Pentax Q - K-mount adapter !

yjcs · 09-06-2011, 07:40 PM

I am pretty new over here. I can feel the excite atmosphere on different topics and really learned alot. But I can see some strong words over here as well. I wish members of this site can freely express their technique ideas but not take (make) it personally. I wish a friendly pentaxforums.

Christopher M.W.T · 09-07-2011, 05:29 AM

Originally posted by snostorm

You're all so funny!!!

I suppose that shooting long tele is a bit beyond you. . .

Here's how it would work -- The Q + K-Q adapter could be used as a virtual 3.6x TC without the 3.6x stop loss of light that rear converter TCs normally cost. This means that a $600 100mm f2.8 which can be carried in a jacket pocket and weighs only 13 oz (add the Q body and the total is @ 20 oz) can be shot as as if it were a 361mm f2.8 lens on an APS-C or a 553mm f2.8 lens on a 36x24 sensored body. If your not aware of the size, weight, and cost of these lenses, the FA* 300 f2.8 uses a 112mm front filter (that's about 4.4 inches in diameter) and weighs in at @ 6 lbs 10 oz ready to shoot (and note that it offers 61mm less reach) -- and it would probably cost in the neighborhood of at least $5000 USD if available new now (figure @ $3000+ used). A lower cost alternative would be the Sigma EX 300 f2.8 APO which is maybe a lb lighter and costs a bit over $3000, but it's not quite as good as the FA*.

Compared to the closest thing for a 36x24 sensored body, the Sigma 200-500 f2.8 zoom weighs in at 35 lbs and costs @ $26,000 USD, and is big enough that you'd need something like a golf bag and cart to protect/transport it . The Sigma EX 500 f4 is a slower option, but still costs @ $4000 USD and weighs over 7 lbs.

The 300/2.8 class of lens is heavy enough that it's not really easily handholdable (take a gallon jug of water and hold it up to your eye like a camera to get an idea of what it's like), so good tripod support is necessary for any extended shooting. To do the job right, add a heavy duty CF tripod and a gimbal head @ something like $1000 if you get one of the cheaper tripods (plus it's about 10-12 lbs more gear to carry). For the Q, you could get comparable support with a CF tripod and quality ballhead in the 3-5 lb range total and probably a cost of $300-400.

Before you go back to the "but IQ would be better with APS-C" argument, I'll concede that you would be correct, I'll counter that by saying that saving about 13 lbs of system carrying weight (camera body, lens, and tripod/head) and about $5000 can be worth more of a tradeoff in IQ than the Q presents vs APS-C. For me, an investment of @ $1000 for the Q kit and K-Q adapter is really not a whole lot for the potential benefit it might bring. I can get out to 1020mm (1530mm EQ) with stacked TCs on a 300/2.8 (2 ea 1.4x TCs and a 1.7x AFA), but I have a max aperture of f9.3. With the Q + adapter and a 300/2.8, I'd have a 1659mm EQ lens that I can shoot at f2.8. Over three and a half stops advantage is nothing to sneeze at when shooting extreme tele (and the inevitable camera shake) at living creatures that don't listen when you ask them to stand still. Shooting at 1/1000 instead of something around 1/100 will make a bigger difference in final IQ than the IQ differences between the sensors, and that doesn't even take into account the optical resolution lost with the stacked TCs (which is actually not as extreme as most people think, but it's noticeable)

Even if it doesn't work as well as I hope --though zxaar's assessment of the IQ potential is pretty positive -- I'd still have a compact camera that seems to be at the top of the class for IQ, handling, and build quality for a compact. I've played around with the high ISO sample images that have been posted, and they are more than acceptable to me for the class of camera -- and I'd still have my K-5 for more serious work.

And then there are the potential benefits for macro shooting. . . I won't waste my time.

Laugh all you want. The Q has some serious potential as a photographic tool for me regardless if you can see the possibilities or not. It's possible that it can get me images that I wouldn't get with my present gear, and that's really what this is all about, isn't it?

Scott

Dude take a chill pill, or how about just smoke some green and relax!

No I was actually saying that the size/ratio of the camera to lens is hilarious, but no doubt the results are pretty impressive.

Definitely would be a great tool for macro shooting, I am seriously considering the Q to play with as I can see its uses.

Finally in regards to being funny, I am actually one of the funniest people on this forum, I have little regards for many things on here and a PARTICULARLY HIGH disdain for camera nerds who care more about the wanky light collecting properties, difftractions physics, megapixel wank and all that....my view on photography is that you camera great images the (how to) behind the scenes of what the camera does and how it does it is the domain of the engineers, if my camera can capture pretty girls (preferably without clothes) and I'm happy.

