Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-14-2009, 11:31 AM   #496
Veteran Member
Miserere's Avatar

Join Date: Sep 2007
Location: Boston
Photos: Gallery
Posts: 1,994
QuoteOriginally posted by apisto Quote
Was the Tamron 1.4 MC4 teleconverter originally made to be mated with a particular lens?
I don't think so. It was probably a general purpose TC.

08-20-2009, 10:49 AM   #497
Senior Member
Malsi's Avatar

Join Date: Aug 2009
Location: Elancourt (close to Versailles)
Posts: 225
Hi,

I would like to by a Teleconverter (my lenses: Sigma 70-300, Pentax 50mm 1.4 and 18-55 II. I will receive a 28-300 next week). I've seen this offer on eBay: 2x TeleConverter for Pentax K20D K200D K2000 Camera NEW en vente sur eBay.fr (fin le 15-sept.-09 14:46:01 Paris). Do you think that it is a good product?

My budget is limited; I can also buy a used or refurbished one.

Thank you for your help and your good links.

Regards.

Malsi
08-20-2009, 11:28 AM   #498
Veteran Member
Ben_Edict's Avatar

Join Date: Jul 2007
Location: SouthWest "Regio"
Photos: Albums
Posts: 3,303
QuoteOriginally posted by Malsi Quote
Hi,

I would like to by a Teleconverter (my lenses: Sigma 70-300, Pentax 50mm 1.4 and 18-55 II. I will receive a 28-300 next week). I've seen this offer on eBay: 2x TeleConverter for Pentax K20D K200D K2000 Camera NEW en vente sur eBay.fr (fin le 15-sept.-09 14:46:01 Paris). Do you think that it is a good product?

My budget is limited; I can also buy a used or refurbished one.
Hi Malsi, the Kenko is at least a brand product. But the MC7 vertsion from Kenko is sure better. Nevertheless my personal opinion is, that neither the 70-300 nor the 28-300 lenses are suited for combination with a 2x teleconverter (and the 18-55 even less). They are too slow to start with and 2x teleconverters further degrade their image quality. At max. I would buy a 1.4x tc for the 70-300. You end up with 420mm (if you buy the Tamron 1.4x tc) or 450mm if you go for the Kenko 1.5x modell.
08-20-2009, 12:26 PM   #499
Veteran Member
Miserere's Avatar

Join Date: Sep 2007
Location: Boston
Photos: Gallery
Posts: 1,994
What Ben said. This TC isn't worth buying with the lenses you have, and probably still not worth it even with a good prime lens.

08-20-2009, 12:53 PM   #500
Veteran Member




Join Date: Sep 2008
Location: Bhavnagar (Gujarat),India
Photos: Gallery
Posts: 338
What an amazing thread!!!

34 pages with messages and all are full with very vital info and great images. This thread is kinda "teleconverter for dummies" material.

After reading this thread I am convinced that Lens+TC is still a usable solution in many situations.

How to find Tamron 1.4x TC nowadays (only ebay?)?
How good is Kenko 1.5x TC that is only MC version for 99$ on B&H?
How good is Pentax 1.7x TC which is rare to find? what could be good price for that?



Atindra
08-20-2009, 02:20 PM   #501
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,631
QuoteOriginally posted by Atindra Quote
After reading this thread I am convinced that Lens+TC is still a usable solution in many situations.
I only read about 20 pages, but I didn't see what I always need to see... evidence that the TC is helping. Yes, there are some great photos in this thread, but I didn't see a comparison of cropping vs TC. Maybe it was in one of the pages I didn't view?

I've seen a few comparisons of crop vs TC for consumer grade lenses, and in every instance cropping was the better solution; better resolution, more contrast, less CA. Can anyone show me that their TC on a consumer grade telephoto (DA 55-300, 18-250, 70-300) actually helps?
08-20-2009, 02:45 PM   #502
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
Dan, it's unfair to compare IQ between a 70-200 and a consumer-grade telephoto like the DA 55-300 with or without a TC, but it's pretty obvious (and clear in the images from each lens) which produced the better images in ALL aspects.

I've tried my Tamron 1.4x TC with the DA 55-300, and found a MUCH more sluggish AF, but no obvious degradation in sharpness or contrast (as long as EC is boosted a little).

I've also tried the TC buddied on my Tamron 70-200 and found AF just as fast as if the TC were not on it, and again, no discernible IQ compromise.

But my litmus test (and as given above, albeit an unfair one), was to know whether the TC + 70-200 produced any better images than my 55-300, particularly at 135mm on the 70-200 (apparently its weak spot) and 200mm on the 55-300.

Whilst I won't post images to back up my claim, one could reasonably believe that regardless of the FL and comparative aperture setting, the 70-200 + TC images were better contrasted, better coloured and sharper (less obvious of course around f/8, where the 55-300 starts shining).

