K-30 AF Accuracy Testing for the Pentaxforums Review: Give Us Your Ideas!

deadwolfbones · 07-13-2012, 05:13 PM - **1 Like**

Hey guys,

So I'm the sucker who's currently writing the K-30 review for the site. Yes, send all your hate mail my way once it's posted.

I'm currently getting down to the final bits of testing, on the way to publishing the review early next week. We've done AF speed tests and some field shooting, but we still have to work on AF accuracy tests. We're wondering if any of you have any fun, creative, interesting ideas for how to test AF accuracy. While we have our own standard tests, this review is primarily for you, the readers, so we'd love to know what you'd test if you were in our shoes (i.e., if you had a K-30 in your hot little hands). So, please feel free to post your ideas in this thread. If we end up using them in the review, we'll give you a shoutout in the review text (unless you don't want us to)!

Any and all ideas are welcome, though we'll only be selecting the best two or three of them (among those that are actually feasible to perform).

Some notes to take into account when devising your devious schemes:
- I live in the desert!
- I have the following AF lenses: DA 15, DA 21, FA 31, DA 35, FA 43, FA 77
- I have tungsten, CFL, and regular fluorescent lights in my house.
- I have cats, which can be very tricky subjects to shoot.
- We want to test the K-30 against the K-5.
- I don't have a flash, aside from the built-in ones on the K-5 and K-30.

And I might add more items to that list as your ideas expose more holes in my plan.

Last edited by deadwolfbones; 07-13-2012 at 05:55 PM.

Docrwm · 07-13-2012, 05:24 PM

Behavior with flash, haven't there been issues reported with hot shoe and off camera flash sync on the K-5?

rawr · 07-13-2012, 05:31 PM

As a general suggestion, what, in your experience, is the D700 good at, and the K-5 not, in terms of AF? Test whatever that may be with the K-30.

Also some tests to try and identify the narrowness or tightness of the centre-spot AF would be useful. For some shooting scenarios (birds amidst foliage, focus on specific players in a team, the fabled 'focus on the eye' for portraits etc) it would be useful to see how tight one can go with just one AF point like the centre one.

You may also like to do some tests equivalent to those Falconeye did on the D800 to identify the weaknesses or variable sensitivity of the various sensor points/zones across the K-30's AF matrix.

panoguy · 07-13-2012, 05:36 PM

Take whichever AF lens has the longest focus throw (FA 77?) and try to track a moving object (car or bird, cats are erratic enough) with AF.C

I'd personally prefer to see the AF.C accuracy results from a slow-poke AF lens like the DA*50-135mm, but I don't think you'll wait for me to ship mine to you...

Quicksand · 07-13-2012, 05:37 PM - **1 Like**

Focus tracking.

The dog-running-toward-you test is always good. Dogs are pretty fast.

For extra credit, focus on a black dog. In the dark.

On a slightly more serious note, my K-5 seems to have the dreaded PDAF low-light front-focus problem. On the K-30, I'd like to see the results of a series of shots of the same still-life subject at various light levels, using a dimmed lamp for example.

Using an f/2.8 lens wide open, start with maximum brightness, focus to infinity, autofocus on the subject, take a shot, watch the meter while you dim the light 1/2 stop (or whatever), then focus to infinity again, autofocus, shoot, dim, repeat ad nauseum.

Does focus remain consistent? If not, at what exposure values does it start having trouble?

rawr · 07-13-2012, 05:45 PM

Originally posted by Quicksand

On the K-30, I'd like to see the results of a series of shots of the same still-life subject at various light levels, using a dimmed lamp for example.

Something similar to this was done here:
https://www.pentaxforums.com/forums/pentax-k-30/192301-k30-tungsten-light-test.html

Imaging Resource also do TONS of these sort of test shots under variable light levels (eg the ISO vs Lux light level test image matrix down the bottom of this page that was part of their K-5 review). It's something to look out for once they complete their K-30 review.

deadwolfbones · 07-13-2012, 05:53 PM

Originally posted by Docrwm

Behavior with flash, haven't there been issues reported with hot shoe and off camera flash sync on the K-5?

Alas, I don't have a flash.

edit: aside from the built-in ones, of course.

loco · 07-13-2012, 05:54 PM

Originally posted by panoguy

Take whichever AF lens has the longest focus throw (FA 77?) and try to track a moving object (car or bird, cats are erratic enough) with AF.C

I'd personally prefer to see the AF.C accuracy results from a slow-poke AF lens like the DA*50-135mm, but I don't think you'll wait for me to ship mine to you...

Yep! In my experience, whenever I walk into a room with a camera and sit down to try to take pics of my cats, they immediately run towards me.

So, if you could see if the K-30 AF.C can track them as they move towards you, that would rock!

Thanks for doing the review, really looking forward to it!

Docrwm · 07-13-2012, 06:00 PM

Originally posted by deadwolfbones

Alas, I don't have a flash.

edit: aside from the built-in ones, of course.