Christopher M.W.T · 09-07-2011, 05:30 AM

Originally posted by hcarvalhoalves

Q's sensor features a higher pixel density (for a premium), but consider, for instance, the effects of diffraction and purple fringing. Even dust spots can be a nightmare in a sensor that size. I have my doubts if featuring an uncropped 12MP makes it automatically better IQ-wise for tele work.

I guess the proof is in the quality of the released images so far, argue you it all you want the little camera is certainly punching above its weight.

Zygonyx · 09-07-2011, 06:28 AM

Well, i am just getting to catch mine i.o. to test and try it in real conditions.

Hope the adapter will soon be released as well...

devorama · 09-08-2011, 09:13 AM

A user in another thread posted this link to a Q with some lens adapters. Google translation seems to indicate they may be producing these in 10 days!

BORG WORLD

falconeye · 09-08-2011, 11:04 AM - **2 Likes**

What has been said here about the diffraction limits is not accurate.

I tried to make a more accurate statements here:

Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, 100% crops look visibly soft).

Therefore, shooting a DA*300 or DA*60-250 with a Q at their sharpest aperture (about f/5.0) will still deliver plenty of detail a K-5 won't render.

But the additional reach will not be that of the crop factor. It will be only roughly be 2-2.5 vs. a K-5 (because you can crop a K-5 image more). And only about 1.8x vs. a 24MP K-5mkII or NEX7, i.e., not more than what a 1.7x TC provides. OTOH, the * lenses do resolve enough detail to exploit this ~2x factor near the center.

devorama · 09-08-2011, 11:18 AM

Originally posted by falconeye

Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, it is visibly soft).

I'm a little confused here. Isn't the amount of the diffraction dependent on the actual aperture size rather than the F-stop? F/4 is a pretty tiny opening on an 8.5mm lens, but is not so tiny an a 300mm lens. So would we need to worry as much about diffraction limits when adapting K mount lenses on the Q?

falconeye · 09-08-2011, 11:22 AM

Originally posted by Christopher M.W.T

a PARTICULARLY HIGH disdain for [...] difftractions physics [...] my camera can capture pretty girls (preferably without clothes) and I'm happy.

Let me assure you that the girls uncloth irrespective of the knowledge about diffraction physics behind the camera

falconeye · 09-08-2011, 11:29 AM - **1 Like**

Originally posted by devorama

Isn't the amount of the diffraction dependent on the actual aperture size rather than the F-stop? F/4 is a pretty tiny opening on an 8.5mm lens, but is not so tiny an a 300mm lens.

Girl unclothed, so I can answer this

No.

Diffraction is caused by interference and is due to the angular difference of light rays hitting a pixel (actually, path length differences between all the rays coming from within the lens aperture). And that difference is indeed proportional to the angle theta and aperture diameter a. Destructive interference happens where this difference becomes half the wavelength, lambda/2 ~ theta * a/2.

The point is that for any given focal length, you want to keep theta * f < eps smaller than a given limit eps, say a pixel.

Substituting theta, this means: lamda * f / a < eps. And f/a is called the f-stop N: N < eps / lambda .

You have to care more about diffraction in a Q because its pixels are smaller (eps is smaller). The effect of the smaller aperture diameter in mm is offset by a shorter path towards the sensor.

**Clinton** · 09-08-2011, 12:49 PM

I cant wait to strap my 2000mm onto this thing and have a 11200mm/13.5 lens

devorama · 09-08-2011, 12:56 PM

Originally posted by falconeye

Diffraction is caused by interference and is due to the angular difference of light rays hitting a pixel (actually, path length differences between all the rays coming from within the lens aperture). And that difference is indeed proportional to the angle theta and aperture diameter a. Destructive interference happens where this difference becomes half the wavelength, lambda/2 ~ theta * a/2.

Thanks for that. After I started to draw a picture of things, I could see how the focal length and aperture scaled together. Looking at these formulas also made me realize I can shoot maybe a stop slower without diffraction effects by shooting only violet light images. I could bring the Q to my upcoming black light party, but then that's a low light event. ;-)

jogiba · 09-08-2011, 01:01 PM

Originally posted by Clinton

I cant wait to strap my 2000mm onto this thing and have a 11200mm/13.5 lens

audiobomber · 09-08-2011, 01:56 PM

Jogiba, can you explain what you're showing here? What are the scopes, what sort of focal lengths do you end up with? What is the cost for a decent scope and adapter? Post some photos, I'm very curious about this.

jay_akita · 09-08-2011, 11:01 PM

Originally posted by falconeye

What has been said here about the diffraction limits is not accurate.

