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05-07-2014, 10:33 AM   #16
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Here is the Pentax Q page of this seller: For Pentax Q - Shop Cheap For Pentax Q from China For Pentax Q Suppliers at Esydream photography on Aliexpress.comFor Pentax Q - Shop Cheap For Pentax Q from China For Pentax Q Suppliers at Esydream photography on Aliexpress.com

05-07-2014, 04:05 PM   #17
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Agreed on the tube lengths

I expected it would be more like 2mm,4mm, 8mm or something
05-07-2014, 06:25 PM   #18
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Not sure you can make the tubes much less than 10mm. There is the two bayonet mounts that are probably about 1 mm thick each since they are metal. Then the electrical contacts are recessed inside the mount. This has to be another 2-3mm. To have a tube connecting the two lens mount faces, allow for a lens lock release, and spring loaded electrical contacts, it has to be getting tight. About the shortest tubes for DSLRs are ~8mm.

I am glad the tubes are so long. coupled with the #06 15-45 we should be able to get 1:1 and much longer working distance vs #01 and tube. #01 and tube would be so close the camera would block the light. There is no Q ringflash-yet.

My only worry is diffraction with the longer tubes.

thanks
barondla
05-07-2014, 09:42 PM   #19
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I think I might still be ahead with the enlarger lens,a 39-42 adapter, a m42 helicoid and a custom built m42 to Q adapter as on the adapted lens thread:
https://www.pentaxforums.com/forums/136-pentax-q/209474-adapted-lenses-tested...ml#post2716126
(or m42 or 110 lens)

05-08-2014, 09:02 AM   #20
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Mechanically, the Q bayonet is 4.2mm from the flange (at least on the Q/PK adaptor. To have any metal at all between the end of the bayonet and the flange of the body, on an extension tube, let's assume add another 1mm

This would mean a minimum extension tube of 5.5mm.

The connections are shaded by the bayonet so no issue there
05-08-2014, 12:16 PM   #21
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I'm curious to see how well these tubes work on the Q lenses. Extension tubes add a lot of optical performance stress to lenses. Anyone willing to experiment and post samples?
05-08-2014, 03:32 PM   #22
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QuoteOriginally posted by 6BQ5 Quote
Extension tubes add a lot of optical performance stress to lenses.
How so? I have never heard this before. In fact, I've always heard that extension tubes have no effect on the optics.
05-08-2014, 04:56 PM   #23
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QuoteOriginally posted by fuent104 Quote
How so? I have never heard this before. In fact, I've always heard that extension tubes have no effect on the optics.
I would assume it's because the extension tube forces the lens away from the sensor so only the center of the lens is projected on the sensor (you are only using the center of the lens for the image, Like the Q does to full frame lenses. I am sure Boris is not talking about physical strain.

05-08-2014, 05:03 PM   #24
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QuoteOriginally posted by hnikesch Quote
I would assume it's because the extension tube forces the lens away from the sensor so only the center of the lens is projected on the sensor (you are only using the center of the lens for the image, Like the Q does to full frame lenses. I am sure Boris is not talking about physical strain.
Correct. I am not referring to physical strain. Macro tubes pull the lens away from the sensor and enlarge the image. When enlarging the image you are also enlarging any and all aberrations and distortions. What was once so small that nobody would notice suddenly becomes bigger than a few pixels and is recorded.
05-08-2014, 05:27 PM   #25
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QuoteOriginally posted by hnikesch Quote
I would assume it's because the extension tube forces the lens away from the sensor so only the center of the lens is projected on the sensor (you are only using the center of the lens for the image, Like the Q does to full frame lenses
Bad science!! All the lens that the diaphram leaves visible is projected onto the sensor.
The Q is harder on the lens coz the focussed image has to be enlarged more from the 4x6mm sensor.
As you progressively go macro DoF issues get tougher and maybe this is seen as "strain".
05-08-2014, 07:09 PM   #26
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My guess is extension tubes don't add or multiply optical distortions. But extension tubes move a lens out of its optimized sweet spot. Optical designers optimize lenses for certain distances. The average lens is ( as I remember) 7-10 feet. Every day macro lenses are 2-3 feet. So the extension tube allows the lens to slide out of its sweet spot. There will also be light loss which could lead to diffraction. The Q is always flirting with diffraction.

Remember if you take a lens past 1:1 it is often sharper when reversed.

No optician here. Just some thoughts.
thanks
barondla

Check out the previous point and shoot contests in the Compact Camera Forum. Enter #78. Any brand camera. The Q is invited.
05-08-2014, 10:38 PM   #27
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QuoteOriginally posted by barondla Quote
My guess is extension tubes don't add or multiply optical distortions. But extension tubes move a lens out of its optimized sweet spot. Optical designers optimize lenses for certain distances. The average lens is ( as I remember) 7-10 feet. Every day macro lenses are 2-3 feet. So the extension tube allows the lens to slide out of its sweet spot. There will also be light loss which could lead to diffraction. The Q is always flirting with diffraction.

