[normhead]

I'm just going to go with "bad lens."

I've taken tons of images like that. I tend to use burst mode, so that if there is a camera does have a problem with SR, one of the images will be good. I never turn SR off, although the 2 second times does that for me on some images.

K-1 and Tamron 300 SP AF 2.8 ED [IF] with 1.4 TC.
ƒ11, ISO 400, 1/640
On a free moving tripod head with SR on.



In your image a better lens would have done better. It's fairly typical that a soft lens will be good for close ups,

Sigma 70-300, ƒ5.6 300mm 1/4000 taken from about 6 feet away.


Because you are close, the image is acceptable.
A close up taken with better lens is more acceptable.


But you really start to see the effects of softness in a bad lens when shooting at infinity. On close ups you might think you can get by with a cheaper lens. I've a place near my house with a rock face with trees growing on it visible from a km away. I've never had a soft inexpensive lens that can resolve it adequately, I don't have a DA* quality lens that won't. ( And I have the DA*200 the DA* 60-250 and my Tamoron 300 2.8.) My DA*60-250 with the 1.4 gives me much better IQ in that circumstance, than the Sigma 120-400 I tried out for a while. And it's hand holdable unlike the Sigma.

That's my guess as to what's going on.

Sometimes if you want sharp, a better lens is your only option. Although learning with a cheaper lens to see if you like that type of photography is also a good way to go. Unfortunately if you do go that way, you end up with images like the above in your collections. I've never had a chance to reshoot that redpoll for my "best image of every bird" album. I really liked that image when all I had was the Sigma 70-300, now that I have better glass, it stands out for it's softness as much as it does as an image of the bird. I can only hope those guys drop in again some year for the migration, and I get another chance.

---

Last edited by normhead; 02-01-2018 at 09:10 AM.

[Astronomersmith]

Thank you all, for the responses. When I can find some spare time, which isn't easy in my world...I plan on doing some testing and working some of the suggestions giving here. I will eventually get around to it, and will post some results here.


I am going to do some research on a couple of things some of you have touched on - namely, backfocus and focus adjustments. I've heard of backfocus, but not very knowledgeable of it, and I didn't even know about there being focus adjustment settings?


A couple of forum posting related questions:


#1 I heard people saying the image I uploaded was too small. So, how can I upload a full sized picture if it is several MB's?


#2 when I hear people saying post a "100% crop" - I'm not sure I know what that means nor how to do it? I know about cropping and have done some photo editing, but that term is new to me. Does it mean to just crop out a small section of interest out of the full sized image?


Thanks so much for all the suggestions, comments and support! This is such a wonderful resource of information and helpful people!


Scott

---------- Post added 02-02-18 at 07:59 AM ----------

As others said, no need for SR if the camera is on a stable platform, but at 1/2000" at 300mm, the SR is not to blame.

Itʻs partly that lens and partly the nature of telephoto zooms. You did indicate it was a "cheap, very cheap" lens. Now you know why. But also keep in mind that at 300mm, you are shooting through a lot of atmospheric dust and air perturbation which contributes to the lack of sharpness and color saturation.

Put a modern digital lens on your K-50, even one that is low on the wish list, a Pentax DA 50-200mm, and youʻll see much better results.

I did use my kit lens, 50-200 DA, on the moon, and it turned out much better. Not perfect (I'm a bit of a perfectionist about my astronomy and photography!), but acceptable. So shooting the moon with the 300mm zoom and the 200mm zoom, there was no comparison.


Another note, I've heard mention about a "sweet spot" on a lens. Where a certain focal ratio is 'best', and I'm going to try taking a bunch of test photos eventually. It is just kind of annoying that you have a lens that has to have a particular setting for it to work properly?


Another question to you or anyone else who might read this...I'm probably embarrassing myself by asking, but, if this particular lens says it is "F4.5 - F6.7"...does that mean that is all it can be used at? I know I have the lens on the "A" setting, and I thought that meant it let the camera set the focal ratio, which could be anything from F4.5 on up to F16 or 22 even. Am I all wrong here?


