[neweinstein]

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hello,

as this is my first post in this forum so I hope I won't scare you too much

I'm looking for a longer tele prime as an addition for my setup.

I now have a Sigma 70-300 APO and a Tokina 400/5.6 manual focus.
I will buy a Tamron 70-200/2.8 with a Kenko 1.5x TC soon.

now I'm looking for a long AF tele to replace the Tokina.

I'm just not quite sure wich path to go:

1) get a 300/4 (Sigma APO, Pentax F(A)*) and use the TC to get a 450/5.6
2) get a 400/5.6 (Sigma APO, Tokina A-TX) and use the TC to get a 600/8

what do you think? 300/4 is also occupied by Tamron with TC, so a 400/5.6 would get me a more suitable range (and its longer, espacially with TC)
But a 300/4 with TC would have a better image quality at 300mm, but I may loose quality at 400/450mm because I have to use a TC to get there...

hmmmm

thanks for your help

PHILIP

[Lowell Goudge]

If you are going to base the new system on the 70-200mm F2.8, and a 1.4x TC, then I would look for something much faster at 300mm than F4.

as for a 400F5.6, I don't know what TCs tamron have, but I have an older sigma APO 70-200 F2.8 EX (non DG non Macro) and use it very successfully with both sigma 1.4x and 2x TCs. I see no need to get a dedicated 400mm F5.6

Again, even with a 1.4x TC in addition to the F5.6 lens you won't have AF at 600mm F8, or if you do, it will be chancy at best.

Your best bet, and I am sure you don't want to hear it is to get an older sigma 70-200 F2,8 screw drive focus lens, get teh sigma TCs and then get a new 300 F2.8 which will also work with both sigma TCs.

[neweinstein]

The old sigma 70-200 is not interesting. The Tamron get better image quality then the Sigma ones and is said to work very well with the Kenko Konverter. A Sigma 300/2.8 is a dream but not affordable for me at these days.

PHILIP

[Lowell Goudge]

The old sigma 70-200 is not interesting. The Tamron get better image quality then the Sigma ones and is said to work very well with the Kenko Konverter. A Sigma 300/2.8 is a dream but not affordable for me at these days.

PHILIP

I am not so sure about image quality. I have not seen any photos that impress me to change from my origonal sigma.

[Ash]

Welcome to the forum Philip.
The new HSM version of Sigma's 70-200 is probably the one that comes under the most scrutiny as its IQ is somewhat less impressive than the old non-HSM versions. The Tamron 70-200 is likely to be on par with the old Sigma in terms of IQ, but also has closer focusing ability.

In any case, your telephoto options are tough, but having a 1.4x TC shouldn't noticeably decrease the IQ from your original lens, so I'm not swayed either way - it'd really depend on how much reach you are after in this telephoto. Of course, the more reach, the smaller the maximum aperture (generally) and the harder it will be to maintain useable AF function with a TC. So if just for AF function, the 300/4 + TC would work better than a 400/5.6 + TC (if that will work at all).

[Lowell Goudge]

re the use of TCs and sharpness of sigma lens

see the following thread, where someone asked about the sigma 70-200F2.8.

I posted 3 shots taken with the origonal non DG non macro version.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/87439-sigma-70...-55-300-a.html

I am not sure you can do better with any other lens out there.

As for using a TC on an F5.6 lens, the cameras can't focus with that combo. AF is really only good to F6.7 not F8.,

Many TC's are not gauranteed to even work that slow.

the pentax 1.7x AF TC is only "gauranteed" to work on F2.8 lenses, i.e. F4.5 resultant aperture, although we all know it works perfectly on F4 lenses and has since it;s introduction in 1990.

The sigma data sheet declares for any lens slower than F4.5 (for ALL camera manufacturers), that the 1.4x will only offer MF, and the same is true for 2x TCs on all lenses slower than F2.8

[David07]

re the use of TCs and sharpness of sigma lens

see the following thread, where someone asked about the sigma 70-200F2.8.

I posted 3 shots taken with the origonal non DG non macro version.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/87439-sigma-70...-55-300-a.html

I am not sure you can do better with any other lens out there.

As for using a TC on an F5.6 lens, the cameras can't focus with that combo. AF is really only good to F6.7 not F8.,

Many TC's are not gauranteed to even work that slow.

the pentax 1.7x AF TC is only "gauranteed" to work on F2.8 lenses, i.e. F4.5 resultant aperture, although we all know it works perfectly on F4 lenses and has since it;s introduction in 1990.

