Full frame or not ???


couls

Link Posted 06/08/2015 - 21:59
Have a k-r and the k5-lls are either of them full frame. I am looking to purchase a lens and it says that camera requires full frame ANY HELP Please

spinno

Link Posted 06/08/2015 - 22:01
what lens?
David

couls

Link Posted 06/08/2015 - 22:05
Sigma AF 120-400mm F/4.5-5.6 APO DG HSM OS

Jonathan-Mac

Link Posted 06/08/2015 - 22:12
It doesn't require full frame but is full frame compatible. No full frame Pentax camera currently exists, though one is due for release at the end of this year, price still unknown.

The lens should work fine with any Pentax DSLR.
Pentax hybrid user - Digital K3 & K200D, film 645 and 35mm SLR and Pentax (&other) lenses adapted to Fuji X digital
Fan of DA limited and old manual lenses
Last Edited by Jonathan-Mac on 06/08/2015 - 22:13

couls

Link Posted 06/08/2015 - 22:14
Thanks for the info will go ahead and purchase unless any of you know a better lens

richandfleur

Link Posted 07/08/2015 - 01:24
Pentax only has smaller APS-C sensor digital cameras presently, as Jonathan-Mac mentions, and these only use the middle area of a FF lens. Therefore you can use any Pentak K FF lens on the camera, which includes the older film era K mount lenses also.

Later on, once the FF camera arrives from Pentax, it won't work in reverse, in that lenses for APS-C sensors will get darker/less sharp around the outsides when used on a FF camera. FF camera owners will need to use a crop mode at that stage to use the smaller APS-C image circle lenses on their FF camera, or crop out the dark bits afterwards etc.

So, for now, you can pretty much use any Pentax K- mount lens on a Pentax digital camera today, as they are all APS-C sensor size.

comstadcity

Link Posted 07/08/2015 - 06:51
The advantage of buying a full frame lense now for an APS sized sensor is that when Pentax do eventually make full frame cameras your lense will still be compatable with them if you decide to upgrade as explained by richandfleur. You will in effect be future proofing your lense collection.
Am now mainly a Canon FF user 5D mk ii, 5D mk iii, 6D but still have some Pentax gear, K7, IST DS, K10D Grand Prix, Metz 32 ct4, Pentax A 50mm 1.7, Pentax M 28mm 2.8, Pentax DA 50-200mm 4-5.6, Pentax DA 18-55mm 3.5-5.6,

bwlchmawr

Link Posted 07/08/2015 - 06:53
Some say that a lens such as the one you cite will be better on a camera with an APS-C sensor since you only make use of the "best" bit, i.e. the middle. The bonus with using a telephoto zoom is that you get more for your money, focal length-wise. For example, a 300mm lens "becomes" 450mm.

Of course, the reverse is true when viewing a scene through a wide angle lens where a 28mm lens loses its width somewhat, becoming c. 42mm.

When the well-heeled buy the rumoured Pentax FF DSLR I worry that some treasured lenses might be found wanting when their outer reaches are scrutinized by the larger sensor.
Best wishes,

Andrew

"These places mean something and it's the job of a photographer to figure-out what the hell it is."
Robert Adams
"The camera doesn't make a bit of difference.  All of them can record what you are seeing.  But, you have to SEE."
Ernst Hass
My website: http://www.ephotozine.com/user/bwlchmawr-199050 http://s927.photobucket.com/home/ADC3440/index
https://www.flickr.com/photos/78898196@N05

nass

Link Posted 07/08/2015 - 09:25
bwlchmawr wrote:
Some say that a lens such as the one you cite will be better on a camera with an APS-C sensor since you only make use of the "best" bit, i.e. the middle. The bonus with using a telephoto zoom is that you get more for your money, focal length-wise. For example, a 300mm lens "becomes" 450mm.

