Search results for 'sensor cleaning' - page 108
Old SMC M lenses
Is there anyting to suggest pentax may produce a full frame sensor in a digital slr ?.
Posted by philstaff on 20/09/2009 - 09:30
Old SMC M lenses
Is there anyting to suggest pentax may produce a full frame sensor in a digital slr ?. Besides Hope? No.( not counting the 645D)
Posted by Malo1961 on 20/09/2009 - 09:50
Pentax 70mm f2,4 Limited
The 70 is DA and hence for the APS sensor - no? It is al the Amazon guy said and is a delightful lens. I will try and take a portrait tomorrow but for now the back of a nice lady's head will have to suffice at f4 in very, very bright sunlight. Not proud of this so no harsh words. The orig...
Posted by mikew on 14/09/2009 - 22:23
Pentax SMC A 50 mm Lens usage
With MF lenses, the only accurate indication you have that an object is in focus is the green hexagon in the viewfinder. Neither the beep or the presence of the red focus indicator in the viewfinder should be relied upon to indicate correct focus, because they don't. The beep simply means that a pa...
Posted by Mannesty on 16/09/2009 - 21:17
Pentax Has No Long Lens
Let's not forget the 1.5x crop factor. The DA* 300mm lens has a film equivalent FOV to a 450mm lens (close enough to 500mm for me). Add to that a 1.7x T/C and you have a 765mm equivalent lens. There was a super-telephoto lens planned, it used to be on the roadmap. I haven't looked lately. This...
Posted by K10D on 20/09/2009 - 16:27
Pentax Has No Long Lens
FOV is equivalent but not object image size on any sensor for a given distance. I still work on actual lens focal length. Always an issue topic this one. Nikon have bodies that auto crop for digital only lenses, that does not alter the actual object image on the sensor. True, the object image cov...
Posted by Anvh on 20/09/2009 - 20:29
Pentax Has No Long Lens
FOV is equivalent but not object image size on any sensor for a given distance. I still work on actual lens focal length. Always an issue topic this one. Nikon have bodies that auto crop for digital only lenses, that does not alter the actual object image on the sensor. True, the object image cov...
Posted by K10D on 21/09/2009 - 03:51
Pentax Has No Long Lens
I think we agree? A 300mm lens on a 35mm is then enlarged by whatever the ratio is, up to 6x7 or there abouts. Do we then say that the 300mm lens is equivalent to 300mm x the ratio? Focal length of a lens is, I believe, fixed. What we do with it's projected image surely cannot alter that? The...
Posted by Anvh on 21/09/2009 - 11:28
Tokina 80-400mm Pentax KAF fit
You could try cleaning the contacts. Of course it's so long since I used manual focus lenses that I might just be wrong.
Posted by johnriley on 22/09/2009 - 15:42
Tokina 80-400mm Pentax KAF fit
You could try cleaning the contacts. Of course it's so long since I used manual focus lenses that I might just be wrong. I think on this occasion you are, John... with all my manual focus KAs it asks for the focal length on start up. That's only with SR on, of course. If it's off, it doesn't. ...
Posted by ChrisA on 22/09/2009 - 16:14
Which Lens
I'll have another round of cleaning up soon, have 28-80mm and 28-70mm and 24-70mm lens to go, plus some bits and pieces... Gotta clean the closet before leaving Edinburgh :?
Posted by edumad on 25/09/2009 - 12:18
Which Lens
Yes George I was sure too that he would know, but since you seem to have a thing about people offering lens that are or were produced for film I mentioned it hoping to avoid your picking me up again. Just trying to remind the OP that it needs to be considered when buying a lens. I don't "have a thin...
Posted by George Lazarette on 25/09/2009 - 19:13
Which Lens
Of course focal length would not change with sensor size it was you that suggested a lens made for film use would not "work" with digital not me, as it happened the lens in question had been developed for the digital market. Now it is clear that both of us understand focal length, crop factor and...
Posted by Thordell on 25/09/2009 - 20:38
Which Lens
I know nothing but --- I understood that CCD and CMOS sensors were much more sensitive to the angle at which the light strikes the film/sensor than good ole 35mm film. Therefore DA or DI or whatever the designation - the inherent design was to ensure that the light always arrive at the film/se...
Posted by ManixZero on 26/09/2009 - 01:33
Pentax TC Converter A-2XS, how it works?
I'd have thought any vignetting would be on 35mm, with the APS-C sensor in a digital body being small enough to avoid the vignetting effect.
Posted by Road_Dancer on 27/09/2009 - 11:46
Standard ND Lee filters: resin or ProGlass?
Thank you Kris, was hoping it would do the job very reasonably up to the point that a ND might not be needed. As for ND, isn't it better to get screw-in of them instead of square. I believe you will get problems with light reflecting from the square filters onto the sensor. I know that I need t...
Posted by Anvh on 20/11/2009 - 12:47
Standard ND Lee filters: resin or ProGlass?
When lights come from the back of the camera it can reflects directly into the lens through the square filter. When you've a screw in only the front of the filter is expose so every light needs to go through that filter if it wants to reach the sensor. A coating might lessen the effect but would...
Posted by Anvh on 20/11/2009 - 13:32
Standard ND Lee filters: resin or ProGlass?
When lights come from the back of the camera it can reflects directly into the lens through the square filter. When you've a screw in only the front of the filter is expose so every light needs to go through that filter if it wants to reach the sensor. A coating might lessen the effect but would...
Posted by Mongoose on 20/11/2009 - 14:19
SDM issues? A straw poll.
Fred that is an auto focus failure not a SDM one, SDM is simply the motor that drives the focus system of the lens, nothing more nothing less. As for your problem, it's quite normal and it's called haunting. The AF sensor needs contrast to see if the focus is "sharp" or not and it does not like ...
Posted by Anvh on 01/10/2009 - 09:40
SDM issues? A straw poll.
Thanks for your reply, Stefan. I know of haunting, especially when there is not enough light, but what I tried to describe is not that I believe. Basically what happened was that there was scene with lots of daylight and stuff and it should focus with no problems, but it never settled and I could he...
Posted by FredEriksson on 01/10/2009 - 10:04
