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11-27-2012, 11:00 PM   #1
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Pentax Q - Cmount lenses. Recommendations?

Hi all- was wondering if we could list here some recommendations for cmount lenses recommended for the Q

11-28-2012, 02:08 AM   #2
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this would be useful for me also!
11-28-2012, 02:23 AM   #3
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I feel like I've been waiting forever for my C mount adapters. Finally one of them arrived yesterday. I have two widely available lenses, a 25/1.4 that doesn't seem to have a manufacturer name and a 35/1.7 labeled Fujian.

My 25mm is possibly broken, it needs to be quite a bit further away than the adapter places it to focus on anything.

The 35mm is worth having, I feel fairly confident saying even though I haven't taken any proper shots yet. It's much better built than the 25mm, but both sell for about $20 (no doubt less if you shop around). I hope to take some shots with it today.

I also have some CS mount lenses, but there aren't any adapters for those. Avoid them unless you feel like trying to modify them or a C adapter.
11-28-2012, 07:54 AM - 2 Likes   #4
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I've recently played with a few c-mount lenses. The Pentax 6mm f/1.2, Pentax 8-48mm f/1.0, and a Computar 16mm f/1.4, but these are not "cheap" lenses at all (for c-mount; most retail for $150-250).

First, the "super-fast" apertures of some of these are only there for low-light video surveillance, and the still image quality when wide-open could be generously called "soft-focus." What this means is that everything is soft and hazy, and the bokeh is horrendous. (The 01 Prime has better bokeh than any of these "made-for-cctv" lenses!) Stop them down to f/2.8 and they are pretty good, but still nowhere near the 01 Prime, at f/1.9, in terms of sharpness.

Speaking of sharpness, the focus-peaking and MF magnification on the Q helps out a lot when focusing its native lenses, but the "soft-focus" effect of my wider aperture c-mounts makes it really hard to judge what is in focus, and the peaking just becomes a vague twinkling on some pixels, not an outline! So, I stop these lenses down, whereupon they hold almost no advantage over something like the 02 Zoom (not faster, not sharper, not easier to focus)... which is why I've ordered an 02 Zoom!

Another issue is distortion. All of these lenses have pretty bad barrel distortion, and because they are adapted, the in-camera distortion correction can do nothing about it. Photoshop can correct this to some degree, but the results still look a bit odd. So they're not for architectural or interior photos! If you turn off distortion correction on the Prime 01, you'll also see a pretty significant barrel effect, so this might just be a downside for all short focal-length lenses likes these (note that my 6mm is ~35mm equiv., and the 16mm is ~85mm equiv., and "regular format lenses" at those focal lengths will have little or no distortion).

Next, be aware of the two types of c-mount adapters out there. One is expensive and made from a single piece of metal (usually around $35-40), and the more common one (~$7) is a "two-piece" design with little screws around the outside holding the interior threaded c-mount into the Q-mount adapter. Mine is a cheaper one, and the little screws come loose and the c-mount lens just twirls inside the adapter without unscrewing (or sometimes not properly screwing all the way in)! Plus, the screw heads are tiny-hex, so I now have a nail that I've filed down to specifically tighten these things...

In conclusion, c-mount lenses are "fun" because they can be very small, cheap, and some very fast... but don't expect to do better than Pentax has with the native lenses. Follow drougge's advice above, and go for the $20 no-name lenses! The worst of my bunch was the most expensive (the Pentax/Cosmicar 8-48mm, @$200 used); relatively big and heavy (think FA 31mm), uselessly soft/hazy at wider apertures, with an enormous zoom range that is really hard to control when hand-held. I'm selling it on craigslist so no one here has to find this out the hard way...

FYI: all of the above is my own opinion based on limited experience. Other opinions can be equally valid, but if this helped you, press the "like" button.


Last edited by panoguy; 11-28-2012 at 08:02 AM.
11-28-2012, 04:42 PM   #5
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The Fujian 35/1.7 is certainly worth the price, it's small enough to be nice on the Q, and I managed to take some decent shots with it today.

