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12-15-2015, 05:56 PM   #1
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How to test DA300 mm without other 300mm lens?

Hey, I've just bought a da 300mm f4 to shoot some outdoors sports next tennis/surfing season and some wildlife.
I'm trying to check my copy's quality, which is expected to be very sharp, but I don't have any other 300mm lens to compare.

Closest focal range lens I have is Tamron 70-200 f2.8. My favorite one. What I tried is I set up a test composition and shoot it with tamron at 200mm. Then I shoot it with da300mm from x1.5 longer distance to get similar composition in a viewfinder. Is that right procedure?

After all, the results were clearly on Tamron's side, it was noticeably sharper at f4-5,6 range. Even at f2.8 the Tamron was still clearly sharper than the DA 300mm at f4. Could it be explained with longer physical distance? Or it is clearly a sign of a bad copy?

Thanks!


Last edited by pukipuki; 12-15-2015 at 06:03 PM.
12-15-2015, 06:09 PM   #2
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QuoteOriginally posted by pukipuki Quote
Hey, I've just bought a da 300mm f4 to shoot some outdoors sports next tennis/surfing season and some wildlife.
I'm trying to check my copy's quality, which is expected to be very sharp, but I don't have any other 300mm lens to compare.

Closest focal range lens I have is Tamron 70-200 f2.8. My favorite one. What I tried is I set up a test composition and shoot it with tamron at 200mm. Then I shoot it with da300mm from x1.5 longer distance to get similar composition in a viewfinder. Is that right procedure?

After all, the results were clearly on Tamron's side, it was noticeably sharper at f4-5,6 range. Even at f2.8 the Tamron was still clearly sharper than the DA 300mm at f4. Could it be explained with longer physical distance? Or it is clearly a sign of a bad copy?

Thanks!
It could also be a focus issue--try focusing on a clear, stable target in live view (which doesn't use the camera's phase detect autofocus) and comparing the shot to the same taken with regular AF. If the live view shot is noticabley sharper you will have to make an adjustment in the body.
12-15-2015, 06:36 PM   #3
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This could be a bad copy or it could need a micoadjustment in the the focus if you have not calibrated that lens and body using the menu focus adjustment. My copy of the lens required a +5 to be truly accurate in the focus, after which it was razor sharp. If you still experience softness after calibrating I would lean to a bad copy as this lens is by far the sharpest of the 11 pentax lenses I own. (200 F2.8 DA*) is a close second though.
12-15-2015, 06:38 PM   #4
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I tried AF adjustments for 300mm even without checking if it is needed Results were worse with +/- 1-2. Thanks for the routine, though

12-15-2015, 11:33 PM   #5
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I'm not sure what the best procedure would be, but were you shooting outside? It could be that a 1.5x greater distance was enough to make the 300 look worse simply due to haze or what have you (just a guess!). But if you were shooting inside then probably not. Did you try shooting any focusing charts?
12-16-2015, 02:22 AM - 1 Like   #6
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The first shot I took on the DA300 just blew me away with its sharpness. Make sure you're not doing anything silly (like trying to focus closer than its minimum focussing distance), otherwise it sounds like a bad copy. Seriously, the DA300 makes my FA limiteds seem 'average' :/
12-16-2015, 08:51 AM - 1 Like   #7
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If focused properly the DA* 300mm F4 is the sharpest lens i ever used, wide open and from corner to corner.
I often crop heavily with a K3 without any resolution problems, mostly for wildlife.

Like robthebloke said, if it doesnt blow you away there is something wrong with the lens or the use of it.
12-16-2015, 01:48 PM   #8
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Any chance you can take a photo with it, with good light, and low ISO, and post it so we can take a look?

12-16-2015, 02:06 PM   #9
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My DA* 300 required significant focus adjustment (+10, or maybe it was -10). But it's a wonderful lens.
12-17-2015, 12:10 AM   #10
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QuoteOriginally posted by apfhex Quote
I'm not sure what the best procedure would be, but were you shooting outside? It could be that a 1.5x greater distance was enough to make the 300 look worse simply due to haze or what have you (just a guess!). But if you were shooting inside then probably not. Did you try shooting any focusing charts?
I was shooting inside, without any focusing charts though.

---------- Post added 12-16-15 at 11:11 PM ----------

QuoteOriginally posted by robthebloke Quote
The first shot I took on the DA300 just blew me away with its sharpness. Make sure you're not doing anything silly (like trying to focus closer than its minimum focussing distance), otherwise it sounds like a bad copy. Seriously, the DA300 makes my FA limiteds seem 'average' :/
That's what I was expecting and was puzzled when I didn't get it
12-21-2015, 02:22 AM   #11
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Also, only with this 300mm I've noticed that auto-focus can't focus if the starting position is minimum and the subject is far away. It just confirms focus to the camera. I need to move the focus ring to some degree and then it starts to focus correctly.

Seems like malfunction, if it's not something that is common between telefoto lenses.
12-22-2015, 09:07 AM   #12
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I use this lens at closest focus distance for macro of flowers and insects quite often when im out in the bushes, in between wildlife and bird shooting, but i never experienced such focusing behaviour when focusing towards infinity again.
Note that i always use the AF button to focus (K3).
12-23-2015, 12:58 AM   #13
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I've sent it back for exchange eventually, thanks for the help everyone.
01-29-2016, 05:03 PM   #14
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Got another copy. Again, after some tests inside, 70-200 looks sharper. But this time I can say they are comparable at the same aperture. Microadjustments didn't help, but outside test might get better results for DA*300. More importantly, no issues with auto focus performance towards infinity this time.
01-30-2016, 03:14 AM   #15
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I have not tried the 70-200 yet but i can hardly imagine it being sharper than the 300. On the other hand i have never used the 300 inside.

Since pictures say more than words this is a full resolution K3 + DA*300 sample shot wide open, slightly sharpened with DxO 10s standard unsharp masking settings but otherwise unaltered:

www.tst-audio.de/uploads/IMGP9214_DxO.jpg

22MB, 24MP, F4, 1/1000th, ISO400, low resolution preview attached
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