Search results for 'sensor cleaning' - page 121
Old vs New
I've just compared my three Ricoh's against the Pentax A 50mm f/1.7 at f/5.6 only, because of the time taken. I used 100ISO and one flashgun on a tripod at 45deg to a £10 held onto a box with blu-tak. The camera was on a tripod 1.25m target to sensor plane. The camera (K20D)was fired by a wirele...
Posted by Algernon on 08/07/2010 - 19:18
Old vs New
Because, overall, the 18-55mm kit lens is demonstrably NOT sharper than an FA 50, or any other Pentax 50mm for that matter. Comparing MTF measures we find that the 50mm beats the kit at f/1.4, f/2, f/2.8 (er, naturally) and also at f/4. At f/5.6 and f/8 they are much the same I've done several tests...
Posted by andrewk on 10/07/2010 - 12:04
pentax 300mm F4.5.
I am sorry to hear this. However, you don't really need any instructions, except perhaps for one thing. This baffled me, and several others. The lens hood has a double screw. When retracted, it should be screwed in tight. To extend it, unscrew, then extend, then screw again to keep it in po...
Posted by George Lazarette on 30/06/2010 - 09:52
Why use a 135format lens mount?
Why did Pentax and most other brands hold their 135format mount for the digital aps-c sensor? Since everything is smaller they could easily make the register distance smaller so that faster lenses are easier to make and the camera is smaller. Since the lenses specially make for APS-C cameras won...
Posted by Anvh on 30/06/2010 - 12:43
Why use a 135format lens mount?
Presumably this is effectively what the manufacturers who use micro 4/3 did. In a way but it differs because the micro 4/3 doesn't have mirrors inside the body so it's not a good comparison since the camera is different. But the normal 4/3 are indeed like that. They make a mount specially for that s...
Posted by Anvh on 30/06/2010 - 13:50
Why use a 135format lens mount?
Pentax using a new mount when the Pentax K mount was designed so well in the first place would be crazy. It's proved itself over 35 years and has been up to being developed further as the electroics have taken over. The K mount is wide enough to design 50mm f1.2 lenses, so I reckon it's good for ...
Posted by Anvh on 30/06/2010 - 16:48
Why use a 135format lens mount?
The sensor can already move rotationally. Hypothetically, could the shake reduction unit be designed to move the sensor forwards to reduce registration distance when the camera detected one of these new smaller lenses? (Would be rather awesome if it could tilt to correct vertical perspective too!) ...
Posted by Pentaxophile on 30/06/2010 - 18:34
Why use a 135format lens mount?
I think we have a confusion between a mount and Camera design here, as a Mount is just that, a mount. What you do with it is the difference. Plus, lens design is also a factor, as is the market. What we have to remember is that in the early years Digital was extremely expensive, and an unknown c...
Posted by Offertonhatter on 30/06/2010 - 21:32
Why use a 135format lens mount?
The puzzling one is that Minolta invested a good deal of money in their APS SLR, and produced a surprisingly complete set of lenses to go with it. They won't, however, work on the Sony cropped sensor bodies. Given that the sensor is the same size as an APS frame why on earth didn't they consider thi...
Posted by Dangermouse on 30/06/2010 - 23:11
Why use a 135format lens mount?
Thank you Matt, it indeed looks like a very strange camera :? The DA*50-135 could most likely be redesigned as a f/2 lens and the DA*60-250 maybe even a f/2.8 if there is some stress in it. The lens might become more expensive because larger glass is needed but at least it's possible to make such...
Posted by Anvh on 02/07/2010 - 18:39
Shift Lens
I just spotted on fleabay with "make offer" - thought it might be of interest to anyone who has a film camera (or a 5D...) and likes shooting architecture/panoramas? (don't bother on a crop-sensor though) More .
Posted by flossie on 30/06/2010 - 13:33
Shift Lens
(don't bother on a crop-sensor though). Why not?
Posted by Anvh on 30/06/2010 - 13:55
Shift Lens
(don't bother on a crop-sensor though). Why not? Because there's not enough shift to make an appreciable difference. Even on a 36x24 sensor / film there's very little shift available. Shift lenses give progressively more noticeable results as the format size increases. Tilt lenses on the other hand ...
Posted by hefty1 on 30/06/2010 - 14:45
Shift Lens
Thank you Hefty for the explanation. Still my mind can't really grasp it. The lens has a smaller angle of view on APS-C sensor so it should behave like a 42mm shift lens on 135 format right?
Posted by Anvh on 01/07/2010 - 20:03
Shift Lens
Thank you Hefty for the explanation. Still my mind can't really grasp it. The lens has a smaller angle of view on APS-C sensor so it should behave like a 42mm shift lens on 135 format right? I'm probably well off target with this Anvh, but I think the the shift is more effective at the image edg...
Posted by K10D on 01/07/2010 - 20:07
Shift Lens
Thank you Hefty for the explanation. Still my mind can't really grasp it. The lens has a smaller angle of view on APS-C sensor so it should behave like a 42mm shift lens on 135 format right? I'm probably well off target with this Anvh, but I think the the shift is more effective at the image edg...
Posted by hefty1 on 01/07/2010 - 21:52
Shift Lens
Actually you get more effective shift in as much as you get 11mm of shift on a 16x24 APS C frame, so you can actually move 3mm 'above' the horizon whereas on at 24x36 full frame the horizon remains 1mm inside the frame on full shift. However usefullness as an architectural lens is diminished by the ...
Posted by amilner on 02/07/2010 - 11:06
Sigma 24-70
David, unreliable SDM, please enlighten me? I know the DA*16-50 was trouble lens but SDM might not be solely to blame but the whole focus system of that lens :roll: Take the 17-70, SDM only, can you find a person that posted they had one with a broken SDM? I could find one on DPreview and on pe...
Posted by Anvh on 01/07/2010 - 20:57
Focus issues.
Sorry, but it seems to me that some people go through a whole of trouble when confronted with focusing issues on K10Ds. My K10D back-focus issue was resolved by our Pentax Service Centre here in Melbourne for $A100 (55GBP) and included a service check and sensor clean. Focus is spot-on and I d...
Posted by bento2 on 03/07/2010 - 07:40
New Tokina lens.
Indeed, I rather have the 11-16 also btw, pentax and tokina already has the DA*16-50 so it's a bit of a strange lens to bring out. Not really, following the link, the text describes a lens that covers a full size sensor, presumably 135mm full frame. At the wide end the two lenses would give rough...
Posted by stevejcoe on 06/07/2010 - 16:10
