Official Pentax K to Q lens adapter

Started Aug 25, 2011 | Discussions
NAsullivan Junior Member • Posts: 49
Official Pentax K to Q lens adapter
Ishpuini Veteran Member • Posts: 6,249
Re: Official Pentax K to Q lens adapter

Interesting, but given the small size of the Q's sensor, the focal length of K mount lenses can be of only limited use. The resulting fields of view would be limited to the tele range only.

I'm not sure about the "crop factor", but I seem to have read somewhere it would be around 5x. Ok, the DA15/4 would result a portrait FoV (around 75mm equiv), but others would become very long...

And every non-pancake lens would probably look ridiculously large on the Q's body.

But still, it's a nice gimmick!

Wim

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Wallace Ross
Wallace Ross Senior Member • Posts: 2,174
100mm would be a 600mm

I wonder if the stabalizer can handle that? If your going to think outside the box you might as well not have one. It's all about the final image though isn't it, and that we just don't know but can get some pretty good guesses about.

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MightyMike Forum Pro • Posts: 40,595
Re: 100mm would be a 600mm

Actually wouldn't a 100mm be 560-566mm depending on the precise crop factor?
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Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

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MightyMike Forum Pro • Posts: 40,595
Re: Official Pentax K to Q lens adapter

image in a 40mm F2.8 becoming a 224mm F2.8 or even better a 43mm F1.9 becoming a 241mm F1.9...

how about a 70mm F2.4 becoming a 392mm F2.4 or a 77mm F1.8 becoming a 431mm F1.8

in DOF terms the 77mm F1.8 would be like a 431mm F10 on FF or a 287mm F6.7 (close enough to stopping down to F6.7 on a 300mm lens or the 60-250 @ 250 and not far off what you get with a 55-300)

I have an M42 135mm F1.8 that would look silly on the Q but for 756mm F1.8 it might be fun... even if i stop down to F2.8 for better sharpness

unfortunately there is no upside on the wide end
--
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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godfrog Senior Member • Posts: 1,463
Re: Official Pentax K to Q lens adapter

MightyMike wrote:

image in a 40mm F2.8 becoming a 224mm F2.8 or even better a 43mm F1.9 becoming a 241mm F1.9...

how about a 70mm F2.4 becoming a 392mm F2.4 or a 77mm F1.8 becoming a 431mm F1.8

in DOF terms the 77mm F1.8 would be like a 431mm F10 on FF or a 287mm F6.7 (close enough to stopping down to F6.7 on a 300mm lens or the 60-250 @ 250 and not far off what you get with a 55-300)

Your 77mm F1.8 does not "become" a 431mm F1.8. It most certainly remains 77mm F1.8. In terms of field of view, depth of field and total shot noise it will be like using a 287mm F6.7 on APS-C, except resolution will be miserable, focus throw will be super short, mechanical tolerances much wider than what is used on 1/2.3" sensors, internal reflections from the lack of mechanical vignetting will zap contrast, and you'll have a lot less dynamic range in scenes where there is enough light to use base ISO on the APS-C camera.

Oh, and the Q does not have a mechanically shutter, so you will have the image degradation of using an electronic shutter as well. Alternatively, the adapter will contain a leaf shutter with limited top speed as well as the issues associated with putting shutters at any point besides the focal plane or the middle of a lens, see Joseph Wisniewski's elaboration in this thread: http://photo.net/large-format-photography-forum/00YGFC

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MightyMike Forum Pro • Posts: 40,595
Re: Official Pentax K to Q lens adapter

godfrog wrote:

Your 77mm F1.8 does not "become" a 431mm F1.8. It most certainly remains 77mm F1.8.

Not arguing that

In terms of field of view, depth of field and total shot noise it will be like using a 287mm F6.7 on APS-C, except resolution will be miserable,

Not sure about the resolution being miserable, without including NR the resolution should be that of the capability of the lens itself assuming the sensor out resolves the lens.

focus throw will be super short, mechanical tolerances much wider than what is used on 1/2.3" sensors,

Hold on here, a larger sensor requires finer tolerances for more precision, i believe therefore it will be the other way around. BTW the focus throw of the 77 is 120 degrees, the focus throw of my 100-300mm F4 is about 60 degrees... the focus throw doesn't change because you're on a different sized sensor

internal reflections from the lack of mechanical vignetting will zap contrast,

If this were true then the centers of all our photos would be equally bad regardless of the sensor size

and you'll have a lot less dynamic range in scenes where there is enough light to use base ISO on the APS-C camera.

