KP custom，DFA*85/1.4 CP+ Exhibit

**monochrome** · 09-27-2019, 03:28 PM

Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be?

bxf · 09-27-2019, 05:01 PM - **2 Likes**

Originally posted by monochrome

Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be?

reh321

**Rondec** · 09-28-2019, 03:08 AM - **2 Likes**

Originally posted by monochrome

Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be?

This is definitely the droid I'm waiting for.

I'm guessing this will be a chunky lens with fast auto focus, sharp at f1.4, excellent contrast, typically good Pentax colors, and nice in focus to out of focus transitions. The FA 77 is no slouch and has wonderful bokeh in many cases, but I'm still looking forward to this lens quite a bit.

Class A · 09-28-2019, 04:06 AM

Originally posted by pres589

Another thing about this lens on APS-C vs FF; as crop doesn't allow for as shallow a DoF for a given f-stop in relation to that same f-stop/DoF on full frame...

If you are talking about a single lens, its focal length cannot change and hence DOF will be shallower on the crop (APS-C) format (compared to FF).

Even the 77/1.8 produces shallower DOF on APS-C than a 85mm at f/1.8 on FF. Even at f/1.6, the 85mm still has deeper DOF on FF than the 77/1.8 wide open on APS-C.

It seems you are confusing how DOF behaves when one changes a single lens between formats compared to how DOF behaves when one assumes the same f-stop but equivalent (not identical) focal lengths. In the latter case, you'd have to put a 128mm lens on the FF camera, if you are using an 85mm on APS-C.

**pres589** · 09-28-2019, 08:36 PM

Er, not exactly, but I'm not going to state this properly enough and I don't want to start this discussion really.

Sandy Hancock · 09-29-2019, 02:16 AM

The FA77/1.8 has a shorter focal length and a smaller maximum aperture. On both counts it must give a less shallow depth of field wide open at the same focal distance as the FA*85/1.4 wide open, regardless of sensor size.

beholder3 · 09-29-2019, 02:28 AM

If same space/distance: both combos create pretty much the SAME DoF (e.g. 9,8 vs 10,2 cm).
If same framing: FF/85 1.4 has about half the DoF of APSC/77 1.8.

Try it out here:

DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

CNunez · 09-29-2019, 02:31 AM

^ uhm what? first of all, you cannot compare a 77 focal length to a 85 focal length.

Furthermore, if you put a 85FF lens on an APSC, it operates as an 85FF but the APSC can only see the inner circle of the lens so it looks more like 105? however the bokeh produced etc will still be the same, just a narrower field of view. If you were to step back to get the same fov, you are technically farther away from your subject than you are if you were using a FF camera. Therefor your bokeh changes.

People ALWAYS get fov and sensorsize wrong when they crosscompare between different sensor sizes.

**Rondec** · 09-29-2019, 02:45 AM - **1 Like**

Originally posted by Class A

If you are talking about a single lens, its focal length cannot change and hence DOF will be shallower on the crop (APS-C) format (compared to FF).

Even the 77/1.8 produces shallower DOF on APS-C than a 85mm at f/1.8 on FF. Even at f/1.6, the 85mm still has deeper DOF on FF than the 77/1.8 wide open on APS-C.

It seems you are confusing how DOF behaves when one changes a single lens between formats compared to how DOF behaves when one assumes the same f-stop but equivalent (not identical) focal lengths. In the latter case, you'd have to put a 128mm lens on the FF camera, if you are using an 85mm on APS-C.

I think the big thing with either the 77mm or an 85mm lens on APS-C is the working distance is larger. If you have space to back up that can be fine. That was the reason that I tended to use the DA *55 for portraits over the FA 77 when I only had APS-C.

As far as depth of field goes, either one should be fine. I don't know that there are many situations where you would have a gorgeous portrait with an 85mm f1.4 on a K-1 where you couldn't figure something out with the either the same lens or an FA 77 on APS-C -- assuming you have space to work with.

biz-engineer · 09-29-2019, 02:48 AM - **1 Like**

Originally posted by CNunez

People ALWAYS get fov and sensorsize wrong when they crosscompare between different sensor sizes.

