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Forum: Pentax DSLR Discussion
01-02-2013, 10:13 AM
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I would definitely like an uncrippled mount.
Also I don't understand why there is an obscure default setting for most DSLRs of not allowing use of the aperture ring. Pentax say that to use old lenses you have to do the following on K10D and many other similar cameras:
Navigate menus to Using aperture ring
Press the right arrow and select Permitted
Press OK.
(This setting allows the camera to operate with older K-mount or S-mount lenses that do not have an “A” setting on the aperture ring).
The first lens I ever used on a K10D was a fixed aperture 500mm Mirror lens. I quickly found out that while the lens physically attaches to the body, easy use of old lenses was not actually high on the Pentax agenda. I suspect that it is still the case that if you attach such a lens to the latest Pentax DSLR straight off the shelf, it will be a big disappointment. After fiddling around in the menus, switching the focus mode lever to manual and pressing of supposed magic green buttons. If the camera allows you to take a picture at all, you can bet that the exposure will be out by a stop or two. Even the focus (manual) may not be right as the focussing screens are designed to be bright at the expense of accuracy.
I rather doubt that Pentax actually test their latest cameras with old manual lenses while still at the design stage when obvious issues could still be sorted out. More likely, if they test at all with old lenses, they find out after the design is set in stone whether it is possible to still use such lenses. If it's possible but awkward, then I think that constitutes a pass in their minds.
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Forum: Pentax DSLR Discussion
09-28-2011, 10:06 AM
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My instructions weren't for the Gallery by the way but to get the pictures right in this thread.
edit them first to keep them small enough (with editor that doesnt remove EXIF) to no more than 1000 pixels wide as already said
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Forum: Pentax DSLR Discussion
09-28-2011, 10:01 AM
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You haven't said if it overexposes, underexposes, or is inconsistent etc?
What does a histogram look like if you photograph a blank wall or sky? Where is the peak of the histogram? I know this is the opposite of high contrast, but it's the starting point for seeing if you are getting over or under exposure. The histogram peak should be just to the left of center by the way although I'm sure there are those who will want to argue about its exact position. If the histogram peak is to the right of center then even a flat image is overexposing, though you might not notice. A contrasty subject with the same settings would undoubtedly show blown highlights.
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Forum: Pentax DSLR Discussion
09-28-2011, 09:53 AM
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When you post a reply, just below this box that I'm typing into there is an Additional Options section. Scroll down and you will see a Manage Attachments box that you should click. The arrow pointer doesnt change to a hand which might confuse you but clicking on this box takes you to the options for adding your photos.
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Forum: Pentax DSLR Discussion
09-26-2011, 09:42 AM
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Perhaps the SR switch is broken and SR is always on?
Check the EXIF data of pictures where you think SR is off.
Or switch the camera on with a manual lens that with SR would ask for the focal length.
If it asks for focal length with SR off, it's not realy off!
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Forum: Pentax DSLR Discussion
09-23-2011, 04:12 AM
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Not forgetting that you can take several overlapping pictures in portrait format with a standard lens and merge them together for stunning panoramas. You will get higher quality, higher pixel count and no lenses to buy.
Lots of software is available for merging pictures like this.
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Forum: Pentax DSLR Discussion
09-22-2011, 02:35 PM
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Karma,
Thanks for your wise words. I've just done a test with my 'standard' 50mm lens that I rarely use and I can't honestly say that I'm seeing the same issue. So although I have 2 Sigma lenses showing the same effect, I think it would be unwise to deliberately misalign the sensor to suit these lenses.
Thanks yet again for your great help. I do think now that the lenses are not sitting quite square to the camera rather than the CCD being off. Probably that is a problem with the lenses that I may just have to live with. When you look too hard you can always find something that isn't perfect.
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Forum: Pentax DSLR Discussion
09-22-2011, 09:47 AM
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Thanks Karma, that's so helpful.
I can see from photos of the K10D that the bottom 2 screws are obscured by the PCB (no special holes), but it looks like it comes off easily enough. Thanks for the tips about screws etc.
