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Forum: Monthly Photo Contests
01-17-2015, 12:20 PM
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Below is the link to my submission.
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Forum: Pentax SLR Lens Discussion
05-20-2014, 12:51 PM
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Oh, sorry. Camera body is a K-5. I don't have any other bodies to test with.
I did my testing from a tripod, using multiple methods:
Focusing using phase AF then switching to live view to check focus accuracy
Focusing in live view to actual optimal focus and then checking to see if phase AF would focus confirm
Focusing using phase AF and eyeballing focus
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Forum: Pentax SLR Lens Discussion
05-20-2014, 12:12 PM
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Hi all,
I've been doing some focus testing on suspicions that my 16-45 might need adjustment. I found that my previously selected fine adjustment of +5 was inadequate when shooting at 28mm.
I found that at BOTH 16mm AND 45mm, a correction of +7 or so is adequate. However, at 28mm even with a +10 correction I still get significant back focus.
I did my tests in moderate indoor fluorescent lighting, at a distance of about 10 feet.
Any suggestions?
(Lens was purchased used from KEH almost a year ago, return / warranty is not an option)
Thanks.
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Forum: Pentax K-5 & K-5 II
07-26-2013, 10:48 AM
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Right, my mistake, I forgot which direction I meant.
What I had in mind was to set the aperture for 22 (or whatever the minimum is), and then add one stop of negative exposure compensation for every stop up from minimum the lens is set to. It's difficult to adjust on the fly, but you ARE guaranteed an accurate exposure.
On the other hand, your method may be preferable if you might need to adjust aperture rapidly.
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Forum: Pentax K-5 & K-5 II
07-26-2013, 09:34 AM
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So you *could* set it for wide open and then control the aperture with the lens's ring... Hm. This is really a huge help, thanks so much.
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Forum: Pentax K-5 & K-5 II
07-25-2013, 07:50 PM
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Alternatively, couldn't you set the aperture to wide open on the body, and then control the aperture using the lens aperture control?
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Forum: Pentax K-5 & K-5 II
07-25-2013, 07:49 PM
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Will it harm the body's aperture control motor to be brought up short by the lens's aperture ring?
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Forum: Pentax K-5 & K-5 II
07-25-2013, 06:58 PM
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Hi Jim,
that's fantastic! I love this. I do like this Tokina, but because of this issue I ordered an SZ-X 60-300 to replace it... Who knows, if the SZ-X isn't as nice optically then I may wind up modding the 50-250 rather than sending it back. It DOES have a rather nice macro.
One thing I'm confused about: If you ARE relying on the camera to attempt to set the lens aperture (albeit somewhat inaccurately), what's the use in setting the aperture on the lens to the desired aperture? Why not keep it at f/22, as with and actual 'A' setting?
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Forum: Pentax K-5 & K-5 II
07-25-2013, 09:47 AM
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I don't want the camera to compensate by auto-adjusting the aperture, I want the camera to compensate by auto-adjusting the ISO in TAv mode.
What I'm picturing is pretty much the same as TAv mode, except with the aperture set not by the E-dial but (indirectly) by exposure compensation, and the shutter set by E-dial, with the ISO varied by the camera body to match the current shutter speed & aperture (+ EC added to compensate for a taking aperture different than the metering aperture).
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Forum: Pentax K-5 & K-5 II
07-25-2013, 07:31 AM
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Again, that's not what I mean. Yes, it sucks that the crippled KAF3 mount doesn't allow the camera to read the lens aperture, but that would require a hardware fix. I'm proposing a software fix.
Here is what I want:
I mount an f/4 K lens.
I set my lens to F/8 (2 stops down from wide open; aperture remains wide open for focusing as per normal operation)
My camera body, set to aperture priority mode, meters based on incoming light (i.e. f/4). IF I took a picture now, and the lens stopped down to f/8, my image would be 2 stops under-exposed.
SO, I dial in 2 stops of positive exposure compensation. THUS, although the camera body is SEEING f/4, it will EXPOSE for f/8, even though it has no way of knowing what aperture it is stopping the lens down to.
This should be achievable by a software fix.
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Forum: Pentax K-5 & K-5 II
07-25-2013, 07:05 AM
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That's not what I meant. I'm not talking about the lens-to-body aperture communication linkage, which communicates the lens's set aperture to the camera, or trying to make the camera control the aperture on a pre-A lens.
What I'm talking about is that when a pre-A lens is mounted on the K-5, it will shoot wide open ONLY, in all modes other than manual. It'll stop down the lens in M mode, but not any other mode. THAT'S what I'd like to be able to fix.
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Forum: Pentax K-5 & K-5 II
07-25-2013, 06:43 AM
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Hi all,
I just got my first non-A lens, a Tokina 50-250. While I like the lens so far, I feel like the camera could easily use this lens MUCH more effectively if it just behaved a bit differently, and I want to know if this is possible.