Hmmm... maybe a lot less then 14.5 stops but looking at DXO for comparison sake we could expect 10-11 stops and that similar to what we were getting just a few years back on DSLRs, about the same amount of stops you get from m43rds or about the same you've get using ISO800-1600 on the K-5 ... not a big deal.

Oh, and the Q does not have a mechanically shutter, so you will have the image degradation of using an electronic shutter as well.

Sometimes this could be useful

Alternatively, the adapter will contain a leaf shutter with limited top speed as well as the issues associated with putting shutters at any point besides the focal plane or the middle of a lens, see Joseph Wisniewski's elaboration in this thread: http://photo.net/large-format-photography-forum/00YGFC

Yes there are those such issues
--
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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Jarda_Houdek Contributing Member • Posts: 812
Re: Official Pentax K to Q lens adapter

DFA 50 or DA35 macro lenses would look great adapted on Q. An easy trick to do 5:1 maginfication due to crop ratio.
--

Through a Pentax Limited prime things may appear sharper than they actually are...
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zxaar Veteran Member • Posts: 4,458
Re: Official Pentax K to Q lens adapter

It seems it exist.

On their site http://www.pentax.jp/japan/index.html , they have an upcoming event, on 3rd and 4rth sept in osaka. Where you can take your memory card and take pictures from camera.

Down there they have put a note that you can not take the pictures taken with k-Q adapter with you others are alright. So it means it would be shown there.

If i have time and there is no prior reservation required i might go there and have a look.

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Gary Martin
Gary Martin Veteran Member • Posts: 4,729
Re: Official Pentax K to Q lens adapter

I think my FA50/1.4 is getting excited.

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zxaar Veteran Member • Posts: 4,458
Re: Official Pentax K to Q lens adapter

Gary Martin wrote:

I think my FA50/1.4 is getting excited.

will get size increase.

Soon pentax will spam our inboxes with increase the size of your   lens emails.

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godfrog Senior Member • Posts: 1,463
Re: Official Pentax K to Q lens adapter

MightyMike wrote:

godfrog wrote:

Not sure about the resolution being miserable, without including NR the resolution should be that of the capability of the lens itself assuming the sensor out resolves the lens.

That is true, the sensor will be the limit. But, if a stellar lens resolves 100lp/mm (at some contrast), then that is great on a sensor that is APS-C 24mm wide, 2400 line pairs resolved along the width. On a 1/2.3", 6mm wide, you'd resolve 600 line pairs along the width.

focus throw will be super short, mechanical tolerances much wider than what is used on 1/2.3" sensors,

Hold on here, a larger sensor requires finer tolerances for more precision, i believe therefore it will be the other way around. BTW the focus throw of the 77 is 120 degrees, the focus throw of my 100-300mm F4 is about 60 degrees... the focus throw doesn't change because you're on a different sized sensor

Smaller sensors most certainly require finer tolerances. Try using a 8x10 view camera and you'll notice that moving a lens 1mm one way or the other won't change much, while the same movement on a APS-C sensor camera will throw your image way out of focus.

Regarding focus throw, the throw will not change, but while a (theoretical) 280/6.7 lens designed for manual focus on APS-C would have a very long throw to take it from infinity focus to say 1.5m, a FA77/1.8 would have a much shorter throw to take it from infinity to 0.7m.

If you have a FA50/1.4 and a camera with live view, you can see what I mean. Zooming the live view to 4x will give you about the same view as the Q will. You'll notice small focus ring movements throw the image out of focus faster as you zoom further in. On APS-C you might use 10x to fine tune focus. 10x on a Q would be a view as narrow as 40x on an APS-C...

internal reflections from the lack of mechanical vignetting will zap contrast,

If this were true then the centers of all our photos would be equally bad regardless of the sensor size

Well yes, at F1.8, the contrast is quite low in the center, and of course, the entire image when shooting on APS-C. You'd probably be shooting at F5.6 if you wanted good contrast, and there would be no problems doing so. If you did that on the Pentax Q, you'd be loosing a lot of detail to diffraction, and you are now shooting an FF equivalent to 431mm without image stabilization on a camera that drops of in image quality much quicker than an APS-C as you start raising ISO to keep decent shutter speeds. DOF would be equal to the FF lens at F32...

