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01-03-2017, 12:54 AM   #31
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Yes, but one doesn't need a fast lens these days - except when fishing for a shallow DOF.

On the K3, I was 100% happy with the 16-85 F4+ and the K3 would start to make just-visible noise at ISO500. The K1 is around the same point at ISO2000. So an F4 lens would be usable most of the time, and would be a lot smaller and better quality.

01-03-2017, 01:29 AM   #32
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QuoteOriginally posted by peterh337 Quote
Yes, but one doesn't need a fast lens these days - except when fishing for a shallow DOF.

On the K3, I was 100% happy with the 16-85 F4+ and the K3 would start to make just-visible noise at ISO500. The K1 is around the same point at ISO2000. So an F4 lens would be usable most of the time, and would be a lot smaller and better quality.
Unfortunately, Bigger (lens)>Stronger (ie sharper edges)>Faster (aperture) catches attention and the ego more than Smaller>Weaker>Slower
Pentax did the smaller more portable lenses route in the digital age with the DA lenses and got hammered on paper based on-line reviews that only focus on MTF on a flat piece of paper (often not at infinity).

Personally, I like small UWA, f4 (even f5.6) since I mostly use them for stopped down shooting.
01-03-2017, 01:58 AM - 1 Like   #33
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QuoteOriginally posted by pinholecam Quote
Unfortunately, Bigger (lens)>Stronger (ie sharper edges)>Faster (aperture) catches attention and the ego more than Smaller>Weaker>Slower
When people tease me about the 20/3.5 Voigtlander I just give them a hit on the head with the DFA 150-450. They only do it once.....

---------- Post added 03-01-17 at 07:30 PM ----------

QuoteOriginally posted by peterh337 Quote
Here is one FA 20 for €1000!
Pentax FA SMC 2.8/20 mm #4970417 Lens | eBay

New Voigtlander here for $599us Hong Kong Buy and Sell Limited

Was $489 a few months ago (what I paid)
01-03-2017, 06:05 AM   #34
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QuoteOriginally posted by noelpolar Quote
When people tease me about the 20/3.5 Voigtlander I just give them a hit on the head with the DFA 150-450. They only do it once.....

---------- Post added 03-01-17 at 07:30 PM ----------




New Voigtlander here for $599us Hong Kong Buy and Sell Limited

Was $489 a few months ago (what I paid)
Ha..ha...

I passed on the Voigtlander recently and I'm regretting it already. (already have the M20/4 which I love)

01-03-2017, 07:50 AM   #35
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What would be a suitable compact 17-20mm AF lens for a K1?

I shoot almost all the time in the TAV mode, which is basically manual+AF.
01-03-2017, 07:51 AM   #36
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QuoteOriginally posted by pinholecam Quote
I passed on the Voigtlander recently and I'm regretting it already. (already have the M20/4 which I love)
Maybe you find some peace of mind in the fact that we Color Skopar 20 users are plagued with a 52mm filter thread, while you can nicely share filters between the M20/4, all all those wonderful M/A/F/FA/DA/D-FA primes with 49mm thread!

Can't tell you how baffled I was when my 49mm ND fell out of my the then new DA 50mm F/1.8 for no obvious reason! My currently 'active' 49mm selection includes HD-DA 15mm (crop), F 28/2.8, DA 35/2.4, F 50/1.7 or FA 50/1.4 or DA 50/1.8 (stepped down), D-FA 50/2.8, DA70/2.4 (soon replaced by 77/1.8), D-FA100/2.8WR, M135/3.5 (while the Carl Zeiss Jena is being repaired). All nice, compact, lightweight and most of them superb quality-wise. Thinking of making a non-protruding step-down ring to screw into the Voigtländer thread. A single slim 49mm filter will not cause vignetting for my use.

And no, I'm not looking to swap my little Voigtländer for anything else.

---------- Post added 2017-01-03 at 07:54 ----------

QuoteOriginally posted by peterh337 Quote
I shoot almost all the time in the TAV mode, which is basically manual+AF.
What do you mean by this? Exposure and focus modes are independent. The A-type manual focus lenses work with any exposure modes, including TAV.
01-03-2017, 08:29 AM   #37
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Sorry if I wasn't clear. What I was getting at is that if I shoot in TAV mode, a lens which does AF, but doesn't have any aperture control from the camera, would work just fine.

But I am probably not understanding how aperture control works. I have a vague recollection from the old film (OM1) days that the lenses all had a pin sticking out of the bottom which, when pushed in, would close down the iris to the aperture selected on the lens aperture ring. So you did the viewfinder stuff (focusing etc) with the aperture wide open, and then when the shutter was pressed, some sort of mechanism in the camera would push that pin and close down the aperture to the set value. But the camera did not control the aperture gradually - it was wide open, or set to the ring-selected value.

Obviously with modern lenses the camera has some sort of fine control over the aperture. I do know that autofocus is done either with a motor-driven screw or with a motor inside the lens.

So, if I have this right, if I use say that Tokina 17mm lens with a K1 in the TAV mode, I have to set the camera F to the same F which the lens is set to.
01-03-2017, 08:36 AM   #38
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QuoteOriginally posted by peterh337 Quote
Sorry if I wasn't clear. What I was getting at is that if I shoot in TAV mode, a lens which does AF, but doesn't have any aperture control from the camera, would work just fine.

