2X teleconverter

Started Oct 3, 2010 | Discussions
Charlie Self
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2X teleconverter
Oct 3, 2010

An old friend is buying a K7 and a couple of lenses. One of the lenses is the Tamron 90mm macro. She wants to add a teleconverter, preferably 2X, to it.

Tamron says theirs does not work with that lens.

Does anyone know of one that does?

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JohnBee
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Re: 2X teleconverter
In reply to Charlie Self, Oct 3, 2010

2x Vivitar Macro TC works.
Pentax SMC-AF 1.7x works.

Those are the ones I've tried that worked.

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Charlie Self
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Re: 2X teleconverter
In reply to JohnBee, Oct 3, 2010

Thanks, John!

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Greyser
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Re: 2X teleconverter
In reply to Charlie Self, Oct 4, 2010

2X TC is not a best choice to enhance the macro ability of your lens. It's not flexible solution and it's very hard to focus. All macro lenses have shallower DOF than usual lenses. 2X TC will make it even twice shallower. The better answer is much cheaper set of extension rings or bellows. I'm not sure how good would be macro close-up lens (like RAYNOX DCR-150/250) paired with very sharp Tamron 90mm. But it's possibly a third option. I personally prefer the bellows. It gives you much more flexibility in one package then rings or lens.

The first image below is quick and dirty hand held shot of something on my fig tree that I made today for you with Tamron 90mm and BOWER MC7 2X Pz/AF TC (identical to Vivitar MC7, but cheaper a bit). The combo does not focus well at AF, if you count on it. The manual focus is also very hard. To get the final focus I just simply pre-focused it manually and then acquired the right spot, moving myself with the camera. You can shoot the same image much less painfully with regular macro lens and then crop it to needed size. The second shot is the same part of a fig tree taken with Tamron 28-75mm macro at 75mm (gives you deeper DOF) and a bellows. I did not have time to tweak my bellows for similar magnification, but, hopefully you'll see the difference.

P.S. The 2X TC is mostly helpful for long zoom shots to have more reach from 300-400mm F/2.8-4 lenses.
My Regards,
SG

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MightyMike
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Re: 2X teleconverter
In reply to Greyser, Oct 4, 2010

I recommend extension tubes with the pin contacts.
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Greyser
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Re: 2X teleconverter
In reply to MightyMike, Oct 4, 2010

Mike, what are the advantages of extension tubes/rings over bellows? I haven't used the pinned ones. Is AF available, or just aperture control? Usually AF is useless at macro shooting anyway. To me the the flexibility of focal length adjustment on the bellows with a sturdy rail looks more convenient than constantly changing extension tubes.
SG

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Pacerr
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Re: 2X teleconverter
In reply to Charlie Self, Oct 4, 2010

There seems to be an assumption here that the TC is for Macro use only.

If that's the case, I much prefer a "gutted" (optics removed), AE-capable TC as a functional extension ring that pretty much doubles the close-up factor.

No reason to disregard the idea of a compact 180mm using the 90mm plus 2X TC. I find the Tamron SP 90mm/2.5 Adaptall paired with either of the the Tamron 1.4X Tc options to be a very compact way to carry what amounts to a 135mm/F3.5 with excellent close-up capability and versatility. The 1.4X TC is much more interesting (and SMALLER) than adding the DA 50-200 or other much larger and heavier options to my field pack.

The 2X TC is also satisfactory paired with the 90mm's, but if I expected to use that FL range I'd carry my SP 180mm PLUS the extension ring and have the 1.4X TC along anyway.

But I'd suggest exploring the excellent "near-macro", close-up capability of the Tamron 28-75 or DA 16-46 to add even more versatility to the lens options rather than adding a high end TC. I find either of those lenses handle anything I want to get close to now short of technical stuff.

A $30, 2X, AE-capable TC with the optics removed adds noteworthy flexibility to every lens you own that's worth using for close-ups and since there's no glass anyway it doesn't make any difference what the optic quality is (was)!.

H2

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Gerry Winterbourne
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Re: 2X teleconverter
In reply to Charlie Self, Oct 4, 2010

Charlie - I can't answer the specific question because I don't have the Tamron 90 macro: I use the Sigma 105 and DA35 macro lenses + other DA non-macro lenses for flower close-up/macro shots.

Others have commented on alternatives to TCs or problems with them. My experience is more positive. I use extension tubes too so my views aren't biased either way.

Resolution : the glass in a TC inevitably causes some deterioration in resolution. However, as long as it is decent one the loss is rarely significant. I think this is because of the way the AA filter and interpolation work: although lens softness and aberrations are doubled at the sensor with a 2X TC, this is before the AA etc, so once the image is processed the effects are less.

