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Forum: Pentax K-1 02-03-2017, 03:06 AM  
Move from Canon to K-1?
Posted By Ptitboul
Replies: 38
Views: 5,128
Do you autofocus, or manual focus with this lens?
If you autofocus, there is no equivalent in K-mount.
If you manual focus, then the Samyang is generally thought to be better than the Canon (but of course, what "better" means depends on who says it).
Note that the Samyang is not weather sealed, while the Canon has seals.
Forum: Pentax K-1 01-29-2017, 03:09 PM  
Move from Canon to K-1?
Posted By Ptitboul
Replies: 38
Views: 5,128
for the pictures you have shown, the autofocus of the K-1 will be OK. Better than the 6D, but not as good as the 5DIV.
If you take the 15-30 along with the K-1, what do you need a 35mm prime for? If it is for large aperture, then I'd recommend the Sigma Art.
I see that you have the Canon 100 macro. You will probably love the Pentax 100 macro if you want to use it as a macro lens.
However, there is no equivalent to the Canon 135/2 : the excellent Samyang is the only possibility in K-mount, and it is not autofocus.
Forum: Pentax News and Rumors 01-26-2017, 03:11 PM  
Pentax KP - Specifications
Posted By Ptitboul
Replies: 666
Views: 83,866
It is not only software development. You need also a lot of fine tuning.

Subject tracking needs to starts with subject recognition. Pentax advertises the use of deep learning techniques (the Real-time Scene Analysis System) but these can only work after some training is done. I don't know how much manpower Nikon has put into this, but the only efficient way of doing this is to train the system with the most frequent scenes where subject tracking is needed: birding, sport shooting, kids and pets, etc.

One drawback of the Real-time Scene Analysis System (at least the way it is described on Ricoh's website) is that its only input is the 86k RGB sensor. Having access to the distance of the various elements of the scene helps to do scene recognition (by the way, this information is easier to get from PDAF systems than from CDAF systems, because the lens can transmit the focusing distance, and the PDAF system can approximately compute the distance to the plane in focus.
To my knowledge, even recent Pentax lenses don't transmit precise focusing distance.
Forum: Pentax News and Rumors 01-25-2017, 03:19 AM  
Pentax KP - Specifications
Posted By Ptitboul
Replies: 666
Views: 83,866
Yes, indeed, this is possible e.g. with my K-5 II.
I was hoping for focus bracketing, which Olympus cameras can do since a few years, for example (E-M1 got this feature through a firmware update...)
Forum: Pentax News and Rumors 01-25-2017, 02:59 AM  
Pentax KP - Specifications
Posted By Ptitboul
Replies: 666
Views: 83,866
What is this? Is it something new, or is it available in previous Pentax cameras?
I hope that it is a way to automate focus stacking (i.e. focus bracketing rather than aperture bracketing).
Forum: Pentax K-1 01-20-2017, 03:10 PM  
When using an APS-C lens on a K-1, is the only performance difference resolution?
Posted By Ptitboul
Replies: 32
Views: 4,657
I have both lenses, and a K-1. I could make a a test, but how do you want to measure Color Depth, DR and ISO ?
I guess that you would do these measurements on RAW files, but how do you downsample the 36MP image taken with the 15-30 to a 15MP RAW that could be compared with the 15MP APS-crop RAW? Or can you simulate the downsampling after having done the measurements on the original RAW?

In theory, if you take one picture with the 10-20 at f/5.6 and ISO 100, and the other with the 15-30 at f/8 and ISO 200, the results (for 15MP images, and in terms of color depth, dynamic range and noise) should be similar.
Forum: Pentax News and Rumors 12-30-2016, 08:25 AM  
New Pentax K-70
Posted By Ptitboul
Replies: 435
Views: 58,824
My guess is a high-end APS to replace the K-3 and K-3 II and a mid-range APS to replace the K-70.

