[Edgar_in_Indy]

To come close to matching the DoF of the K-30 with the D800 (or K-1) you need to close your aperture a stop, and it still doesn't quite make it.

So for the same image ( which would be the image with the same DoF you need to shut down the K-1 another stop, and the total light for the same image is the same.

I don't know why people keep bring DOF into a discussion about the relative ISO performance of APS-C vs FF.

Your example, where the FF camera needs to shut down an extra stop, assumes that more depth of field was required. Why make that assumption? We're not conducting an experiment where we must get identical images from two different camera formats. What we're focusing on right now is trying to get the cleanest images at high ISO.

It could be that either camera would have enough DOF at f4, or it could just as easily be the reverse, where the photographer would prefer less DOF for the given image, in which case the APS-C user is just SOL at some point. But that was not the point of the discussion.



Real world scenario: When I photograph my daughters' dance performances using my K-30, I often switch between my Sigma 50-150mm f/2.8, and my Sigma 100-300mm f/4, both frequently shot wide open. Both work just fine, providing enough DOF for photographing the dancers from a distance. So if/when I pick up a K-1, I am confident that I will be able to use it for shooting dance without having to stop the Sigma 100-300mm f/4 down to f/5.6.

And if I were to get a 70-200mm f/2.8 lens for the K-1 (the 50-150mm is an APS-C lens), I am confident that I could use it at f/2.8, since I have successfully used my Sigma 85mm at f/1.4 - f/2 on my APS-C camera for the same dance performances. So the K-1 with the 70-200mm f/2.8 would let me get cleaner images than does my K-30/Sigma 50-150mm f/2.8 combo.

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Last edited by Edgar_in_Indy; 06-11-2017 at 12:36 PM.

[Ian Stuart Forsyth]

Only when you cheat on the DoF do you get more total light. Same image, same distance, same DoF, same total light. Your "simple physics proves" point actually proves you can prove anything you want with simplel physics by leaving out relevant parameters (clearly over simplified) , and hoping your readers are too ignorant to pick up the mistake.

Before going all snarky on photoptimist you might want to look up exposure duration and scene luminosity, 2 other setting photographers can change while not affecting DOF and FOV.
Try putting the same total light as an image taken a FF at iso 100 F32 1/125sec on a cropped body.

Even a 300mm lens on FF can be handheld at F8 1/320 sec down to LV 14

Add IS with that 300mm lens and you can get a very sharp image down to LV 12.6 handheld

---------- Post added 06-11-2017 at 01:00 PM ----------

And if I were to get a 70-200mm f/2.8 lens for the K-1 (the 50-150mm is an APS-C lens), I am confident that I could use it at f/2.8, since I have successfully used my Sigma 85mm at f/1.4 - f/2 on my APS-C camera for the same dance performances. So the K-1 with the 70-200mm f/2.8 would let me get cleaner images than does my K-30/Sigma 50-150mm f/2.8 combo.

And for these kinds of shooting conditions I would gladly swap 1 stop less DOF for half the duration in the exposure time.

[normhead]

Your example, where the FF camera needs to shut down an extra stop, assumes that more depth of field was required. Why make that assumption? We're not conducting an experiment where we must get identical images from two different camera formats. What we're focusing on right now is trying to get the cleanest images at high ISO.

If the image doesn't matter then why even take the image? Taking a high ISO image has no value in it's own right.

It could be that either camera would have enough DOF at f4, or it could just as easily be the reverse, where the photographer would prefer less DOF for the given image, in which case the APS-C user is just SOL at some point. But that was not the point of the discussion.

