[madison_wi_gal]

Snagged one of the 3 remaining "demo" ones on the Pentax-Ricoh site. 30 day return policy, so I need to check this little guy out asap. I know it won't be 28-105 on my K-3 III but a K-1/K-1 II is not in my immediate future (unless I rent one for a week and go nuts with the testing).

What do you folks want to see?

[MaineNative]

One thing I do is take a picture of a brick wall using a tripod. If you shoot at something like f/8 you want to make sure the edge focus is equal all the way around. (If one dude is in focus and one side is not, the lens could be de-centered.)

For checking sharpness, I take pictures of a bookcase or a wall map. They both have text of various sizes to see what is sharp. (Kind of like an eye test chart.)

I check to make sure I can focus at infinity…. I had one less that hit the infinity stop before it come into sharp focus.

Another test shot is to focus on a tree limb at various f-stops and look for purple fringing and see what to bokeh looks like. Maybe also take a picture with the sun in the frame to see if there is any strange flaring.

Hope you have a good one!

[UncleVanya]

Snagged one of the 3 remaining "demo" ones on the Pentax-Ricoh site. 30 day return policy, so I need to check this little guy out asap. I know it won't be 28-105 on my K-3 III but a K-1/K-1 II is not in my immediate future (unless I rent one for a week and go nuts with the testing).

What do you folks want to see?

Still 28-105. But what it isn’t is wide angle on apsc.

Testing is difficult. Smart option Lensrentals rents cameras. If you don’t have any mirrorless full frame or k mount friends witha k-1 that’s an option.

Testing on apsc means not really testing the edge performance at all. You can validate focusing, center sharpness, and zooming all work. You can even verify the sides are even but the extreme corners and edges will be outside the image circle of the apsc sensor.

[madison_wi_gal]

Still 28-105. But what it isn’t is wide angle on apsc.

Testing is difficult. Smart option Lensrentals rents cameras. If you don’t have any mirrorless full frame or k mount friends witha k-1 that’s an option.

Testing on apsc means not really testing the edge performance at all. You can validate focusing, center sharpness, and zooming all work. You can even verify the sides are even but the extreme corners and edges will be outside the image circle of the apsc sensor.

Yes, I was thinking lensrentals (and then I'd see a K-1 II in action). Can do when I get back from a fishing trip.

[othar]

I can't remember how this feature is called, but for a stationary target you can move the APS-C sensor around and take an image for each corner of the frame. Not exactly the FF area, but close to it.

I usually take images of far away treelines (@ ~infinity focus) with open apertures (at the wide and the long end of the lens) at different positions in the frame (trees at the top, the middle and the bottom of the frame - 1 image for each position / or 2 if you also move the sensor into the corners).That way you can check for a de-centered lens too (don't change focus between images though)

[James O'Neill]

Brick wall test as above or the indoor test used to be an open page of a broadsheet newspaper.

When doing the lest make sure the camera is horizontal, and square on to the target, and it is much easier (and removes unknowns) if you use a tripod and one of the modes that takes IS and mirror shake out of the equation. As well as overall quality you're looking for differences along the edges which suggest something distorted. Things being bent may also show up as not moving smoothly as it focuses.

I can't remember how this feature is called, but for a stationary target you can move the APS-C sensor around and take an image for each corner of the frame

You can use composition adjust to look beyond the normal edges of the image. I would focus manually with LV, and not change focus between shots. Composition adjust is intentionally de-centring the lens (!) so these images will be slightly sharper on the edge which has been moved towards the lens centre and slightly less sharp on the edge that has moved away from the centre - ensure you compare the corresponding parts of different images - i.e. is the left edge of the shifted left image the same sharpness as right edge of shifted right image.

[mlag]

You can use composition adjust to look beyond the normal edges of the image. I would focus manually with LV, and not change focus between shots. Composition adjust is intentionally de-centring the lens (!) so these images will be slightly sharper on the edge which has been moved towards the lens centre and slightly less sharp on the edge that has moved away from the centre - ensure you compare the corresponding parts of different images - i.e. is the left edge of the shifted left image the same sharpness as right edge of shifted right image.

I would be amazed if composition adjust can move the aps-c sensor all the way to the Full-Frame equivalent corners....but it allows indeed to move outside normal aps-c image but only slight.
That would be several millimetres and allow earth quake resistant SR on aps-c...
if you want to rest the lens for Full-Frame, you need a K1....

[pepperberry farm]

Single In Challenge - slap that lens on a camera and shoot every day with it for a month....

you'll know by the end of the month whether or not it's a keeper...

[bdery]

I need to check this little guy out asap

I'm not sure I agree with that assessment. Do you "need" to test? Do you have true worries?

If you do, print a high-resolution pattern, of take a printed sheet with a clear focus point, and check sharpness. That's the best you can do apart from taking actual pictures and seeing if you like the output.

[gatorguy]

Only my personal experience with the 28-105:

I bought and sold that lens, not once but twice, to use with my KP and K-70's. It never did impress me no matter how much I wanted to like it. It was an awkward range considering my other lenses that were made with APS-C in mind. It was not until I bought a second K1 that came with the kit-lens DFA28-105 that I understood the usefulness, and the better-than-expected performance.

If I didn't own K-1's I still wouldn't keep the lens, but on the K1 it is a really useful zoom that delivers excellent images. But this is me, I'm sure there's many a crop-camera owner who likes the lens.

But as to the question you asked, I agree with BDery, unless you suspect something is wrong with it there's really nothing to test other than does it work for you and your photography interests.

[madison_wi_gal]

Only my personal experience with the 28-105:

I bought and sold that lens, not once but twice, to use with my KP and K-70's. It never did impress me no matter how much I wanted to like it. It was an awkward range considering my other lenses that were made with APS-C in mind. It was not until I bought a second K1 that came with the kit-lens DFA28-105 that I understood the usefulness, and the better-than-expected performance.

If I didn't own K-1's I still wouldn't keep the lens, but on the K1 it is a really useful zoom that delivers excellent images. But this is me, I'm sure there's many a crop-camera owner who likes the lens.

Yes, my plan is to get a K-1 II (or III when they come out). I am being stubborn and waiting for the one I want (J Limited in Viridian) to get to an eBay seller with a sane price.

---------- Post added 05-16-23 at 08:32 ----------

I'm not sure I agree with that assessment. Do you "need" to test? Do you have true worries?

This is a demo lens with no warranty.

[pres589]

How to check how decentered your lens is - phillipreeve.net

[madison_wi_gal]

and one of the modes that takes IS and mirror shake out of the equation.

Uh... ? I can do electric shutter, but what is the rest?

[Oldbayrunner]

I just don't see the logic in buying a 28-105mm for an Apsc camera when there a good Da lenses with better field of view for those cameras, such as the Da 18-135mm. I love the lens for my K1 and haven't bought a D Fa 24-70mm because I just don't need another lens that is bigger in the same focal range as I have the 15-30mm, 70-200mm & just added the 150-450mm.

Ps I tried my new 150- 450mm in crop mode on my K1 and am super impressed using it in that mode.

[madison_wi_gal]

I just don't see the logic in buying a 28-105mm for an Apsc camera when there a good Da lenses with better field of view for those cameras, such as the Da 18-135mm. I love the lens for my K1 and haven't bought a D Fa 24-70mm because I just don't need another lens that is bigger in the same focal range as I have the 15-30mm, 70-200mm & just added the 150-450mm

I bought it because I truly believed that I would be able to get a K-1 II J Limited from Japan while my friend visited. That fell through for now. I'll rent a K-1 II from lensrentals and test this one out.

I will EVENTUALLY get a FF Pentax.