I tried to make a more accurate statements here:

Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, 100% crops look visibly soft).

Therefore, shooting a DA*300 or DA*60-250 with a Q at their sharpest aperture (about f/5.0) will still deliver plenty of detail a K-5 won't render.

But the additional reach will not be that of the crop factor. It will be only roughly be 2-2.5 vs. a K-5 (because you can crop a K-5 image more). And only about 1.8x vs. a 24MP K-5mkII or NEX7, i.e., not more than what a 1.7x TC provides. OTOH, the * lenses do resolve enough detail to exploit this ~2x factor near the center.

Thanks for the great post - this is exactly what I was wondering about. I just pulled the trigger on the 60-250 and am thinking the Q would make a great "accessory" (once the price drops to something more reasonable anyway) even if it means my 60-250 would "only" become a 500mm F4 lens when mounted to the Q.

The 60-250 is about the biggest lens I could imagine lugging around on a mountain hike although often wish I had something longer when spotting wildlife...looks like the Q will make a good comprimise although it would be even better with autofocus!!! Now I just have to convince my wife how nice it will be for her to have a high quality compact camera that I won't mind carrying around for her!

SteveM · 09-08-2011, 11:59 PM

I'd like to try one on my longer glass as well (just out of interest as it's obvious it doesn't have capabilities beyond the K-5). Falk, longer glass starts at f8...so if I understand your previous post, for longer lenses, we are limited to glass that is sharp wide open at F5.6?

09-07-2011, 05:29 AM	#62
Christopher M.W.T Veteran Member Join Date: Jun 2009 Posts: 1,689	Originally posted by snostorm You're all so funny!!! I suppose that shooting long tele is a bit beyond you. . . Here's how it would work -- The Q + K-Q adapter could be used as a virtual 3.6x TC without the 3.6x stop loss of light that rear converter TCs normally cost. This means that a $600 100mm f2.8 which can be carried in a jacket pocket and weighs only 13 oz (add the Q body and the total is @ 20 oz) can be shot as as if it were a 361mm f2.8 lens on an APS-C or a 553mm f2.8 lens on a 36x24 sensored body. If your not aware of the size, weight, and cost of these lenses, the FA* 300 f2.8 uses a 112mm front filter (that's about 4.4 inches in diameter) and weighs in at @ 6 lbs 10 oz ready to shoot (and note that it offers 61mm less reach) -- and it would probably cost in the neighborhood of at least $5000 USD if available new now (figure @ $3000+ used). A lower cost alternative would be the Sigma EX 300 f2.8 APO which is maybe a lb lighter and costs a bit over $3000, but it's not quite as good as the FA. Compared to the closest thing for a 36x24 sensored body, the Sigma 200-500 f2.8 zoom weighs in at 35 lbs and costs @ $26,000 USD, and is big enough that you'd need something like a golf bag and cart to protect/transport it . The Sigma EX 500 f4 is a slower option, but still costs @ $4000 USD and weighs over 7 lbs. The 300/2.8 class of lens is heavy enough that it's not really easily handholdable (take a gallon jug of water and hold it up to your eye like a camera to get an idea of what it's like), so good tripod support is necessary for any extended shooting. To do the job right, add a heavy duty CF tripod and a gimbal head @ something like $1000 if you get one of the cheaper tripods (plus it's about 10-12 lbs more gear to carry). For the Q, you could get comparable support with a CF tripod and quality ballhead in the 3-5 lb range total and probably a cost of $300-400. Before you go back to the "but IQ would be better with APS-C" argument, I'll concede that you would be correct, I'll counter that by saying that saving about 13 lbs of system carrying weight (camera body, lens, and tripod/head) and about $5000 can be worth more of a tradeoff in IQ than the Q presents vs APS-C. For me, an investment of @ $1000 for the Q kit and K-Q adapter is really not a whole lot for the potential benefit it might bring. I can get out to 1020mm (1530mm EQ) with stacked TCs on a 300/2.8 (2 ea 1.4x TCs and a 1.7x AFA), but I have a max aperture of f9.3. With the Q + adapter and a 300/2.8, I'd have a 1659mm EQ lens that I can shoot at f2.8. Over three and a half stops advantage is nothing to sneeze at when shooting extreme tele (and the inevitable camera shake) at living creatures that don't listen when you ask them to stand still. Shooting at 1/1000 instead of something around 1/100 will make a bigger difference in final IQ than the IQ differences between the sensors, and that doesn't even take into account the optical resolution lost with the stacked TCs (which is actually not as extreme as most people think, but it's noticeable) Even if it doesn't work as well as I hope --though zxaar's assessment of the IQ potential is pretty positive -- I'd still have a compact camera that seems to be at the top of the class for IQ, handling, and build quality for a compact. I've played around with the high ISO sample images that have been posted, and they are more than acceptable to me for the class of camera -- and I'd still have my K-5 for more serious work. And then there are the potential benefits for macro shooting. . . I won't waste my time. Laugh all you want. The Q has some serious potential as a photographic tool for me regardless if you can see the possibilities or not. It's possible that it can get me images that I wouldn't get with my present gear, and that's really what this is all about, isn't it? Scott Dude take a chill pill, or how about just smoke some green and relax! No I was actually saying that the size/ratio of the camera to lens is hilarious, but no doubt the results are pretty impressive. Definitely would be a great tool for macro shooting, I am seriously considering the Q to play with as I can see its uses. Finally in regards to being funny, I am actually one of the funniest people on this forum, I have little regards for many things on here and a PARTICULARLY HIGH disdain for camera nerds who care more about the wanky light collecting properties, difftractions physics, megapixel wank and all that....my view on photography is that you camera great images the (how to) behind the scenes of what the camera does and how it does it is the domain of the engineers, if my camera can capture pretty girls (preferably without clothes) and I'm happy. Last edited by Christopher M.W.T; 09-07-2011 at 06:37 AM.*