This review from Photozone is the only one I can find with a measured result (he also does on Canon mount). http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/369-sigma-af-100-300mm-f4-nikon?start=1

The resolution using a 1.4X TC varies slightly between f/stop and Nikon or Canon but it averages as about 10% loss. Shooting without TC and cropping to the same size would give a 40% loss so the TC is still advantageous. I have done non-measured tests with my lenses and various TCs and I always get better results from the TCs than from cropping.

Focus range : Extension tubes physically move the glass away from the sensor. This restricts the focus range - often you have to move the camera for focus because it can't reach even a few feet, never mind infinity. For studio work this isn't a problem but it's a pain walking round a garden. Where focus is achieved there is, of course, no degradation of IQ.

DOF : at close ranges this is always restricted, so TC or tube makes little difference. If your friend is into PP she might find focus stacking useful.

I haven't used bellows, although I'm tempted. They must be great for fine focus but it is their bulk that puts me off.

Just to show I'm not biased here's a shot using both 2TX and extension tubes. f/13 and the DOF barely covers the end of the ink/ball section.

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Tan68
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Re: 2X teleconverter
In reply to Gerry Winterbourne, Oct 4, 2010

this answers a question i have had... (TC v. crop, macro or not). thanks.

Gerry Winterbourne wrote:

This review from Photozone is the only one I can find with a measured result (he also does on Canon mount). http://www.photozone.de/nikon--nikkor-aps-c-lens-tests/369-sigma-af-100-300mm-f4-nikon?start=1

The resolution using a 1.4X TC varies slightly between f/stop and Nikon or Canon but it averages as about 10% loss. Shooting without TC and cropping to the same size would give a 40% loss so the TC is still advantageous. I have done non-measured tests with my lenses and various TCs and I always get better results from the TCs than from cropping.

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Gerry Winterbourne
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Interesting web link
In reply to Charlie Self, Oct 4, 2010

This article about TCs in general is quite interesting. Although based on Canon equipment I think the conclusions are pretty universal. In a nutshell: good lenses (such as macros) can benefit from TCs; poor ones can't.
http://www.bobatkins.com/photography/tutorials/tc3.html

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Gerry

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duncsuss
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Re: 2X teleconverter
In reply to Charlie Self, Oct 4, 2010

Charlie Self wrote:

One of the lenses is the Tamron 90mm macro.

Which version of the Tamron 90mm macro? The original (manual focus) Adaptall-2 lens, or one of the autofocus versions of more recent vintage?

The version I used to own, the Adaptall-2 SP 90mm/2.5 (model #52B), came with a Tamron Adaptall 2x teleconverter (model # 01F) and it worked just fine.

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Duncan

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MightyMike
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Re: 2X teleconverter
In reply to Greyser, Oct 4, 2010

Greyser wrote:

Mike, what are the advantages of extension tubes/rings over bellows?

aren't most bellows M42? or are there M and K mount bellows? the issue with bellows although flexible its big bulky and the unit isn't always easy to find without holes

I haven't used the pinned ones. Is AF available, or just aperture control?

There is an extremely hard to find set of Kenkos that actually had the AF ability but as you said below AF is useless, its good when using a non-macro lens that you want to make focus closer though. easier to find but still hard are the ext. tubes with the aperture pins, then the M42/M/K ext. tubes are all over the place.

Usually AF is useless at macro shooting anyway. To me the the flexibility of focal length adjustment on the bellows with a sturdy rail looks more convenient than constantly changing extension tubes.

I use all 3 ext. tubes on my F 100mm F2.8, i get 2:1 magnification if i set the lens to 1:1, i get 1:1 magnification if i set the lens to 1:4 (i think, have to check again) and then much less then 1:1 if i set the lens to infinity so from moderate close-up to double life size and i don't have to take the extension tubes off, kinda makes me wonder what you're actually doing with the bellows unless you use a non macro lens with limited focusing range to begin with

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Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

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Greyser
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Re: 2X teleconverter
In reply to MightyMike, Oct 5, 2010

MightyMike wrote

aren't most bellows M42? or are there M and K mount bellows? the issue with bellows although flexible its big bulky and the unit isn't always easy to find without holes

I recently bought a new PK-mount bellows from e-Bay (somewhere from Hong Kong or Singapore, I believe) for about $39, free shipping. It works just fine with Tamron 90mm, Tamron 28-75mm, and DA 16-45. If you are interested, I can dig up the seller's link. The leather is not genuine though ;-).
SG

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MightyMike
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Re: 2X teleconverter
In reply to Greyser, Oct 5, 2010

I'm willing to take a look, see whats out there
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Mike from Canada

'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

http://www.airliners.net/search/photo.search?sort_order=views%20DESC&first_this_page=0&page_limit=180&&emailsearch=mighty_mike88%40hotmail.com&thumbnails=

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KentG
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Re: 2X teleconverter
In reply to Greyser, Oct 5, 2010

For the best of both worlds manually I recommend getting the Vivitar 2x Macro-Focusing Teleconverter and removing the optics. That way you will have an infinitely variable extension tube that should give as much as 4:1 on a 1:1 macro lens.
Kent Gittings

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Anastigmat
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Re: 2X teleconverter
In reply to Pacerr, Oct 5, 2010

Pacerr wrote:

There seems to be an assumption here that the TC is for Macro use only.

