Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-28-2014, 03:44 AM   #31
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by derekkite Quote
Fstop of the lens is a fixed number arrived at by measuring the focal length and the aperture size. It doesn't change with the sensor size. If I put a 45mm 2.8 lens on the Q I would get roughly the same field of view as the 06 lens. And if I could adapt the Q 06 lens to the K3 it would be like a 45mm except it wouldn't cover the sensor. Or I could crop a shot made with a 45mm 2.8 lens on the K3 down to the size of the Q sensor to get an equivalent field of view. The f stops of the lens don't change. They are fixed in hardware. The equivalency numbers represent the field of view.

That is pretty impressive for such a small body. I was disappointed with the iq of the original Q, and have been eyeing the Q7 or later for improvements.
That's very true but as you say it is valid for both focal length and apperture. That was is written on the lense.

If you start using equivalence, this is to understand what setting you should have on a different body to get the same result. You can't apply equivalence only on what setting and keep the other setting unchanged. So you'd get the same looking image at 207mm f/13, iso2000 on an FF than 45mm f/2.8 isos 100 on Q. And there no issue going f/13 because well the apperture is not fixed in hardware, only the min/max apperture are fixed and so an f/2.8 lense can typically be closed down to f/13.

This is very important to know what to expect, understand what is possible on different systems.

I'd say you can see it as a game, try the Q @ f/2.8, then try a shoot at equivalent focal length but keeping f/2.8 apperture on a larger format camera or going f/13 on FF or f/8 on APSC iso 800. Maybe 207mm for FF f/2.8 is not practical so why not try a shorter focal length on APSC at f/2.8 and f/8 and see what setting look the most similar to the Q @ f/2.8 ?

You can even print the different photos and ask your friend what photo look the most similar to them.

You are all amazed by this f/2.8 because you map it to what f/2.8 does on FF on APSC... On theses systems f/2.8 is for high end zoom and the "pro" standard. The lenses are big and expensive So when you see f/2.8 on a smaller body you continue to think the same way. It should be big, heavy and expensive. If it is not it must be a fantastic achievement. But f/2.8 become average... RX100 III has an f/1.8-2.8 variable apperture, Fuji X30 f/2-2.8. and Canon G7X has f/2-2.8.

Even through the number are the same, f/2.8 everywhere, they do not translate in the same engineering effort or the same possibilities in term of shooting low light or deph of field.


Last edited by Nicolas06; 12-28-2014 at 04:09 AM.
12-28-2014, 01:41 PM   #32
Senior Member




Join Date: Nov 2013
Location: Lake District
Posts: 222
QuoteOriginally posted by Nicolas06 Quote
That's very true but as you say it is valid for both focal length and apperture. That was is written on the lense.

If you start using equivalence, this is to understand what setting you should have on a different body to get the same result. You can't apply equivalence only on what setting and keep the other setting unchanged. So you'd get the same looking image at 207mm f/13, iso2000 on an FF than 45mm f/2.8 isos 100 on Q. And there no issue going f/13 because well the apperture is not fixed in hardware, only the min/max apperture are fixed and so an f/2.8 lense can typically be closed down to f/13.

This is very important to know what to expect, understand what is possible on different systems.

I'd say you can see it as a game, try the Q @ f/2.8, then try a shoot at equivalent focal length but keeping f/2.8 apperture on a larger format camera or going f/13 on FF or f/8 on APSC iso 800. Maybe 207mm for FF f/2.8 is not practical so why not try a shorter focal length on APSC at f/2.8 and f/8 and see what setting look the most similar to the Q @ f/2.8 ?

You can even print the different photos and ask your friend what photo look the most similar to them.

You are all amazed by this f/2.8 because you map it to what f/2.8 does on FF on APSC... On theses systems f/2.8 is for high end zoom and the "pro" standard. The lenses are big and expensive So when you see f/2.8 on a smaller body you continue to think the same way. It should be big, heavy and expensive. If it is not it must be a fantastic achievement. But f/2.8 become average... RX100 III has an f/1.8-2.8 variable apperture, Fuji X30 f/2-2.8. and Canon G7X has f/2-2.8.