The high-end APS will probably not be named K-3 III, and should have improved AF tracking capabilities (using a better CPU, maybe the PRIME IV from K-1 or a dual CPU approach as some other competitors).

The mid-range APS will probably be very similar to the K-70. It may receive the AF module and the light metering of the K-3: the current TTL 77 metering appeared in the high-end APS in 2009 with the K-7 and was taken by the mid-range APS three years later with the K-30; four years after the K-3 is the right time to expand its use.

2018 will probably be a more critical year for Pentax: 645z will need a replacement, and the K-1 too, but I doubt they will be able to do both.
Forum: Pentax News and Rumors 12-29-2016, 01:18 PM  
New Pentax K-70
Posted By Ptitboul
Replies: 435
Views: 58,824
2016 saw the release of two Pentax DSLR : K-1 and K-70.
2015 saw the release of two Pentax DSLR : K-3 II and K-S2.
2014 saw the release of two Pentax DSLR : 645z and K-S1
2013 saw the release of 2+1 Pentax DSLR : K-3 and K-50+K-500
2012 saw the release of 2+1 Pentax DSLR : K-5 II+IIs and K-30
There is a trend : each year, one DSLR with DLI109 batteries, one DSLR with DLI90 batteries.
Forum: Pentax DSLR Discussion 12-29-2016, 07:11 AM  
Thom Hogan's look on 2017
Posted By Ptitboul
Replies: 38
Views: 3,495
You can also notice that the year without DSLRs (2011) is when the Q has been released.
2013 - 3 DSLRs (K-3, K-50, K-500)
2014 - 2 DSLRs (645z, K-S1)
2015 - 2 DSLRs (K-3 II, K-S2)
2016 - 2 DSLRs (K-1, K-70)
Forum: Pentax K-1 12-23-2016, 12:16 PM  
What is your sharpest Lens on K-1?
Posted By Ptitboul
Replies: 67
Views: 7,738
I have used the DA 35/2.4 on the K-1. It is sharp, even in the corners at full aperture. Not as sharp as the DFA 100 WR, but sharp.
The main issues I had with the DA 35/2.4 are caused by focusing errors. I think that the plastic contruction is responsible for it, because it is very difficult to determine a value to correct FF/BF, and this value seems to change when unmounting the lens and mounting it again. Therefore, when I want sharp pictures with no AF issues, I use the LiveView.
The DA 35/2.4 is also prone to flare, but that is a different issue.
Forum: Pentax K-1 12-19-2016, 02:47 PM  
What is your sharpest Lens on K-1?
Posted By Ptitboul
Replies: 67
Views: 7,738
My sharpest is probably the DFA 100 macro WR. I did not use the DFA 15-30 enough, but it is probably as good as the 100.
The DA 35/2.4 is very sharp, but AF microadjustments are difficult with this lens. If you want to avoid this issue, LiveView might be the solution.
My other lenses are not as good when fully open (maybe the DA* 60-250 at full aperture at longer focals, but the vignetting makes its corner sharpness less useful) but they can be very good with smaller apertures (e.g. FA 50/1.4).
Forum: Pentax Film SLR Discussion 12-02-2016, 12:03 PM  
Calculated focal length at MFD - Focus Breathing
Posted By Ptitboul
Replies: 19
Views: 5,363
Another way to find the effective focal length at MFD is (for Pentax lenses) to look in the EXIF the value that is transmitted to the Shake Reduction system.
e.g. for the 60-250 at 250mm and MFD it is 148mm, and for the 18-135 at 135mm and MFD it is 100mm.
Forum: Pentax K-1 12-02-2016, 12:17 AM  
K1 AF issues at a wedding...
Posted By Ptitboul
Replies: 146
Views: 19,377
I also noticed this wake-up issue with my K-1, and here is my workaround: I press the shutter to wake up the camera, release the shutter, and press the shutter again to take the picture. If I only do one long shutter pressing, then it takes about 2s to take the picture. With my K5II, there is no delay when doing one shutter pressing to wake up the camera and take the picture.
Forum: Pentax K-1 12-01-2016, 03:40 PM  
Lensfun profiles for DA lenses on K-1 in FF mode
Posted By Ptitboul
Replies: 2
Views: 1,399
Lensfun is an open source initiative to create a database and a tool for lens corrections.
It is natively used by darktable | the photo workflow software for example.
Here is the profile I made, that corrects the vigneting of the (unmodified) 60-250 on K-1.