Lets do the maths using x 1.5 crop factor: 56mm x 1.5 = 85mm, which means 56mm on full frame is equivalent to 85mm on apsc

pinholecam · 09-29-2019, 02:52 AM - **1 Like**

Originally posted by Rondec

I think the big thing with either the 77mm or an 85mm lens on APS-C is the working distance is larger. If you have space to back up that can be fine. That was the reason that I tended to use the DA *55 for portraits over the FA 77 when I only had APS-C.

As far as depth of field goes, either one should be fine. I don't know that there are many situations where you would have a gorgeous portrait with an 85mm f1.4 on a K-1 where you couldn't figure something out with the either the same lens or an FA 77 on APS-C -- assuming you have space to work with.

Indeed!
The practical aspect of working distance is often lost in the discussions.

Sandy Hancock · 09-29-2019, 04:06 AM - **1 Like**

....I should have added at the end of my last post that the technical difference in depth of field makes absolutely no practical difference.

The FA77 and FA*85 are both wonderful portrait lenses. I'm sure the DFA*85 will be as well.

Class A · 09-29-2019, 06:28 AM - **1 Like**

Originally posted by Sandy Hancock

On both counts it must give a less shallow depth of field wide open at the same focal distance as the FA*85/1.4 wide open, regardless of sensor size.

Nothing works "regardless of sensor size".

In particular, at the same focal distance (say 3m in both cases), the 77/1.8 @ f/1.8 produces a shallower DOF on APS-C than the 85/1.4 @ f/1.8 does on FF.
That's what I meant in my original post. The reason is that the APS-C format requires a higher magnification factor to produce the same output size (e.g., a 8x10 print); this reduces the DOF (as the blur discs are more enlarged than those of the FF image).

Originally posted by beholder3

If same space/distance: both combos create pretty much the SAME DoF (e.g. 9,8 vs 10,2 cm).

At 3m and f/1.8 I get 10.2cm for the 77/1.8 on APS-C and 12.7cm for the 85/1.4 on FF (so the 77/1.8 has shallower DOF, as I said).

Originally posted by beholder3

If same framing: FF/85 1.4 has about half the DoF of APSC/77 1.8.

At 3m (85/1.4 @ f/1.8 on FF) vs 4.19m (77/1.8 @ f/1.8 on APS-C) I get 12.7cm vs 19.4cm, i.e., the 85/1.4 has about 65% the DOF.

Of course, the "same framing" comparison is the one to make for (as closely as possible) "equivalent" images. In my post above, I assumed "same distance" for simplicity (we were already assuming the same f-ratio), which I should have pointed out.

Originally posted by beholder3

DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

That's the nicest I've ever seen!

normhead · 09-29-2019, 07:22 AM

From the Depth of Field calculator
Online Depth of Field Calculator

76 @ ƒ1.8 total .37 feet. on APS_c ( 10 feet away.)
85mm @ ƒ1.4 on FF .35 feet

Practically identical. But of course, not identical images. The APS-c will appear to be a lot closer.

Class A · 09-29-2019, 07:52 AM - **1 Like**

Originally posted by normhead

Practically identical.

The reason why I chose f/1.8 for both lenses (and not used them wide open as you did) was because the post I was referring to stated

"crop doesn't allow for as shallow a DoF for a given f-stop in relation to that same f-stop/DoF on full frame"

