Free Shipping on ALL Products
camera reviewsbest cameraslens reviewsphotography tipscamera forumvideo toursphotography bookssupport me
It is currently Sat Aug 02, 2014 4:55 am

All times are UTC




Post new topic Reply to topic  [ 11 posts ] 
Author Message
 Post subject: aperture FZ28
PostPosted: Sat Mar 27, 2010 2:38 pm 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
Hi all,

The minimum aperture (A) of my FZ28 is F/8
Isn't that the same as F/22 on a DSLR? So yes, what about F/4.5 on my panny, F/2.8 etc?

Question two: The min. A of my panny is F/8 as mentioned, but: when recording videos the min. A is F>13 (not had any higher)
How could this happen? When in M/A mode I could choose a higher number than 8, when in videomode is selects F/13?!
Thanks;)

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 29, 2010 1:33 am 
Hi,
Answer to question 1:
To my knowledge, the minimum aperture is f/8 at wide angle, but can go to f/11 at max telephoto. And f/8 on your camera should be equivalent to f/8 only on a dslr or full frame camera, since I believe you already have the equivalent value.
To question 2, I don't have a ready answer, but hopefully your manual may be of some help....
Jinay.


Top
  
 
 Post subject:
PostPosted: Mon Mar 29, 2010 9:26 am 
Offline
Moderator
User avatar

Joined: Sat Sep 30, 2006 4:30 pm
Posts: 9805
Location: UK
Hi Ruben,

Given that a camera's f-number is just the measured focal length of a lens divided by the diameter of the entrance pupil there is no "equivalent" value for a DSLR. f/8 is f/8 regardless of the size of the sensor behind the lens.

But things get a little muddier in practice because of diffraction and depth of field. Your FZ28 has an effective crop factor of 5.625, obtained by dividing the 35mm equivalent focal lengths of your lens by the actual focal lengths. Both figures are given in the camera's specifications. So compared to a DSLR with the same pixel count as the FZ28 and a crop factor of, say, 1.5 the f-number needed to give the same DoF when both cameras are zoomed in to show the same angle of view is different by a factor of 5.625/1.5 = 3.75. So if the DSLR was shooting at f/11 for good DoF the FZ28 only needs to be stopped down to f/2.9. :shock:

Just as well because with the very high pixel density typical of its class the FZ28 needs to work near these sort of apertures to be sure that diffraction from the lens doesn't soften the image. The problems start if you want a shallow DoF on the FZ28, of course, because the lens aperture just can't go wide enough. I explored some of the trade-offs in my post Full-frame Sensors Are Better - Fact or Fiction?. The principles involved are equally valid when comparing the sensors in compacts or superzooms with DSLRs.

As for your f/13 while shooting video, I can see no mention of it in the manual. But my understanding is that when shooting at the low resolutions, compared to stills, of video the camera "bins" pixels together so each "pixel" on the video takes information from several pixels on the sensor. That means that the diffraction softening I mentioned doesn't kick in nearly so quickly so it would be reasonable for the camera to be able to stop the lens down further than usual. Maybe the iris can physically reach f/13 but is prevented from doing so unless video is being shot. If so it's a shame the fact isn't mentioned in the manual but I doubt many users would ever be aware of the fact.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 29, 2010 2:05 pm 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
Thanks Bob for explaining :)

That is really clear, in the future Im buying a dslr, because a week after buying my FZ28, I decided to use my cam. for astrophotography. Argh.
Thanksfully it has a max. exposure of 60 sec, and with several programs Im able to lower the noise.

Thanks again,
Ruben

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
 Post subject:
PostPosted: Tue Mar 30, 2010 1:58 pm 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
Maybe there are some FZ38/35 owners those can check it in Aperture Priority on their camera? As far as I know the FZ38 has a manual movie mode..

