An alternative 28-105 for the K1 ?


PeterKR

Link Posted 11/02/2020 - 17:41
When I moved up from APSC to FF my problem was that none of my favourite DA lenses are FF compatible so I embarked on a search for a lower cost alternative to the advertised 'Kit lens' for the K1 family i.e. the D FA 28-105mm F3.5-5.6 ED DC WR. I came across a Sigma 28-105 UCIII AS IF which, apart from the lack of the WR, has similar specs to the DFA lens and has received very similar reviews on the well known US Forum.
My copy is in immaculate condition with 'sparkling' glass so here are some initial test shots using my K50.
All were taken hand held with the camera on TAv at 1/250s and either f/8 or f/11. I tried to cover the full zoom range from 28 to 105. All used auto focus.
The images below are all out of camera jpg with no PP except for size reduction for posting
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All C & C welcome
Peter

bforbes

Link Posted 11/02/2020 - 22:19
I'm unclear as to why the testing is not done on your FF body.
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

HarisF1

Link Posted 11/02/2020 - 22:59
The lens looks good from the samples you've provided. At f/8 and f/11 it seems pretty sharp. The D-FA lens almost certainly will have the edge from wider apertures although stopped down might be much closer. Some FF samples would be interesting too.

PeterKR

Link Posted 11/02/2020 - 23:18
bforbes wrote:
I'm unclear as to why the testing is not done on your FF body.

A very good question and I hope to post such shots soon.

For now though, since I've not got used to the (more complicated) K1ii yet I thought I'd do the first tests on my familiar K50.
I can then compare the results and it will also be a good test of whether the big cost outlay was worth it !!!

Peter

bforbes

Link Posted 11/02/2020 - 23:57
If the comparison is with your old Apsc lenses I can see the logic. But I don't believe it will give an indication of how the lens will perform on a full frame body given the difference in pixel count and Anti-aliasing filter
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

PeterKR

Link Posted 12/02/2020 - 14:43
bforbes wrote:
I'm unclear as to why the testing is not done on your FF body.

To put this right I have now taken some more shots using my K1ii.
I taken a similar range of shots and again all taken hand held with the camera on TAv at 1/250s and f/8, to provide a comparison with those taken with the K50.

As davidwozhere has pointed out in his comment on the gallery pic I posted, the exposure settings are not neccessarily ideal but they serve as a standard setting for the comparisons.

As above all images are the camera jpg with np PP except for size reduction for posting.

Firstly are some taken around 9:15 this morning with slightly dull sunlight and after that are some taken around noon in brighter sun. The main differenc then is the ISO value chosen by the TAv setup.

I'll start the numbering at 12 to continue the sequence from above.

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And now the later set:-
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What I do notice is that even at f/8 there is limited DoF in many of the shots and in the wide end shots there is a bit of vignetting ?

All C&C welcome

Peter

Benz3ne

Link Posted 12/02/2020 - 14:58
Seems like a reasonable lens, especially for the price. Wonder how it stacks up towards sunlight versus the HD coating on the D-FA 28-105mm WR and how much louder the focus is (not an issue for most but may be an issue for some).

bforbes

Link Posted 12/02/2020 - 15:24
I don't think the vignetting is uncommon for wide angles. If it helps for a comparison this is the Pentax 28-105 @28mm and F3.5 on a K1-mk1. (Jpeg out of the camera)



Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes

PeterKR

Link Posted 12/02/2020 - 19:45
bforbes wrote:
I don't think the vignetting is uncommon for wide angles. If it helps for a comparison this is the Pentax 28-105 @28mm and F3.5 on a K1-mk1. (Jpeg out of the camera)



Many thanks, Barrie, you've put my mind at rest. Guess I'll just have to PP out any dark corners if they bother me ?

Thanks again
Peter

PeterKR

Link Posted 13/02/2020 - 10:16
Benz3ne wrote:
Seems like a reasonable lens, especially for the price. Wonder how it stacks up towards sunlight versus the HD coating on the D-FA 28-105mm WR and how much louder the focus is (not an issue for most but may be an issue for some).

All these shots were taken without a lens hood (it didn't come with one) and the ones of the buds were backlit (i.e. into the sun).

I had a close look at the images last night and here are two '100% crops', i.e. Actual Pixels, from the jpg image 23 & 24 above.







I think these say it all !

(PS. the dng images look even better !)

Peter

davidwozhere

Link Posted 13/02/2020 - 22:56
I think you got yourself an excellent lens there ! One of my favourites is the Pentax-F 35-105. That too vignettes slightly at the wide end on the K1.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd - link

PeterKR

Link Posted 17/02/2020 - 19:29
I managed to get a genuine Sigma lens hood and also work out how to set the Auto Focus to spot focus so took a few more shots today.
For completeness here is another 100% crop of one of the magnolia buds. Taken at 1/500s and f/8. Again the camera jpg with no PP except for the crop.


johnha

Link Posted 17/02/2020 - 23:08
bforbes wrote:
I don't think the vignetting is uncommon for wide angles. If it helps for a comparison this is the Pentax 28-105 @28mm and F3.5 on a K1-mk1. (Jpeg out of the camera)



Have to say that unless there's a fault, it looks worse than the vignetting with my ancient FA PZ 28-105/4-5.6 @ 28mm and f/4 on my K-1. It's probably worse than my FA PZ 28-80/3.7-4.5 but I don't have that to hand. It may be easy to correct in post but I'd rather not have to.
PPG Flickr

bforbes

Link Posted 18/02/2020 - 09:58
johnha wrote:
bforbes wrote:
I don't think the vignetting is uncommon for wide angles. If it helps for a comparison this is the Pentax 28-105 @28mm and F3.5 on a K1-mk1. (Jpeg out of the camera)



Have to say that unless there's a fault, it looks worse than the vignetting with my ancient FA PZ 28-105/4-5.6 @ 28mm and f/4 on my K-1. It's probably worse than my FA PZ 28-80/3.7-4.5 but I don't have that to hand. It may be easy to correct in post but I'd rather not have to.

May be the fault of the operator
Barrie
Too Old To Die Young

http://www.pentaxphotogallery.com/artists/barrieforbes
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