09-08-2011, 11:04 AM - 2 Likes	#66
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Diffraction and the Q What has been said here about the diffraction limits is not accurate. I tried to make a more accurate statements here: https://www.pentaxforums.com/forums/1632986-post1079.html https://www.pentaxforums.com/forums/1634097-post1098.html Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, 100% crops look visibly soft). Therefore, shooting a DA300 or DA60-250 with a Q at their sharpest aperture (about f/5.0) will still deliver plenty of detail a K-5 won't render. But the additional reach will not be that of the crop factor. It will be only roughly be 2-2.5 vs. a K-5 (because you can crop a K-5 image more). And only about 1.8x vs. a 24MP K-5mkII or NEX7, i.e., not more than what a 1.7x TC provides. OTOH, the * lenses do resolve enough detail to exploit this ~2x factor near the center. Last edited by falconeye; 09-08-2011 at 11:19 AM.

09-08-2011, 11:29 AM - 1 Like	#69
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by devorama Isn't the amount of the diffraction dependent on the actual aperture size rather than the F-stop? F/4 is a pretty tiny opening on an 8.5mm lens, but is not so tiny an a 300mm lens. Girl unclothed, so I can answer this No. Diffraction is caused by interference and is due to the angular difference of light rays hitting a pixel (actually, path length differences between all the rays coming from within the lens aperture). And that difference is indeed proportional to the angle theta and aperture diameter a. Destructive interference happens where this difference becomes half the wavelength, lambda/2 ~ theta a/2. The point is that for any given focal length, you want to keep theta * f < eps* smaller than a given limit eps, say a pixel. Substituting theta, this means: lamda f / a < eps. And f/a* is called the f-stop N: N < eps / lambda . You have to care more about diffraction in a Q because its pixels are smaller (eps is smaller). The effect of the smaller aperture diameter in mm is offset by a shorter path towards the sensor. Last edited by falconeye; 09-08-2011 at 12:02 PM. Reason: reformulated

09-08-2011, 11:01 PM	#74
jay_akita Forum Member Join Date: Jul 2010 Posts: 64	Originally posted by falconeye What has been said here about the diffraction limits is not accurate. I tried to make a more accurate statements here: https://www.pentaxforums.com/forums/1632986-post1079.html https://www.pentaxforums.com/forums/1634097-post1098.html Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, 100% crops look visibly soft). Therefore, shooting a DA300 or DA60-250 with a Q at their sharpest aperture (about f/5.0) will still deliver plenty of detail a K-5 won't render. But the additional reach will not be that of the crop factor. It will be only roughly be 2-2.5 vs. a K-5 (because you can crop a K-5 image more). And only about 1.8x vs. a 24MP K-5mkII or NEX7, i.e., not more than what a 1.7x TC provides. OTOH, the * lenses do resolve enough detail to exploit this ~2x factor near the center. Thanks for the great post - this is exactly what I was wondering about. I just pulled the trigger on the 60-250 and am thinking the Q would make a great "accessory" (once the price drops to something more reasonable anyway) even if it means my 60-250 would "only" become a 500mm F4 lens when mounted to the Q. The 60-250 is about the biggest lens I could imagine lugging around on a mountain hike although often wish I had something longer when spotting wildlife...looks like the Q will make a good comprimise although it would be even better with autofocus!!! Now I just have to convince my wife how nice it will be for her to have a high quality compact camera that I won't mind carrying around for her!

