands on one of the infamous 500mm mirror lenses and I have to say I'm quite amazed! After all the bad press these lenses received Mine performs very good considering the price point and the difficulties of the Mirror construnction.
I use one of the User presets on my K30 with beefed up contrast and sharpness and more vivid colours. I also ordered two T2-PK adapters for comparison and one of them performed much better than the other one.

Now onto the main topic: I'm considering modifing the adapter to trick the camera into believing it's an a-mount lens to get full frame metering. Any thoughts on this and has someone already tried this?

Cheers, mf
if you are really into it, you can purchase solder in pins used for surface mount press contact connectors, they are all contained spring contact pins about 1.5-2.0mm long, and you drill and insert it into the mount where the A pin is located.

then you need to polish off the paint / anodizing from the T2 mount to make contact to the camera mount base.

the only risk is the pin is similar in size to the dreaded roicoh pin and it can get caught in the AF drive if you are not careful and keep the release button depressed for both install and remove
08-04-2016, 03:36 PM   #11
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Theres a 2x TC that came with my copy(Rocky)....does Macro well too
08-04-2016, 05:05 PM   #12
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QuoteOriginally posted by manufocus Quote
Also I really wouldn't want to lose the f6.3 which is pretty limiting as it is. with shutter times 1/250 and downwards for handheld I'm often pushing ISO above 800 on a bright cloudy day or in shadows in Sunlight.
Have you tried using a flash with a flash extender? We tend not to think of flash for wildlife and outdoors, but it makes a big difference with a slow lens.
See this thread and those linked from it: https://www.pentaxforums.com/forums/22-pentax-camera-field-accessories/320077...ird-photo.html
I think you might need to use manual flash settings with a manual lens (I defer to others on that), but that's not difficult.

Last edited by Des; 08-04-2016 at 05:17 PM.
10-30-2016, 02:10 AM   #13
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Good news Everybody!

The A-Conversion works beautifully! There is actually no need to bother with the correct pins since the camera will always meter correctly for whatever is the widest aperture. So after some frustrating time with some tape and sticky contacts I've got an f1.2 500mm lens. Since the proclaimed f-stop of 6.3 is not available in the presets, I'm not bothered that exif data will be incorrect.

The really great thing of this conversion is that it is now possible to shoot in TAV mode! Finally allowing to preset the shutter speed (at 1/500) as opposed to being limited to the 1/125 preset the K30 defaults to when in M42 mode :-) (-:
10-30-2016, 05:27 AM   #14
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I used a Needle head for the A contact and some hot glue to fix the needle elastically in position. However I think some fixture with a softer springy material would be nicer towards the bayonet.
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