Remember if you take a lens past 1:1 it is often sharper when reversed.
+1 on these points

---------- Post added 05-09-14 at 05:48 PM ----------

QuoteOriginally posted by barondla Quote
My guess is extension tubes don't add or multiply optical distortions. But extension tubes move a lens out of its optimized sweet spot. Optical designers optimize lenses for certain distances. The average lens is ( as I remember) 7-10 feet. Every day macro lenses are 2-3 feet. So the extension tube allows the lens to slide out of its sweet spot. There will also be light loss which could lead to diffraction. The Q is always flirting with diffraction.

Remember if you take a lens past 1:1 it is often sharper when reversed.

No optician here. Just some thoughts.
thanks
barondla

Check out the previous point and shoot contests in the Compact Camera Forum. Enter #78. Any brand camera. The Q is invited.
I have often noticed with the old lenses, that on the Q they are superb for closer work (portraits) thru to macro but are really disappointing for landscape/infinity work. I have thought the issue may have been that with any distant subject matter the sky is in or near the picture and flaring out the inferior coatings. So I have baffled and hooded the hell out of my lens to try and counter this but with limited effect. I wonder if there is something about the physics of tiny Q format that shifts that designer sweet spot.
As you birders know the older lens are not up to your task but I am quite keen on them for closeup.
05-09-2014, 06:40 PM   #28
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If real world lenses are optimum at 7-10 ft., then they are not in their sweet spot at landscape distances. Guessing that the Q makes this very apparent.

On the extension tube front, I tried a mock up. Used construction paper to make a 10mm tube. Set the 01 lens to infinity focus, and f1.9 aperture. The results were a little depressing.

The working distance was so close, focus could not be achieved. The subject touched the pancake lens hood before reaching focus! The Pentax pancake hood sticks out about 8mm. With the hood removed, the focus seemed to be roughly 2-4mm in front of lens. Useless out doors.

Apparently the tubes are only useful with the 02 lens near 15mm, or the 06 zoom. The 02 at 15mm would have very little working distance. The Toy Tele lens would be forced to use the electronic shutter, so we would do better using the Pentax Q-Pk adapter( with shutter), and a K lens. This leaves only the 06 tele zoom. Wow. More thinking to do.
thanks
barondla
05-13-2014, 05:12 AM   #29
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QuoteOriginally posted by barondla Quote
On the extension tube front, I tried a mock up. Used construction paper to make a 10mm tube. Set the 01 lens to infinity focus, and f1.9 aperture
Have I got this right?
To use the lens disconnected as above you have to remove it from the camera while the camera is on otherwise the lens internal shutter is closed?
And we are stuck with full open aperture?

---------- Post added 05-14-14 at 12:48 AM ----------

OK-- before someone else gets the same silly idea-- I took a spare 40.5mm uv filter and smashed the glass out of it. I then took a Dmount to Q adapter and ground a little off the rim so I could then mount in in the female end of the filter ring. Presto-- a reversing ring for the 01 and 02. About 4mm depth between filter thread and mount..
But same result as Barondla-- way too close for the 01 and not much better for the 02 out at 15.
Of course it is a moot point how much extension that was because you need to know where the optical centre of the lens is.
I take it the focussing is electrical with no physical connection to the focuss ring--- So no focussing available.
So a total waste of cunning scheming
05-13-2014, 07:38 AM   #30
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QuoteOriginally posted by GUB Quote
Have I got this right?
To use the lens disconnected as above you have to remove it from the camera while the camera is on otherwise the lens internal shutter is closed?
And we are stuck with full open aperture?

There is a way to stop the lens down. I shoot on Raw, set aperture with lens on camera, and take a picture. While camera is blinking remove lens. Shutter stays open and lens will be at the selected aperture. Works well, just a little slow.

---------- Post added 05-14-14 at 12:48 AM ----------

OK-- before someone else gets the same silly idea-- I took a spare 40.5mm uv filter and smashed the glass out of it. I then took a Dmount to Q adapter and ground a little off the rim so I could then mount in in the female end of the filter ring. Presto-- a reversing ring for the 01 and 02. About 4mm depth between filter thread and mount..
But same result as Barondla-- way too close for the 01 and not much better for the 02 out at 15.
Of course it is a moot point how much extension that was because you need to know where the optical centre of the lens is.
I take it the focussing is electrical with no physical connection to the focuss ring--- So no focussing available.
So a total waste of cunning scheming
Never a total waste of scheming time! Major FUN was created and knowledge was harvested. We now know that the 01 lens is pretty useless with any kind of mechanical close focus assistance. All mechanical methods lead to almost zero working distance. Even if an extesion tube could be made around 6mm, I fear, the lens would still be bumping into every thing.

I will use the 01lens with the 4 and 10 diopter lenses. These don't give extreme magnification and work well.

thanks
barondla

The Q is fun.
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