Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
10-30-2017, 06:29 PM   #1
New Member




Join Date: Oct 2017
Posts: 4
Thought FF (k1) would give me. Significant increase in light gathering vs k70

Hello everyone. I was under the impression that an FF would increase the shutter speed at the same fstop and ISO given that the sensor gathers more light when using the same lens. And that ISO on crop was actually equivalent to 1.5 FF ISO. So I went ahead and purchased the k1 and compared it to my k70. It turns out that nothing changes and to my eyes, high ISO performance up to 1600 is pretty much the same. Where exactly is the advantage of investing 4x the dollar amount except for the 36mp output. I used a sigma art 18-35 on crop k70 @ 18mm and the same lens on its equivalent 28mm (perfectly usable with little vigneting. Any thoughts?

10-30-2017, 06:39 PM - 2 Likes   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 48,432
QuoteOriginally posted by Mazzoman Quote
Hello everyone. I was under the impression that an FF would increase the shutter speed at the same fstop and ISO given that the sensor gathers more light when using the same lens. And that ISO on crop was actually equivalent to 1.5 FF ISO. So I went ahead and purchased the k1 and compared it to my k70. It turns out that nothing changes and to my eyes, high ISO performance up to 1600 is pretty much the same. Where exactly is the advantage of investing 4x the dollar amount except for the 36mp output. I used a sigma art 18-35 on crop k70 @ 18mm and the same lens on its equivalent 28mm (perfectly usable with little vigneting. Any thoughts?
Exposure parameters are the same regardless of sensor format, since the amount of light per pixel remains the same. There's more sensor area to capture that light, though, hence more data overall.

What you get from a larger sensor format is usually (a) more resolution, (b) more dynamic range and better color accuracy, (c) less noise, (d) the option of using higher ISOs without negatively impacting the image quality. Beyond this, there are changes in lens selection, since it's easier to build high-quality wide-angle lenses for FF, and the same focal lengths give a wider field of view (=shallower dof -> fancier bokeh).

Note that if you are not shooting in RAW then you're throwing away a big chunk of these advantages. Also, as the K-70 is quite good in its own right, you probably won't be able to appreciate the difference unless you feel constrained by print size, lens selection, etc. It will take a bit of experimentation both out in the field and in post to make the most of your new camera.

What 28mm lens are you using on the K-1? The Sigma 18-35mm is an exceptional lens, and to match it you'd want an equally good lens on your K-1, such as the Samyang 24mm F1.4 or Pentax 15-30mm.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

10-30-2017, 07:17 PM - 1 Like   #3
Pentaxian
CarlJF's Avatar

Join Date: Sep 2014
Location: Quebec City
Posts: 1,072
I don't know why, but recently we see on PF and other forums this misconception that the rules of exposure work differently on FF camera.

In the situation you describe, a K1 will allow you to use a faster speed by increasing the ISO about a stop more than the K-70 will allow you. So it's somewhat true that a FF allow you to use a fadter SS, but not because it's lens gather more light.
10-30-2017, 07:53 PM - 1 Like   #4
Site Supporter
Site Supporter




Join Date: Mar 2011
Location: Fairbanks, AK
Photos: Gallery
Posts: 1,385
...no, it won't. Dammit that's not how this works.

The exposure triangle is a rule, and it the same for all formats.

If the proper exposure for a scene is 1/125s at f4 at 1600iso, it doesn't matter if it's a m43, aps-c, 35mm, medium format, or large format sheet film.

It might be true that the K-1 might give a more acceptable image at 1/250s and iso3200 than the K70 at 1/125 and iso1600 , but that's a function of the sensor tech not the format. It's not a free lunch; you haven't gained a stop of light for free as it's still shooting at a higher ISO. It might also be true that the K1 at 1/250s at iso1600 and pushed a stop in Lightroom might give a cleaner image than the aps-c camera, but again that's because the sensor technology is better rather than any inherent advantage of the larger format.

