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02-16-2012, 11:21 PM   #1
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RJ adapter and coming Pentax adapter?

What is the difference between the two?
I know the Pentax one has a built in shutter, so what does that mean compared to the RJ (ie. ebay ) ones?

thx in advance

02-17-2012, 12:35 AM - 1 Like   #2
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Hi PHC,

My understanding is that the Pentax version has both aperture control and a mechanical shutter in the adapter. The RJ has an aperture control ring only.
This would result in the ability to use the manual shutter with adapted lenses instead of being limited to the electronic shutter. For my use, the main difference would be sync speed with flash. With the electronic shutter, flash sync is limited to 1/3 sec (edit -- should be 1/13 sec), which essentially makes flash irrelevant when ambient light levels get higher, so it would eliminate flash use to freeze motion in outdoor macro shots for example.

My assumption is that the shutter is just a shutter in the adapter, and not a shutter/aperture combination like in the 01 prime and the 02 zoom. My understanding is that the aperture blades need to be located inside the lens assembly to be the most effective, so it's likely that the aperture control will use the lever in the lenses to control the aperture blades in the lenses. I assume stopped down metering will need to be used, though Av priority works fine with current adapters just as it does on MF lenses and the DSLR line. The shutter can still be a leaf shutter and allow virtually unlimited speeds for flash sync, and while that might be hailed as a great feature, fast flash sync only comes into play in certain situations. . . most of which I don't need very often if ever. I wouldn't be surprised if the shutter is just a rudimentary one with a limited range of speeds, like up to 1/250, and that the electronic shutter would take over at that point. This would be satisfactory for me. . .

From an implementation standpoint, the aperture ring on the Pentax unit seems to have a wider rotational throw, so it's assumed that either half or 1/3 stop accuracy might be possible in choosing the aperture setting. The RJ's aperture ring has 6 very closely placed indents from max to stopped down completely, so the most you could adjust the aperture on the lens would be full stops as I see it. Since you don't have meny stops until you start running into diffraction effects from too small an aperture for the sensor, having finer control would seem to be more desireable, but this might actually be a fine distinction with no real practical value.

I assume that the Pentax model will be nicely finished and would probably be more robust in construction. It will undoubtedly be more expensive, possibly considerably more. I'm awaiting the Pentax version, and will get it as soon as it's announced if it's not insanely priced. . . if it has a functional shutter, and If the shutter works out some current flash problems, and Pentax fixes some flash anomalies currently present with a firmware update, I'd probably get it even if it was insanely priced.

Other possible feature might be the capability to use SR with adapted lenses and focus peaking for MF. . . it's been rumored that there might be a firmware update when Pentax releases its K to Q adapter . . . I'm hoping that this is the case, and looking forward to it.

Scott

Last edited by snostorm; 02-17-2012 at 11:25 AM.
02-17-2012, 02:37 AM   #3
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Thank you for this post. It was very valuable to me. Useally I am never so informed and simply barge into the adventure, which of course is somtimes a bit desastrous.
I have a tiny question, please. Will this pentax adapter have a fitting for a tripod? Would be nice with not too heavy short/medium tele lenses that don't have tripod mounts.
02-17-2012, 07:11 AM   #4
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snostorm,
many thanks for your information and insights.

I must say that 1/3 sync speed is quite a shocker and rather useless.
Looks like I have to wait for the adapter then.

02-17-2012, 11:22 AM   #5
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QuoteOriginally posted by pinholecam Quote
snostorm,
many thanks for your information and insights.

I must say that 1/3 sync speed is quite a shocker and rather useless.
Looks like I have to wait for the adapter then.
That was a typo, it is actually 1/13, not that it is so great either, but a bit better than 1/3
02-17-2012, 11:23 AM   #6
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QuoteOriginally posted by pinholecam Quote
snostorm,
many thanks for your information and insights.

I must say that 1/3 sync speed is quite a shocker and rather useless.
Looks like I have to wait for the adapter then.
Sorry, that's a typo -- it's 1/13, but that's still pretty slow.

Scott
02-17-2012, 12:11 PM   #7
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QuoteOriginally posted by PentaxMom Felua Quote
Thank you for this post. It was very valuable to me. Useally I am never so informed and simply barge into the adventure, which of course is somtimes a bit desastrous.
I have a tiny question, please. Will this pentax adapter have a fitting for a tripod? Would be nice with not too heavy short/medium tele lenses that don't have tripod mounts.
Hi PentaxMom Felua,

I've only seen pictures of prototypes, and IIRC, they did not include a tripod mount, but if they included a rotating tripod ring, it would probably be a good thing. My RJ adapter did include a non rotating tripod mount, but the screws were so tiny that it could not support the weight of anything more than the lightest lenses which doesn't help me much. Also, because it was a fixed mount, I'd be forced to shoot in portrait orientation with my preferred tripod mounting methods (Sidekick or a ballhead in faux gimbal mode).

I've worked around this by using a relatively rare optional OEM tripod ring for the Tamron SP 80-200 f2.8 Adaptall 2. This ring is widely adjustable, and can accommodate quite a few of the lenses that I plan to use with the Q -- F 50/1.7, D FA 100 Macro, DA 50-200, DA 55-300, FA 300/4.5, SP 80-200/2.8 (of course) and more if I make up some foam spacers.







I've not been much of a tripod user in the past, preferring handholding when possible, but with the Q, it's much more practical to use a tripod because of the LCD VF, its very light weight, and no SR available at this time (and even if SR is made available with a firmware update, I doubt if it could compensate for much past @ 150mm on the Q). I'm thinking I should be able to get away with using a very lightweight travel tripod for most uses, hopefully even with some very long glass.

Scott
02-17-2012, 12:16 PM   #8
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QuoteOriginally posted by pinholecam Quote
snostorm,
many thanks for your information and insights.

I must say that 1/3 sync speed is quite a shocker and rather useless.
Looks like I have to wait for the adapter then.
+1, bravo snostorm

02-17-2012, 12:37 PM   #9
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Thank you, Snostorm, for your answer. I do appreciate it. The new pentax k to q adapter ought to be a stirdy one, I hope. A rotating and adaptable ring - tripod mount fixation seems ideal. Sigh. I once had boxes full of adaptalls, I gave them away. That was before I had discovered how useful spare parts can be. Thanks again.
02-17-2012, 12:46 PM   #10
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According to pictures in this thread, https://www.pentaxforums.com/forums/pentax-news-rumors/174815-more-photos-cp.html, it does have a tripod mount. Looks like the same design as on DA60-250/4.

02-17-2012, 01:11 PM   #11
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QuoteOriginally posted by StigVidar Quote
According to pictures in this thread, https://www.pentaxforums.com/forums/pentax-news-rumors/174815-more-photos-cp.html, it does have a tripod mount. Looks like the same design as on DA60-250/4.
Hi StigVidar,

Thanks for that, I missed it. If everything rumored is delivered in the final product, this should be easily the ultimate K to Q adapter.

Scott
02-17-2012, 02:02 PM   #12
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That's nice! And if the foot isn't included with the adapter, I know you can order one, I did that for the 300mm, same fit, because I don't like the foot of the 300mm.
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