If the FF is good enough at ƒ4, then APS-c is good enough at ƒ2.8. The FF has a one stop advantage if the lens is wide open, narrower depth of field but a 1 stop noise advantage. And that's a real advantage. But it's only an advantage shooting wide open. Any other time the same results can be achieved with either system. And the APS_c doesn't camera does,t really affect that at the long end. Generally diffraction means you get an extra stop with an FF body, although only for bodies with the same MP. Once you close your FF a stop, anything FF can do APS-c can do. SO do you really want to buy an FF system for better high ISO performance with the lens wide open? It's a pretty small window of opportunity. For that you trade the extra reach of the APS-c camera with the same lens. There's no free lunch.

Try putting the same total light as an image taken a FF at iso 100 F32 1/125sec on a cropped body.

At ƒ32 you have serious diffraction problems on either FF or APS-c but worse on APS-c. Not so much on 4x5 or 8x10 film. On 8x10 film even ƒ64 is still pretty good.

But at the long end of the scale say in your example
-FF-__ ISO 100 ƒ32. 1/125
APS-c ISO 100 ƒ32 1/125

It's a trade off, more total light (less noise) for more DoF. You decide which is more important and you take your pick. Which system you use depends on which advantage you want. However it's not a clean trade. The FF sensor is going to handle the diffraction a bit better, so you'd really have to want that depth of field for it to be worth while before going to APS_c.

But we are talking about the extreme ends of the lens range, and there are good reasons for not going there, 99% of the time. So we are discussing not the everyday shooting, but the extreme cases. Straight up, there's no sense in giving theoretical importance to things you don't very often do.

Same image, same total light. I'm not seeing where you are going with this. At that end the DOF on the APS-c gives the APS-c the advantage.

This if course would be pretty moot for K-1 users. Technological processing advantages have increased the ISO of the K-1 to nearly a 2 stop advantage, meaning the only real advantage to the K-3 is reach in good light.

[skierd]

And seriously, what does all of this equivalence bull have to do with what ISO you actually use?

Bring it back please...

[Ian Stuart Forsyth]

It's a trade off, more total light (less noise) for more DoF.

A lot of times there is no trade off needed to put more light into an image with the same DOF on FF

Using 100mm lens on FF at F1.4 will give more DOF than needed for a full body torso shot in landscape. So how can there be a trade off if you never needed more DOF than using a 100mm at F1.4?
It can also be said with the same framing with a 50mm@ F1.4, same framing with a 24mm@ F1.4, same framing with a 200mm @ F2 and so on and so on. More than enough DOF for all of these shots

However it's not a clean trade

A lot of times there is a clean trade same DOF while retaining the DOF needed as for my example of the iso 100 F32 1/125 sec shot, cropped could not put the same total that was captured into the image

At that end the DOF on the APS-c gives the APS-c the advantage.

You do know you can just stop down the FF lens so what is this apsc advantage ?

[honey bo bo]

and seriously, what does all of this equivalence bull have to do with what iso you actually use?

Bring it back please...

amen !

[normhead]

You do know you can just stop down the FF lens so what is this apsc advantage ?

Reach.

As I said, except for the extreme ends of the exposure range and aperture range, any thing you can do on one you can do on the other. That's about 85% of possible images and 99% of practical images.

Now can you guys maybe answer the question?

Which in case you missed it was, "what ISO do you really use?", I've already answered.

[pathdoc]

The biggest issue of all is how big are you printing? 8x10" for a 35mm negative is quite a significant enlargement - for some people, it's a contact print and for a few rabid enthusiasts at the ragged edge of large it is a significant scaling DOWN.

[GlennG]

My challenge to you: go through your catalog. What ISO's are you using the most on photos you actually want to keep? Knowing that, what would a better high-ISO camera realistically gain you over what you have now?

100-800 for almost all. Using K-5. I'm either outside in good light or using flash. Though on a rare occasion I've gone up to 12,800 with acceptable results. I basically don't print, so this is viewed only on the computer. From a sensor standpoint I don't think I would see an improvement in image quality with a newer camera. A newer camera MIGHT give me more/better keepers from a focus speed and accuracy standpoint, however. But I am not seeking a change now.