09-29-2019, 06:28 AM - 1 Like	#373
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by Sandy Hancock On both counts it must give a less shallow depth of field wide open at the same focal distance as the FA85/1.4 wide open, regardless of sensor size. Nothing works "regardless of sensor size". In particular, at the same focal distance (say 3m in both cases), the 77/1.8 @ f/1.8 produces a shallower DOF on APS-C than the 85/1.4 @ f/1.8 does on FF. That's what I meant in my original post. The reason is that the APS-C format requires a higher magnification factor to produce the same output size (e.g., a 8x10 print); this reduces the DOF (as the blur discs are more enlarged than those of the FF image). Originally posted by beholder3 If same space/distance: both combos create pretty much the SAME DoF (e.g. 9,8 vs 10,2 cm). At 3m and f/1.8 I get 10.2cm for the 77/1.8 on APS-C and 12.7cm for the 85/1.4 on FF (so the 77/1.8 has shallower DOF, as I said). Originally posted by beholder3 If same framing: FF/85 1.4 has about half the DoF of APSC/77 1.8. At 3m (85/1.4 @ f/1.8 on FF) vs 4.19m (77/1.8 @ f/1.8 on APS-C) I get 12.7cm vs 19.4cm, i.e., the 85/1.4 has about 65% the DOF. Of course, the "same framing" comparison is the one to make for (as closely as possible) "equivalent" images. In my post above, I assumed "same distance" for simplicity (we were already assuming the same f-ratio), which I should have pointed out. Originally posted by beholder3 DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation. That's the nicest I've ever seen! Last edited by Class A; 09-29-2019 at 06:43 AM.*

09-29-2019, 07:52 AM - 1 Like	#375
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by normhead Practically identical. The reason why I chose f/1.8 for both lenses (and not used them wide open as you did) was because the post I was referring to stated "crop doesn't allow for as shallow a DoF for a given f-stop in relation to that same f-stop/DoF on full frame"

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09-27-2019, 03:28 PM	#361
monochrome Loyal Site Supporter Join Date: Mar 2008 Location: Working From Home Photos: Gallery \| Albums Posts: 26,276	Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be?

09-27-2019, 05:01 PM - 2 Likes	#362
bxf Veteran Member Join Date: Jul 2010 Location: Lisbon area Posts: 1,660	Originally posted by monochrome Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be? reh321

09-28-2019, 03:08 AM - 2 Likes	#363
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,650	Originally posted by monochrome Whatever. I have three fast 85’s. I’m in for the pre-order as soon as it is available. Who wouldn’t be? This is definitely the droid I'm waiting for. I'm guessing this will be a chunky lens with fast auto focus, sharp at f1.4, excellent contrast, typically good Pentax colors, and nice in focus to out of focus transitions. The FA 77 is no slouch and has wonderful bokeh in many cases, but I'm still looking forward to this lens quite a bit.

09-28-2019, 04:06 AM	#364
Class A Pentaxian Join Date: Aug 2008 Location: Wellington, New Zealand Posts: 11,251	Originally posted by pres589 Another thing about this lens on APS-C vs FF; as crop doesn't allow for as shallow a DoF for a given f-stop in relation to that same f-stop/DoF on full frame... If you are talking about a single lens, its focal length cannot change and hence DOF will be shallower on the crop (APS-C) format (compared to FF). Even the 77/1.8 produces shallower DOF on APS-C than a 85mm at f/1.8 on FF. Even at f/1.6, the 85mm still has deeper DOF on FF than the 77/1.8 wide open on APS-C. It seems you are confusing how DOF behaves when one changes a single lens between formats compared to how DOF behaves when one assumes the same f-stop but equivalent (not identical) focal lengths. In the latter case, you'd have to put a 128mm lens on the FF camera, if you are using an 85mm on APS-C.

09-28-2019, 08:36 PM	#365
pres589 Site Supporter Join Date: Jan 2014 Location: Wichita, KS Photos: Albums Posts: 4,529	Er, not exactly, but I'm not going to state this properly enough and I don't want to start this discussion really.

09-29-2019, 02:16 AM	#366
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	The FA77/1.8 has a shorter focal length and a smaller maximum aperture. On both counts it must give a less shallow depth of field wide open at the same focal distance as the FA*85/1.4 wide open, regardless of sensor size.