Wide open (admittedly not that telling):


And two night shots at f/2.8 (or thereabouts, there is no indication of where the selected aperture is, and I don't really trust the markings anyway)


11-28-2012, 08:28 PM - 2 Likes   #6
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QuoteOriginally posted by sifun Quote
Hi all- was wondering if we could list here some recommendations for cmount lenses recommended for the Q
Are you looking for wide angle or telephoto C mount?

These are Pentax branded lenses...


Some Computars..



And the rest (last two are D mounts)



As far as the adapters I would personally go with the 2 piece adapters, not solid adapters. First, the two piece allows you to orient the aperture scale to always be upright. Second, and more importantly, I find that the registration distance varies somewhat between C mount lenses. Some need to be slightly further away, some need to be closer. The two piece adapters let you shim or reduce them if needed to dial in a lens. For this reason I leave an adapter on each of the lenses I typically will use the most.

As far as the lenses themselves....The Pentax lenses are all pretty nice. The 4.8mm f1.8 Pentax/Cosmicar fixed focus lens is a great FOV on the Q. It took some work to get that lens to be sharper as the adapter needed to be shimmed. The 6mm is good too but a little odd in that focus shifts when stopped down. I haven't used the 12.5 much yet but it seems like it could work for portraits. The 25 1.4 is sharp with a very circular bokeh.

The Computar 25s are very soft at 1.3 but are sharper around 2.8. The 25 f0.95 is sharper at 0.95 than the Computars and it can have a very great look to it with razor thin DOF if shooting close up. I haven't tried the computar 8.5 yet (have 01 prime). The 3.6mm f1.2 Computar I am working on dialing in better. It needs to be closer to the camera than the mount is allowing so I have to sand one down slightly until that gets are sharp as it can.

The fixed focus Tamron 6.5mm looks like it may be interesting too. I need to spend a little more time with that one making sure the mount is correct for it.

Of the two D mounts the 6.5mm vingettes pretty badly and I haven't used the 13mm much yet.

Comparing the Pentax/Cosmicar against the Computar's the Pentax lenses seem to be optically a little better and for the most part feel better built. They also have better IRISs in them, the Computar as 3 bladed and have a triangular IRIS when stopping them down.

Shawn
11-28-2012, 09:06 PM   #7
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i'm looking at wide angle it seems will have to consider the above mentioned!
11-30-2012, 12:53 AM - 1 Like   #8
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Hi everyone, I just registered to contribute to this thread. Thanks to the OP for starting it. I've been looking for C-mount lenses to adapt to my Q since I got it 2 weeks ago. Thanks to Shawn67, too for the good info.

Anyway, I bought a generic 6mm 1.4 cctv lens off ebay and I'm pleased to report that it does really well on the Q in the image quality department. The only negatives I see are fringing and barrel distortion, but can easily be corrected in Lightroom.

Here is the ebay link 1/2" Security CCTV 6mm Lens for 1/2" CCD Box Camera | eBay But there are sellers that sell it cheaper. I don't know why I didn't look around This one seems to be based in Singapore because I got a tracking number stating that was the origin.

I also have a Pentax 12mm/1.2 but IQ is terrible. Shame because it's fast and build quality is good. A Computar 8.5mm/1.3 is on the way, but I'm not really hopeful anymore because apparently you need high definition cctv lens to get good IQ. I almost considered buying the Pentax 8-48mm zoom. I'm also looking at the Tamron 4-12mm.

Here is the first wide open shot I took in jpg straight from the camera, but distortion is already corrected in Lightroom.



I hope this helps someone looking for c-mount lenses for the Q. This camera is a gem

11-30-2012, 06:33 AM   #9
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Chinese C-mount Fujian 35 mm f1,7 and 6 mm f1,4

QuoteOriginally posted by drougge Quote
I feel like I've been waiting forever for my C mount adapters. Finally one of them arrived yesterday. I have two widely available lenses, a 25/1.4 that doesn't seem to have a manufacturer name and a 35/1.7 labeled Fujian.

My 25mm is possibly broken, it needs to be quite a bit further away than the adapter places it to focus on anything.