Perhaps one of the strobists here would be willing to loan a good one for the sake of the review? I would but I don't have pTTL model.

deadwolfbones · 07-13-2012, 06:08 PM

Originally posted by Docrwm

Perhaps one of the strobists here would be willing to loan a good one for the sake of the review? I would but I don't have pTTL model.

Would have to be overnighted by Monday to meet the pub date. :/

I think we'll have to skip that test and maybe do a followup, or one of our strobists can do so independently, later on.

Docrwm · 07-13-2012, 06:13 PM

Originally posted by deadwolfbones

Would have to be overnighted by Monday to meet the pub date. :/

I think we'll have to skip that test and maybe do a followup, or one of our strobists can do so independently, later on.

Fair enough, thanks for asking for ideas. I was trying to go with something other than the AF. Looking forward to the results!

**luftfluss** · 07-13-2012, 06:21 PM - **1 Like**

Would love to see a review of the cats. They are generally quick to focus and track moving objects well. However, they can generate a lot of noise, and the output always stinks.

Franky2step · 07-13-2012, 07:01 PM - **1 Like**

I would be interested in the low light autofocus capabilities, at pedestrian speeds...not cat speed.

goldenarrow · 07-13-2012, 09:10 PM

brainstorming ideas:

- set up cones on the ground over different distances to check mid to long focusing and apertures.

- different distances of objects with light and dark coloring, some with little contrast.

- focusing accuracy while panning

- while shooting live action, like an equestrian training center

- different parts of stands of a stadium, like a baseball game, sunlit and shadow

- macro accuracy objects with ruler next to them

SteveB · 07-14-2012, 12:10 AM

Show us how big the centre AF sensor is relative to the VF markings.

Is the AF accurate in the dark using the af assist light and pop-up flash (so there's an image to look at!).

07-13-2012, 05:13 PM - 1 Like	#1
deadwolfbones Veteran Member Join Date: Sep 2007 Location: La Crescenta, CA Posts: 7,450	K-30 AF Accuracy Testing for the Pentaxforums Review: Give Us Your Ideas! Hey guys, So I'm the sucker who's currently writing the K-30 review for the site. Yes, send all your hate mail my way once it's posted. I'm currently getting down to the final bits of testing, on the way to publishing the review early next week. We've done AF speed tests and some field shooting, but we still have to work on AF accuracy tests. We're wondering if any of you have any fun, creative, interesting ideas for how to test AF accuracy. While we have our own standard tests, this review is primarily for you, the readers, so we'd love to know what you'd test if you were in our shoes (i.e., if you had a K-30 in your hot little hands). So, please feel free to post your ideas in this thread. If we end up using them in the review, we'll give you a shoutout in the review text (unless you don't want us to)! Any and all ideas are welcome, though we'll only be selecting the best two or three of them (among those that are actually feasible to perform). Some notes to take into account when devising your devious schemes: - I live in the desert! - I have the following AF lenses: DA 15, DA 21, FA 31, DA 35, FA 43, FA 77 - I have tungsten, CFL, and regular fluorescent lights in my house. - I have cats, which can be very tricky subjects to shoot. - We want to test the K-30 against the K-5. - I don't have a flash, aside from the built-in ones on the K-5 and K-30. And I might add more items to that list as your ideas expose more holes in my plan. Last edited by deadwolfbones; 07-13-2012 at 05:55 PM.

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07-13-2012, 05:24 PM	#2
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Behavior with flash, haven't there been issues reported with hot shoe and off camera flash sync on the K-5?

07-13-2012, 05:31 PM	#3
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	As a general suggestion, what, in your experience, is the D700 good at, and the K-5 not, in terms of AF? Test whatever that may be with the K-30. Also some tests to try and identify the narrowness or tightness of the centre-spot AF would be useful. For some shooting scenarios (birds amidst foliage, focus on specific players in a team, the fabled 'focus on the eye' for portraits etc) it would be useful to see how tight one can go with just one AF point like the centre one. You may also like to do some tests equivalent to those Falconeye did on the D800 to identify the weaknesses or variable sensitivity of the various sensor points/zones across the K-30's AF matrix.

07-13-2012, 05:36 PM	#4
panoguy Pentaxian Join Date: Sep 2007 Location: Washington, D.C. Photos: Gallery \| Albums Posts: 3,327	Take whichever AF lens has the longest focus throw (FA 77?) and try to track a moving object (car or bird, cats are erratic enough) with AF.C I'd personally prefer to see the AF.C accuracy results from a slow-poke AF lens like the DA*50-135mm, but I don't think you'll wait for me to ship mine to you...

