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Full Version: Pentax Q-S1 announced
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I think the reason is that most who needs a long focus lens would buy the k adapter to get crazy telephotos with their K lenses. So in this light, the wide angle lens is of higher priority.

Yes, with the Pentax Q-to-K mount adapter and old lenses multiplied by the 4.6x (Q7/Q-S1) crop factor you can get some reach on the system in a hurry.  

 

Some neat old compact M series lenses would be suitable

 

M50 --> 230mm equiv

M85/2 --> 391mm equiv

M120/2.8 --> 552mm equiv

M135/3.5 --> 621mm equiv

 

or the current 55-200 kit lens --> 253-920mm equiv

 

The official Pentax adapter has built in leaf-shutter, aperature control ring and tripod mount:

http://www.pentaxforums.com/reviews/pent...ction.html

(The original Q has a 5.6x crop factor.)

 

On the other hand, it's pricey and doesn't transmit any electronic information to the body so only M and Av control.  And no AF either.  So, a native super-tele such as 45-100mm (207~460mm equiv) would be a nice option.

Honestly I do not think that K-mount lenses are good enough for the Qs.


 

Just to put a perspective on things here:


Full format sensor = 36*24mm = 864 sqmm


Q: 7.44 x 5.58
<span style="font-weight:bold;color:rgb(84,84,84);">mm = 41.5 sqmm
</span>

 

864/41.5 * 12 megapixel = 250 megapixel.

 

That's just to visualize the pixel density of the Q sensor. SLR lenses are just not designed for this kind of requirement.

Lenses are designed to deliver quality across the whole image frame. As a simplified rule - the bigger the area, the lower the peak performance. e.g. medium format lenses are technically slightly worse than 35mm lenses (usually).

 

Of course, a SLR lens will produce a relatively decent quality but pixel-level sharpness will be difficult.

 

This doesn't mean that there are no option - there's a world of them (C-mount) actually:

http://www.bhphotovideo.com/c/search?atc...4073573422

 

Fisheye, high speed primes ... you got it all ... except long tele lenses. The Q tele zoom has 45mm max. That's also about the limit that I can spot over at B&H (among the "megapixel"-grade C-mount lenses).

Of course, cheap C-mount lenses will produce correspondingly cheap results (unsurprisingly).

 

At some stage I looked into a fisheye option but then I thought it would be mental to invest that much money into an experiment.  Rolleyes

Quote:Hum. I just don't get it.
 

Seems as if you never felt the itch to own a Mini Cooper.  Tongue
Here's a nice review of a not-all-that-super-crappy c-mount lens on the Q (and MFT):

http://danielpua.blogspot.com.au/2014/03...-lens.html
I think something like a good ~100mm macro would give high sharpness on the Q despite the high pixel density. I saw on another forum where someone was seeing aliasing in the blue channel with a tamron 90mm macro on the original Q. 

I think in the centre, well corrected SLR lenses are capable of very high resolution. 

You will never get that "pixel sharpness" anyway, as just about with any lens you put on it you will already get hit by diffraction... I would not worry too much, therefore, about "peak performance".

 

Say you get the best results at f5.6, due to diffraction, on APS-C. Or f8 on FF. Then you will get the best results at f1.8 with the Pentax Q (if the lenses would exist). Just about any lens you put on there will add quite a bit of diffraction softening, due to the very small pixel pitch.

PZ tested this f/1.9 native lens on the older Q  (1/2.3″ sensor):

[Image: mtf.png]

Looks like it's OK up to about f/2.8?  Or is it already diffracted, which is why it's flat across the graph?  

 

(The newer Q's have the slightly larger 1/1.7" sensor, so diffraction will kick in a bit later.)

 
Quote:Honestly I do not think that K-mount lenses are good enough for the Qs.


 
Just to put a perspective on things here:

Full format sensor = 36*24mm = 864 sqmm

Q: 7.44 x 5.58
mm = 41.5 sqmm



 

864/41.5 * 12 megapixel = 250 megapixel.

 

That's just to visualize the pixel density of the Q sensor. SLR lenses are just not designed for this kind of requirement.

Lenses are designed to deliver quality across the whole image frame. As a simplified rule - the bigger the area, the lower the peak performance. e.g. medium format lenses are technically slightly worse than 35mm lenses (usually).

 

Of course, a SLR lens will produce a relatively decent quality but pixel-level sharpness will be difficult.
 

I understand what you are saying and do recall that many MF lenses were manufactured to a lesser quality than 35mm lenses.  I would suppose that's why many of the uFT lenses are relatively pricey.  

But do you think that Pentax (sorry Ricoh...) are making the Q lenses to an even higher level than their APS-C lenses?   I'm not so sure about that...

 

Quote:This doesn't mean that there are no option - there's a world of them (C-mount) actually:
http://www.bhphotovideo.com/c/search?atc...4073573422

 

Fisheye, high speed primes ... you got it all ... except long tele lenses. The Q tele zoom has 45mm max. That's also about the limit that I can spot over at B&H (among the "megapixel"-grade C-mount lenses).

Of course, cheap C-mount lenses will produce correspondingly cheap results (unsurprisingly).

 

At some stage I looked into a fisheye option but then I thought it would be mental to invest that much money into an experiment.  Rolleyes
 

Heh heh, between the "controversy" of the performance of K mount lenses and the "diamonds-to-be-mined" in the C mount lenses available and your natural experimental curiosity I see a whole new set of Lens Tests to keep you busy for a long time!  

 

Buy the Q7 Klaus...buy it !!!    :lol:

Quote:Seems as if you never felt the itch to own a Mini Cooper.  Tongue
 

 

Quote:Hum. I just don't get it.
 

[Image: tumblr_mdzyb0ThgQ1r23tsqo7_1280.jpg]

 

[Image: pentaxq_1a_800.jpg]

 

[Image: ZUR_KITLENS.jpg]
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