For example, if I set this particular lens with my camera setting at F16...is it really shooting at F16 or at the F6.7 that shows as the upper range of the lens? Sorry for the dumb questions, but I really want to learn and asking is the only way I know how. So, maybe somebody will answer after they stop laughing at my questions! <haha>


Scott

[normhead]

If the camera is set to ƒ16 it shoots at ƒ16. But it will use ƒ6.3 for AF. One of the big advantages of faster glass is better AF based on more light wide open. The 4.5-6.3 are the widest you can open the aperture. ƒ 4.5 at the wide end, ƒ6.3 at the long end.

So if you have an ƒ4 lens, you'll be focusing with 3x more light than if you have extended your lens and ƒ6.3 is the best you can do. 6x more light with a 2.8 lens.

PS. at ƒ16 on APS-c, you are going to have noticeably degraded images due to diffraction in many instances, although I have pulled off a few ƒ16 images, and even the occasional ƒ22 image.

[pres589]

I think that if you were able to get an image of that scene that you were more happy with when using the DA 50-200, then the Sigma you've got is not a very good lens. I really like what Norm shared about a soft lens, working close, being more acceptable than when focusing on a distant subject or something that fills the entire frame.

Looking at the Photozone review of the DA 50-200, I don't know that it really has a sweet spot per se; Pentax SMC-DA 50-200mm f/4-5.6 ED - Review / Test Report - Analysis
I own a copy of this lens and it's nice for items that are close to the camera, like house plants, or a cat. It's not so great for birding or aircraft or other far away things. I've had some fun with cheap macro focusing filters and my DA 50-200.

My advise would be to keep playing with these lenses, figure out what kind of focal length / zoom factor you want, and then step up to a better lens after selling both the Sigma zoom and the 50-200 that you own now.

p.s. I never turn off shake reduction either.

EDIT: p.s.s. I've got a lens that performs quite well at f16. I believe it is at its sharpest at that aperture, and I wish it offered f22, just to see what that is like. I think a general rule of thumb is to stop a lens down three f-stops from wide open for whatever focal length you're at, and you should be about where the lens performs best. Or at least, it should be quite acceptable at that point, very generally speaking.

[normhead]

Another note, I've heard mention about a "sweet spot" on a lens. Where a certain focal ratio is 'best', and I'm going to try taking a bunch of test photos eventually. It is just kind of annoying that you have a lens that has to have a particular setting for it to work properly?

Here's a test chart for my Sigma 70-300. Notice at 70 mm, it's a pretty good lens, in my experience that goes from 70mm to about 150mm. By 200mm it still excellent in the centre but the edges are soft.


By 300mm it's notso hotso every where. Cheap zooms are like that. Even the DA 55-300 to some extent. Th sweet spot of this lens (the highest resolution) is ƒ5.6 at all settings. For Depth of Field you may want to use higher ƒ numbers.

Now look at the numbers for the DA* 60-250


Notice how the 60-250 is already better than the sigma at 60mm, but by 250 mm it's still holding it's own excellent in both centre and edges. There is no "sweet spot" solution available for the cheaper zooms, because even in their sweet spots, they just aren't that good in their long end.

MY guess is my DA*60-250 enlarged will be sharper than my Sigma 70 at 300. Technically the Sigma is longer, but if you look at the resolution charts, you have more subject resolution with the 60-250 even if you reduce it by 17%.

[Astronomersmith]

If the camera is set to ƒ16 it shoots at ƒ16. But it will use ƒ6.3 for AF. One of the big advantages of faster glass is better AF based on more light wide open. The 4.5-6.3 are the widest you can open the aperture. ƒ 4.5 at the wide end, ƒ6.3 at the long end.

So if you have an ƒ4 lens, you'll be focusing with 3x more light than if you have extended your lens and ƒ6.3 is the best you can do. 6x more light with a 2.8 lens.

PS. at ƒ16 on APS-c, you are going to have noticeably degraded images due to diffraction in many instances, although I have pulled off a few ƒ16 images, and even the occasional ƒ22 image.

Hmmm, very interesting. I am just getting a wonderful photography lesson with all the responses people have made! I know (or know of) some of the things I've read here, but there is plenty more that I don't know as well. Thanks.


