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01-16-2009, 08:46 AM   #1
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Photos Blury with doubler

Hi,
I was taking photos with my new 18-250 pentax lens and had a Kenko Teleplus MC-7 "DG" 2x AF Teleconverter shooting the moon. It seems like no mater how hard I try to focus, the moon photos are blury. The lens is all the way out at 250mm. The aperture was at f6.5. Is this normal due to the doubler? I also tried to use the auto focus and it still didnt come out clear. If you pull back to around 150-200mm then the photos seem nice and clear. Would using a smaller aperture help? Thanks for any advice. Using K200D body.

david

P.S. Sorry I didnt mention it, but I am using a heavy duty tripod and also a cable release. Also the aperture on the lens was set at F8.0 and the shutter speed was 1/45 sec. in Manual mode on the best shots at 250mm., but still were blurry.

thanks


Last edited by David Tooker; 01-18-2009 at 09:55 AM. Reason: added more details
01-16-2009, 10:01 AM   #2
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What shutter speed?
Are you using a tripod?
01-16-2009, 11:26 AM   #3
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Handholding a 500mm Effective Lens?

Sounds like you are trying to handhold a 500mm lens to take shots of the moon. Using the one over focal length rule, and if you have good techinque, your shutter speed needs to be at least 1/500th second. Your 18-250 has a f6.3 widest apeture at 250mm and with the doubler, you are looking a an actual f12.6.
If you were shooting at ISO 100, the shot was certainly not hand holdable. At ISO 200, you are right on the edge of being hand holdable with good technique.
Your lens will give much better results stopped down but this will just make the shutter speed slower.
The bottom line is you are not going to get decent results from this setup without a tripod and that is assuming that the teleconverter works well with your lens to begin with. It may not be possible to get the results you are looking for with this combination.
Have you achieved good results with the doubler and lens in other situations?
01-16-2009, 12:10 PM   #4
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Superzoom + teleconverter = lousy image quality.
And a tripod is a must with such focal length and tiny aperture.
Teleconverters are meant to be used with high quality fast prime lenses, this is where they can give decent results (although some people claim that sometimes the results are quite undistinguishable from just cropping and then resizing the picture )

01-16-2009, 03:20 PM   #5
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QuoteOriginally posted by David Tooker Quote
Hi,
I was taking photos with my new 18-250 pentax lens and had a Kenko Teleplus MC-7 "DG" 2x AF Teleconverter shooting the moon. It seems like no mater how hard I try to focus, the moon photos are blury. The lens is all the way out at 250mm. The aperture was at f6.5.
With the 2x teleconverter in line you have a minimum aperture of f/13 and and effective field of view of a 750mm lens. This combination is way to slow and long to handhold effective. You will need a good, solid tripod and probably need to use the two second delay and a cable release. You will also have to use manual focus as I doubt if the lens can effectively autofocus with an f/13 aperture. Most AF systems generally work well up to f/5.6, perhaps f/8....it gets to be hit or miss after that.
01-21-2009, 04:26 PM   #6
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Ahh, well, ok, I see. Your 18-250 is defective, and you need to trade it with me for my 18-55 II ;-) ;-)
01-21-2009, 04:34 PM   #7
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Did you leave the SR on? I just got a C5 1250mm lens (spotting scope) and no matter how hard you try - moon pictures will always be a tad blurred. The idea is take several pictures and stack them with a program like RegiStax to bring out the details.

-Brian
01-21-2009, 04:43 PM   #8
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old thread is old >_>

01-21-2009, 05:16 PM   #9
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QuoteOriginally posted by Vylen Quote
old thread is old >_>

Am I missing something in translation, thread is old = original posted too long ago. Or, drop it because the subject manner is too boring and/ or has been covered in the past on several occasions?.

Cheers. Mike.
01-21-2009, 05:24 PM   #10
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the former... mainly in response to sodbuster..
01-21-2009, 05:42 PM   #11
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Thanks. I stand clarified..
Cheers. Mike,
01-21-2009, 08:34 PM   #12
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Definitely make SURE you have shake reduction turned OFF if you are using a tripod.
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