The 35mm is worth having, I feel fairly confident saying even though I haven't taken any proper shots yet. It's much better built than the 25mm, but both sell for about $20 (no doubt less if you shop around). I hope to take some shots with it today.

I also have some CS mount lenses, but there aren't any adapters for those. Avoid them unless you feel like trying to modify them or a C adapter.
Pictures with Fujian 35 mm f1,7:

Sepia Rope




Blue_Ropes




Fur Face




QuoteOriginally posted by m_perete Quote
Anyway, I bought a generic 6mm 1.4 cctv lens off ebay and I'm pleased to report that it does really well on the Q in the image quality department. The only negatives I see are fringing and barrel distortion, but can easily be corrected in Lightroom.

Here is the ebay link 1/2" Security CCTV 6mm Lens for 1/2" CCD Box Camera | eBay But there are sellers that sell it cheaper. I don't know why I didn't look around This one seems to be based in Singapore because I got a tracking number stating that was the origin.
This is from the same lens from the above quote (CCTV 6 mm f1,4)

Back Yard Perspective




Sepia Wide Crop Cat
This was cropped from the center of the image




Autumn Storm




I like barrel distortion, personally.......so much so that I also bought a f:1,6/4-10mm C-mount zoom. Zoom C-mounts are a different story, though. Do not make the mistake of thinking it will have the same functionality as a "real" zoom lens. The ones I have tried works more like a number of primes in the same barrel: whenever you change focal length (or F:stop) you will also have to refocus the lens.

Thanks/Erik

Last edited by Erich_H; 01-14-2013 at 06:44 AM.
12-02-2012, 10:58 PM   #10
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QuoteOriginally posted by Erich_H Quote
I like barrel distortion, personally.......so much so that I also bought a f:1,6/4-10mm C-mount zoom
How does it perform on the Q? And has anyone tried a Tamron 4-12mm on the Q?

Last edited by m_perete; 12-02-2012 at 11:09 PM.
12-03-2012, 03:30 AM - 1 Like   #11
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4mm/2,8mm C-mounts

QuoteOriginally posted by m_perete Quote
How does it perform on the Q? And has anyone tried a Tamron 4-12mm on the Q?
Hi - this is samples from two C-mount zoom lenses [1,6/4-10 mm] & [1,6/2,8-12mm]:

4 mm Circuit Board




2,8 mm Circuit Board




Thanks/Erik

Last edited by Erich_H; 12-03-2012 at 07:28 AM.
12-03-2012, 03:42 AM   #12
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Interesting!

Thanks for that, Erich_H.
12-11-2012, 11:34 PM   #13
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Are you guys putting the Q in manual mode? Or is the Q like the m4/3s where it will figure out the exposure for you? I got a 3 C-Mounts from Amazon.. the 25 & 35 are Fujian (Both $25) and the 50 is Fotasy ($30)... I bought them for my m4/3... I have a K-5 and considered the Q but at the end I picked the Oly. But there is always room for another small mirrorless in my bag and I do love the looks of the Q!
12-12-2012, 02:11 AM - 1 Like   #14
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QuoteOriginally posted by EdwardConde Quote
Are you guys putting the Q in manual mode? Or is the Q like the m4/3s where it will figure out the exposure for you? I got a 3 C-Mounts from Amazon.. the 25 & 35 are Fujian (Both $25) and the 50 is Fotasy ($30)... I bought them for my m4/3... I have a K-5 and considered the Q but at the end I picked the Oly. But there is always room for another small mirrorless in my bag and I do love the looks of the Q!
I'll just leave it at auto, pick an f:stop & the Q chooses the time...
thanks/Erik
01-10-2013, 09:57 AM   #15
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QuoteOriginally posted by Shawn67 Quote
Comparing the Pentax/Cosmicar against the Computar's the Pentax lenses seem to be optically a little better and for the most part feel better built. They also have better IRISs in them, the Computar as 3 bladed and have a triangular IRIS when stopping them down.
Shawn if you get around to doing a review of any of these please add it to the 'adapted lenses to Q' reference thread. If you already have a review of any of these on the Q elsewhere send me a link so i can add it to the thread. Thanks!
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