Gear advice lens test

[TMG1961]

How do you test your lenses for sharpness and to see if it is not decentered?

 

[Andy Smith]

Usually with any new lens I will take a series of about 10 images of the same subject, with each image using a different f/ number. Starting at the extremes and stopping up/down until I cover a good range of the lens capabilities.
For zoom lenses I would do the same, but with additional photos at different zoom lengths.
I then have a series of images I can compare to see at what settings the lens get softer, and if it is actually noticeable.
I then know where the best range is for the lens.

I have never checked any of my lenses to see if they are decentered, but you could do a similar series of test shots of a distant object.
use a tripod, use manual focus and set it on a prominent point that sticks out.
use the widest aperture you can and then take a shot with the prominent object centred.
Move the camera until that object is in the upper left corner (do not change focus) and take another shot.
Repeat this step moving the object to the other 3 corners for each shot.

You can then compare the shots of the corners and see if any are sharper or have less detail than the others.

 

[Jack]

That's a good question TMG1961. That's already dependening during post processing, and what you want to achieve.

If you want to see the sharpness, put it at f2.8 or the max aperture and focus on subject, upload the photo on laptop or PC and zoom in, see the details of the subject.

 

[TMG1961]

Usually with any new lens I will take a series of about 10 images of the same subject, with each image using a different f/ number. Starting at the extremes and stopping up/down until I cover a good range of the lens capabilities.
For zoom lenses I would do the same, but with additional photos at different zoom lengths.
I then have a series of images I can compare to see at what settings the lens get softer, and if it is actually noticeable.
I then know where the best range is for the lens.

I have never checked any of my lenses to see if they are decentered, but you could do a similar series of test shots of a distant object.
use a tripod, use manual focus and set it on a prominent point that sticks out.
use the widest aperture you can and then take a shot with the prominent object centred.
Move the camera until that object is in the upper left corner (do not change focus) and take another shot.
Repeat this step moving the object to the other 3 corners for each shot.

You can then compare the shots of the corners and see if any are sharper or have less detail than the others.

Not sure how to move the camera around to get the subject in each corner without changing focus.

 

[Andy Smith]

Not sure how to move the camera around to get the subject in each corner without changing focus.

I would have the camera on a tripod TMG1961, and if the subject is focused when in the centre of the image you will not need to change focus when you move the camera to place it in the corners. Each corner should have the same quality, but if you re-focus for each corner you are going to get inaccurate results.
A better explanation of the method is here:

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

How to check if your lens is decentered? You may have already heard of sample variation or decentered lenses. In this article we will show you how to easily test your lenses for proper centering. If you know how it works it will take you less than 5 minutes per lens! Where this test originates …...

phillipreeve.net

There are a few different approaches really, so you could follow this one which will do the same job, and uses indoor and outdoor images for testing.

 

[TMG1961]

I would have the camera on a tripod TMG1961, and if the subject is focused when in the centre of the image you will not need to change focus when you move the camera to place it in the corners. Each corner should have the same quality, but if you re-focus for each corner you are going to get inaccurate results.
A better explanation of the method is here:

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

How to check if your lens is decentered? You may have already heard of sample variation or decentered lenses. In this article we will show you how to easily test your lenses for proper centering. If you know how it works it will take you less than 5 minutes per lens! Where this test originates …...

phillipreeve.net

There are a few different approaches really, so you could follow this one which will do the same job, and uses indoor and outdoor images for testing.

Thanks for the links. It is a bit more work with my tripod to move the camera to the corners. But i just did a test run to see how to do it and will try it with next lens purchase.

 

[Jack]

I would have the camera on a tripod TMG1961, and if the subject is focused when in the centre of the image you will not need to change focus when you move the camera to place it in the corners. Each corner should have the same quality, but if you re-focus for each corner you are going to get inaccurate results.
A better explanation of the method is here:

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

How to check if your lens is decentered? You may have already heard of sample variation or decentered lenses. In this article we will show you how to easily test your lenses for proper centering. If you know how it works it will take you less than 5 minutes per lens! Where this test originates …...

phillipreeve.net

There are a few different approaches really, so you could follow this one which will do the same job, and uses indoor and outdoor images for testing.