Using lenses with way oversized image circles is not a good idea...

and you'll have a lot less dynamic range in scenes where there is enough light to use base ISO on the APS-C camera.

Hmmm... maybe a lot less then 14.5 stops but looking at DXO for comparison sake we could expect 10-11 stops and that similar to what we were getting just a few years back on DSLRs,

I'm pretty sure I do not want to go back to that But I know many people care less than me about dynamic range.

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MightyMike Forum Pro • Posts: 40,595
Re: Official Pentax K to Q lens adapter

I hear where you are coming from but i think you're exaggerating the problems a little more then realistic... I'm sure Pentax considers the same issues before making an adapter, essentially if its crap not many people will buy it and there is no point in making it.

BTW the Contrast and resolving capability of the 77Ltd peak at F4.0 and at still good at F2.8, and decent at F1.8/2.0. Also diffraction doesn't suddenly drop the IQ its quite a bit more gradual, I remember on the FZ30 i believe the diffraction limit was F5.0 but it was sharpest(best res. or contrast or both) at F7.1. Just look at any lens review where it shows smaller apertures, it takes quite a few stops past the diffraction limit before the resolution drops by a factor of 2.

The 77Ltd peaks at F4.0 at 48.5lpmm on the K20D on a lenstip review... it takes until F14 before the res. drops by a factor of 1.4 and F22 before it drops by a factor of 2 from its peak.

EDIT add: I forgot to mention that both my Tamron 300/2.8 and 400/4 have a focus throw of approx. 120 degrees but my old M42 Alpex 200mm F3.5 has an impressive focus throw of 270 degrees. I think when it comes to telephoto what is most important is how long its focus throw is at longer ranges. My 800mm F8 has a 90 degree focus throw but it jumps out of focus with just breathing on it a near infinity ranges
--
Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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imatom Regular Member • Posts: 134
the image of KQ adaper

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imatom

steelski Senior Member • Posts: 2,555
Re: the image of KQ adaper

Those pancakes sure are small. Very pocket-able.

People just can not trully fathom the size of the Q.
.

imatom wrote:

ogl
ogl Senior Member • Posts: 1,822
Re: the image of KQ adaper

DA40/2.8 ~ 224 mm/f16 equiv. for FF.

FA77/1.8 ~ 430 mm/f10

FA50/1.4 ~ 280 mm/f8

hard to say that such adapter has any serious sense. just for fun IMO.

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steelski Senior Member • Posts: 2,555
Re: the image of KQ adaper

ogl wrote:

DA40/2.8 ~ 224 mm/f16 equiv. for FF.

FA77/1.8 ~ 430 mm/f10

FA50/1.4 ~ 280 mm/f8

hard to say that such adapter has any serious sense. just for fun IMO.

DOF wise, yeah, As you put it, but for speed wise, the F number stays the same. Although I would not want to use the 1.4 wide open.

MightyMike Forum Pro • Posts: 40,595
Re: the image of KQ adaper

ogl wrote:

DA40/2.8 ~ 224 mm/f16 equiv. for FF.

150mm F11 on APS-C

FA77/1.8 ~ 430 mm/f10

287mm F6.7 on APS-C

FA50/1.4 ~ 280 mm/f8

187mm F5.3 on APS-=C

hard to say that such adapter has any serious sense. just for fun IMO.

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Mike from Canada

"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

Luis Fonseca Regular Member • Posts: 413
Re: the image of KQ adaper

ogl wrote:

hard to say that such adapter has any serious sense. just for fun IMO.

Indeed but I don't think that Pentax Q has any serious sense too. It is just for fun.

But, with me, photography is just for fun so I can understand the K-Q adapter with the same ease as I understant Pentax Q.

Have fun,
Luis

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Gary Martin
Gary Martin Veteran Member • Posts: 4,729
Re: the image of KQ adaper

DA40/2.8 ~ 224 mm/f16 equiv. for FF.

FA77/1.8 ~ 430 mm/f10

FA50/1.4 ~ 280 mm/f8

hard to say that such adapter has any serious sense. just for fun IMO.

Fun is good.

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