10-30-2017, 09:04 PM   #5
Loyal Site Supporter
Loyal Site Supporter
clackers's Avatar

Join Date: Jul 2013
Location: Melbourne
Photos: Albums
Posts: 12,761
QuoteOriginally posted by Mazzoman Quote
So I went ahead and purchased the k1 and compared it to my k70. It turns out that nothing changes and to my eyes, high ISO performance up to 1600 is pretty much the same.
In fact, your K70 has more resolution than your K-1, too.

Look, there are other advantages/disadvantages, everyone has to do their own calculation in their head before buying into a new format.
10-30-2017, 10:39 PM - 2 Likes   #6
Pentaxian
Billk's Avatar

Join Date: Jun 2012
Location: Melbourne, Victoria
Posts: 309
High ISO performance at lower light might be better with the K1 than the K70. I think you need to distinguish bright light high ISO performance from low light high ISO performance. (I shot with the X1D recently (medium format) and it blew my K3ii out of the water in low light. But my K3ii is great for high ISO shooting in bright light - birds in flight etc).


I would be amazed if the K1 doesn't have better dynamic range than any crop DSLR. (In a recent workshop, we measured the DRs of our cameras and the 645Z left everything else for dead.)
10-30-2017, 11:39 PM - 1 Like   #7
Pentaxian
Culture's Avatar

Join Date: Sep 2011
Location: Vaasa
Photos: Gallery | Albums
Posts: 796
All I have to say is sorry. There is nothing annoying than having a full understanding or not doing a full research.

Back in the day I used to think the K-7 was a full frame just because it was the flagship of Pentax then. And my aim was to buy FF. Imagine buying that and finding out it was APS-C.
10-31-2017, 12:03 AM - 1 Like   #8
Pentaxian
Digitalis's Avatar

Join Date: Mar 2009
Location: Adelaide.
Posts: 9,530
QuoteOriginally posted by CarlJF Quote
I don't know why, but recently we see on PF and other forums this misconception that the rules of exposure work differently on FF camera.
Lack of education. Arm chair experts that lack the respect for their elders and pretend to know everything, which is of course an affront to those of us that do.

QuoteOriginally posted by Adam Quote
The Sigma 18-35mm is an exceptional lens
If you luck out and get a copy that isn't de-centered or suffering from inconsistent focusing. When full frame taken into consideration the Pentax FA31 is a superior lens, as it designed to be used on both APS-C and full format cameras and deliver superb results.

10-31-2017, 12:46 AM - 1 Like   #9
Pentaxian




Join Date: Apr 2007
Location: Sweden
Posts: 2,078
QuoteOriginally posted by skierd:
It might also be true that the K1 at 1/250s at iso1600 and pushed a stop in Lightroom might give a cleaner image than the aps-c camera, but again that's because the sensor technology is better rather than any inherent advantage of the larger format.
I would argue that it IS the larger format that gives you one stop better SNR performance, anything above that is due to better sensor tech. (Under condition that the pictures are viewed at the same size when compared.)
10-31-2017, 01:59 AM   #10
Pentaxian




Join Date: Dec 2011
Posts: 2,211
QuoteOriginally posted by Mazzoman Quote
Any thoughts?
You need to learn a couple of basics to understand.

If you want to compare then you need to export/develop both images to the same size/resolution (e.g. 8 MPx for viewing on a UHD monitor).
Then you shoot your test image at the exact same settings for time and aperture, but for the K-1 you go for a one (actually 1.5 divided by 1.4) stop higher ISO (e.g. 3200 vs 1600).
And: Obviously you have to use a FF lens, not that Sigma on the K-1.

Now you should see that at this higher ISO the K-1 image looks the same as the K-70.