I was under the impression, that the higher the "f" number, the sharper the image would be. I know it gives more depth of field, and I thought made focusing less critical? But I also thought it created sharper images than a wide open lens would at say, f4.


I also appreciate the lesson on AF using what is on the lens, and only in Aperture priority or Manual, was the camera in full control of the focal ratio. My head is practically expanding with all this useful and helpful information!


I see I've got lots of things I need to try and do and get a little scientific in my testing of my lenses. Know, I know 'what' I need to do, it is just making the time to get out and doing it that is holding me back.




Scott

[pres589]

The higher numerically the f-stop that you've dialed in, the greater the depth of field, yes. Sharpness does increase as one stops a lens down from wide open. Take a nice prime 50mm lens like the DA 50 1.8. It's okay sharp at f1.8 because it's a nicely designed optical package. But sharpness is greatest at f5.6. You can see that here;



Then things start to fall off. This is due to diffraction. That said, things are still pretty hot at f8. At f8, you can effectively set the camera to manual focus, have the focusing distance just a bit off of infinity, and everything from a few yards in front of you to a long distance out will be in focus. So as long as your AF lens isn't hunting for focus for some reason at f8, you should be in the clear as far as "good enough" focusing.

[Astronomersmith]

Use 2 sec timer when you place the camera on a tripod or some other platform. 2 sec timer removes another big factor, which is the pressing of the button. When people push the shutter button they often press it really hard, suddenly, which shakes the camera. 2 sec timer will also do Mirror up mode, which removes another factor. When the mirror moves it causes some vibrations. More on some cameras than others. But 2 sec timer is MLU so you don't have to worry about mirror. Oh, and 2 sec timer turns off SR. SR should not be enabled when you are using tripod or something. SR is also not for panorama photos. SR is only for handheld and moving photos.

The photo does not seem super terrible to me. That is about what you get with a cheap telephoto. Of course, I only see a small resized photo. If you want us to see the detail, you need to upload a 100% crop of the in-focus area. There are some threads about how to make a crop like that. Basically you just make a copy of the photo that is cropped down to only some the middle area. Then you save without resizing.

You can do some other things, like post processing. If you shoot raw, you can add sharpness and contrast. If you shoot jpeg, you can change some of the jpeg settings. For example, change the jpeg mode to Film reversal, play with the clarity and sharpness sliders to add a little..

I went ahead and tried to crop another picture of the same general area but at the low end of the zoom - 100mm. I did the 100% crop thing (I think?) just showing part of the image to make the file size smaller for the forum.
This image was taken at f/16, 1/1000 second, ISO-800, again, same car roof top support as my earlier image.
In my opinion, this one looks better, sharper, although maybe the exposure is just a little darker. But I am more concerned right now, with the focus, clarity, and sharpness of the image through this lens.


Comments? Opinions? Constructive criticism?


Scott

[pres589]

I'd probably try to get the ISO down a step or two by running a longer exposure. I'm not sure if the lens is sharper at f11 or f16 per Norm's charts above as they don't show resolution data for f16. f11 might be preferable.

May want to go manual focus, use Live View, and a few steps of magnification to see how well you're focus on your target if you aren't already.

[dsmithhfx]

I went ahead and tried to crop another picture of the same general area but at the low end of the zoom - 100mm. I did the 100% crop thing (I think?) just showing part of the image to make the file size smaller for the forum.
This image was taken at f/16, 1/1000 second, ISO-800, again, same car roof top support as my earlier image.
In my opinion, this one looks better, sharper, although maybe the exposure is just a little darker. But I am more concerned right now, with the focus, clarity, and sharpness of the image through this lens.


Comments? Opinions? Constructive criticism?


Scott

I think you are making your self-appointed task of obtaining maximum perceived sharpness all the more difficult by shooting into and through a scrim of small, dense tree branches (made more dense by spatial compression of long tele), and chain link fencing. This kind of subject with a lot of superfine detail really needs MF (or more) to come out looking sharp, or you need to move in closer and isolate smaller areas of detail. It's really important to match the subject and framing to the capabilities of your gear, instead of fighting it or trying to make it do the impossible.