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
 Post subject:
PostPosted: Thu Apr 01, 2010 2:56 pm 
Hi Bob,
I read the link about full frame vs cropped sensors and it provided a very interesting read! (At least as far as my knowledge supported!) However, I do have some questions:
1. I understood that though the f-numbers are same on a full frame and cropped sensor, the depth of field can vary. Am I correct?
2. I would like to consider a 1/2.33" sensor against a full frame one, simply because they are most common in p&s. So, an f/8 aperture will give the same effect of a f/(8*5.625) aperture on a full frame? Does the same calculation apply to the entire aperture range?
3. If the above is true, does that mean that f/2.8, which is the biggest aperture on most p&s will give more back to front sharpness than a full frame f/2.8? Is that the reason that larger frame cameras are known for the wonderful background blurring effects which are hard to get on small sensor cameras?
Thanks in advance,
Jinay.
P.S. Now I believe Angel-slo was right in saying you got your theories perfect! Fantastic explanation, man!


Top
  
 
 Post subject:
PostPosted: Fri Apr 02, 2010 11:42 am 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
because of the bigger sensor you get a smaller DoF. For instance, for 2.8 on a p&s, you get the same DoF with 5.0 on a dslr. that's why dslrs can take more blurry backgrounds. However, I can say you, with my FZ28 with macro glass I can make macro shots of a fly that's only the eyes are sharp.

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
 Post subject:
PostPosted: Sat Apr 03, 2010 1:23 am 
Hi,
Ruben, I didn't understand the calculation of 2.8 on p&s to f5.0 on dslr. What is the formula to use?
Thanks,
Jinay.


Top
  
 
 Post subject:
PostPosted: Sat Apr 03, 2010 7:20 am 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
Hi, there isnt a formula :lol:
the only thing you've to understand is: a bigger sensor means smaller dept of field.
a p&s has a small sensor (so: great DoF)
a dslr has a big sensor (so: small DoF)
I know how to explain it in Dutch, but my English is not very good, Ill give a try.
When using F/2.8 on a p&s you get a small DoF
When using F/2.8 on a dslr you get a smaller DoF because of the bigger sensor. you understand this?
When closing the aperture on a dslr to, let's say, F/5.6, you get a bigger DoF, BUT, not as big when using a compact when using F/5.6
So, I hope Im right, the aperture is almost the same (however: when my lumix is set to 2.8 is has a much smaller iris when I set my rokkor-w to f5.6, anyone could explain this me?) But, because of the bigger sensor, you have to close the aperture for getting the same effect.
This is however almost never a problem: many people buy dslrs because of getting a small DoF!

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
 Post subject:
PostPosted: Sun Apr 04, 2010 3:17 am 
Hi,
Thanks for the answer, but I was wondering how you came to the f2.8 on a p&s is same as f5.0 on dslr in terms of DoF? What is the sensor size you have been considering?
Thanks in advance,
Jinay.


Top
  
 
 Post subject:
PostPosted: Sun Apr 04, 2010 6:12 am 
Offline

Joined: Mon Jan 18, 2010 3:52 pm
Posts: 2173
Location: The Netherlands
the sensor of a dslr is almost (correct me if Im wrong) 5X as big as the lumix'.
I dont know exactly of 5.0 the same is as 2.8, 5.6 could also be the same.
I dont own (yet) a dslr, so it's hard for me to explain ;)

_________________
Ruben

Panasonic DMC-FZ18, Panasonic DMC-FZ28, Canon G5, Canon 350D, Canon 50D + BG-E2N
Tamron 17-50 2.8, Canon EF 70-200mm f/4L USM,
Canon 18-55 II plus lots of Minolta MD/M42 lenses and bodies


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  

All words, images, videos and layout, copyright 2005-2012 Gordon Laing. May not be used without permission.
/ How we test / Best Cameras / Advertising / Camera reviews / Supporting Camera Labs

Webdesign by Alphabase IT
Powered by phpBB® Forum Software © phpBB Group