Pentax Full Frame

Crop a FF down? you mean to say 15.6 x 23.4.... Isn't that
the same as APS-C? I could use FF for birds and then crop
them all to 15.6 x 23.4 but I can't see any point when I
could use a K-5.

Why have photographers become so poor/incompetent all of a
sudden with 35mm they learnt to fill the frame. Nobody ever
mentioned buying a 6x4.5 so that they could crop it down to
35mm size..... that's what all the lenses were for.

Regarding DOF the end of this video explains it quite well.
Image sensor size does not change DOF
The presenter is excellent, but this video was done in the
freezing cold.. BRR! Worth checking out his other videos.
http://www.youtube.com/watch?v=L0n4pyhx7Dk

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

Agreed, no format does. A 50mm lens is a 50mm lens, end of story.

What changes is the lens required for a given field of view.

So a Minox sub-miniature requires a 15mm lens as a standard lens. 15mm lenses have immense DOF when taken in this context. So the small format has more DOF than the larger format, in a practical sense.

We do understand the technical point you are making Algi, but I think we need to recognise the practical upshot of this for most users. So when people say that wide angle lenses give more DOF and that APS-C gives more DOF than FF, they are right enough in the context in which they are using the cameras to shoot images.

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Best regards, John

This has nothing to do with Minox cameras, we are talking
about cameras that take the same lenses.

I find it quite alarming that people on here just don't understand
the very simple practical basics of photography and how
to use cameras and lenses in a purely practical sense.

The video above almost fully explains everything you need to
know about DOF and it is by one of the best filmmakers/directors
in the business and we should be grateful that he is willing to
share his knowledge for free. This is a Demo of some of
his work....believe me he knows what he's talking about

He did mention in the video that the only thing that would
change the DOF was moving the camera... which has nothing to
do with format.

I don't think he mentioned that if you wanted to maintain the
same DOF and field of view without moving the camera you would
of course have to change the focal length of the lens.

I shouldn't have to explain to photographers how to adjust
the aperture, but It seems I might have to

Very simply the ratio of APS-C to FF is 1.5 and the
ratio between stops is 1.4..... for practical purposes
we will call them both 1.4, so if I'm using 75mm at f/2.8
on FF for APS-C I would need for the same DOF from the
same spot 50mm at f/2..... the f/2 is needed to keep the
same aperture diam. which as mentioned previously is what
controls DOF. The 1.4/1.5 is constant so we always need
to open up 1 stop. 120mm at f/5.6 on FF would need 80mm
at f/4 on APS-C...... Hardly Rocket Science

I would have thought the extra DOF of APS-C was an
advantage and not a disadvantage. It's only 1 stop
anyway not 4 and it gives you an extra stop of
film/shutter speed if you open up the aperture

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

May I say that 'I find it quite alarming that people on here just don't understand the very simple practical basics of photography and how
to use cameras and lenses in a purely practical sense.' displays, in my opinion, a rather elitist and snobbish mindset.

Many of our members are beginners just as we all were at one time and this is, after all, a knowledge sharing website.

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Ken
“We must avoid however, snapping away, shooting quickly and without thought, overloading ourselves with unnecessary images that clutter our memory and diminish the clarity of the whole.” - Henri Cartier-Bresson -

It's not beginners who are calling out for a FF camera which
if they ever produce it will probably mean the end of Pentax
so it's quite a serious matter. The people calling for this
camera SHOULD know about DOF

The DOF stuff I've mentioned here would have been known by
children on a school photography course a few years ago and
I'm surprised that no one calling out for a FF camera seems
to know anything about it.

It wasn't beginners either who wanted a mirrorless camera
which when eventually produced in the form of the K-01, they
then decided that it wasn't such a good idea after all and
kept the money in their pockets. It will be the same with
the 560mm lens... ask for it... it gets made.... people
won't/don't want to pay for it

I've all the time in the world for beginners. I've
directed them to some very good tutorial videos in this
thread which a few years ago they would have to buy.
Over 5 hours worth
http://www.youtube.com/watch?v=7XwEefm9Ccw
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http://www.youtube.com/playlist?list=PL3AF9B2B010B69D0C

I can't see why you feel the need to start an argument,
your time would be better spent also sharing knowledge.

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

Algi, do you honestly think Pentax produced the K-01 because they read people wanted it on our forum? I don't buy it for a moment, and anyway, in no way does the K-01 resemble the product most people were talking about. Fine product though it may be.

John is right - you seem to be ignoring the practical context in which people are taking images. On APSC people need to choose a wider lens and move further away from their subject. That is what increases DOF at a given aperture setting. Pictures speak louder than words - so find the two images below both shot at f5.6.

