Using APS-C lenses with a FF sensor

**Rondec** · 03-02-2020, 03:48 AM

What the others have said is true. You can shoot your DA lenses in full frame mode and then crop after the fact. I don't know that you would gain much from that. With some of the DA limiteds like the 40 and the 70, you can get pretty decent performance in all but the corners in this fashion.

I would figure out a standard lens that you can use with a K-1 as you really have telephoto and macro covered. Reasonably priced options would be the DFA 28-105 and the Tamron 28-75 f2.8. I think with either of those lenses you would be pretty satisfied in combination with what you already have. Then, maybe pick up a used fast 50 and you're set.

Oldbayrunner · 03-02-2020, 07:39 AM - **1 Like**

And don't forget some of the old in good condition Pentax SMC-F lens can be found inexpensive and work superb on the K1, like the F 35-70mm macro or F 70-210mm.

**fs999** · 03-02-2020, 08:41 AM - **1 Like**

Don't forget that the Sigma 150-500 DG must have been modified by Sigma before using it on the K-1.
Else you will scratch and freeze your body...

**savoche** · 03-02-2020, 11:29 AM - **1 Like**

I love my K-1 but with your lenses I'd rather stick with APS-C. FF is no magic bullet that automatically makes your images better. It can be better at certain things provided you have the right lenses and know what you're doing. But it also has some drawbacks that may or may not be a problem.

Attacking this from a different angle: Is there anything in particular that you feel the K-3 II stops you from doing?

Last edited by savoche; 03-02-2020 at 11:36 AM.

beachboy2 · 03-02-2020, 07:16 PM

None of my Sigma lenses has had to be modified to work on, or not to scratch my K1ii, including my 70-200 EX 1:2.8 II Macro HSM.

Austro-Diesel · 03-02-2020, 11:30 PM

Yes, no problems here with my Sigma lenses: 35/1.4 Art, 50/1.4 EX, 85/1.4 EX, 70/2.8 EX Macro, 180/3.5 Macro, 70-300 DG OS

**fs999** · 03-03-2020, 02:07 AM

Originally posted by beachboy2

None of my Sigma lenses has had to be modified to work on, or not to scratch my K1ii, including my 70-200 EX 1:2.8 II Macro HSM.

Originally posted by Austro-Diesel

Yes, no problems here with my Sigma lenses: 35/1.4 Art, 50/1.4 EX, 85/1.4 EX, 70/2.8 EX Macro, 180/3.5 Macro, 70-300 DG OS

I didn't say that Sigma lenses need to be modified,
I said that the Sigma DG 150-500mm F5-6.3 APO HSM needs to be modified by Sigma to be used on a K-1...

biz-engineer · 03-03-2020, 03:38 AM

Originally posted by peso54

Using APS-C lenses with a FF sensor

There is no benefit to buy a full frame camera when using apsc lenses. Apsc lenses are for apsc cameras and full frame lenses are for full frame cameras.

HarisF1 · 03-03-2020, 01:35 PM - **1 Like**

Originally posted by biz-engineer

There is no benefit to buy a full frame camera when using apsc lenses. Apsc lenses are for apsc cameras and full frame lenses are for full frame cameras.

Strong comment, easily disproven. Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1. You may need to crop but you still get excellent results from existing equipment until the opportunity to upgrade appears.

Of course the objective should be to eventually get a complete full frame system.

**dwalt** · 03-03-2020, 01:45 PM

Originally posted by Austro-Diesel

Well, the Sigma 150-500 DG and the Pentax D-FA 100 Macro will work fine. The DA 1.4x Rear converter may be useful with some limitations. The rest of the gang will not be meaningful usable in FF mode, as far as I know.

Go for a K-1 II (or a used K-1, there is no significiant difference) with a D-FA 28-105. And keep looking for a new or used Sigma 70-300 DG OS (no other one, no APO, no Tamron, only the Sigma DG OS), this tele zoom is quite good for the few bucks to pay, you may find a new one for about 170 Euros at eBay.

Remember the Sigma 150-500 needs a mount update and firmware update (free from Sigma) to work with the K1. Without the mount update you will scratch the K1.
Sorry, Looks like someone beat meet to the punch on this.

**aslyfox** · 03-03-2020, 01:45 PM

Originally posted by HarisF1

Strong comment, easily disproven. Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1. You may need to crop but you still get excellent results from existing equipment until the opportunity to upgrade appears.

Of course the objective should be to eventually get a complete full frame system.

cheapest way to get a full frame sensor system is to buy a Pentax 35mm SLR camera body

of course, there is the cost of film, processing and scanning

biz-engineer · 03-04-2020, 02:11 AM

Originally posted by HarisF1

Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1

you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal.

HarisF1 · 03-04-2020, 02:33 AM

Originally posted by biz-engineer

you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal.