Though to answer your question, AFAIK a 1.4x TC should not make matters worse for a consumer telephoto (except in AF performance), but I'm not sure the images you get from the combination will leave you smiling for long...
08-20-2009, 03:02 PM   #503
Pentaxian
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,862
QuoteOriginally posted by audiobomber Quote
I didn't see a comparison of cropping vs TC.
Your question is valid. But nobody seems to care. I found it strange as well but I won't argue anymore.

Actually, a serious test would be required to find out. Even with a perfect TC, an image from a 1.4x TC (when pixel-peeped at 100%) will look like an image w/o TC on a 28.6 MPixel sensor. And a real TC will be worse, say like on a 35 MPixel sensor.

So, by restricting your question to consumer zooms, you already gave the answer ...

TCs are for execellent prime lenses or film or 6-10 MPixel sensors.

Except that a TC may help to achieve better AF accuracy.

08-20-2009, 03:16 PM   #504
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,631
QuoteOriginally posted by Ash Quote
Whilst I won't post images to back up my claim, one could reasonably believe that regardless of the FL and comparative aperture setting, the 70-200 + TC images were better contrasted, better coloured and sharper (less obvious of course around f/8, where the 55-300 starts shining).

Though to answer your question, AFAIK a 1.4x TC should not make matters worse for a consumer telephoto (except in AF performance), but I'm not sure the images you get from the combination will leave you smiling for long...
I wasn't trying to compare a 7-200 + TC with a 70-300, but it's an interesting thing to hear anyway.

I was asking about a consumer zoom (F4.0 to F5.6, 5.8 or 6.3) and a TC, vs cropping with the same lens. As I said, I've seen a number of these comparisons, and the cropped version always wins. Here's one that still has the test photos attached:

LBA - DA55-300 obligatory 1st shots [Page 1]: Pentax SLR Talk Forum: Digital Photography Review

And Richard Day's conclusion using a 55-300mm and Tamron 1.4X TC:

The one with the TC shows a reduction in sharpness and IQ compared to not using a TC. In other words cropping gives a sharper result and better IQ. Personally I wouldn't use a TC with this lens and the Tamron is about as decent a TC as you can get.

This jibes with other tests I've seen in the same vein using consumer telezooms. My opionion based on these tests is that a consumer grade 18-250, 70-300, 55-300 etc will be degraded by adding a TC.
08-20-2009, 03:25 PM   #505
Ash
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,679
Probably more pertinent to the consumer grade zooms, whereas I wouldn't say the same with the 70-200s, ie. a 70-200 + TC doesn't degrade the image yet provides an extra 80mm of FL, which IS handy in things like concerts and events where you have to be some distance away from the action (and a consumer lens just couldn't fit the bill).
08-20-2009, 03:31 PM   #506
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,631
QuoteOriginally posted by falconeye Quote
Actually, a serious test would be required to find out. Even with a perfect TC, an image from a 1.4x TC (when pixel-peeped at 100%) will look like an image w/o TC on a 28.6 MPixel sensor. And a real TC will be worse, say like on a 35 MPixel sensor.

So, by restricting your question to consumer zooms, you already gave the answer ...
Could you explain in more detail? I'm not following.

QuoteOriginally posted by falconeye Quote
TCs are for execellent prime lenses or film or 6-10 MPixel sensors.

Except that a TC may help to achieve better AF accuracy.
Well, I did run out of pixels frequently when trying to photograph birds with the K100DS. A TC would have helped with that. Manual focussing may have been easier but the TC causes a darker viewfinder, no?
08-20-2009, 04:29 PM   #507
Pentaxian
falconeye's Avatar

Join Date: Jan 2008
Location: Munich, Alps, Germany
Photos: Gallery
Posts: 6,862
QuoteOriginally posted by audiobomber Quote
Could you explain in more detail? I'm not following.
My fault.
What I meant is this:

Consider image A: the lens projecting the image onto a 14.6. million pixel sensor, no TC.

Consider image B: the lens projecting the image onto 14.6. million pixel sensor, now with a perfect 1.4x TC.

Consider image C: the lens projecting the image onto 28.6 million pixel sensor, no TC. And then cropped to inner 14.6 million pixels (1.4 x 1.4 x 14.6 = 28.6).

(All sensors same size like APS-C).

Then, image B and C must look identical (please, think about it).

So, to answer if it has same pixel peep qualities as image A, just answer the question if the lens would still outresolve a 28.6 MP sensor.
QuoteOriginally posted by audiobomber Quote
Well, I did run out of pixels frequently when trying to photograph birds with the K100DS. A TC would have helped with that. Manual focussing may have been easier but the TC causes a darker viewfinder, no?
A TC goes much better with a K100D than a K20D. Yes, the TC makes you loose one stop brightness in the VF. But I meant AF actually. And brightness available to the AF sensors remains the same because they work at f5.6.
08-20-2009, 10:05 PM   #508
Veteran Member




Join Date: Sep 2008
Location: Bhavnagar (Gujarat),India
Photos: Gallery
Posts: 338
QuoteOriginally posted by audiobomber Quote
I only read about 20 pages, but I didn't see what I always need to see... evidence that the TC is helping. Yes, there are some great photos in this thread, but I didn't see a comparison of cropping vs TC. Maybe it was in one of the pages I didn't view?