Even through the number are the same, f/2.8 everywhere, they do not translate in the same engineering effort or the same possibilities in term of shooting low light or deph of field.
And yet it's still a great lens producing great pics on a Q7, especially for its size and the sensors limitations.
J
12-28-2014, 02:35 PM   #33
Pentaxian




Join Date: Sep 2011
Location: Nelson B.C.
Posts: 3,267
QuoteOriginally posted by Nicolas06 Quote
207mm f/13, iso2000 on an FF than 45mm f/2.8 isos 100 on Q
Heh. Or if you want to put it differently, 207mm iso 100 f2.8. If you close your aperture 4 or 5 stops you would need to up the sensitivity the same amount to get the same exposure. We know that, and it has nothing to do with equivalency.

I take shots like that often. On a day with good light in an enclosed location like that a 300mm at 400 iso f4 1/320 would be about right. I'd try to get a bit higher shutter speed, but great shot nonetheless.
12-28-2014, 03:54 PM   #34
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by jethro10 Quote
And yet it's still a great lens producing great pics on a Q7, especially for its size and the sensors limitations.
J
of course !

12-29-2014, 04:29 AM   #35
Junior Member




Join Date: May 2014
Location: Paris, France
Posts: 42
QuoteOriginally posted by Nicolas06 Quote
a 207mm equivalent f/13 lens. That all it is about. You said you did understood isn't it ? So why do you continue to use the wrong equivalence numbers?

This is not to say this tele is no good. I have nothing against it. This is conveniant and in good light you get nices shoots. That the whole point isn't it ? But you know all smartphone have f/2.5 or wide apperture prime now. Their lenses are few mm wide. Many compact also have f/2-f/2.8 zooms lens now. f/2.8 is pretty standard for such sensor size.

This is not bad or good, and for sure f/2.8 still allow for shallower deph of field and more light than f/5.6... This is all valid while you keep a given sensor.

But from practical point of view, if you take 2 shoots with same framing at 200mm (FF framing), one with the Q-S1 the other one with an FF, both at f/2.8:
- the deph of field will be dramatically different.
- iso setting will be the same for both... Meaning the FF will offer much better quality... Same at iso 2000 on FF than at iso100 on Q-S1.

Anybody looking at the 2 image will immediately spot the difference. First of deph of field at low isos setting, second of noise at high isos setting. While if you set f/13 on the FF lense... Well it will look the same.

I insist because some people might think for example that their 55-300 f/3.5-5.6 might be not as suitable as f/2.8 Q-S1 lense due to the f/5.6 only while it is obviously wrong. Another example. DA70 ltd is not that big. Still put it on K3, shoot at f/4, crop to 50% size and you get equivalent of 210mm FF framing f/11 6MP shoot... Half the pixels that what you would get Q-S1 45mm @ f/2.8, but still 0.5EV more for noise performance. And the lense isn't that big.
All you say is right, but shooting at 100 iso is absolutely not the same thing than shooting at 2000 iso. The noise produced by the sensor is not the same. At 2000 iso the gain of the sensor is high, at 100 iso it is nominal, so the sensor will produce noise at 2000, not at 100 iso. In the film days, nobody would have say that shooting at 100 iso was equivalent to shooting at 2000 iso
12-29-2014, 07:41 AM   #36
Loyal Site Supporter
drougge's Avatar

Join Date: Jan 2010
Location: Malmö
Photos: Gallery
Posts: 787
QuoteOriginally posted by morane_j Quote
All you say is right, but shooting at 100 iso is absolutely not the same thing than shooting at 2000 iso. The noise produced by the sensor is not the same. At 2000 iso the gain of the sensor is high, at 100 iso it is nominal, so the sensor will produce noise at 2000, not at 100 iso. In the film days, nobody would have say that shooting at 100 iso was equivalent to shooting at 2000 iso
This seems to be a common misunderstanding. No one is saying that the sensors that actually exists today have these properties. This is about theoretical sensors. In principle, you can make a range of size invariant sensors (in the reasonable range of sizes at least). With such a sensor you can increase the size of the sensor (and the individual pixels) and the base ISO to get the same result on a longer and slower lens. Note that I'm talking about making the sensor with the goal of being equivalent here. You need to scale the base ISO in practice, possibly not in theory.

So the formats do have differences in practice, but this is because of limitations of what we can (and choose to) make. Both sensors and lenses.

Almost everyone agrees that larger sensors give better results at the same (actual) ISO. This means a larger sensor gives you a lower equivalent base ISO, which is a lovely thing, but not the thing usually claimed.
12-29-2014, 01:34 PM   #37
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by morane_j Quote
All you say is right, but shooting at 100 iso is absolutely not the same thing than shooting at 2000 iso. The noise produced by the sensor is not the same. At 2000 iso the gain of the sensor is high, at 100 iso it is nominal, so the sensor will produce noise at 2000, not at 100 iso. In the film days, nobody would have say that shooting at 100 iso was equivalent to shooting at 2000 iso
Sometime I think a good picture is better than endless disucssion.