[normhead]

I think you are making your self-appointed task of obtaining maximum perceived sharpness all the more difficult by shooting into and through a scrim of small, dense tree branches (made more dense by spatial compression of long tele), and chain link fencing. This kind of subject with a lot of superfine detail really needs MF (or more) to come out looking sharp, or you need to move in closer and isolate smaller areas of detail. It's really important to match the subject and framing to the capabilities of your gear, instead of fighting it or trying to make it do the impossible.

Some really good points there. Some of the time when I miss focus, it's because I'm not accounting for nearby objects. I have many shots with a tree branch in the foreground or back ground in focus and the bird that was my target out of focus. I thought I was good for focus on the bird. You find out different when you get home.

[Na Horuk]

Yeah, maybe testing in better conditions would help. Like photographing in clear daylight, a simple, contrasty object with nothing in between it and the lens. Something like a focus chart can usually give you a good idea on a lens' sharpness, even though its usually used for AF tests.

Overall, I think the lens is fine. Look at the chainlink fence, look at the writing on the vehicles. Its recognizable. It has a little overall glow, but the sharpness is there. Maybe adding a really tight lens hood would help. Older lenses benefit the most from a good lens hood. Even something like a stop down filter ring can be used, just as long as it isn't smaller than the lens' aperture

My verdict: Get lens hood (can be cheap, online, just make sure its for telephoto and fits the lens filter threads), work on your technique and stance, take lots of photos, adjust the PP (sharpening), use tripod/platform with 2 sec timer when possible. After a couple hundred photos you will be able to judge the lens and decide if you want to sell it. I don't think the lens is defective. It seems to be about as good as a DA L 50-200mm and other affordable telephoto zoom lenses. Check user reviews of similar lenses here:
https://www.pentaxforums.com/userreviews/

[Astronomersmith]

You have talked me into it. I'll do some testing using all the great suggestions everyone has given. I just wanted to post that other image because it was considerably better in focus (to me). It was at 100mm while the really blurry, hazy, bad focused one at 300mm was pretty bad. I just hate to think I have a 100 to 300mm zoom that is only acceptable at 100mm! I already had a much better 50-200mm DA kit lens that'll do this good, actually better!
But, I'll not give up yet. I have a challenge and when I get a chance, I'll do some serious testing, keeping notes and maybe even post my findings and conclusions? Thanks to all.


Scott

[pres589]

Let me make an editorial comment, and don't take it personally, because I own one of these things as well; if you have a zoom lens that is at all noticeably worse in overall ability / image quality / etc, I would try to get rid of it and purchase something better than both the DA 50-200 and this Sigma that you're mucking with. I purchased my 50-200 because it was inexpensive and I wanted to see how interesting the focal lengths covered would be to shoot at. I almost never pick that lens up because it's just not that good. I can't imagine sticking with something that is worse.

That said, if you can work out how to take better photographs with this specific lens, those skills will be useful in the future, and I commend you for trying.

My two cents, take it with a grain of salt.

[Astronomersmith]

I took the lens we've been discussing in this thread, out for a more controlled testing. As was suggested by members of this community. I'll try to post some pictures of my results. I don't know if I did the 100% crop correctly, but I just cropped out a small section of the image and saved it separately.


In this semi-scientific (haha) test, I hand held my K-50, used autofocus, shake reduction on, and tried to focus on a singular subject. I used the lens (Sigma 100-300 DL) at multiple focal ratio settings.


My lens seems to be sharpest at the f9 to f13 range, most seem best at f9, but one at f13 was better. Although, in fairness, I wasn't using a tripod and was taking some relatively slow (for me anyway) handheld shots that could have caused a little blur on one particular f9 image that I expected to be better than the f13 shot.


Regardless, I have to say that I'm not as ready to send my lens to the bottom of the river any more. It isn't great by any stretch of the imagination, but, it is better than my first impressions of it a week or so ago. I guess I'll give it another chance.


I think the image will show, as I named them with the subject, f/ratio, and shutter speed, but just in case, f67 is of course f6.7, I just didn't think I could put a period in the name?


Thanks for all the suggestions and tips and helpful criticism!


Scott