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04-24-2014, 08:22 AM   #1
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Tak 300mm f4, PP, thoughts vs/ modern equip

Some of you may remember the thread about this lens not focusing to infinity. I got that solved with a trip to Eric.

I thought I would share some of my initial impressions now that I've had some time to play...

First off, the lens is reasonably sharp. The CA that others mention is there, and I really don't have a handle on preventing it yet, because it's not always there. The biggest cause seems to be overexposure in high contrast situations, which is fine if the subject will eventually be cropped out, but otherwise you are stuck doing a fair amount of PP to fix. The Adobe Camera RAW import doesn't really allow enough movement vertically to get rid of it all, so I'm stuck doing manual selections of edges, selecting the offending color and desaturating it. Pretty time consuming.

A couple of samples. Hopfully I do this right...
Before, untouched straight from overexposed raw to jpg (You'll want to view the full size original on Flickr to illustrate maximum effect)





And here is cropped and after post in photoshop:





It's a passable image for one that was overexposed and fringed all to heck, but it does make me take stock of the situation... I have a Tamron 70-200 F2.8, and I also own a Tamron 1.4x AF teleconverter, and it does a fine job, plenty sharp, autofocuses, and doesn't take hardly any post process.

This pick was taken much closer with the Tamron, I was stalking the hawk a few steps closer at a time, knowing he would take flight soon as I got too close. He let me get crazy close, like within 30ft before he finally bailed.





I inserted links and images to see which worked... first time posting from flickr... please bear with me while I figure this out. (I think I've finally fixed the embedded pic's this last edit, yay! Was way to easy *face-palm* .

Lastly, I also own the DA55-300mm, and in the long run, I am now asking myself, even though the DA isn't stellar at the 300mm end as some people have noted, it's not a lot worse than the Tamron with the 1.4x Teleconverter on it if used properly... but it's a whole lot lighter.

Seems everything is a compromise in life, heh. The Tamron is the sharpest lens of the 3 by a fair margine, also the heaviest. With the 1.4x it makes the most sense for an all around lens if I can stomach the weight. If I'm traveling light, the DA makes the most sense. I guess it's always good to have choices.

Eric


Last edited by Erictator; 04-25-2014 at 11:41 AM. Reason: To fix embedded pics to flickr, got it!
04-24-2014, 12:43 PM   #2
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Hi Eric,

If you're just looking for a PP solution, I'd assume that PS has a Saturation tool that will allow you to select specific color channels, with some adjustment for the actual colors effected. I use PSPP, and it's had such a tool for quite a few versions. After you desaturate in Camera RAW, you can further desaturate the Magenta channel, and either adjust the specific color towards the red, or do two different desaturations with the second for the red that remains. Be careful with this, in this image, this might alter the colors in the hawk, so one way to handle this might be to first select the hawk, then reverse the selection so that everything except the hawk is selected, then do the desaturation. There might be better solutions available in PS, I don't know. . .

As far as lens selection goes, your present lenses should serve you well up to @ 300mm. To get better, you'd have to go to more modern models that use ED elements, so for Pentax, that would mean the F*/FA* 300/4.5, FA* 300/2.8, DA* 300/4, Sigma EX 100-300/4 APO, and the Sigma EX 300/2.8 APO and the later variants of either of the Sigmas. These run into some money, but they all would allow you to add TCs to go longer since they're fast enough to allow the AF system to function reasonably. FYI, with Pentax the line where the AF system starts to struggle is when the max aperture starts to approach f8. There is no hard line -- newer models are a bit more sensitive, and it's somewhat lens dependent since a sharper lens will more easily gain a lock than one that's softer wide open. All of these lenses will also be bigger and heavier than your DA 55-300. but possibly not quite as heavy as your Tamron but at least in the same class (starting at @ 2+ lbs). If avoiding CA/PF is a priority, I'd avoid the K, M*, and A* 300/4s because they all are less corrected for this than the later models, so that means any lens that will solve the problem will be significantly pricier.

There is a possibility that the Tamron 70-200/2.8 could give acceptable performance using stacked 1.4x TCs. I can't say since I don't own one. . . This would give you close to 400mm f5.6, which is well within the max Av range for AF. Two disadvantages would be that actual Av would not be picked up by the body (f2.8 at the lens would report f2.8 to the body without conversion for the light lost to the TCs) and the body would still think that you're using a 200mm lens for SR purposes which would detract from it's effectiveness. The Av thing would not effect normal outdoor shooting because your camera will still be metering through the lens, but it would likely be a problem if you wanted to add P-TTL flash to the equation. IQ could also suffer because, in my experience, zooms do not take to TC use as well as primes since the optics are usually compromised somewhat to deliver IQ over the FL range, whereas a prime only needs to be optimized for one.

Scott
04-24-2014, 06:58 PM   #3
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Thanks for sharing, erictator. I have a nice Kenko Pz-AF 1.5X Teleplus SHQ, and I've been trying to find an inexpensive long lens that can make good use of it. I've tried a variety of older primes and zooms up to 300mm. What I'm discovering that the best of those lens isn't worse w/ the teleconverter, but it isn't particularly better than just enlarging the image without it. (I've tried a TeleTakumar 200 f5.6; Soligor 250 f4.5; Vivitar 300 f5.6; Vivitar 75-205; Tokina 80-200 -- none of those may be as good as the Tak 300 you are using.)
Further, like you, I have become more and more impressed with the results of my DAL 55-300. It's just hard to beat it with any of those lens with or without the tc. (BTW, the DAL 55-300 does fine w/ the tc, but not enough improvement to make it worth using.)
04-24-2014, 07:25 PM   #4
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it doesn't help that your subject is slightly out of focus. i'm not seeing any ca on the right side where the fence is properly in focus.

04-25-2014, 03:40 AM   #5
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I find the 300/4 STak is much better than the 300/6.5 TeleTak. But I also find it is not particularly easy to get good results. So I will not get any longer ones in the series. I have most of the shorter ones and most of those are much better. The 200/4 SMCTak is fairly easy to use on the K3 but was difficult on the K100DS - focusing.
04-28-2014, 01:05 PM   #6
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The only thing I ran into with this lens was the 270 degree focus throw. I had a heck of a time focusing quickly enough. But that's just me. My ST 300 f/4 was sharp as a tack! A new feature in LR 5 is one click removal of any CA. Just my two cents.
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