I've seen a few comparisons of crop vs TC for consumer grade lenses, and in every instance cropping was the better solution; better resolution, more contrast, less CA. Can anyone show me that their TC on a consumer grade telephoto (DA 55-300, 18-250, 70-300) actually helps?
There is still an advantage of using TC over cropping specially for shooters who dont have whopping 14.6MP sensors.
I have K100D which is 6.1 MP and I have DA 50-200mm lens, now suppose I shoot at 200mm. To achieve 300mm equivalent I need to crop 1.5x this 6.1MP image.
This would give me 4.07MP image with magnification equivalent to 300mm. To achieve 400mm, similarly I need to crop it by 2x factor and that would give me 3.05 MP image.

While with TC I wont loose any pixel to achive magnification, all I will loose is f-stop and therefore with fast lenses TC is very much useable while with slow consumer zoom lenses one need lot of light to use TC. And therefore if one go by all the consumer xx-300mm lens shots achieved with TC, they all are in very good light.

Atindra
08-20-2009, 10:25 PM   #509
Pentaxian
jgredline's Avatar

Join Date: Oct 2007
Location: LosAngeles, Ca.
Photos: Albums
Posts: 10,530
Original Poster
Personally, I will only use a TC when I really need it...I avoid them when I can..But if you need it then you need it...Will a TC improve image quality? I can't imagine it would...How can it if your adding more glass? The best TC is the tamron 1.4mc-4 and at that you still loose a full stop of light. A TC is not meant to replace a long lens, but to enhance what you already have.
Example. The 70-300Sigma APO lens and 1.4tamy tc is a great combo to get 420mm, but it will still not outperform my 400mmF/5.6APO sigma lens in speed or quality...
08-21-2009, 01:38 AM   #510
Veteran Member
Ben_Edict's Avatar

Join Date: Jul 2007
Location: SouthWest "Regio"
Photos: Albums
Posts: 3,303
QuoteOriginally posted by jgredline Quote
Personally, I will only use a TC when I really need it...I avoid them when I can..But if you need it then you need it...Will a TC improve image quality? I can't imagine it would...How can it if your adding more glass? The best TC is the tamron 1.4mc-4 and at that you still loose a full stop of light. A TC is not meant to replace a long lens, but to enhance what you already have.
Example. The 70-300Sigma APO lens and 1.4tamy tc is a great combo to get 420mm, but it will still not outperform my 400mmF/5.6APO sigma lens in speed or quality...
Javier, your comment supports the general experience: consumer zooms and tele converters don't mix well, independent how good the tc is.

Ash is quite right: the sensible application of a tc is, to multiply the longest prime fl on hand. Otherwise only matched tcs for certain zooms give really good results, like the old Sigma 70-200/2.8 with the two Sigma Apo tcs. These combinations show no evidence at all of a quality loss.

Consumer zooms in genral are more compromised in IQ (due to cost restrains) and the tc will multiply (and make visible) the inheren abberrations of these lenses. Secondly they are too slow to use a tc, which not only affects shutter speed (or afffords high ISO settings, with increased noise), but also AF speed and reliability. Too iften I read, that this and that combinations "works great", just to read in the next line, that AF will only lock in bright sunlight etc.

Many people will not realize the limitations of these combos, because they invested their hard earned money... I symphathize - nevertheless consumer zooms and tcs are only a very poor compromise.

In most situations the photographer would get better results, when buying an el cheapo low-end longer prime, like the ubiquos 400/6.6 full manual lenses to complement his 70-300 (or the like) zoom.

Ben

P.S.: by the way, in my own experience the best tcs for Pentax are the two Pentax A L-modells... though without AF.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
di, k-mount, k100d, lens, pentax lens, pics, shot, sigma, slr lens, tamron, tc
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
misty tamron 2x converter richardk20d Pentax SLR Lens Discussion 0 08-25-2009 12:47 AM
Tamron 1.4x pz-af mc4 converter on f2.8 jon pafford Pentax SLR Lens Discussion 7 11-13-2008 11:03 PM
tamron af 1.4 converter jon pafford Pentax Camera and Field Accessories 0 11-17-2007 08:36 PM
Tamron SP 2x converter Shelob1 Pentax SLR Lens Discussion 10 09-26-2007 12:13 PM
Tamron converter or new lens? WMBP Pentax DSLR Discussion 11 12-14-2006 08:49 PM



All times are GMT -7. The time now is 10:15 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top