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04-24-2015, 01:54 PM   #991
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QuoteOriginally posted by Pentaxians Quote
So far we have Pentax Q (the first) => Q10 => Q7 => Q-S1 (the latest). Can I check in order to fully utilize the crop factor of 5.6, Q and Q10 is the best to go, for Q7 and Q-S1 the crop factor will be 4.7 right?

Any of one will be good to pair up with the "Fotodiox Lens Mount Adapter with Aperture Dial"?

Is this the correct and the latest Fotodiox mount to go with?
Amazon.com : Fotodiox Lens Mount Adapter with Aperture Dial, Pentax K Lens to Pentax Q Series Camera : Camera & Photo
That will work to use Pentax K mount lenses on any Q model

05-03-2015, 11:38 AM   #992
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Pentax-A* 600mm f/5.6 (w/ Q7)

600/5.6 on Q7 w/ OEM Pentax K adapter
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PENTAX Q7  Photo 
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PENTAX Q7  Photo 
05-10-2015, 02:50 AM - 3 Likes   #993
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Pentax 110 70mm f2.8 lens with front aperture disc.

We were discussing the possibilities of stopping down the 110 70mm lens with a disc on the front in another thread.
https://www.pentaxforums.com/forums/136-pentax-q/294184-pentax-auto-110-lenses-q-2.html
So I thought I would have a go.
The disc is black paper cut to fit in the 49mm filter thread of the lens and held in place by the lens hood.
I used a cheap panel steel circle cutter in my drillpress.
I removed one of the blades and sharpened up the other.
And clamped the black paper on top of a cutting board onto the base of the drill.
Cut the centre first and cut the outer ring without moving the paper.
I suspected that even wide open the lens used only the centre 25mm of the front lens.
So I cut one disc with a 25 mm aperture and the other as small as the cutter would go which was about 19 mm and should be about one stop slower than 25mm.
Test image is a ruler placed on mattboards-- one light grey -- one dark grey.
the camera is at about 45 degrees to the subject to display DOF on the ruler.
The 2 tones of grey was to create a 2 spiked histogram to compare exposure.
The results are screenshots with histogram included and turned on their side to better fit the format here.
The result show no difference in exposure between the 25mm disc and the lens wide open, confirming my suspicions the lens doesn't use the outer glass.
The 19mm disc is indeed one stop slower but only slightly sharper.
I will leave the 25mm disc permanently there to keep light from scattering off the unneccessary extra glass.
The last image is there to remind us that the lens can not make a decent image unless it is attached to a camera and used!
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05-19-2015, 02:18 AM   #994
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Super Takumar 150/4 at 5.6





Made with the original Q on monopod, developed from RAW - moderate crop, sharpened after web resize. Light and settings were not ideal so I'm sure this could be a little bit sharper (1/320 and 1/500 at ISO 160).
This lens seems really capable. Some abberations are present, but not the worst I've seen.

05-22-2015, 02:43 PM   #995
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Tamron SP Adaptall 60 - 300 23A (3.8 - 5.4) at 300/5.4

Today I tested my 23A lens with the original Q supported by the tripod. Sorry for the boring subjects, but I really had no time. All photos wide open at 300 mm. All were developed from raw. These are just test images, but I applied standard PP which I use for wildlife photos (including some abberation removal, simulation of Velvia slide film, use of Topaz Detail and sharpening after resampling to the web size).



... and 2 100% crops from the image above








Last edited by Piotrek K; 05-22-2015 at 03:04 PM.
05-26-2015, 03:17 PM   #996
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Index updated with latest contributions.
Thanks, and send me a note if you spot any errors.
05-26-2015, 08:59 PM   #997
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Thanks for the update crewl1...good works!
05-28-2015, 06:37 PM   #998
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QuoteOriginally posted by Pentaxians Quote
Thanks for the update crewl1...good works!
what glue is safe to use for adapting? say m42 body cap to d-mount adapter that wont leak fumes inside the lens.

05-28-2015, 07:58 PM   #999
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Super Glue or epoxy works -- just let it set til it's hard. If the instructions say to thin or clean it with a volatile fluid be careful.
05-28-2015, 11:45 PM   #1000
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QuoteOriginally posted by xerxal Quote
what glue is safe to use for adapting? say m42 body cap to d-mount adapter that wont leak fumes inside the lens.
Personally I find super glue can produce a white fog residue, so I don't use it near lenses.
Two part epoxy or the specialized epoxy for plastic (like Plastic Welder by Devcon) works great.
05-29-2015, 08:57 AM - 1 Like   #1001
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Re: Super Glue. while it's possible to experience a residue under certain circumstances, IME it's only an issue during a phase when cyanoacrylates are capable of out-gassing and when other needed components are present.

I've never had an issue with this - especially when using the tiny amount necessary for temporarily tacking small parts for trial fitting. An accessory component left to "season" a bit in sunlight and/or over time has never been a problem either.

Do a search on "super glue fingerprinting" for instance to better understand the chemical and physical processes and let your own experience be your guide.

Like radioactive lenses, I consider this a non-issue for any practical uses.
05-29-2015, 11:01 AM   #1002
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I've glued the aperture pin down on several m42 lenses with gel-type superglue, never had fogging. I have gotten a whitish haze appear on internal elements on some lenses for no apparent reason (that did wipe off if I was able to get to the element) -- possibly certain kinds of foam that might be off-gassing shouldn't in airtight cases for storage, that's my working theory....
06-05-2015, 09:11 AM   #1003
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QuoteOriginally posted by Professor Batty Quote

Nice little lens. 1/350th of a second @ f4, ISO 100 on Pentax Q-S1. I removed the filter ring adapter, it made an unattractive vignette.
This has that 'door peephole' effect.
06-15-2015, 09:12 PM   #1004
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Okay, a request here. I've been eyeballing a few old Tamrons, in particular the 300mm f2.8 SP Adaptall2 lenses, and was wondering if anyone had one to test? Apparently those lenses where very sharp for long, fast telephotos (We're talking, like, around 45-50 lpm wide open apparently) and I was wondering how they held up on the Q.

Probably going to hunt one down reguardless, but still, Hoping someone has one to show off.
06-15-2015, 09:43 PM   #1005
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QuoteOriginally posted by Mothballs Quote
Okay, a request here. I've been eyeballing a few old Tamrons, in particular the 300mm f2.8 SP Adaptall2 lenses, and was wondering if anyone had one to test? Apparently those lenses where very sharp for long, fast telephotos (We're talking, like, around 45-50 lpm wide open apparently) and I was wondering how they held up on the Q.

Probably going to hunt one down reguardless, but still, Hoping someone has one to show off.
I had the Tamron SP 400/4 65B for a year or two, which by all accounts is a very similar performer to the 60B 300/2.8. It was very sharp, but also prone to fringing. Constrast could be lowish wide-open. If you can get a good price, they are good values. Nice lenses, but then I got the Pentax-A* 300/2.8 and it blows the Tamrons out of the water (and cost $1000 more). I did use the Tamron on the original Q some -- very challening but got some ok pics after processing (expect to have to deal with purple). I'm sure it would have been a little easier on one of the newer Q's with bigger sensor, and the faster 2.8 lens will give more leeway to stop down from wide-open...
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