I have been here: Nikon D810 Review: Now Shooting! - Samples . They test the D810 (an FF camera) at different isos level. As there no iso 2000 image, but only 1600 & 3200 isos image available, I took the nearest value: iso 1600.

I downscaled the image original image to Q-S1 12MP resolution and extracted a 100% crop for you to see. Look at this crop at iso 1600 and let us know what you think of the picture quality. How does 100% crop of Q-S1 at iso 100 compare?
Attached Images
 

Last edited by Nicolas06; 12-29-2014 at 01:51 PM.
12-30-2014, 03:14 AM   #38
Junior Member




Join Date: May 2014
Location: Paris, France
Posts: 42
I can see noise on the brick wall on your picture, I don't know what kind of image the Q-S1 would have, but I don't think that at 100 iso you have noise. You speak theory of optics, I speak reality of electronic sensors that produce noise on high ISO. You will always have more noise at 2000 iso than at 100 iso, just because you rise the gain of the analog stage of your sensor. That's why having a wide aperture is always better, regardless of the DOF, you can lower your iso with constant shutter speed, and so you can lower the noise produced by the sensor

12-30-2014, 03:40 AM - 3 Likes   #39
Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 5,724
Nicolas06, for the last time: NOBODY who enjoys the Q system gives a flying f*** about shallow depth of field. In fact, the extra depth of field is a major POSITIVE. Macros can be made which would be impossible without focus stacking. Ultra-telephoto shots can be made with enough depth of field to make manual focus relatively easy. The native lenses are just so easy to use and so much fun. As far as exposure is concerned, f/2.8 is f/2.8 whatever the crop factor. That is what the vast majority of photographers care about. Bokeh w*nk*rs are in the infinitesimal minority.

If you don't get it by now you never will.
12-30-2014, 06:16 AM - 2 Likes   #40
Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 5,724
When I captured these images, I certainly wasn't thinking "gee, I wish I had a shallower depth of field"....


Jagger swagger




Benchmark




Green Day


Ritchie and Orianthe



12-30-2014, 07:03 AM   #41
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by morane_j Quote
I can see noise on the brick wall on your picture, I don't know what kind of image the Q-S1 would have, but I don't think that at 100 iso you have noise. You speak theory of optics, I speak reality of electronic sensors that produce noise on high ISO. You will always have more noise at 2000 iso than at 100 iso, just because you rise the gain of the analog stage of your sensor. That's why having a wide aperture is always better, regardless of the DOF, you can lower your iso with constant shutter speed, and so you can lower the noise produced by the sensor
QuoteOriginally posted by morane_j Quote
I can see noise on the brick wall on your picture, I don't know what kind of image the Q-S1 would have, but I don't think that at 100 iso you have noise. You speak theory of optics, I speak reality of electronic sensors that produce noise on high ISO. You will always have more noise at 2000 iso than at 100 iso, just because you rise the gain of the analog stage of your sensor. That's why having a wide aperture is always better, regardless of the DOF, you can lower your iso with constant shutter speed, and so you can lower the noise produced by the sensor
Look on Q-S1 page on Ricoh website: http://www.ricoh-imaging.co.jp/english/products/q-s1/ex/img/bod_mainImg_05.jpg, show it at 100%. There visible noise in the grass for example.

Iso is sensibility by definition not by any mean a level of noise. You try to associate iso 100 with a fixed level of noise on all sensors while each behave differently.

DxO measure the noise of different sensor at different senssibilities. On the following graph you can see:
- The minimum level of noise is very different depending of the sensor. Q-S1 max quality at base iso is significantly lower than max quality on K5 or max quality on D600.
- Noise level of Q10 at iso 100 is the same as noise level of K5 at iso "700" more or less and D600 at iso 1600 more or less.

In the end if the FF owner shoot at say iso 400 or 800 his picture will be higher quality than what Q-S1 achieve at iso 100. This is just how it is.

This is not by random. This is because with same sensor technology, the laws of physics can be used to compute this equivalent. That your 45mm f/2.8 iso 100 on Q-S1 is equivalent to 207mm f/13 iso 2000.

