[Guest]

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.

[dave9t5]

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.

[Klaus]

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. 

[Klaus]

Hum. I just don't get it.

 

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

[Klaus]

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

[Ayoh]

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. 

[Brightcolours]

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.

[dave9t5]

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



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.)

 

[dave9t5]

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...

 

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. 

 

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:

[dave9t5]

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

 

 

Hum. I just don't get it.