Pentax K-1


Pentax KAF2



smc Pentax-DA* 60-250mm f/4 ED IF SDM

Pentax K


I will probably make another one for the smc 55-300, which is the other lens I own that generates a lot of vignetting at its long range.
Please contribute if you can :)
Forum: Pentax K-1 09-24-2016, 02:44 PM  
Finally: DxO Optics Pro v11 support for K-1
Posted By Ptitboul
Replies: 16
Views: 2,394
I would be interested to know how DxO handles K-1 crop modes.
More precisely, when used with the DA 35/2.4 or the 60-250 in FF mode, does DxO process the whole 36Mpix picture? How does it correct vigneting for example?
Forum: Pentax K-1 08-21-2016, 11:32 AM  
Satisfied with K-1's AF-C performance
Posted By Ptitboul
Replies: 42
Views: 4,588
Thank you.

I guess that the metering mode does not have any influence on the behaviour of the autofocus, and you mention it because it is part of your usual settings.
My practice is to use TAv mode when I want to freeze the movement, and spot metering with a -1 to -2 EV correction when shooting artists indoor. I never used the possibility to link spot metering to the autofocus point, therefore usually I crop the resulting picture when I don't want the subject to be in the center of the resulting picture.
Forum: Pentax K-1 08-21-2016, 04:03 AM  
Satisfied with K-1's AF-C performance
Posted By Ptitboul
Replies: 42
Views: 4,588
Your message is useless! You should at least give recommendations or return of experience.

For example, for the type of photo showed by the OP, would you recommend the same setting (AF-C with release-priority, single center AF point)? Would it depend on the lens?
Personally, and because I am not very good at following a target, I would have chosen a group of 9 AF points around the center point. And I use AF-C with focus-priority, but I am thinking to change to release-priority, based on report from various users.
Forum: Pentax K-1 08-21-2016, 12:11 AM  
Satisfied with K-1's AF-C performance
Posted By Ptitboul
Replies: 42
Views: 4,588
Using the last version of ExifTool (the one that knows how to decode AF information) I get slightly different results.
All three photo have
Focus Mode : AF-C (Release-priority)
AF Point Selected : Center; Single Point
AF Points Selected : 17
but only the first photo has:
AF Points In Focus :
The second and third photos have:
AF Points In Focus : 17
which means that the K-1 knew that the center point was in focus.
Forum: Pentax SLR Lens Discussion 08-09-2016, 07:54 PM  
60-250mm/f4 to cover all needs between 100-250mm?? Opinions/advice welcome
Posted By Ptitboul
Replies: 34
Views: 4,823
The 60-250 and the 100WR are currently my two favorite lenses on the K-1, for all the reasons mentioned in the previous messages.
In addition, portraits at 250mm and f/4 have a nice swirling bokeh on the K-1.
Forum: Pentax Full Frame 07-28-2016, 10:37 AM  
Wide angle advantage of full frame.
Posted By Ptitboul
Replies: 44
Views: 5,545
The equivalent (in terms of FOV and DOF) of the Sigma 10-20/3.5 for APS would be a 15-30/5.0 for FF that would probably have similar price and weight, but it does not exist.
But if one wants low price and weight, I think that the K-1 is not the best option.
If fully understand why the 15-30 proposed by Pentax opens at f/2.8, because it offers something that was not available on APS cameras.

