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06-08-2010, 11:00 AM   #1
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Cheap AND sharp autofocus 300mm?

Hi,

Just bought a Sigma AF 100-300mm f4.5-6.7 DL (rated 6.3 PentaxForums.com Third-Party Lens Review Database - Sigma 100-300mm f4.5-6.7 DL Lens Reviews) for 50 as I urgently wanted a longer lens than what I had with me.

To me, "wide open" (f6.7 doesn't sound very wide...) at the long end is unacceptably soft for me - see 100% crop straight from the camera below, click for full size:


1/1000s at f6.7, ISO400

Is it possible to get a sharp 300mm AF lens for not much cash?! Options (ie ones that come up frequently on eBay UK):
  • Tamron 70-300mm F/4-5.6 Di LD Macro 1:2 (rated 7.6)
  • Pentax SMC FA 100-300mm F/4.7-5.8 (8.6)
  • Pentax SMC DA 55-300mm F/4.5-5.8 ED (8.94)
  • Pentax SMC FA 80-320mm F/4.5-5.6 (6.75)
  • Pentax SMC FA 100-300mm F/4.5-5.6 (6.75)
  • Pentax SMC FA J 75-300mm F/4.5-5.8 AL (7.75)
  • Sigma 70-300mm F/4-5.6 APO DG Macro (7.8)
  • Sigma SLD 28-300mm F/3.5-6.3 DG Macro (unrated)
  • Tamron 75-300mm F/4-5.6 LD (unrated)


If not, is better to get a potentially sharper 200mm and crop?
  • Pentax SMC DA 50-200mm F/4-5.6 ED (7.6)
  • Pentax SMC FA 80-200mm F/4.7-5.6 (5.0)
  • Pentax SMC F 70-210mm F/4-5.6 (8.3)
  • Sigma 70-210mm F/4-5.6 (7.0)
  • Tamron 80-210mm f4.5-5.6 (8.0)
  • Pentax SMC F 80-200mm F/4.7-5.6 (7.5)


I also own an original Tamron 28-200 F/3.8-5.6 (same as SMC Pentax-FA 28-200mm F3.8-5.6 AL (rated 7.3)), but find this soft too.

Looks like 55-300mm has the best score, but am keen that FF glass is effectively cropped on APS-C which contributes to edge sharpness.

Am I on an impossible mission!? Would be grateful of any opinions and experiences.

PS Obviously what I'd really like is a DA*300mm / DA*60-250 / FA*300mm ...

06-08-2010, 11:59 AM   #2
Ira
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300s scare me.

Do you really think you need autofocus though for this length?
06-08-2010, 12:07 PM   #3
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I am unable to see the 100% crop. At 300mm sharpness depends a lot on technique. Also, you cannot expect a lot out of cheap 300mm AF lens.

This thread should be helpful....
https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/80818-inexpens...200-200mm.html

IMO, the Pentax DA 55-300 would be your best bet, but it is not very cheap, and I like my FA80-320 f4/5-5.6 very much as well, but it's not that sharp at 100% crops, neither would i expect it to be.
06-08-2010, 12:07 PM   #4
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Depending on your definition of "not much cash" I'd recommend the DA L 55-300
Same optics as DA 55-300 but cheaper due to plastic mount, no hood and no quick shift focus.
The only problem I've found with mine is that it is addictive........

Thanks,

06-08-2010, 12:19 PM   #5
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I would not recommend the Tamron 70-300mm F/4-5.6 Di LD WTF EIEIO.

I own that one. It's reasonably sharp, but there is A LOT of purple fringing in high-contrast scenes, and stopping down doesn't help much. I would gladly trade some sharpness to reduce the purpleness of it all.

Answering Ira, yeah, I think autofocus is pretty helpful on long lenses. At least handheld, the image bounces around a lot in the viewfinder, and it's hard (for me at least) to really see how sharp it is, even with a split prism viewfinder screen. I can manage OK with my 200mm Takumar, but my 400mm Tele-Takumar is pretty difficult.

QuoteQuote:
Obviously what I'd really like is a DA*300mm / DA*60-250 / FA*300mm
You and me both, buddy. I'd settle for two out of three.
06-08-2010, 12:22 PM   #6
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I've just bought the DA 55-300. It is sharp at the long end even wide open.

Some samples at 300mm-and these are not easy to catch..even sharper if you don't try to catch birds in flight at iso800!





this lens really worth the price!

Andras

Last edited by planedriver; 06-08-2010 at 12:27 PM.
06-08-2010, 01:10 PM   #7
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Many thanks all.

I had a feeling the 55-300 might be the winner! It is in the window of a local shop for 169, so a bit more.

Can anyone compare it, from experience, to the FA 100-300 (f4.7 version)?

Seems to be a really big gap (in price and IQ) from lenses like the DA55-300 to the Sigma 100-300 f4, Pentax 300* f4 etc...?

PS I like autofocus: spent my youth using MF and haven't made the switch to digital AF to go back!

PPS Planedriver - great pics! Any chance of a 100% crop straight from the camera?
06-08-2010, 01:19 PM   #8
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I recently did some planes spotting with that same sigma, it could be sharper but i think ity does alright for its 6.33 rating!
https://www.pentaxforums.com/forums/post-your-photos/101553-machinery-plane-spotting.html

06-08-2010, 01:29 PM   #9
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this is 100%:





AF can be sluggish-my technique is to set it manually to near infinity and then it gets much faster when you focus on these birds.

Andras
06-08-2010, 01:37 PM   #10
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Many thanks - that's pretty good IQ I reckon, and certainly a lot better than my Sigma would give.

Will try stopping the Sigma down a bit, but f8 onwards is pretty damned slow for handholding a 300mm lens, even with SR.

Doing a bit of internet research, 169 seems a pretty good price for the non-L version of the 55-300mm. Anyone feel differently?
06-08-2010, 01:44 PM   #11
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that's a very good price!
06-08-2010, 04:51 PM   #12
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Nice shots planedriver, 55-300 is a pretty nice lens.

Cheers, Mike.
06-08-2010, 05:50 PM   #13
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QuoteOriginally posted by planedriver Quote
this is 100%:





AF can be sluggish-my technique is to set it manually to near infinity and then it gets much faster when you focus on these birds.

Andras
I wouldn't give up my DA*300 in favor of one but you make the 55-300 pretty difficult to argue against. Nice shots!

06-08-2010, 11:57 PM   #14
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Thanks!
06-09-2010, 12:46 AM   #15
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The 55-300 is a good deal. Sharp wide open. You can't compare to the much more expensive F*, FA* or DA*, but imho, its the best option from the ones you listed.
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