07-13-2012, 05:37 PM - 1 Like	#5
Quicksand Pentaxian Join Date: Apr 2008 Location: Central Ohio (formerly SF Bay Area) Posts: 1,519	Focus tracking. The dog-running-toward-you test is always good. Dogs are pretty fast. For extra credit, focus on a black dog. In the dark. On a slightly more serious note, my K-5 seems to have the dreaded PDAF low-light front-focus problem. On the K-30, I'd like to see the results of a series of shots of the same still-life subject at various light levels, using a dimmed lamp for example. Using an f/2.8 lens wide open, start with maximum brightness, focus to infinity, autofocus on the subject, take a shot, watch the meter while you dim the light 1/2 stop (or whatever), then focus to infinity again, autofocus, shoot, dim, repeat ad nauseum. Does focus remain consistent? If not, at what exposure values does it start having trouble?

07-13-2012, 05:45 PM	#6
rawr Veteran Member Join Date: Jun 2009 Posts: 11,913	Originally posted by Quicksand On the K-30, I'd like to see the results of a series of shots of the same still-life subject at various light levels, using a dimmed lamp for example. Something similar to this was done here: https://www.pentaxforums.com/forums/pentax-k-30/192301-k30-tungsten-light-test.html Imaging Resource also do TONS of these sort of test shots under variable light levels (eg the ISO vs Lux light level test image matrix down the bottom of this page that was part of their K-5 review). It's something to look out for once they complete their K-30 review.

07-13-2012, 05:53 PM	#7
deadwolfbones Veteran Member Join Date: Sep 2007 Location: La Crescenta, CA Posts: 7,450 Original Poster	Originally posted by Docrwm Behavior with flash, haven't there been issues reported with hot shoe and off camera flash sync on the K-5? Alas, I don't have a flash. edit: aside from the built-in ones, of course.

07-13-2012, 05:54 PM	#8
loco Veteran Member Join Date: Mar 2011 Location: Virginia Photos: Gallery \| Albums Posts: 2,846	Originally posted by panoguy Take whichever AF lens has the longest focus throw (FA 77?) and try to track a moving object (car or bird, cats are erratic enough) with AF.C I'd personally prefer to see the AF.C accuracy results from a slow-poke AF lens like the DA*50-135mm, but I don't think you'll wait for me to ship mine to you... Yep! In my experience, whenever I walk into a room with a camera and sit down to try to take pics of my cats, they immediately run towards me. So, if you could see if the K-30 AF.C can track them as they move towards you, that would rock! Thanks for doing the review, really looking forward to it!

07-13-2012, 06:00 PM	#9
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Originally posted by deadwolfbones Alas, I don't have a flash. edit: aside from the built-in ones, of course. Perhaps one of the strobists here would be willing to loan a good one for the sake of the review? I would but I don't have pTTL model.

07-13-2012, 06:08 PM	#10
deadwolfbones Veteran Member Join Date: Sep 2007 Location: La Crescenta, CA Posts: 7,450 Original Poster	Originally posted by Docrwm Perhaps one of the strobists here would be willing to loan a good one for the sake of the review? I would but I don't have pTTL model. Would have to be overnighted by Monday to meet the pub date. :/ I think we'll have to skip that test and maybe do a followup, or one of our strobists can do so independently, later on.

07-13-2012, 06:13 PM	#11
Docrwm Veteran Member Join Date: Sep 2010 Location: Somewhere in the Southern US Photos: Gallery \| Albums Posts: 12,285	Originally posted by deadwolfbones Would have to be overnighted by Monday to meet the pub date. :/ I think we'll have to skip that test and maybe do a followup, or one of our strobists can do so independently, later on. Fair enough, thanks for asking for ideas. I was trying to go with something other than the AF. Looking forward to the results!

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07-13-2012, 06:21 PM - 1 Like	#12
luftfluss Site Supporter Join Date: Jun 2011 Location: NJ Photos: Gallery \| Albums Posts: 11,619	Would love to see a review of the cats. They are generally quick to focus and track moving objects well. However, they can generate a lot of noise, and the output always stinks.

07-13-2012, 07:01 PM - 1 Like	#13
Franky2step Veteran Member Join Date: Aug 2011 Location: Niagara Photos: Gallery \| Albums Posts: 793	I would be interested in the low light autofocus capabilities, at pedestrian speeds...not cat speed.

07-13-2012, 09:10 PM	#14
goldenarrow Veteran Member Join Date: Jun 2009 Location: Chicago Suburbs. Photos: Gallery Posts: 501	brainstorming ideas: - set up cones on the ground over different distances to check mid to long focusing and apertures. - different distances of objects with light and dark coloring, some with little contrast. - focusing accuracy while panning - while shooting live action, like an equestrian training center - different parts of stands of a stadium, like a baseball game, sunlit and shadow - macro accuracy objects with ruler next to them

07-14-2012, 12:10 AM	#15
SteveB Veteran Member Join Date: Mar 2007 Location: U.K. Posts: 685	Show us how big the centre AF sensor is relative to the VF markings. Is the AF accurate in the dark using the af assist light and pop-up flash (so there's an image to look at!).