That is correct. We must not forget that all Pentax DSLR cameras are APS-C. That means diffraction is going to limit resolution to 7mp no matter what, if f/11 is used. Who would use anything wider than f/11 to photograph macros anyway? Therefore, for all practical purposes, a TC would not degrade image quality since the limiting factor is not the lens but the sensor. Slap a good quality TC on a macro lens, any you end up with higher resolution than the sensor can resolve anyway.

OTOH, if you are using a full frame DSLR, diffraction is less of a factor, and the sensor can resolve 16mp at f/11. If you use a TC with a macro lens, you are going to reduce the resolution of the macro lens from around 100 line pair/mm to about 50 lp/mm. That combination may therefore have a noticeable effect on the sharpness of the image.

In sum, don't worry about using TC (high quality of course) when shooting with a Pentax camera and a top notch macro lens like the Tamron. Only worry if you are zoom lens with a TC to shoot macro.

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Anastigmat
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Re: 2X teleconverter
In reply to Charlie Self, Oct 5, 2010

There are many versions of the Tamron 90mm macro lens. The original was a 90mm f/2.5 with a 49mm filter. That was replaced by a 90mm f/2.5 with a 52mm filter. Both versions are adaptall lenses with changeable mounts. There was a 2x SP adaptall teleconverter with 6 elements designed for this and other SP tele lenses. This teleconverter should fit and yield reasonably good results.

Later, the Tamron 90mm macro was made in AF versions, with a max aperture of f/2.8. An adaptall version was also made, presumably with the same optical design as the AF versions. The adaptall teleconverters of course won't fit on the AF lenses, but there is no reason why Tamron's AF teleconverter would not fit on the AF 90mm or even the Tamron 90mm adaptall versions with the correct mount in place. Therefore what you quoted Tamron does not make sense.

Fact is that Tamron's AF teleconverter should work with all versions of their 90mm macro lenses.

Charlie Self wrote:

An old friend is buying a K7 and a couple of lenses. One of the lenses is the Tamron 90mm macro. She wants to add a teleconverter, preferably 2X, to it.

Tamron says theirs does not work with that lens.

Does anyone know of one that does?

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Greyser
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Re: 2X teleconverter
In reply to MightyMike, Oct 5, 2010

Could not confirm exact seller name. I deleted an e-mail already. I believe there is the one, but not sure 100%: http://cgi.ebay.com/Macro-Bellow-Pentax-PK-K-M-K-7-K20D-K10D-K200D-K-X-/250675738707?pt=Lens_Accessories&hash=item3a5d703853#ht_2055wt_1000

If the link doesn't work, search e-Bay on this item: Macro Bellow For Pentax PK K-M K-7 K20D K10D K200D K-X
good luck
SG

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Charlie Self
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Re: 2X teleconverter
In reply to Anastigmat, Oct 5, 2010

Anastigmat wrote:

There are many versions of the Tamron 90mm macro lens. The original was a 90mm f/2.5 with a 49mm filter. That was replaced by a 90mm f/2.5 with a 52mm filter. Both versions are adaptall lenses with changeable mounts. There was a 2x SP adaptall teleconverter with 6 elements designed for this and other SP tele lenses. This teleconverter should fit and yield reasonably good results.

Later, the Tamron 90mm macro was made in AF versions, with a max aperture of f/2.8. An adaptall version was also made, presumably with the same optical design as the AF versions. The adaptall teleconverters of course won't fit on the AF lenses, but there is no reason why Tamron's AF teleconverter would not fit on the AF 90mm or even the Tamron 90mm adaptall versions with the correct mount in place. Therefore what you quoted Tamron does not make sense.

Fact is that Tamron's AF teleconverter should work with all versions of their 90mm macro lenses.

My friend has already placed her order. I didn't ask the contents, but my bet is it's the newest version of the Tamron 90 that she ordered, along with a few thousand bucks of other gear. Unfortunately, Adorama is holding the order until her credit clears--she and her husband bought a new house in May, so Adorama's people cannot find them in the phone book.

You want to talk about pi$$ed? She's unhappy, and now so am I, because I recommended Adorama as one of two places in NYC where a Texan, albeit a former New Yorker, could expect good service and fair treatment.

She may get the gear in time for her vacation, but she won't get any shakedown or practice time with it. Nor, I'm convinced, will she order from Adorama again, though that's not because of the hold. Yesterday, she was about six phone calls into a runaround on getting this straightened out. No one could answer her questions. Not good customer service, IMO.

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