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Forum: Pentax DSLR Discussion
09-22-2011, 08:49 AM
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I see that there are 3 adjuster screws and not one of them is really the horizontal adjuster. They just all have to be in exactly the right place. Easier to introduce problems than fix them I think without specialized equipment. :(
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Forum: Pentax DSLR Discussion
09-22-2011, 07:31 AM
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Thanks Karma,
Your description sounds spot on. I'm not too sure about doing this, but if I did, is it obvious which is the horizontal adjuster?
Thanks again for your expert input.
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Forum: Pentax DSLR Discussion
09-20-2011, 04:02 PM
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The approximate line of sharpest focus I have indicated here.
The fact that it is curved is probably down to the lens, but I'm thinking that the difference between one side and the other may be down to the CCD.
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Forum: Pentax DSLR Discussion
09-20-2011, 03:03 PM
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Sample picture taken at 45% to pavement using Sigma 70-300mm lens set to 70mm at f5.6.
Take a look at left and right sides of the picture just above center.
I used auto focus at the center.
Similar effect with 400mm Sigma lens where I first noticed this.
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Forum: Pentax DSLR Discussion
09-20-2011, 02:52 PM
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CCD Position Adjust (AF adjust)
I'm sure you're all fed up with the run of the mill back and front focus issues that people have with their K10Ds and GX10s.
I had such a problem on my GX10 and now that is mostly corrected through an offset entered in debug mode.
But on looking closely at the distance beyond or in front of the focus confirmation point, I have suddenly realized why some parts of my photos are not as sharp as they might be.
While there was an overall back focus that would ruin many a shot, the problem was worse on one side of the pictures than the other.
Having corrected the main back focus I now see that the focus plane is not square to the camera.
The focus point on the right of my pictures is closer than on the left.
Now that I look for this I see it in many photos. Often it is very subtle and not really an issue, but sometimes it is a problem.
Presumably this is a mechanical issue with either lens, camera or both.
However I have now noticed this same issue on 2 different lenses (but both Sigma telephotos).
My thinking is that maybe the CCD is not 100% square to the light path from the lenses.
The service manual (page 70) mentions an adjustment that can be made to the CCD called 'CCD Position Adjust' that is described in the manual like this:
1) Remove the Bottom Cover (Don't remove the Power and USB port cover)
2) Remove 3 screws
3) Lift the Front cover to the side and rotate the adjustment screw.
My question is whether anyone knows what this adjustment actually does.
I guess it physically moves the CCD, but in what direction? Can this straighten the CCD if not quite square?
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Forum: Pentax DSLR Discussion
09-20-2011, 12:03 PM
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Thanks, Yes in fact TAv mode it turns out does work with my lens which is an A series Sigma. I'm sure I couldn't get it to work well on the fully manual Mirror lens that I used to use, but for now TAv looks useful.
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Forum: Pentax DSLR Discussion
09-12-2011, 03:40 PM
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dlacouture: Sounds interesting. How do you cut it?
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Forum: Pentax DSLR Discussion
09-12-2011, 03:37 PM
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Darren: I don't think the TAv mode stops down the aperture on manual lenses, for no good reason that I can tell. so for my 400mm lens I would have to use it at f5.6 rather than my preferred f8. I really don't think that Pentax have taken account of long manual lenses, this really isn't their strong point.
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Forum: Pentax DSLR Discussion
09-12-2011, 03:30 PM
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Ron: thanks for your reply. The diopter adjustment is OK and correct for my long sight. I can see the circular mark on the Katz Eye screen pin sharp. The K5 being good at AF might not help me with my manual focus lens although it might mean that the focus confirmation light is more reliable.
The GX-10 doesn't automatically pick up that the lens is 400mm though strangely the EXIF data of photos does seem to know this and I usually manually choose 400mm as the focal length for the anti-shake - it asks for this at power on.
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Forum: Pentax DSLR Discussion
09-12-2011, 09:16 AM
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I'm considering getting a K-5. Currently I have a GX-10 (K10D).
Mostly I use a manual focus 400mm Sigma lens for bird photography.
With the GX-10 I was disappointed in the manual focussing and discovered that the focus screen sees more in focus than the sensor does. Apparently that helps the focus screen brightness. It certainly doesn't help with manual focus.