Not to ever get in the way of another person's GAS, but I feel like you are selling the K-30 a little short. I think it is a high ISO champ, and only recently have any APS-C cameras been released that had any significant improvement. The K-70 and K-P come to mind.

I have to agree with you, Edgar, on this point about the K-30. As for the recent cameras, I know Pentax is working this "iso accelerator" aspect, but I don't know what to what extent one will see a real benefit.

Also....nice photos from the Nutcracker. I did not look at them larger, but they looked great above.

[Ian Stuart Forsyth]

Reach.

As I said, except for the extreme ends of the exposure range and aperture range, any thing you can do on one you can do on the other. That's about 85% of possible images and 99% of practical images.

Now can you guys maybe answer the question?

Which in case you missed it was, "what ISO do you really use?", I've already answered.

I don’t use iso in the conventional way anymore.

With the sensor I either use it at full saturation level based on the clipping level of the sensor ( if I was to give it an iso level it would be iso 70-80). And for everything else I increase iso to reduce the level of noise the camera introduces, I usually stop raising iso above 1600 as I see no benefit for increasing.

[beachgardener]

where possible at any given settings I prefer between 80-125, and using up to 400 or maybe 800. On the odd occasion i use 1600 but not past 3200, in short between 80 and 400 is my preferred limit.

[luftfluss]

Bring it back please...

Yes.

What makes your query so difficult is that many of us are generalists. I'd bet my photos are fairly evenly distributed from ISO 100 to 1600.

[BrianR]

Bring it back please...

k5iis... mostly 80-200, nearly always 80-400. But I'm typically using a tripod and/or flash(es), so I'm not really limited by low light. I've no real worries hopping up to 800 or 1600 if I'm trying to use a telephoto in fading light, or up to 3200 for night time stuff, especially if I only have small prints planned (mostly 8x12").

Moving to a new camera would have little to nothing to do with better iso performance for me. How I use it, I'm pretty happy with my current cameras iso performance.

[jpzk]

My challenge to you: go through your catalog. What ISO's are you using the most on photos you actually want to keep? Knowing that, what would a better high-ISO camera realistically gain you over what you have now?

I don't have a "catalog" but here it goes:

K5 w/ DA*16-50 ... up to ISO 3200, "pushed" to ISO 6400 in case of emergency!
I used to use the K5 with the DA*300/4 for wildlife/birding and the parameters would have been similar.
K5 keepers: ISO 100 to 1600

K3 w/ DA*300/4 ... up to ISO 800 and sometimes up to 1600 "on bad days".
K3 keepers: ISO 100-800 are the better ones.

Summary: ISO 100-800 range for keepers for both cameras.

I suppose the K-1 would be ideal (for me) for wildlife/birding when paired with the DA*300/4 + HD 1.4x TC since it apparently can be ISO-pushed quite high (seems like my old K5 is close to that, without all the megapixels!)
And of course a Sigma 500/4 to pair the K-1 would actually be my choice ... if the budget would allow for that.
A KP might cut it ... a "hybrid" between the K-1 and KP would rock!

[skierd]

I don’t use iso in the conventional way anymore.

With the sensor I either use it at full saturation level based on the clipping level of the sensor ( if I was to give it an iso level it would be iso 70-80). And for everything else I increase iso to reduce the level of noise the camera introduces, I usually stop raising iso above 1600 as I see no benefit for increasing.

lol wut

---------- Post added 06-11-17 at 09:39 PM ----------

Yes.

What makes your query so difficult is that many of us are generalists. I'd bet my photos are fairly evenly distributed from ISO 100 to 1600.

I thought I would be too, until I checked Lightroom. I shoot portraits (with and without flash) landscapes, large slow wildlife, and the northern lights.

I fully and freely admit that my own noise reduction process is minimal and I rely 100% on box stock Lightroom 6. It's something I need to work on. My K-30 really is great at everything up to 1600. I regularly print 11x17 and up to 20x30 often.