My point was more about someone transitioning to FF over time. There aren't many drawbacks. What you gain from using crop lenses is greater FoV and DoF from images. To get similar stuff on crop sensors would require faster lenses. It's really about getting a few extra percent detail here or there and ultimately it's not necessary to upgrade unless DoF is your goal.

normhead · 03-04-2020, 07:09 AM

Originally posted by biz-engineer

you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal.

With all due respect, that is not right. I take my DA 55-300 on long trips just to save weight?

The other day in Algonquin...

How are these soft corners in anyway objectionable or unprintable?
This being a 26 MP file. Cropped the same way on APS-c it would be 15 MP. The benefits to using APS-c lenses on FF are absolutely undeniable. And in situations like this, using the same crop you'd use on APS_c will give you 50% more resolution. You may need to be bit more judicious in the type of image you take, but APS-c lenses can be quite valuable on FF.

You may have to be a bit more selective in where you use the lens for what type of image, but there are scenarios where an APS-c lens makes more sense. The lens doesn't care what forms it's on, I don't either as long as it does what I want. And there are many scenarios where it does exactly what I want.

Any photo that uses a subject away from the edge and uses out of focus backgrounds to achieve subject isolation can use APS-c lenses as long as they cover the image circle without vignetting, because edge sharpness isn't part of the shooting strategy.

**peso54** · 03-05-2020, 02:59 PM - **1 Like**

Thanks to all contributions, fascinating to have his combination of expert knowledge and expereince to draw on. My overall take out is that apart from 2 of my current APS-C lenses, the sigma 10-20 and pentax 16-85, all others will give acceptable results, or even great results as shown my norrmhead. I am a bit perplexed about why sigma would need to modify my 150-500 mount for a K1 since the mount is the same as the K3 II (unless my ignorance is showing.........again).
So I do remain tempted to make the upgrade and in time get 1 or 2 of the FF lenses recommended.
Just loving the pentaxian community, thanks again.

03-03-2020, 01:45 PM	#25
dwalt Loyal Site Supporter Join Date: Sep 2016 Location: Big Sky, MT Photos: Albums Posts: 217	Originally posted by Austro-Diesel Well, the Sigma 150-500 DG and the Pentax D-FA 100 Macro will work fine. The DA 1.4x Rear converter may be useful with some limitations. The rest of the gang will not be meaningful usable in FF mode, as far as I know. Go for a K-1 II (or a used K-1, there is no significiant difference) with a D-FA 28-105. And keep looking for a new or used Sigma 70-300 DG OS (no other one, no APO, no Tamron, only the Sigma DG OS), this tele zoom is quite good for the few bucks to pay, you may find a new one for about 170 Euros at eBay. Remember the Sigma 150-500 needs a mount update and firmware update (free from Sigma) to work with the K1. Without the mount update you will scratch the K1. Sorry, Looks like someone beat meet to the punch on this. Last edited by dwalt; 03-03-2020 at 01:47 PM. Reason: didn't notice someone posted info earlier in thread.

03-04-2020, 07:09 AM	#29
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	Originally posted by biz-engineer you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal. With all due respect, that is not right. I take my DA 55-300 on long trips just to save weight? The other day in Algonquin... How are these soft corners in anyway objectionable or unprintable? This being a 26 MP file. Cropped the same way on APS-c it would be 15 MP. The benefits to using APS-c lenses on FF are absolutely undeniable. And in situations like this, using the same crop you'd use on APS_c will give you 50% more resolution. You may need to be bit more judicious in the type of image you take, but APS-c lenses can be quite valuable on FF. You may have to be a bit more selective in where you use the lens for what type of image, but there are scenarios where an APS-c lens makes more sense. The lens doesn't care what forms it's on, I don't either as long as it does what I want. And there are many scenarios where it does exactly what I want. Any photo that uses a subject away from the edge and uses out of focus backgrounds to achieve subject isolation can use APS-c lenses as long as they cover the image circle without vignetting, because edge sharpness isn't part of the shooting strategy. Last edited by normhead; 03-04-2020 at 07:27 AM.

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03-02-2020, 03:48 AM	#16
Rondec Loyal Site Supporter Join Date: Mar 2009 Location: Gladys, Virginia Photos: Gallery Posts: 27,653	What the others have said is true. You can shoot your DA lenses in full frame mode and then crop after the fact. I don't know that you would gain much from that. With some of the DA limiteds like the 40 and the 70, you can get pretty decent performance in all but the corners in this fashion. I would figure out a standard lens that you can use with a K-1 as you really have telephoto and macro covered. Reasonably priced options would be the DFA 28-105 and the Tamron 28-75 f2.8. I think with either of those lenses you would be pretty satisfied in combination with what you already have. Then, maybe pick up a used fast 50 and you're set.

03-02-2020, 07:39 AM - 1 Like	#17
Oldbayrunner Pentaxian Join Date: Mar 2013 Posts: 1,665	And don't forget some of the old in good condition Pentax SMC-F lens can be found inexpensive and work superb on the K1, like the F 35-70mm macro or F 70-210mm.

