Using the 20mm prime lens (newbie questions)

[k4t]

Great thread. Like dabbler I knew about the focal length conversions when comparing to SLR but didn't how aperture was affected as well. This forum is an excellent resource for beginners like us. Thanks!

 

[GaryAyala]

It seems my arrows are pointed away from each other more often than not.

 

[Alanroseman]

It seems my arrows are pointed away from each other more often than not.

Gary,

Some of us have noticed this about you.... but hey, we're all friend here, so who cares?

 

[sherlock]

Thanks for this question and the helpful responses. I knew that the effective (35mm equivalent) focal length of a lens on m4/3 is double, but didn't realize we need to mentally convert apertures as well. That kind of limits the range of useful apertures on legacy lenses, doesn't it, since many of them are not very sharp wide open?

On the Hexanon 40/1.8 for example, this would imply that the recommended apertures are only 2.8, 4, 5.6, and 8 (maybe 11)?

Not at all. I mean, you wouldn't want to stop down to f/22 anyway, even on APS-C (diffraction), but anything down to f/16 would be acceptable, f/11 preferably.

 

[sprinke]

Does this mean that the "Sunny-16" rule is actually "Sunny-8" on m4/3?

 

[sherlock]

Does this mean that the "Sunny-16" rule is actually "Sunny-8" on m4/3?

No, exposure doesn't change. It's just that you might not want to shoot at f16 if you can help it — bring up your shutter speed & open your aperture a bit (f/11 is good) to manage any potential diffraction.

Keep in mind diffraction isn't going to matter too much unless your printing A3 or bigger.

 

[GaryAyala]

Does this mean that the "Sunny-16" rule is actually "Sunny-8" on m4/3?

Just use the Sunny 16 rule on very overcast days ...

 

[dabbler]

Similar experience here. I can get away with slower shutter speed, but only when bracing the camera (EVF or strap) and then it is not always effective. I suppose it also depends upon what you find acceptable. Where possible I prefer 1/40 and up with the 20.

I'll try using a strap to brace the camera, thanks! I've started to put the 2 second self-timer on for low light shots, but my hand needs all the steadying it can get - I don't think I'll ever be known as Dead-Eye Dabbler! I really can't understand Panasonic's thinking about image stabilisation- there could be a reason why in-lens stabilisation is better despite the added size, I guess, but why use Mega-OIS rather than Power-OIS? The POIS in my petit TZ10 is ludicrously good- in some lights I can deliberately bounce up and down and it still comes out as sharp as normal!

Thanks for pointing my arrows in the right direction, Brianetta! I guess that if I want maximum sharpness my arrows need to be pointing inwards, then!

 

[thearne3]

With micro 4/3, because of the smaller sensor that gets revised to 1/(2*focal length)

so for the 20mm that is 1/(2*20) or 1/40 of a sec

Just wondering about the rationale for the change in formula for m4/3, Kevin...

'Holding at arms length' (lack of EVF) and (for the GF1 and this lens) lack of stabilization will affect blur - I understand those reasons. But sensor size by itself? Could you explain further? Am I understanding you correctly?

BTW, this is only for clarification of 'why', the formula is good in practice!

 

[kevinparis]

Just wondering about the rationale for the change in formula for m4/3, Kevin...

'Holding at arms length' (lack of EVF) and (for the GF1 and this lens) lack of stabilization will affect blur - I understand those reasons. But sensor size by itself? Could you explain further? Am I understanding you correctly?

BTW, this is only for clarification of 'why', the formula is good in practice!

I have no idea whether my theory actually holds any water - but it is based on my thinking that if a 50mm lens on a micro 4/3 appears to act like a 100mm lens on 35mm then you should double the old 35mm rule of thumb to compensate

K

 

[sherlock]

The real answer is more to do with pixel density, than sensor size. It's just that smaller sensors typically happen to be more dense.

More pixels per square inch + hand shake = more blur in your image.

 

[Hyubie]

I have another noobish question: say you're in a dark-lit restaurant with friends, and you asked somebody else to take a group picture. If I use an Olympus body with IBIS and the Panny 20mm:
- I'm thinking of putting it in f/1.7 (since it is low light), but wouldn't that make the others in the group who are away from the focus point blurred?
- Is flash the only option here?
- In fact, is there a guideline "maximum" aperture for group pictures?
- What would you suggest?

Thanks!

 

[iliakoltsov]

Hyubie , depends on what you are after flash will certainly help but as you said by raising the ISO and the IBIS from olympus you can get very good pictures without flash in a restaurant or with poor lighting especially with the 20 1.7 which seems very good in low light.

The thing that you may want to ask as well, Pen have a more proprietary raw format which means free software may have a bit of a pain to derawtize it ( ufraw and rawtherapee crashes) i tested it a while ago maybe it has evolved and i hope so.

Why this comment is important:
Demosaicing algorithm is as important as levels and contrast, by shooting in raw you can through software obtain very good results at 400, 800 and even 1600 iso where you can barely see the noise.

Basically :
You compensate the flash light by raising the sensitivity to get back to somewhere around the rule of thumb 1/the focal length or as some people suggested 1/2*Focal length. the best way to learn is to play with your camera

 

[Amin]

The real answer is more to do with pixel density, than sensor size. It's just that smaller sensors typically happen to be more dense.

More pixels per square inch + hand shake = more blur in your image.

Sherlock, that is true if you're talking about apparent blur when looking at the 100% pixel level. For apparent blur on a final image level, it's not the pixel density but rather the lens angle of view that determines the amount of blur for a given amount of handshake.

 

[Amin]

Wow, I'm moving to m4/3 from a DSLR and hadn't realised things would be so different. Brian Peterson was my favourite book while learning to drive my 30D; if that no longer applies, who should I be reading now?

It's actually easier to apply what Bryan wrote to MFT than it is to your 30D. With the 30D, all of the f-numbers Bryan gave as a guide for desire DOF should be adjusted downwards by ~1.3 stops. For MFT, they can simply be halved.

 

[thearne3]

The real answer is more to do with pixel density, than sensor size. It's just that smaller sensors typically happen to be more dense.

More pixels per square inch + hand shake = more blur in your image.

There is an interesting article that speaks to several topics we've touched upon in this thread written by Steve Hoffman:

DSLR SENSOR SIZE AND PIXEL DENSITY

Quite a good read with lots of illustrations.