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09-06-2011, 07:40 PM	#61
yjcs Junior Member Join Date: Dec 2010 Location: calgary Photos: Gallery Posts: 39	I am pretty new over here. I can feel the excite atmosphere on different topics and really learned alot. But I can see some strong words over here as well. I wish members of this site can freely express their technique ideas but not take (make) it personally. I wish a friendly pentaxforums.

09-07-2011, 05:30 AM	#63
Christopher M.W.T Veteran Member Join Date: Jun 2009 Posts: 1,689	Originally posted by hcarvalhoalves Q's sensor features a higher pixel density (for a premium), but consider, for instance, the effects of diffraction and purple fringing. Even dust spots can be a nightmare in a sensor that size. I have my doubts if featuring an uncropped 12MP makes it automatically better IQ-wise for tele work. I guess the proof is in the quality of the released images so far, argue you it all you want the little camera is certainly punching above its weight.

09-07-2011, 06:28 AM	#64
Zygonyx Pentaxian Join Date: Jun 2011 Location: Ile de France Posts: 4,033	Well, i am just getting to catch mine i.o. to test and try it in real conditions. Hope the adapter will soon be released as well...

09-08-2011, 09:13 AM	#65
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	A user in another thread posted this link to a Q with some lens adapters. Google translation seems to indicate they may be producing these in 10 days! BORG WORLD

09-08-2011, 11:18 AM	#67
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	Originally posted by falconeye Basically, the Q is "influenced" by diffraction between f/2 and f/4 (loosing contrast in a recoverable way using sharpening tools as MTF doesn't become zero at Nyquist) and then looses resolution when going beyond (e.g., at f/8, it is visibly soft). I'm a little confused here. Isn't the amount of the diffraction dependent on the actual aperture size rather than the F-stop? F/4 is a pretty tiny opening on an 8.5mm lens, but is not so tiny an a 300mm lens. So would we need to worry as much about diffraction limits when adapting K mount lenses on the Q?

09-08-2011, 11:22 AM	#68
falconeye Veteran Member Join Date: Jan 2008 Location: Munich, Alps, Germany Photos: Gallery Posts: 6,871	Originally posted by Christopher M.W.T a PARTICULARLY HIGH disdain for [...] difftractions physics [...] my camera can capture pretty girls (preferably without clothes) and I'm happy. Let me assure you that the girls uncloth irrespective of the knowledge about diffraction physics behind the camera

09-08-2011, 12:49 PM	#70
Clinton Site Supporter Join Date: Feb 2010 Location: Salt Lake City, UT Photos: Gallery \| Albums Posts: 1,912	I cant wait to strap my 2000mm onto this thing and have a 11200mm/13.5 lens

09-08-2011, 12:56 PM	#71
devorama Veteran Member Join Date: Apr 2009 Location: Chicago, IL Photos: Gallery \| Albums Posts: 638	Originally posted by falconeye Diffraction is caused by interference and is due to the angular difference of light rays hitting a pixel (actually, path length differences between all the rays coming from within the lens aperture). And that difference is indeed proportional to the angle theta and aperture diameter a. Destructive interference happens where this difference becomes half the wavelength, lambda/2 ~ theta a/2*. Thanks for that. After I started to draw a picture of things, I could see how the focal length and aperture scaled together. Looking at these formulas also made me realize I can shoot maybe a stop slower without diffraction effects by shooting only violet light images. I could bring the Q to my upcoming black light party, but then that's a low light event. ;-)

09-08-2011, 01:01 PM	#72
jogiba Banned Join Date: Sep 2006 Location: Millstone,NJ Posts: 6,491 Original Poster	Originally posted by Clinton I cant wait to strap my 2000mm onto this thing and have a 11200mm/13.5 lens

09-08-2011, 01:56 PM	#73
audiobomber Veteran Member Join Date: May 2008 Location: Sudbury, Ontario Photos: Albums Posts: 6,806	Jogiba, can you explain what you're showing here? What are the scopes, what sort of focal lengths do you end up with? What is the cost for a decent scope and adapter? Post some photos, I'm very curious about this.

09-08-2011, 11:59 PM	#75
SteveM Veteran Member Join Date: Jan 2009 Location: Vancouver Island, BC, Canada Photos: Gallery Posts: 3,294	I'd like to try one on my longer glass as well (just out of interest as it's obvious it doesn't have capabilities beyond the K-5). Falk, longer glass starts at f8...so if I understand your previous post, for longer lenses, we are limited to glass that is sharp wide open at F5.6?