03-02-2020, 08:41 AM - 1 Like	#18
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,639	Don't forget that the Sigma 150-500 DG must have been modified by Sigma before using it on the K-1. Else you will scratch and freeze your body...

03-02-2020, 11:29 AM - 1 Like	#19
savoche Master of the obvious Join Date: Jun 2011 Location: Lowlands of Norway Posts: 18,311	I love my K-1 but with your lenses I'd rather stick with APS-C. FF is no magic bullet that automatically makes your images better. It can be better at certain things provided you have the right lenses and know what you're doing. But it also has some drawbacks that may or may not be a problem. Attacking this from a different angle: Is there anything in particular that you feel the K-3 II stops you from doing? Last edited by savoche; 03-02-2020 at 11:36 AM.

03-02-2020, 07:16 PM	#20
beachboy2 Senior Member Join Date: Dec 2012 Location: Perth Western Australia Photos: Gallery Posts: 222	None of my Sigma lenses has had to be modified to work on, or not to scratch my K1ii, including my 70-200 EX 1:2.8 II Macro HSM.

03-02-2020, 11:30 PM	#21
Austro-Diesel Forum Member Join Date: Nov 2011 Posts: 78	Yes, no problems here with my Sigma lenses: 35/1.4 Art, 50/1.4 EX, 85/1.4 EX, 70/2.8 EX Macro, 180/3.5 Macro, 70-300 DG OS

03-03-2020, 02:07 AM	#22
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,639	Originally posted by beachboy2 None of my Sigma lenses has had to be modified to work on, or not to scratch my K1ii, including my 70-200 EX 1:2.8 II Macro HSM. Originally posted by Austro-Diesel Yes, no problems here with my Sigma lenses: 35/1.4 Art, 50/1.4 EX, 85/1.4 EX, 70/2.8 EX Macro, 180/3.5 Macro, 70-300 DG OS I didn't say that Sigma lenses need to be modified, I said that the Sigma DG 150-500mm F5-6.3 APO HSM needs to be modified by Sigma to be used on a K-1...

03-03-2020, 03:38 AM	#23
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by peso54 Using APS-C lenses with a FF sensor There is no benefit to buy a full frame camera when using apsc lenses. Apsc lenses are for apsc cameras and full frame lenses are for full frame cameras.

03-03-2020, 01:35 PM - 1 Like	#24
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	Originally posted by biz-engineer There is no benefit to buy a full frame camera when using apsc lenses. Apsc lenses are for apsc cameras and full frame lenses are for full frame cameras. Strong comment, easily disproven. Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1. You may need to crop but you still get excellent results from existing equipment until the opportunity to upgrade appears. Of course the objective should be to eventually get a complete full frame system.

03-03-2020, 01:45 PM	#26
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,581	Originally posted by HarisF1 Strong comment, easily disproven. Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1. You may need to crop but you still get excellent results from existing equipment until the opportunity to upgrade appears. Of course the objective should be to eventually get a complete full frame system. cheapest way to get a full frame sensor system is to buy a Pentax 35mm SLR camera body of course, there is the cost of film, processing and scanning

03-04-2020, 02:11 AM	#27
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232	Originally posted by HarisF1 Take any APS-C lens with a near full-frame circle and you get a greater field of view on the K-1 you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal.

03-04-2020, 02:33 AM	#28
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	Originally posted by biz-engineer you get soft corners, which is ok to post images on the web, but certainly not up to full frame image quality standards. You can also use apsc lenses on a medium format camera with some sort of adapter. There is a reason why Ricoh classified lenses good for full frame and not good for full frame. I was recently at a camera shop , we discussed a medium format kit, the guy told me "you can print 2 meters wide with a smartphone image, you don't need medium format". His statement is correct, you can print even 10 meters wide from a smartphone image, it's not illegal. My point was more about someone transitioning to FF over time. There aren't many drawbacks. What you gain from using crop lenses is greater FoV and DoF from images. To get similar stuff on crop sensors would require faster lenses. It's really about getting a few extra percent detail here or there and ultimately it's not necessary to upgrade unless DoF is your goal.

03-05-2020, 02:59 PM - 1 Like	#30
peso54 Site Supporter Join Date: Jan 2019 Posts: 8 Original Poster	Thanks to all contributions, fascinating to have his combination of expert knowledge and expereince to draw on. My overall take out is that apart from 2 of my current APS-C lenses, the sigma 10-20 and pentax 16-85, all others will give acceptable results, or even great results as shown my norrmhead. I am a bit perplexed about why sigma would need to modify my 150-500 mount for a K1 since the mount is the same as the K3 II (unless my ignorance is showing.........again). So I do remain tempted to make the upgrade and in time get 1 or 2 of the FF lenses recommended. Just loving the pentaxian community, thanks again.