Best way to test a lens

PistolPete

PistolPete

PistolPete

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Hey All,


It is possible for a lens to become soft over time and is there anything you can do about it?

I have a Tamron 28-200 3.8-5.6 lens and I've noticed that over time since I got it from the MM that it's getting softer. I've not done anything more scientific that taking pics on a tripod at a range of zoom and aperture settings and then looking at the 100% crop but comparing it to older shots it's certainly not looking as good.

I thought it might be the autofocus, so I tried in manual and it's the same.


I'd like to test it in a way that's a little more conclusive - any ideas??


Pete
 
Use a focus chart, otherwise just some printed text and eyeball the sharpness and contrast. Best to compare against other lenses you think are sharp. Soft lenses are easy to see ... they are soft, otherwise you wouldn't notice and wouldn't care.

The only way I think a lens will get softer over time is focus misalignment.
 
Thanks guys.

I'm hoping it's not fungus, all my lenses are stored in the same bag and the other 2 seem OK.

I've got a 24-70L coming this weekend so I'll have a play and see what it's like against that as I'm fairly sure that'll be sharper than my 50mm 1.8 and my kit lens (I would hope!)
 
A brick wall is a good test subject for a lens. Tripod mount then take photos at various apertures. Some will be softer as with all lenses, but you should be able to see if there are any problems

...........or, have you changed your monitor, or monitor settings?
 
PistolPete said:
I dont think my monitor can tell when the photos were taken and soften them accordingly. ;)
Click to expand...

Oh, you haven't got one of those monitors then lol, just wondered if you had altered any settings, are you using a different colour space profile on your camera now from then, i.e. you were shooting with Adobe 98 now gone to sRGB, shouldn't affect softness, just throwing ideas out. Lenses do from time to time need calibration. Or - did you apply any sharpening to the earlier photos, if you use a Canon body they do shoot slightly soft to reduce noise, but a bit of post processing brings out the detail.
 
I've read reviews. I've shot sheets with lines and numbers downloaded. I've shot brick walls.

There is a danger that you focus too much on the image quality your lens can produce instead of focusing on the quality of your photography.

Nowadays, I simply judge lenses by the results I get on print. My cheap 70-300 zoom is not great, but good enough in many situations, my 100mm macro is amazing. Thats all I need to know.

Bottom line is you get what you pay for, except that the laws of physics will make a 50mm prime better than some ultra wide ultra expensive zoom lens, simply because it requires a much simpler design to make the former, and a lot of complexity and extra glass to make the latter while addressing all the distortions and abberrations that are encountered at those extremes.
 
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The main reason I noticed is that it looked like I'd slightly missed focus on a lot of shots recently but when I looked into it that it was the softness - I'm not the soft that's being picky on a IQ, it was quite noticeable.

It might just be time to retire that lens - I was using the kit lens and 50mm a lot more as the Tamron was quit a bit larger so I may just look at getting a newer lens.
 
OK forget large being an issue - I'm in love!

I hired a 24-70L 2.8 from Lensesforhire.co.uk for a friends wedding this weekend.
Review said it was a bit heavy....wasn't expecting it to be as heavy or as large is it is.
Thankfully I have a grip on my 450D otherwise it'd feel really odd to handle.

I appreciate that the 450D is not a top notch body, but the difference is amazing.
 
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