Solution (part solution anyway) was to get a new focus screen at great expense from Katz Eye. I say part solution as I may have a small back focus issue as well.
Now on to the K-5. Should I expect the same issue with the K5 and have to replace the focus screen. Would the one I bought for the GX-10 fit (same size as K10D)?
Does Live View make all this redundant? i.e. stop using the viewfinder and zoom in to focus? I guess not for birds in flight etc.
Another question is whether I can expect auto ISO to be any use on the K-5. It's hopeless on the GX-10, there seems to be no way to set the shutter speed at say 1/500th, set the aperture at f8 and let auto ISO do its thing. When I used to use a mirror lens I thought auto ISO would be perfect as the aperture was fixed, shutter speed always had to be high, so best control was by ISO adjustment. For some reason, the auto ISO thought it a good idea to reduce the shutter speed down to 1/90 before it would consider upping the ISO.
Of course any wisdom about K10D and GX-10 welcomed too.
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Forum: Pentax News and Rumors
07-16-2009, 05:23 AM
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The UK address is cheap residential housing. Although they say they take paypal, it may not work when you actually try.
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Forum: Pentax DSLR Discussion
06-04-2009, 09:38 AM
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If this is true, it would mess up the shots when you happen to hold the camera real steady as well. Or perhaps just always? I've never heard anyone say that hand held SR shots are ever worse because of SR.
I don't want the button, I do want to leave SR on and for it not to mess up my shots!
In my own tests I find it mostly difficult to tell the difference on or off although I don't have a majorly expensive tripod to guarantee no movement.
What does happen sometimes is that you shoot before the hand is ready and that can mess up shots. I'm thinking that this is the real reason that Pentax say not to use it on a tripod?
Why doesnt the camera stop you taking the picture until the hand is ready - or an option for that anyway?
When taking pictures of birds as I do with long lenses, SR seems like a godsend, but you never know if the bird will suddenly fly and you have to pan. I've taken some panned shots that are OK with SR on. Surely lots of subjects are static one second (SR on) and then they move and you pan (SR off). You can't keep turning it on and off according to the random movements of wildlife (or people).
Is a steady pan actually affected by SR? How does the camera know?
In summary if SR can just be left on all/most of the time then no button is needed.
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Forum: Pentax DSLR Discussion
05-29-2009, 06:34 AM
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There is talk of a brighter focus screen in the K-7. The K10D had a brighter screen than some previous models, but that seemed to be at the expense of accurate manual focusing. If you were slightly off it still looked OK on the screen.
For this reason lots of people buy replacement focussing screens for Pentax cameras.
Does the brighter K7 screen use the same 'micro lens' technology to make itself brighter? Is it worse, the same or better than K10D/K20D for showing actual depth of field and accurate manual focussing? If it is brighter at the further expense of accurate manual focussing, that could be a bad thing.
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Forum: Pentax DSLR Discussion
04-24-2009, 05:54 AM
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You should try the same conversation with Pentax before you start making comparisons. The chances of speaking to anyone at any large electronics company who have even heard of a particular model of product is remote.
About 25 years ago I did once manage to get through to some techies at Philips Electronics who knew what they were talking about.
I dont think I've managed it with any other company since.
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Forum: Pentax DSLR Discussion
04-15-2009, 02:55 AM
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I have had a situation like this on the K10D. I put it down to poor battery contacts. No one has suggested cleaning the battery contacts!
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Forum: Pentax DSLR Discussion
04-07-2009, 02:58 PM
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I am thinking of replacing the viewing screen with a Katz Eye plain matte one to use with a 500mm f8 mirror lens.
Is anyone certain that the screens are identical between GX-10 and K10D.
Everyone guesses that they are without being sure and I don't want to end up with a screen that doesn't fit, especially as the Katz screens are expensive.
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Forum: Pentax DSLR Discussion
03-03-2009, 06:41 AM
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If your pictures suffer from even the slightest camera shake or subject motion blur, then use iso 200 or even higher if necessary to get a shutter speed that stops the movement. Otherwise stick with 100.
If iso 100 works for you, that's fine, but don't be afraid of iso 200 if it would give you some advantage.
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