The sigma data sheet declares for any lens slower than F4.5 (for ALL camera manufacturers), that the 1.4x will only offer MF, and the same is true for 2x TCs on all lenses slower than F2.8

Hello Philip,

I agree with this. If your goal is to have autofocus with a long tele lens, adding a TC on a 400/5.6 is not a good idea as it most probably won't AF.

If you will buy a non-HSM 70-200/2.8 + 1.4X or 1.5X TC, also buying a 2X TC may be a good idea and give you the reach you need.

Another possibility is the Pentax DA* 300/4. Very good image quality, but because of SDM, some people are having trouble with AF when used with Tamron 1.4X/Kenko 1.5X. For me, it is ok with my Kenko 1.5X in very good light. However, when I need more reach than 300mm, I prefer using the DA* 300 with the Pentax-F AF 1.7X TC. AF works very well and IQ still good. Sure, contrast suffers from the addition of the TC, but pictures are still sharp.

Some people are also happy using the Sigma 100-300/4 +1.4X TC.

[neweinstein]

Hello Philip,

I agree with this. If your goal is to have autofocus with a long tele lens, adding a TC on a 400/5.6 is not a good idea as it most probably won't AF.

If you will buy a non-HSM 70-200/2.8 + 1.4X or 1.5X TC, also buying a 2X TC may be a good idea and give you the reach you need.

Another possibility is the Pentax DA* 300/4. Very good image quality, but because of SDM, some people are having trouble with AF when used with Tamron 1.4X/Kenko 1.5X. For me, it is ok with my Kenko 1.5X in very good light. However, when I need more reach than 300mm, I prefer using the DA* 300 with the Pentax-F AF 1.7X TC. AF works very well and IQ still good. Sure, contrast suffers from the addition of the TC, but pictures are still sharp.

Some people are also happy using the Sigma 100-300/4 +1.4X TC.

yes, maybe the 400/5.6 wont give AF with TC. But I have the possibility to go to 600mm. And I think I will have better IQ at 400mm than with 70-200 + 2xTC or 300/4 + 1.5TC. But I also thought about getting a 2x TC for "light travelling" :-)

DA* 300/4 is too expensive and I want to get a TC solution that works well. Thats why I'm thinking more of a F(A)* 300/4.5 or a Sigma 300/4 APO for this position. The Sigma 100-300 is very expensive and would have a huge overlap with the 70-200

so for me it's more: 300 or 400?

PHILIP

[netuser]

For birds ? The longer the better

[netuser]

Seems finding one FA*400/5.6 is quite impossible

I'm looking for one almost for a year now

[jogiba]

For birds ? The longer the better

1480mm F6.3:
[yt]http://www.youtube.com/watch?v=UJcI2uDOMCc[/yt]

[Oggy]

TCs are really not the way forward. They will stuff your autofocus and image quality. A crop from my 300 without the TC will make a picture with the TC look fairly sad.

Another thought for you - the Sigma 150-500 is a lot less than the 100-300, but will produce a remarkably good picture when you know haw to use it.

[Lowell Goudge]

TCs are really not the way forward. They will stuff your autofocus and image quality. A crop from my 300 without the TC will make a picture with the TC look fairly sad.

Another thought for you - the Sigma 150-500 is a lot less than the 100-300, but will produce a remarkably good picture when you know haw to use it.

I think it depends upon the TC and the lens. The sigma TCs are designed specifically to work with only ha handfull of their long tele's and zooms. They are not general purpose teleconverters, As a result, and since they only work with a small number of lenses (all of which have similar design philosophy) they work very well together.

Go look at the shots I linked to.

but this is with a very good lens to start with,.

ALso the BIGMA gets soft above 400mm from what other members have posted/

[pentaxman]

If you go the Sigma 400/5.6 route, be aware that there are several versions that were produced over the years. The Sigma 400/5.6 non-APO is a mediocre lens. The Sigma 400/5.6 APO is an OK lens, but nothing special. The Sigma that you want is this one:

PentaxForums.com Third-Party Pentax Lens Review Database - 400mm f5.6 Tele-Macro AF

I just bought one a month ago. It was ranked better than the Pentax FA* 400/5.6 by Photodo. It is an amazingly sharp lens and it will do 1:3 Macro from over 5 feet away! They are very hard to find in Pentax mount, though.

Here is a moon picture I took with it recently:



It is a JPEG straight from the camera with no post processing.

[neweinstein]

Seems finding one FA*400/5.6 is quite impossible

I'm looking for one almost for a year now

http://cgi.ebay.de/SMC-Pentax-FA-400mm-F5-6-ED-IF_W0QQitemZ330395175973QQcmd...item4ced164c25

but that's waaaay to expensive for me

PHILIP