Tamron 200-400mm max aperture issue

[soulcarve]

Hi photoforum community, this is my first post as I just registered here today.

I acquired a Tamron 200-400mm 5.6 (for Nikon). I know, I know, I can hear everyone in the background saying, "Oh Gawd!".
Anyway, using my trusty old Nikon D100 this lens only reaches max aperture between 200-275mm (approximately). So, anything greater than 275mm, the aperture registers as f6, at least that is what the D100 is reporting. I know my camera is old, and I'm thinking of an upgrade soon. However, I have no problems with my Nikon/Nikkor 80-200 2.8 D lens -- (i.e., it will stay at 2.8 throughout the zoom range). I have no problems with other zooms.

Anyway, time is of the essence since I can return this for up-to 14 days. I will say the image quality is quite decent, and sharp for what it is.
I know some say that this lens is best at f8 and above, so it's likely I'll be stopping it down a bit. It does seem to hunt a bit, but I factored this
in for such a slow lens. I've played with focus, focusing at infinity etc, nothing seems to make a difference to reach f5.6 above 275mm.

NOTE: I will say, a fellow photog has a Sigma 70-210 2.8 , on his Nikon D80 his lens won't register 2.8 at all, it registers at f/3. So, I've seen this before in third party lenses.

So my questions are:
does this sound like the beginning of an internal aperture failure,
or is this par for the course with this lens?

Any help appreciated.

Thanks In Advance,
Rob

 

[Overread]

I don't have experience of this lens on Nikon, but its well known that a few of the lenses (sometimes 3rd party, not always) do tend to stop down their effective aperture and miss-report a bit to the camera. It might just be that the f5.6 is a rough value or is based upon the aperture only at a specific focusing distance (normally these things are set where the focus is at infinity) and that focusing the lens closer causes the effective aperture to reduce; ergo why its reporting f6.

Nikon tends to be a bit more sensitive to this than Canon -- you see a lot with Macro lenses where most of the current market options for prime true macro lenses report as f2.8 on the lens name; but in fact will stop down to around f5.6 when set to their closest focusing distance (part of the arrangement in how they focus closer). Canon never reports this (though of course the meter still reads the light correctly) whilst Nikon does.

 

[soulcarve]

I don't have experience of this lens on Nikon, but its well known that a few of the lenses (sometimes 3rd party, not always) do tend to stop down their effective aperture and miss-report a bit to the camera. It might just be that the f5.6 is a rough value or is based upon the aperture only at a specific focusing distance (normally these things are set where the focus is at infinity) and that focusing the lens closer causes the effective aperture to reduce; ergo why its reporting f6.

Overread,

Thank you for your prompt and informative reply. So, from what you are saying and my own experience, this is not uncommon for 3rd party lenses.
I sort of figured as much. It's not like I'm 2 stops off, and I wondered if there was some "rounding up values feature" built in to the lens. Headed to work here, but
I will check this thread later when I return home. Again, thank you!

 

[Overread]

There's actually lots of rounding up or odd things that happen with lenses. Quite a few shorten their stated focal length as they focus closer - some close down effective apertures etc.... Even two lenses at f2.8 can allow different levels of light through the whole setup due to varying t values.

Own brand or 3rd party all use these tricks and methods; part of it is giving us lenses that we want with certain features which require certain compromises - other times its budget and the simple fact that giving "perfection" would drive the complexity and the price of the lens up

 

[soulcarve]

... part of it is giving us lenses that we want with certain features which require certain compromises - other times its budget and the simple fact that giving "perfection" would drive the complexity and the price of the lens up

Thanks again Overread!

I agree, and have learned this lesson as it pertains to amateur astronomy as well -- but that's another story. However, what sort of threw me is the fact that this "does" register max aperture (e.g., 5.6) in at least part of the zoom range. Just didn't know if it was a real cause for concern as far as the internals go. For the reasonable price I paid, $150 w/large Tamrac case -- I'm happy. Hoping to acquire a Nikon 400/3.5 MF one of these days, but the used prices are still (to me at least) through-the-roof. For my weekend bird outings, in good light, this should keep me happy for a while.

I really do appreciate you taking the time to break this down for me.

BTW, I'll tell my buddy the next time I talk to him not to worry too much about that Sigma 70-210/2.8 either .

 

[Derrel]

The Nikkor 400mm f/3.5 ED-IF is a good performer in terms of handling and focusing...it's a lens that was built like a battle tank, but is also very slender in the main part of the entire barrel, so it's EASY to shoot from a monopod. Tamron also built a 400/3.5...but as I understand it's not optically as good as the Nikkor at wide apertures--BUT I suspect it might actually be BETTER than the 400/3.5 Nikkor when that lens is shot at f/5.6, the 400/3.5 Nikkor is NOT good at f/5.6--it actually drops in performance at f/5.6...it's BETTER wider-open. Which is a good thing. I'm not sure how good the 400/3.5 is on these new high-rez bodies...I've seen some reports of these older Ai and Ai-S superteles not being uop to snuff for use on today's high-high rez sensors...

The way that sensors are improving the last few years, that f/5.6 to f/6 aperture is not the huge limitation it WAS back in the ASA 64 to ASA 100 days...

 

[soulcarve]

Thanks Derrel! I've always wanted the Nikkor 400/3.5, I'll keep looking.
Good to know it'll handle well on my Manfrottopod (monopod), I love that thing.
For now ... the Tammy will have to do.

 

[Derrel]

Thanks Derrel! I've always wanted the Nikkor 400/3.5, I'll keep looking.
Good to know it'll handle well on my Manfrottopod (monopod), I love that thing.
For now ... the Tammy will have to do.

It is a simply SUPERB lens when used on a monopod...the balance is excellent! The front element group is big and heavy, and the central part of the tube is basically empty and nearly weightless, so it balances superbly with a body hanging off the back. It handles more-easily than the 300/2.8...it's truly a very,very easy "big-glass" lens to use, due to balance and physical size and placement of the controls. The manual internal focusing system is dreamy too. it focuses pretty quickly. I used mine mostly for track and field and baseball. It's a good lens for baseball...it's "light"...about 7 lbs...a 400/2.8 is around 15 lbs...