For the "why" and "how" use the search here or google. It all has been explained a million times in detail.
10-31-2017, 02:11 AM - 1 Like   #11
Pentaxian
D1N0's Avatar

Join Date: May 2012
Location: ---
Photos: Gallery
Posts: 5,587
The K-1 made my Pentax-m 20mm F4 an ultra-wide lens instead of a moderately wide one. That's why I got it. All my lenses are like new now. Recent improvements in noise reduction make the K-70 noise levels almost as good as the K-1. In future full frames this technology will draw the larger sensor ahead again. The K-1 will still give you more detail than the KP because it has more and larger pixels. DR is probably also better. The main advantage is shooting full frame lenses. When you are indifferent about lenses, there is probably no use for a full frame.
10-31-2017, 06:05 AM - 2 Likes   #12
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 3,284
All of the technical fundamentals of photographic exposure especially the definition of ISO and the way lens apertures are defined by a ratio to focal length are engineered so that ALL cameras get the same overall brightness of image if they use the same ISO, aperture, and shutter speed. If 15 photographers with 15 different film & digital cameras of different formats shoot side by side, they should be able to use the same ISO, aperture, and shutter speed and get the same overall brightness of exposure.

That said, it is true that larger format cameras collect more light. But instead of creating a brighter image, the collected light is rescaled to create the same relative output brightness. That effect reduces the relative contribution of noise to create a cleaner image. So you can operate the K-1 at a higher shutter speed and either boost the ISO on the camera or boost the exposure in software on your computer and get the same quality of image as you had with the K-70.

It's the same phenomenon as in film days. A huge piece of ISO 100 film in a 4x5 view camera did not create a brighter image than a tiny piece of ISO 100 film in a pocket 110 camera but it did create a much cleaner image.
10-31-2017, 06:18 AM   #13
New Member




Join Date: Oct 2017
Posts: 4
Original Poster
Thanks for the replies. Will make the most out of the k1.
10-31-2017, 06:46 AM   #14
Pentaxian
Site Supporter
normhead's Avatar

Join Date: Jun 2007
Location: Near Algonquin Park
Photos: Gallery | Albums
Posts: 32,640
The big thing to me on the K-1 is useable, meaning print worthy exposures up to 3200 ISO instead of 1600 ISO, but that's pretty much a saw off because of depth of field.

The big advantage of the K-1 over a K-70/K-P is 36MP instead of 24. If you don't need that, you are way better off with APS_c. More modern lenses, more range in lenses means you need to buy fewer lenses, my 2 lens APS-c kit DA 18-135 and DA*60-250, would need 3 or 4 lenses on FF to cover the same field of View. Pentax has a lot more APS-c lenses than it has FF lenses with a good mix of quality primes and zooms.

That being said, when I can, I take my K-1. When things are uncertain and I might need range or reach, I take my K-3.
10-31-2017, 07:29 AM   #15
Site Supporter
Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 19,755
What you typically will see is a one stop improvement in noise and dynamic range with a full frame versus APS-C camera. Now, the K-70 is a newer generation sensor with an accelerator chip which gives it really excellent performance and its noise levels are really good for a crop camera.

The places where you would typically see a difference are either going to be at high iso or situations where you are pushing an image pretty hard by bumping shadows/exposure in certain places. Crop cameras just don't tolerate those sorts of adjustments as well before you start seeing artifacts and noise -- particularly once you get above base iso.
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!
24x36mm, crop, equivalent, ff, full-frame, increase, iso, k1, k70, lens, light, pentax
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-5 vs MZ-S vs LX vs PZ-1p vs ist*D vs K10D vs K20D vs K-7 vs....... Steelski Pentax K-5 2 06-28-2017 04:59 PM
Any significant improvement in mid ISO quality since K5? PPPPPP42 Pentax DSLR Discussion 22 05-02-2017 09:59 AM
K1 price increase robthebloke Pentax K-1 8 09-18-2016 03:44 PM
If you could take photos at one significant moment, when and where would ASheffield General Photography 34 08-14-2014 06:04 PM
FF vs APS-C light gathering / noise CypherOz General Photography 21 06-13-2014 10:25 AM



All times are GMT -7. The time now is 07:07 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