I still don’t think you can get 100% everything in focus. Unless you can do stacking.

 

[TMG1961]

I still don’t think you can get 100% everything in focus. Unless you can do stacking.

No need to get everything 100% in focus but the lens should be sharp and should have the same level of sharpness or close to the same level in all corners.

 

[Jack]

No need to get everything 100% in focus but the lens should be sharp and should have the same level of sharpness or close to the same level in all corners.

Depending on the lens, if I'm not wrong, the more you zoom, the more you loose sharpness in the corners.

 

[TMG1961]

Depending on the lens, if I'm not wrong, the more you zoom, the more you loose sharpness in the corners.

I don't mind loosing a bit of sharpness in the corners, but some lenses loose almost all their sharpness in corners.

 

[Andy Smith]

Depending on the lens, if I'm not wrong, the more you zoom, the more you loose sharpness in the corners.

Some do yes Jack, but some are not that noticeable.
However, all corners should still be the same quality within a single image, no matter the focal length used.
Decentered lenses will have some corners that are much worse than others.

 

[Jack]

Some do yes Jack, but some are not that noticeable.
However, all corners should still be the same quality within a single image, no matter the focal length used.
Decentered lenses will have some corners that are much worse than others.

I believe you will find that issue on a cheaper lenses , I have never checked my images if the quality on the corners are the same as on the centre.

 

[TMG1961]

I believe you will find that issue on a cheaper lenses , I have never checked my images if the quality on the corners are the same as on the centre.

It can happen with all lenses, cheap or very expensive. That is why i test all my lenses so in case it is not good i can return it and either get another one or get my money back.

 

[Jack]

It can happen with all lenses, cheap or very expensive. That is why i test all my lenses so in case it is not good i can return it and either get another one or get my money back.

If you bought the lens brand new, I’m sure you shouldn’t have any issues with it. The company must check them before sending them to the shop or selling. If you purchase from reliable shop, they also should check the lens before buying it from other photographers.

 

[TMG1961]

If you bought the lens brand new, I’m sure you shouldn’t have any issues with it. The company must check them before sending them to the shop or selling. If you purchase from reliable shop, they also should check the lens before buying it from other photographers.

Even with new lenses you should check for sharpness and decentering. The lenses are checked by the companies but as long as they fall within tolerance they ship it. Could be that you get a lens that is not up to what you expect from it, if you check it you find out if it is ok and if not you can send it back to have it replaced.

 

[Andy Smith]

Even with new lenses you should check for sharpness and decentering. The lenses are checked by the companies but as long as they fall within tolerance they ship it. Could be that you get a lens that is not up to what you expect from it, if you check it you find out if it is ok and if not you can send it back to have it replaced.

I do hear of people getting 'bad' lenses from time to time, even with new, high end and expensive lenses - so it is good that you check TMG1961, especially as you are mainly buying online and lenses can get banged about in transit.

 

[TMG1961]

I do hear of people getting 'bad' lenses from time to time, even with new, high end and expensive lenses - so it is good that you check TMG1961, especially as you are mainly buying online and lenses can get banged about in transit.

I also need to not focus that much on sharpness and decentering. In the end that only spoils the fun you get from shooting photos. And to be honest how many people start looking at the corners of your photos, most of the time there is nothing interesting to see there.

 

[Jack]

Even with new lenses you should check for sharpness and decentering. The lenses are checked by the companies but as long as they fall within tolerance they ship it. Could be that you get a lens that is not up to what you expect from it, if you check it you find out if it is ok and if not you can send it back to have it replaced.

Yes I do agree. I’m very lucky, so far I don’t have any issues with any of my lenses. The only problem I have, is with camera sensor which I’ve cleaned but still there are some dots presented when taking a photo and increasing the dehaze

 

[TMG1961]

Yes I do agree. I’m very lucky, so far I don’t have any issues with any of my lenses. The only problem I have, is with camera sensor which I’ve cleaned but still there are some dots presented when taking a photo and increasing the dehaze

How did you clean the sensor?

 

[Jack]

How did you clean the sensor?

I bought a cleaning kit from amazon. I didn't spayed inside the camera, just whipped gently with a small cotton cloth.