[Sandy Hancock]

As PK was specifically referring to DoF and bokeh, rather just exposure, I agree with Rondec.
But do we really need to derail every thread with this stuff?

To back up clackers' comment though - I had the FA20-35 for a while, and the DFA15-30 is ridiculously better.

[PiotrKrochmal]

Oh... Accidentally released a demon.
@clackers
thank you for link very usefull article. And I agree with it.

I agree also that my sentence was over simplify the whole problem. Shame on me!

Can you answer this question.

I determine that the exposure on my APS_c camera is 100 ISO, ƒ.5.6, 1/100s

What is the correct exposure on a 36x24 sensor (pick the best answer)

1. 100 ISO, ƒ.5.6, 1/100s
2. 100 ISO, ƒ.8, 1/100s
3. 200 ISO, ƒ.5.6, 1/100s

If you're so messed up you can't accurately answer the question, i's because you don't know as much about exposure as one of my photography students would have known after a week. Anyone who has used the same hand held light meter for exposures on different formats will know the answer immediately.

Exposure is not affect by format. What is good on one is good on them all. However when looking at your light meter, it' like a little hand held computer that gives you all the different exposures you could use. And you will select one of them based on the desired depth of field for that format. The exposure value however is unaffected.

Exactly, if you choose the same ISO and the same aperture, time of exposure will be the same regardless of format.

Theoretically in the same light condition you could set almost infinite number of combinations of t, f and A. So you should choose what is your desired DOF, sharpness, time freez etc.
So if we need to hold same DOF on 35mm film as on APSC with 1,5 crop factor we have to choose one full stop slower aperture but as we need to compensate exposure we need to higher the ISO to 200.

So answer is ISO 200 f/8 and 1/100s. or ISO 100 f/8 1/50s .

If I misunderstood something please do not hesitate to correct me .

About lenses: 15-30 too expensiv. I'm thinking also about FA 20 2.8. of just wait for something new

---------- Post added 11-09-16 at 02:45 PM ----------


So one thing from me. K1 is two camera in one body. FF 36 mpix and APSC 15mpix. It give much more flexibility!

[normhead]

The F35-70mm, is a great little lens(well my 2 are)...highly recommend it....Plenty of other F series and FA series produce very good images on the K1.


It has an affinity with 1...because the images from the K-01 are also impressive.

I like my FA 35-80, it's just not wide enough in it's range. Back in the day, most people thought you had to go below 35mm to be truly wide angle, 35mm was the bottom of normal. I feel much the same about the 21 on APS-c. If mt 21 was an FF lens, I probably wouldn't have a care in the world.