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DA 15 Limited reverse macro experiment
Posted By: pjalves, 10-09-2017, 02:45 PM

Just a quick and dirty experiment.
The photos are of the DA badge on the side of my 18-135 and a few millimeters from my son's spiderman ruler...
I've got to try this again with better subject and lighting. Just wanted to share.

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10-09-2017, 02:50 PM   #2
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Some more photos, this time of a 1 cent Euro coin... the last one is just for illustration and scale purposes.
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10-09-2017, 02:59 PM   #3
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the setup...
equipment used, besides K-5 and DA15:
- reverse mount adapter 49mm;
- de-glassed filter ring (to clear DA15's built-in hood and allow the attachment to the reverse mount adapter);
- 3d-printed hood (optional).
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10-09-2017, 04:04 PM   #4
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QuoteOriginally posted by pjalves Quote
the setup...
equipment used, besides K-5 and DA15:
- reverse mount adapter 49mm;
- de-glassed filter ring (to clear DA15's built-in hood and allow the attachment to the reverse mount adapter);
- 3d-printed hood (optional).
Nice.

I've tried this without the hood and with the lens stopped down with my finger on the aperture lever. Some true genius (I forget who, which is a shame because they really do deserve the credit) suggested getting one of those cheap Pentax-Sony adapters that has a manual aperture manipulator and use that as a combined hood and stopdown control, so that I wouldn't have to be touching the rig and could trigger it with a cable or time release. I considered it, but I am worried that the length of it would be such as to prevent getting the requisite close subject distance.

10-10-2017, 04:02 AM   #5
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QuoteOriginally posted by pathdoc Quote
Nice.

I've tried this without the hood and with the lens stopped down with my finger on the aperture lever. Some true genius (I forget who, which is a shame because they really do deserve the credit) suggested getting one of those cheap Pentax-Sony adapters that has a manual aperture manipulator and use that as a combined hood and stopdown control, so that I wouldn't have to be touching the rig and could trigger it with a cable or time release. I considered it, but I am worried that the length of it would be such as to prevent getting the requisite close subject distance.
Thanks! I was so excited with the incredible magnification that I forgot to do my homework and see if anyone had already done it and how...

I think it's indeed a better idea to use one of those adapters and gain aperture control. In my case I had to hold the aperture fully opened with a t-shaped plastic piece (big enough not to fall inside the lens), as this 3D-printed hood doesn't do it by itself. It's based on a rear cap 3D model which I altered to include a hole and the protruding hood. I didn't think about it in the first place as it was made for use with a reversed A50 f/1.7, which of course has an aperture ring, and thus an aperture coupling on the hood would be redundant and less functional (fixed).

As for the working distance to the subject, it's about 5 centimeters from the rear element, so my hood is a little bit too big, but one of the aforementioned adapters would be just fine, I guess...

Last edited by pjalves; 10-10-2017 at 04:09 AM.
10-10-2017, 08:32 AM   #6
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You're welcome. Here are mine:


This is one of the tightening knobs on a two-point lens wrench.



And this is a closeup of a 2mm clutch pencil. For this shot, I reversed the lens on the front of a 135mm prime.

10-10-2017, 03:54 PM - 1 Like   #7
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QuoteOriginally posted by pjalves Quote
As for the working distance to the subject, it's about 5 centimeters from the rear element, so my hood is a little bit too big, but one of the aforementioned adapters would be just fine, I guess...
The working distance for any reversed lens will be the flange distance. Thus, 46 mm for Pentax.
10-11-2017, 12:14 PM   #8
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QuoteOriginally posted by pathdoc Quote
You're welcome. Here are mine:

This is one of the tightening knobs on a two-point lens wrench.
And this is a closeup of a 2mm clutch pencil. For this shot, I reversed the lens on the front of a 135mm prime.
Wow, this is indeed a whole new world to explore. And with depths of field so thin, using an adapter with adjustable aperture really must be much more convenient, or rather a must. Stacking lenses? Didn't think of it... Now I'll have to try that out too...

---------- Post added 2017-10-11 at 20:17 ----------

QuoteOriginally posted by smigol Quote
The working distance for any reversed lens will be the flange distance. Thus, 46 mm for Pentax.
Thanks, smigol.
I really must study all the math and details that go into this.
Cheers!

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