Nevertheless, you can use the Sigma 10-20/3.5 in the range 15-20 on your K-1, and it will do the job almost as efficiently as a dedicated FF 15-20/5.0.
Forum: Pentax K-1 07-10-2016, 04:22 PM  
Pentax K-1 Continuous AutoFocus Performance
Posted By Ptitboul
Replies: 135
Views: 18,819
Very interesting question. I usually don't use continuous autofocus and I never use Scene Analyze Auto, but I think that the website (Features5 | PENTAX K-1 | RICOH IMAGING) is mistaken.

When you are in "Scene Analyze Auto" (the green AUTO on the top dial) then you cannot choose another custom image mode than "Auto Select". The website did not need to mentions both settings. Moreover, the K-1 manual says (page 51) than in AUTO mode, the autofocus mode is fixed to AF-S, and indeed on my K-1 it is not a continuous AF.

In the K-1 manual, there is only one reference to tracking pages 51 and 53, which says that it is available when shooting with liveview.
Forum: Pentax K-1 07-09-2016, 01:05 AM  
Pentax K-1 Continuous AutoFocus Performance
Posted By Ptitboul
Replies: 135
Views: 18,819
I don't have the K-3. And I don't think that the AF-C tracking of my K-1 is much better than my K-5 II.
However, tracking is not the only thing that may be required in AF-C.
And I have good success in using continuous autofocus on subjects that are not coming towards the camera.

I don't know, but I have hypothesis, and it comes down to software.

I don't think that Pentax AF does subject tracking. The "Group AF" modes use simultaneously many AF sensors, and apparently recognise that the subject has moved when there is another sensor that is in focus. It is very efficient when following a subject that is moving laterally, because it may be difficult to be sure that the same AF sensor is always on the subject. I have been able to take pictures of swallows in flight using this technique. And the K-1 is better than the K-5 II because it has more AF sensors. However, some other bodies (e.g. D750, but not 6D) do subject tracking: they use the metering sensor to recognise the shape and color of the subject, and decide which AF sensors to use, knowing where the subject is. The K-3 or K-1 have a metering sensor with enough pixels to be able to do the same, therefore I think that the issue is inferior software.

I don't think either that Pentax AF does predictive AF. It doesn't seem to compute the distance of the subject, to predict what is the subject speed in the z axis, and to focus where the subject will be. Therefore, on subject moving quickly towards the photographer, the AF is always a bit late, because when it computes focus confirmation and decides to take the picture, the subject has already moved a bit. This is partly a software issue, and partly a hardware issue: fast focusing lens are a hardware improvement, and lenses that report precisely the focusing distance are another improvement. I know that old Pentax lenses report the focusing distance, but in a very imprecise manner. I don't know if recent lenses report it more precisely. Nikon is more explicit on that subject, they tell which lenses are compatible with predictive focus tracking, and they say that they take into account the "release time lag". Cf. Nikon | Technology | Predictive Focus Tracking System

Improving the software can improve it a lot.
Forum: Pentax K-3 07-07-2016, 04:01 PM  
Does it make sense to keep an APS-C camera when you have a new fullframe?
Posted By Ptitboul
Replies: 50
Views: 4,484
I will certainly keep my K-S1 along my K-1, because it is a lightweight and very capable camera. The K-S1 with the DA 21 make an excellent match!
I am not certain to keep the K-5 II, but currently it is my only camera that can wireless trigger an external flash...
Forum: Flashes, Lighting, and Studio 07-04-2016, 01:44 PM  
Smallest "Master" P-TTL flash for K1
Posted By Ptitboul
Replies: 56
Views: 10,029
According to the operating manual, downloaded at, it has no wireless mode.
Forum: Pentax SLR Lens Discussion 07-04-2016, 11:40 AM  
The Bokeh Club
Posted By Ptitboul
Replies: 20,098
Views: 1,775,723
The unmodified DA* 60-250 has a swirling bokeh on a K-1 (250mm, f/4).
I did not see it mentioned in this thread, but certainly someone else has noticed it :p
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