50mm on FF

35mm on APSC

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[link=https://500px.com/will_brealey/[/link]

Pentax will produce a FF when they determine the market is right, no sooner and no later. I don't really understand why you think this would be the 'end of Pentax' particularly when you consider that the investment required would probably be much less than, say, the 645D. You could argue that Pentax might eventually become a niche market, forever being nibbled away at by the mirrorless market at the bottom end, and the FF system market at the more expensive end, if it doesn't address the FF issue.

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[link=https://500px.com/will_brealey/[/link]

I think SRS are selling K-01 bodies for £219 and Q bodies for £99.
This is happening worldwide and Pentax must be losing a lot of money
on them, plus the losses due to early problems with the K-5 and the
only cameras they have in the Japanese top 80 are the Q's due to
low price. These were asked for wordwide by the Pentax community,
they wouldn't make things if the market didn't look like it
wanted them.

They need something profitable very quickly. Strangely the
Q10 seems to be their best bet.


You lose a stop due to DOF so if you want the same DOF from the
APS-C as the FF you open up to f/4 which gives you the advantage
of an extra stop on the speed making it 1/15th second instead of
1/8.... that would be better from a handholding POV.

If it was a group shot the larger DOF of the APS-C would be handy.

There isn't much interest in shallow DOF's so it's hardly a reason
for going FF. This lens hasn't sold and it's been through a few
times looks OK to me and the price is low.... very nice bokeh and
much cheaper than a FF camera.
Porst 55mm f/1.2 K mount

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

SRS are offering 10 ex-demo K-01 cameras for £219 on eBay, the regular price on their website is somewhat higher.

The outgoing Q body is also available at what loooks like a clearance price of £99, again from SRS and eBay. Excellent news, if you don't have one here's your chance!

Always nice to have the heads up on bargains! I'll put this is Leads to Deals.

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Best regards, John

They must have had punters queuing up for a demo if they
needed 10 Without lenses as well??

That's about the price of a SH K10D

Very silly putting a 40mm lens with it.... 60mm on
35mm only any use for portraits No wonder
they didn't sell.

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

Yes you can open up to f4 but that's often not the 'sweet spot' of a lens (think of the DA16-45mm or FA28-70mm). The aberrations you get shooting wide open aren't going to be made any better by APSC's 1.5x crop either. And if you're comparing two lenses shot at maximum aperture, that option obviously isn't available!

Conversely, to get greater DOF on full frame, you can always close the aperture down. Diffraction is going to be less of an issue on FF as you stop down, and as good as the K5 is, FF high ISO performance is likely to be better too, so there's no disadvantage in this.

The fact that the all-manual Post 50/1.2 is priced that high demonstrates some interest in the sort of DOF it can deliver. But I imagine the results from a reasonably good 75-85mm f2 lens on full frame would probably be better - less prominent aberrations, and 'glow', etc, and you could probably buy such a lens with all mod-cons like AF and auto-exposure.

Now I'm not saying that shallow DOF should be an overriding concern in anyone's choice of kit, but I am just addressing the argument that it is not a concern at all, and that differences between the formats don't exist, because clearly they do.

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[link=https://500px.com/will_brealey/[/link]

I think the choice of the 40mm as the kit lens was a pity, as I agree it's not really the optimal 'walkabout' focal length. But I think the reason it didn't sell was really that it just wasn't small or light enough, and looked odd. I think the project was a bit of a case of 'lets do this with the minimal amount of R&D we can possibly get away with'. Because it's basically just a DSLR body, sans mirror, and the 40mm XS lens is basically just a 40mm ltd. It's fine for what it is, but it doesn't seem much technical innovation went into it. Probably hence the 'designer camera' strategy.

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[link=https://500px.com/will_brealey/[/link]

Retailing is all swings and roundabouts, you only have to visit the January sales to discover that, if I buy 100 items and sell 75% of them with a 20%-30% (or higher) profit margin I can afford the sell the remaining stock at cost or less and still come off with a handsome profit.

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My Names Alan, and I'm a lensaholic.
My PPG link
My Flckr link

If you see any Leicas in the sales for 1/6th of their
usual price let me know

The f/1.2 on ebay is the same as one I've got. It's quite a
good lens and is a K mount. I've also got the M42 Chinon
Tomioka (labeled) one and the Pentax K 50mm f/1.2.

The one similar to the ebay one is the easiest to focus and
might be the sharpest wide open, but only just.

They are quite handy lenses, quite a few of the shots on
Flickriver were taken with K-5's and K20D's and show that
current cameras are up to the job.

http://www.flickriver.com/search/tomioka+f1.2/

Click on Interesting on that page

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi

Nice CZ 55mm f/1.2 only £5,580 can be adapted to Pentax

ebay

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Half Man... Half Pentax ... Half Cucumber

Pentax K-1 + K-5 and some other stuff

Algi