09-29-2019, 02:28 AM	#367
beholder3 Pentaxian Join Date: Dec 2011 Posts: 3,112	If same space/distance: both combos create pretty much the SAME DoF (e.g. 9,8 vs 10,2 cm). If same framing: FF/85 1.4 has about half the DoF of APSC/77 1.8. Try it out here: DOF simulator - Camera depth of field calculator with visual background blur and bokeh simulation.

09-29-2019, 02:31 AM	#368
CNunez Senior Member Join Date: Dec 2014 Photos: Gallery Posts: 168	^ uhm what? first of all, you cannot compare a 77 focal length to a 85 focal length. Furthermore, if you put a 85FF lens on an APSC, it operates as an 85FF but the APSC can only see the inner circle of the lens so it looks more like 105? however the bokeh produced etc will still be the same, just a narrower field of view. If you were to step back to get the same fov, you are technically farther away from your subject than you are if you were using a FF camera. Therefor your bokeh changes. People ALWAYS get fov and sensorsize wrong when they crosscompare between different sensor sizes.

09-29-2019, 02:45 AM - 1 Like	#369
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,650	Originally posted by Class A If you are talking about a single lens, its focal length cannot change and hence DOF will be shallower on the crop (APS-C) format (compared to FF). Even the 77/1.8 produces shallower DOF on APS-C than a 85mm at f/1.8 on FF. Even at f/1.6, the 85mm still has deeper DOF on FF than the 77/1.8 wide open on APS-C. It seems you are confusing how DOF behaves when one changes a single lens between formats compared to how DOF behaves when one assumes the same f-stop but equivalent (not identical) focal lengths. In the latter case, you'd have to put a 128mm lens on the FF camera, if you are using an 85mm on APS-C. I think the big thing with either the 77mm or an 85mm lens on APS-C is the working distance is larger. If you have space to back up that can be fine. That was the reason that I tended to use the DA *55 for portraits over the FA 77 when I only had APS-C. As far as depth of field goes, either one should be fine. I don't know that there are many situations where you would have a gorgeous portrait with an 85mm f1.4 on a K-1 where you couldn't figure something out with the either the same lens or an FA 77 on APS-C -- assuming you have space to work with.

09-29-2019, 02:48 AM - 1 Like	#370
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,225	Originally posted by CNunez People ALWAYS get fov and sensorsize wrong when they crosscompare between different sensor sizes. Lets do the maths using x 1.5 crop factor: 56mm x 1.5 = 85mm, which means 56mm on full frame is equivalent to 85mm on apsc

09-29-2019, 02:52 AM - 1 Like	#371
pinholecam Pentaxian Join Date: Oct 2009 Location: North Photos: Gallery Posts: 4,706	Originally posted by Rondec I think the big thing with either the 77mm or an 85mm lens on APS-C is the working distance is larger. If you have space to back up that can be fine. That was the reason that I tended to use the DA *55 for portraits over the FA 77 when I only had APS-C. As far as depth of field goes, either one should be fine. I don't know that there are many situations where you would have a gorgeous portrait with an 85mm f1.4 on a K-1 where you couldn't figure something out with the either the same lens or an FA 77 on APS-C -- assuming you have space to work with. Indeed! The practical aspect of working distance is often lost in the discussions.

09-29-2019, 04:06 AM - 1 Like	#372
Sandy Hancock Moderator Site Supporter Join Date: Feb 2012 Location: Adelaide Hills, South Australia Photos: Gallery \| Albums Posts: 11,267	....I should have added at the end of my last post that the technical difference in depth of field makes absolutely no practical difference. The FA77 and FA85 are both wonderful portrait lenses. I'm sure the DFA85 will be as well.

09-29-2019, 07:22 AM	#374
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	From the Depth of Field calculator Online Depth of Field Calculator 76 @ ƒ1.8 total .37 feet. on APS_c ( 10 feet away.) 85mm @ ƒ1.4 on FF .35 feet Practically identical. But of course, not identical images. The APS-c will appear to be a lot closer.

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