The K-5 will do stop-down metering in M mode when a non-A lens is mounted, or it can shoot in Av / TAv, but it won't stop down the lens to shoot. This would be a LOT simpler if the camera would simply stop down the lens to shoot in other shooting modes... I could just turn on TAv, set the lens for the aperture of my choice, and dial in exposure compensation equal to however many stops down from wide open I set it for. But the camera refuses to stop down to shoot in any mode but manual.
What I want to know is whether there's a fix for this. Can I, for example, through going into debug mode, set the camera to actuate the aperture control motor in Av / TAv mode?
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Forum: Troubleshooting and Beginner Help
05-06-2013, 12:20 PM
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I'll be damned... That worked. Thanks!
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Forum: Troubleshooting and Beginner Help
04-30-2013, 09:22 AM
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Anyone else? I'm really scratching my head here.
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Forum: Troubleshooting and Beginner Help
04-28-2013, 10:42 AM
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Hi all,
A few days ago my K-5 stopped focusing properly to infinity with my Tokina 28-70mm AF lens. This lens has played just fine with this body up until now. I tested the issue with another lens and infinity focus was fine. I tried switching to manual focus, and when the lens was focused to infinity the camera would not confirm focus. The AF did successfully lock at short distances and with the lens in 'macro' mode, but attempting to focus on anything more than about 30-ish feet away resulted in the camera focusing out as far as possible and then displaying the blinking 'cannot obtain focus' hexagon. (i.e. there was no hunting; there was also plenty of light out.)
Fine AF adjust was initially set to -10 all, +2 this lens. I tested at -10/-10, 0/0, and +10/+10, and failed to obtain infinity focus at any combination of settings.
Is this likely to be a physical issue with the lens? I can't afford to replace this lens.
Thanks for any advice you can offer.
[edit]
I also tested the camera with one more lens, and can confirm that on 2 different lenses the infinity focus is fine. Whew.
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Forum: Pentax SLR Lens Discussion
04-09-2013, 12:47 PM
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You make a compelling case with startlingly few actual words.
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Forum: Pentax SLR Lens Discussion
04-09-2013, 12:27 PM
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I'm assuming that a large part of the price difference between a 500mm mirror lens and a refractive lens of the same focal length is due to the refractive lens having autofocus, a faster aperture, and the internal electronics to communicate aperture to the body. But the good things I hear about the 55-300 do seem to suggest it'd beat most 500mm catadioptric lenses. Thanks for your input!
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Forum: Pentax SLR Lens Discussion
04-09-2013, 12:10 PM
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I currently make occasional stabs at bird photography using my manual focus Tokina 80-200 f/4.5-5.6. I know it's not a great lens, but I got it for $15. It's not the worst, but I'm sure I could do much better. I'm looking for a sub-$300 lens for bird and wildlife photography, somewhere in the 300mm to 500mm range. Options I am currently considering are:
Vivitar Series 1 500mm f/6.3 mirror lens
PRO:
Reach
Price (130 USD)
CON:
IQ?
Said to be hard to focus
Aperture not variable
Pentax DA 55-300
PRO:
IQ
AF
Handling
Usable at shorter lengths for portraits etc.
CON:
Would need to be cropped more heavily than with the 500mm
Does anyone with experience with one / both of these lenses have anything to add? I know that reach doesn't always mean better IQ at a given magnification; e.g. the DA 55-300 is known for giving better IQ when cropped than when using a teleconverter. Obviously, I do know that the 55-300 will handle a lot better (AF, zoom, faster aperture, auto aperture, etc.). The question I'm interested in is whether the difference in IQ between the 55-300 and the mirror lens might be large enough that the 300 might give better images when cropped to the equivalent of 500mm.
Thanks for any input you can provide!
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Forum: Troubleshooting and Beginner Help
03-07-2013, 01:40 PM
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Hi all.
Thanks to my girlfriend's cat, who is the worst cat in the world, my K-5 took a little tumble after being stored in what was supposed to be a cat-proof closet. The startup noise (cycling of the aperture control motor) has changed in timbre, and now sounds a little more 'buzzy.' The aperture still works fine (lenses stop down without issue), but I'm concerned. Is there any possibility that there's a problem here that could be exacerbated by further use? I can't afford servicing at the moment, but I want to make sure that I'm not going to cause a minor problem to become major if I continue to use the camera.
Thanks!
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Forum: Pentax K-30 & K-50
09-19-2012, 07:05 AM
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I see. And you find that, in practice, this more reliably produces in-focus images thank using other focus methods?
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Forum: Pentax K-30 & K-50
09-19-2012, 06:39 AM
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Will focus peaking give better results than using focus confirmation or catch-in-focus with the K-5?
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Forum: Pentax K-30 & K-50
09-19-2012, 06:12 AM
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*IS* the K-30 substantially preferable to the K-5 for a manual lens user? I plan on either a used K-5 or a K-30, and my budget is tighter than a really tight thing. I'll barely be able to afford 28mm/2.8 for a first lens, as it is. Given that I will probably use mostly manual lenses for the foreseeable future, will the K-30's focus peaking feature enable me (someone with less than tack sharp optics in my eye sockets) to get better focus than I would with a K-5?
Thanks!
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