Search results for 'back focus' - page 1073
Best use
A few from an evening stroll along the Grand Union Canal last summer, all taken using the Pentax-A 28mm f/2.8 manual focus prime on a K-r: Philip
Posted by MrB on 15/01/2013 - 22:40
Best use
Following on from the topic Old Glass and trying to stretch the topic a little more. I have a number of manual focal lenses and wonderd if some of the members might point out the best use of the lens or may be a use genurly not thought of that may have worked out well. I agree by the way these lense...
Posted by DaveHolmes on 16/01/2013 - 20:30
F stops converters?
Closest focus point moves away proportionally, unless you also add an extention tube. Because the near point is a product of the aperture (unchanged), focal length (increased), circle of confusion (unchanged). You'll find all the maths you require in Wiki under the above topics. Alternatively...
Posted by Frogherder on 16/01/2013 - 13:19
F stops converters?
Closest focus point moves away proportionally This well known manufacturer , and a quick shows a lot of people think the same.
Posted by wasleys on 16/01/2013 - 20:11
F stops converters?
Closest focus remains the same.
Posted by johnriley on 16/01/2013 - 23:17
F stops converters?
Confused? I know I am! LOL They're not confusing at all. Add a 2x converter to a 50mm f2 lens you effectively now have a 100mm f4 lens; the closest focus remains the same. Add a 1.4x converter to that 50mm f2 lens and you have the equivalent of a 70mm f2.8 lens. That's all there is to it! Dep...
Posted by JAK on 17/01/2013 - 00:29
F stops converters?
They're not confusing at all. Add a 2x converter to a 50mm f2 lens you effectively now have a 100mm f4 lens; the closest focus remains the same. Add a 1.4x converter to that 50mm f2 lens and you have the equivalent of a 70mm f2.8 lens. That's all there is to it! Depth of field would be same as an...
Posted by gwing on 17/01/2013 - 16:00
F stops converters?
Closest focus point moves away proportionally, unless you also add an extention tube. Because the near point is a product of the aperture (unchanged), focal length (increased), circle of confusion (unchanged). You'll find all the maths you require in Wiki under the above topics. Alternatively...
Posted by petrochemist on 18/01/2013 - 15:28
F stops converters?
Look at this site which calculates depth of field and hyperfocal distances: http://www.dofmaster.com/dofjs.html and you will see that with a 2X converter, at the same distance, and at the same aperture set on the lens (so that, say, f/4 is set, but the aperture is f/8 because of the converter) there...
Posted by Spotmetre on 24/01/2013 - 00:11
Must have Pentax lenses
DA35 Limited. Sure, it's slower and more expensive than the DA-L 35, but having a normalish FOV and essentially no minimum focus distance means its value as a walkaround should not be underestimated.
Posted by MrCynical on 16/01/2013 - 23:44
Must have Pentax lenses
According to the AP Test Report the 43mm LTD was the best standard lens ever made, although I prefer to use the A Series 50mm f/1.7 which handles just about any job I throw at it superbly. I rarely use my 43mm. Lately I've been going back to the A Series 50mm f/2.8 Macro because of it's very ...
Posted by Algernon on 17/01/2013 - 09:53
Must have Pentax lenses
I'm with Unlocker - it's the FA*85 that's the must have.... As it's been disqualified I will go for the DA*16-50 and DA*60-250 - since they've come back from JPS with new SDM motors the cameras deliver better quality than my D3 and Nikkors.
Posted by ilovesaabs on 17/01/2013 - 13:04
Must have Pentax lenses
Yes I do Algi, I think it's the AF gears or cogs or whatever you call them. It also sometimes has a bit of a clacking noise from the AF at 90mm and I have to back off to 85mm or so to get it to stop. Not had any images soft on one side or anything though, but I mainly use it at f8 or f11.
Posted by aliengrove on 18/01/2013 - 09:43
Must have Pentax lenses
DA * 16-50mm Sharp at 2.8 Fast to focus with the k-5 Great IQ I put oiff buying this lens for so long due to all the negativity that surrounds it over failed SDM and too heavy at the end etc and yet i love it. I had a tamron 17-50mm for over four years and whilst its a good lens the Pentax i...
Posted by cabstar on 18/01/2013 - 15:06
Help da*200 maybe faulty
This is my second copy of this lens. The lens hesitates to lock focus. The centre point flickers and I can here the elements clicking and when it does the image quality is inconsistent sometime sharp sometimes soft. Is this usual.
Posted by kiwao on 16/01/2013 - 23:04
Additions to my Lens collection (call it LBA-ish)
To be honest Andrew - YES! Why? Well the following:- AF F2.8 Sharp wide open Weather sealing, and then some! Rendition contrast Did mention sharp? Ultimately, I cannot see the 75-150 beating the mighty DA* in most areas, the DA* is such a beautiful beast, and faster to focus than the 75...
Posted by Offertonhatter on 22/01/2013 - 23:53
Additions to my Lens collection (call it LBA-ish)
To be honest Andrew - YES! Why? Well the following:- AF F2.8 Sharp wide open Weather sealing, and then some! Rendition contrast Did mention sharp? Ultimately, I cannot see the 75-150 beating the mighty DA* in most areas, the DA* is such a beautiful beast, and faster to focus than the 75...
Posted by cabstar on 23/01/2013 - 12:54
Additions to my Lens collection (call it LBA-ish)
Vivitar 80-200mm F4.5 M42 screw mount. Is te Vivitar a fixed mount? A few years back I sold an 80-200 with the M42 mount but kept the Pentax K and still have it lying around.
Posted by Gamka on 13/03/2013 - 18:04
Additions to my Lens collection (call it LBA-ish)
Yes the mount is fixed. I liked my Vivitar - but it was 30 years back when I bought it for am M42 camera but knowing I was going to get a Pentax Bayonet fairly soon ... I moved from that to a Pentax 70-210. One day, someone will need the adapter.
Posted by Gamka on 13/03/2013 - 19:46
12-24 zoom or 14mm prime
If you are after 14/2.8 lens...I couldn't recommend Samyang 14/2.8 UMC highly enough - its a very very gooood lens for landscapes. Very sharp with great rendering of colours and pretty much flare resitant and on top of it great build quality for a price that couldn't be challenged. However keep in m...
Posted by kingfisher on 24/01/2013 - 18:01