But I am probably not understanding how aperture control works. I have a vague recollection from the old film (OM1) days that the lenses all had a pin sticking out of the bottom which, when pushed in, would close down the iris to the aperture selected on the lens aperture ring. So you did the viewfinder stuff (focusing etc) with the aperture wide open, and then when the shutter was pressed, some sort of mechanism in the camera would push that pin and close down the aperture to the set value. But the camera did not control the aperture gradually - it was wide open, or set to the ring-selected value.

Obviously with modern lenses the camera has some sort of fine control over the aperture. I do know that autofocus is done either with a motor-driven screw or with a motor inside the lens.

So, if I have this right, if I use say that Tokina 17mm lens with a K1 in the TAV mode, I have to set the camera F to the same F which the lens is set to.
No, TAv will only work with lenses that have the A setting or no aperture ring at all. Manual focus lenses that have the A contacts will work just fine with TAv if they are set to A. Once you take them out of A and use the aperture ring they can only be used in M mode. The same goes for Auto Focus lenses that have an aperture ring. There is only one FA lens that doesn't have an A setting, the 85mm Soft Focus. That lens can only be used in M.

Bojidar Dimitritov has info on how the K-mount works...

Features and Operation of the Ka Mount

Features and Operation of the Kaf Mount

Features and Operation of the Kaf2 Mount

The "Crippled" Kaf2 just removes the aperture linkage that would allow open aperture metering with non-A lenses.


Last edited by boriscleto; 01-03-2017 at 08:42 AM.
01-03-2017, 08:41 AM   #39
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The Tokina 17mm is clearly just M then:



Are there any lenses 17-20mm which are AF and have the A mode?
01-03-2017, 08:52 AM   #40
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QuoteOriginally posted by peterh337 Quote
The Tokina 17mm is clearly just M then:



Are there any lenses 17-20mm which are AF and have the A mode?
The Cosina 19mm F3.8 had a A version. In the US it was sold as a Vivitar

Vivitar (Cosina) 19mm f/3.8 Lens Reviews - Vivitar Lenses - Pentax Lens Review Database

Tamron had a 17mm Adaptall.

Tamron Adaptall-2 SP 17mm f/3.5 (51B/151B) Lens Reviews - Tamron Adaptall Lenses - Pentax Lens Review Database
01-03-2017, 08:56 AM   #41
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From cruising the lens database here on Pentax Forums, I'm not finding a lens that works. If I don't consider lenses described as "large", and it needs to be a prime, probably the best option is this;

Sigma 15mm F2.8 EX DG Diagonal Fisheye Lens Reviews - Sigma Lenses - Pentax Lens Review Database

This lens + de-fish in post is probably what I'd recommend. This is why I'd consider a 15mm Limited and fly in crop mode until there's a lens that works for you. There's a couple out of production 19/20-35mm zooms in the third party database that fit but they're not small.

EDIT: Duh, this only applies to the 3rd party lens database. Pentax FA 20 would probably fit the bill if you want to spend up to $600 on a good one. They're somewhat rare and now in greater demand due to the K-1's existence on the market.

Last edited by pres589; 01-03-2017 at 09:13 AM.
01-03-2017, 09:05 AM   #42
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QuoteOriginally posted by peterh337 Quote
The Tokina 17mm is clearly just M then:



Are there any lenses 17-20mm which are AF and have the A mode?
Yes, the Pentax 20mm prime shown in post #22....albeit fairly rare to find a used one.
01-03-2017, 09:17 AM   #43
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Hmmm... interesting it comes back to that. Here is a nice Ebay specimen, from Japan, and with a later S/N than any of the others
"Rare" "As-is" SMC Pentax A 20mm F/2.8 MF Wide Angle Lens From Japan A627 | eBay

The reading on the K mounts is good too - thanks.
01-03-2017, 09:25 AM   #44
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QuoteOriginally posted by peterh337 Quote
Hmmm... interesting it comes back to that. Here is a nice Ebay specimen, from Japan, and with a later S/N than any of the others
"Rare" "As-is" SMC Pentax A 20mm F/2.8 MF Wide Angle Lens From Japan A627 | eBay

The reading on the K mounts is good too - thanks.
Just $339 with haze...
01-03-2017, 09:28 AM   #45
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Yes; I did see that last time round and forgot... This one has fungus
Pentax SMC A 20mm F2.8 Lens. Filter | eBay

The others are all bad according to the description so probably worse

OK... looking at the somewhat pricey Sigma 15mm now
http://www.srsmicrosystems.co.uk/sigma-15mm-f2-8-ex-dg-fisheye-lens-pentax-fit.html
http://www.ebay.co.uk/itm/Sigma-15mm-F2-8-EX-DG-AF-Diagonal-Fisheye-Lens-for...-/232165962591

It appears to still be in production.

One thing which concerns me is damage to the front. There is no filter. How can one protect it? I would assume the hood prevents the glass touching a flat surface.

How would one de-fish it? I have Lightroom 6.5. I would need to check if it has support for it, or is this intended to mean some general geometric correction? I already do do-barrel in Vegas with videos because all action cams have a lot of barrel distortion. But the correction is far from complete. OTOH I could crop to say 20mm equivalent, which is important since I am sure a 180mm FOV lens cannot be fully corrected, ever.

Last edited by peterh337; 01-03-2017 at 10:13 AM.
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