[dmjjr]

Wondering about using the APS-C lenses on the new full frame body. I have the K3 ll & quite a collection of lenses. How will they work on the full frame body?

[Bob 256]

APS-C lenses will work fine on the K-1 as long as they have a Pentax mount. In crop mode and Live-view, the LCD screen will "stretch" the image to full coverage of the screen. Through the viewfinder (in VF & crop mode), you have crop marks which appear, indicating the crop field (and the periphery of the viewfinder will fade to black due to the less than FF coverage of the APS-C lens unless it happens to cover FF). You'll have a reduced file size in crop mode compared to a FF lens and FF mode (fewer pixels).

An option with the K-1 is you can shoot in FF mode even with a APS-C lens and then crop the image in post. Some APS-C lenses have coverage beyond the official APS-C range and this will allow you to make use of that extra. In this case, you get the full-size FF file size which will be reduced in size when you crop in post. It can be advantageous to shoot in crop mode since the smaller file size for each frame will allow more (frames) on an SD card, but that's usually of secondary importance given the huge storage size of today's cards.

Note: You can also do the reverse and use crop mode with a FF lens, in which case you get a smaller file, and the APS-C portion of the FF field. However, you permanently lose the extra part of the FF field as it is not saved to the card.

[cmohr]

This will show you what lens will do what, on what camera.

Check Lens Compatibility with Your Pentax Camera

[Unregistered User 8]

There is also a specific K-1 article for lenses.

Pentax K-1 Lens Compatibility Guide - Articles and Tips | PentaxForums.com

[mattt]

Crop Files are similar to what you might have got from a K5 IIs. Similar pixels but with added benefit of improvements in AF. When compared to your K3 II - smaller files. The APS-C lenses I often use on my K-1 in Full Frame are all normal to Tele ( 40mm -> 55mm -> 70mm primes. On the zooms vignetting is underwhelming.


I bought a k-1 because I had lots of legacy glass. If I didn’t I would have stayed with crop because FF glass is heavy and expensive. That being said I now have all focal lengths covered from 15-450mm.

[dmjjr]

Some more info please. My main concern is IQ-would the crop sensor lenses give better results on the K1ll because of the larger sensor. I know they would be smaller files but is the K1ll sensor better quality? I have the following Ltds-DA 15, DA 21, & DA 70.. Based on what I have read the K3lll is not worth 2k (at least not to me)
Thanks

[vector]

I have used my DA15, DA21, DA18-135 on my K1 in crop mode. The resolution is about equal to the K5 (slightly lower) and the image quality is good. For handling I prefer my K1 over my K5 or K3 despite the extra weight. The viewfinder puts a thick black outline around the apsc frame. Some find it distracting, I really don't mind it. I don't use my K1 for birds with my DA*300+1.4TC because the extra resolution from the 24mpix K3 really makes a difference there with cropping. But for more general shots of people and landscapes its fine.

Here are some recent examples where I went on a hike in the rain and my only WR lens available was the DA18-135. Higher resolution would be nice but totally not necessary for some snaps on a hike. This is Johnston Canyon in the Banff National Park from a few weeks ago.

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Last edited by vector; 09-07-2021 at 09:07 PM.

[dmjjr]

Thanks for all the info-definitely leaning towards the K1ll

[robgski]

I regularly use DA lenses on my K-1 in both crop and FF mode, I am please with the results.

[marnoon]

It is also interesting to use the 1:1 crop fore DA lenses. It has the medium format style...

[UncleVanya]

Thanks for all the info-definitely leaning towards the K1ll

Why? I’m curious what advantage you are expecting over something Like a KP or K70. My assumption is that you are planning to shoot cropped lenses only. If you plan any full frame then I get it. You are giving up 1/3 of the potential 24mp that the older apsc cameras since the original k-3 offer. The k-70/KP also offers the same level of sensor plus the accelerator chip.

The advantages I see of the crop mode K-1ii over the KP and K70:

Battery life
Shutter/Aperture life (over k70)
Screen articulation (particularly vs KP)
Easily Available new (vs KP)
1:1 Crop mode for crop lenses
Some crop lenses are full frame.
Deep buffer for burst shooting

The downsides:
Heavier & larger
Lower resolution in crop mode (15 vs 24)
Screen isn’t fully articulating (vs k70 - and that may not be a factor for you)
Slower frame rates for continuous shooting.

Bear in mind that shooting in crop mode removes a bit of sensor performance - not making it worse than the k70 cameras but on par. The KP provides slightly better sensor performance than the k1ii in crop mode.

[Sakura]

BTW, the DA* 60-250 is very easy converted to a FF lens.

[stevebrot]

The downsides:

Don't forget price.


Steve

[UncleVanya]

Don't forget price.


Steve

Lol. Yes that too.

[stevebrot]

Some more info please. My main concern is IQ-would the crop sensor lenses give better results on the K1ll because of the larger sensor.

Crop results are similar to those from the K-5IIs. There is a noise reduction benefit due to the so-called "accelerator chip". Whether the quality of those results are equal or better than the higher resolution images from your K-3II depends on one's definition of quality.


Steve