The results vary slightly because well sensor technology is not exactly the same on both bodies. But the hard tendancy is here.
Attached Images
 
12-30-2014, 07:22 AM - 1 Like   #42
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by Sandy Hancock Quote
Nicolas06, for the last time: NOBODY who enjoys the Q system gives a flying f*** about shallow depth of field. In fact, the extra depth of field is a major POSITIVE. Macros can be made which would be impossible without focus stacking. Ultra-telephoto shots can be made with enough depth of field to make manual focus relatively easy. The native lenses are just so easy to use and so much fun. As far as exposure is concerned, f/2.8 is f/2.8 whatever the crop factor. That is what the vast majority of photographers care about. Bokeh w*nk*rs are in the infinitesimal minority.

If you don't get it by now you never will.
I never said that shallow deph of field is bad or good. Most would think that sometime this is bad, something this is good. Depend what kind of photo you take, what kind of esthetics you prefer, and your current mood.

I just said if you use focal F on Q-S1 with apperture f/A and iso S to get the same result on an FF you need to use F*4.6 focal length, apperture f/(A * 4.6) and iso S * (4.6^2).

That just how it is. This is neutral. That f/2.8 Q-S1 get same deph of field as f/13 on FF, this is how is. That globally Q-S1 at iso 100 is not better at noise level in theory than FF at iso 2000 and in practice at iso 1600 is just again how it is.

Everybody then is free to juge and interpret. By all means in your case where you want dof for your shoot and let say you get unlucky with an heavy and big FF in hand this time (I do not like big camera and don't want an FF body!), equivalence allow you to understand that what you want to achieve need a much longer focal length and much smaller apperture and that consequently the iso will have to be put much higher to get the right exposure but that the final quality of the image will be similar.

For me knowledge is usefull. I don't think I need to ingore things to feel better.
12-30-2014, 01:56 PM - 1 Like   #43
Site Supporter
Sandy Hancock's Avatar

Join Date: Feb 2012
Location: Adelaide Hills, South Australia
Photos: Gallery | Albums
Posts: 5,724
QuoteOriginally posted by Nicolas06 Quote
For me knowledge is usefull. I don't think I need to ingore things to feel better.
Re-hashing common knowledge might make you feel better, but it is not particularly useful for those who already understand equivalence and decide that the Q system is uniquely portable, versatile and fun despite its well-known limitations
12-30-2014, 02:42 PM   #44
Senior Member




Join Date: Nov 2013
Location: Lake District
Posts: 222
QuoteOriginally posted by Sandy Hancock Quote
When I captured these images, I certainly wasn't thinking "gee, I wish I had a shallower depth of field"....


Jagger swagger
The Q must be amazing. The folks from the rolling Stones almost look alive and well!

Excellent pictures in general there..

J
12-31-2014, 08:03 AM   #45
Pentaxian




Join Date: Nov 2013
Posts: 4,703
QuoteOriginally posted by Sandy Hancock Quote
Re-hashing common knowledge might make you feel better, but it is not particularly useful for those who already understand equivalence and decide that the Q system is uniquely portable, versatile and fun despite its well-known limitations
Fully agree! But then why did we need so many posts to clarify this? I find Q fun too.

I would have expected just a single acknowledgement on the first post with maybe "yes we already know that don't repeat obvious all the time" but instead I got lot of argumentation on how this was not true equivalence should apply only on focal length but not apperture or isos while the evidence of the contrary are easily accessible to anybody.

To me it showed that for at least some here it was far from behing.obvious even if for you or me it is. I think some are even not really convinced... For them if they don't want to accept it that's their problem. But I didnt want it could mess others understandings.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, ephotozine reviews, images, lee, lens, lenses, mirrorless, pentax, pentax q, pentax q10, pentax q7, q-s1, q10, q7, settings
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
A brief, unscientific comparison : Original Q vs Q-S1 6BQ5 Pentax Q 29 11-30-2014 07:21 AM
It's here, the Pentax Q-S1 knightzerox Pentax Q 52 09-27-2014 07:26 AM
Q-S1 and K-S1 New Naming? LaurenOE General Photography 8 08-21-2014 09:36 PM
The Verge, Ephotozine, Techradar K30 reviews schufosi777 Pentax K-30 & K-50 6 07-31-2012 01:37 PM
ephotozine reviews DA55-300mm jamesm007 Pentax SLR Lens Discussion 6 05-25-2011 05:31 PM



All times are GMT -7. The time now is 09:32 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top