Hello couls,

Just to clarify on this, I found it quite confusing when I started so hopefully I can explain. APS-C, today's Pentax DSLRs, have a sensor area that is smaller that the sensor area of a full frame camera. In other words it records a smaller view that a full-frame would. This smaller view means a smaller angle of view. To throw in some imaginary figures:

a 300 lens on fullframe might record a 10 degree field of view
The same 300 lens on APSC might only record an 8 degree field of view
a 400 lens on fullframe might also record an 8 degree field of view

So what the marketers do is try and persuade us that the 300 on APSC is actually a 400, based on the field of view number. Personally I've always thought it a bit dubious, as a 300 is a 300 whatever camera you put on, but dubiousness has never stopped a marketer pushing a good line

Hope that vaguely helps,

-Johan
... just another middle-aged guy with a hobby. I have an extreme macro learning site at extreme-macro.co.uk - Pentax-centric, your feedback and comments would be appreciated!
Last Edited by nass on 07/08/2015 - 09:25

pgweber

Link Posted 07/08/2015 - 09:39
I would try to explain it like this:

A 300mm film/full-frame lens on an APS-C digital body will give the same perspective as a 450mm lens on a full frame body.

As Johan explained, the angle-of-view is narrower on APS-C than on 35mm/full-frame, giving a cropped view and the illusion of being closer to the subject.

The focal length is constant (as it is a physical characteristic of the lens).
Peter

Pentax K5
Pentax DA 18-55 Mk1, 50-200 (Samsung), 16-45, 55-300 Mk1, 35 f/2.4
Pentax MZ6 + FA28-90, FA50 f/1.4, M 50 f/1.7
Tamron 80-210mm & 28mm
Last Edited by pgweber on 07/08/2015 - 09:41

McGregNi

Link Posted 07/08/2015 - 09:48
I too have not felt very convinced by such focal length 'equivalent' comparisons. This often translates into statements such as 'aps-c has the advantage for wildlife' .... The supposed advantage being that (for example) you only need to buy a 300mm lens rather than a more expensive 400mm for FF.

The truth is that distance and magnification is the same whatever the format. What changes is how much of your sensor space is filled up by an object at each distance and magnification. An aps-c sensor will be more ' filled up' by an object shot at 300mm than the same object shot at 300mm on a FF camera would 'fill up' that larger sensor.

So the supposed difference is really an illusion ... An optical illusion of scale, both in the viewfinder and on the image. The key technical components that really matter, focal length , distance and magnification, remain the same ....
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Last Edited by McGregNi on 07/08/2015 - 09:49

nass

Link Posted 07/08/2015 - 10:12
That's a really good way of putting it Peter, to talk about perspective. makes it very clear.
... just another middle-aged guy with a hobby. I have an extreme macro learning site at extreme-macro.co.uk - Pentax-centric, your feedback and comments would be appreciated!

McGregNi

Link Posted 07/08/2015 - 10:52
I'm not so sure ... Perspective is really a component of the focal length. As such it is another constant, so doesn't change with sensor size. Perspective effects are things like how flat or deep something appears ... So a face portrait looks good in the range from, say, 70mm through 135m, due to the nice rendering of shape caused by those lengths. Again, none of that changes with sensor size.
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
Last Edited by McGregNi on 07/08/2015 - 10:52

pgweber

Link Posted 07/08/2015 - 11:21
Oh dear.
Perhaps I should have said 'field-of-view' instead of 'perspective'.

The main thing that I wanted to convey, was that a lens's focal length remains the same, regardless of sensor size.
Peter

Pentax K5
Pentax DA 18-55 Mk1, 50-200 (Samsung), 16-45, 55-300 Mk1, 35 f/2.4
Pentax MZ6 + FA28-90, FA50 f/1.4, M 50 f/1.7
Tamron 80-210mm & 28mm
Last Edited by pgweber on 07/08/2015 - 11:22

McGregNi

Link Posted 07/08/2015 - 12:58
Sounds like we're singing the same tune then It doesn't take much in these sort of discussions for word definitions to be treated many different ways.

I think when people go FF they won't need longer lenses ... They might just have to crop a little if they want their sensor space filled more .....
My Guides to the Pentax Digital Camera Flash Lighting System : Download here from the PentaxForums Homepage Article .... link
Pentax K7 with BG-4 Grip / Samyang 14mm f2.8 ED AS IF UMC / DA18-55mm f3.5-5.6 AL WR / SMC A28mm f2.8 / D FA 28-105mm / SMC F35-70 f3.5-4.5 / SMC A50mm f1.7 / Tamron AF70-300mm f4-5.6 Di LD macro / SMC M75-150mm f4.0 / Tamron Adaptall (CT-135) 135mm f2.8 / Asahi Takumar-A 2X tele-converter / Pentax AF-540FGZ (I & II) Flashes / Cactus RF60/X Flashes & V6/V6II Transceiver
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