wide angle

Spoke to Nikon Rep Today.....
He said 17-35 is not parfocal either. So if i were You i would be more careful and invest 100% in some PL glass as i have.
Anyway your money will be safer in glass then camera.
p.s. Lastly - I have not worked as a film tech in rental department but i have worked for 28 years as a Lighting Cameraman. Cheers
 
Well... Avro you should send your Nikon tech to my house. Actually I should thank you because our stupid little pissing match made me go back with a chart and check my lenses with a 17" monitor. Granted a bigger monitor would be more precise and maybe I'll try that when i get a chance.
At first my 80-200 looked good as did the 11-16 but everythings in focus with that one.

Both my 17-35 and 28-70 focused closer at wide. So i made a shim out of a piece of paper and tried again and glory be they all hit the mark. So next I got an Allen wrench and adjusted the the back focus on the F3.
Yikes they are all Parfocal and adjusted on the F3 with my MTF adapter! All reach infinity also.

Thanks for kicking my butt.

Might I find some small discrepancy with a bigger monitor? Perhaps, but Generally I will be focusing each shot as well as I can anyway, and they are f2.8 lenses not 1.4's. I wouldn't trust marks on these lenses and that's a big difference between these and real PL's but for $1000 the glass is sharp and they are very functional for lots of purposes. I want them for when people need to move faster than they can with primes or want more flexibility and for run and gun work and handheld where primes are just a nuisance. Of course the 11-16 and 80-200 also improve the range beyond most primes sets. Were i shooting for big screen I would do test with a big monitor.

So the question remains why your 17-35 is not holding focus. Could be your specific lens or your Nikon camera. I don't expect QC to be very good on either and am frankly surprised that all four of mine hit the target.

I still need to check focus marks on the zooms and my Zeiss ZF's, but am very happy at this moment. I also sent a message to Nikon support asking whether these lenses were parfocal and could be adjusted but no response so far.

BTW- We have about the same number of years in the biz.

Lenny
 
Just checked my focus marks on the Nikon zooms and Zeiss ZF primes and a few Nikon primes as well. They are all pretty much right on except for the 11 - 16 which is way off reading much higher distances than are accurate , and the 80-200 which reads a few inches short. Again a little better than I expected from still lenses. Pretty good luck I think.
 
Hello Lenilenapi,
sorry for problems..............
I just ordered MTF e-mount to Nikon for my FS100. I hope i did not waste my money ...
I also ordered MTF PL mount adaptor for FS100. All up almost $1000 for 2 MTF adaptors-hope they will work.
Since i have got my PL zoooms i might sell my Nikons and use money towards some fast PL primes.(Russian)

regards Jiri
 
No problems , you kicked my ass to test stuff that I had been putting off. I finally know what my lenses are doing.

Good luck. Does the FS100 have a back focus adjustment?
 
I have Nikon primes and Tokina zooms. I'm wondering if the Tokina zooms, particularly the 28-70mm F2.6-2.8 and 80-200mm F2.8 are parfocal and its simply that they haven't been back focused properly.

Some articles say the Tokinas are parfocal and some say they aren't. One article said the 28-70mm is from 28-65mm. Tokina was formed by a bunch of Nikon lens engineers and this is the lens that is reported to be based on the Angenieux formula.

The Tokina is actually F2.6-2.8 so the Angenieux is a little brighter at some settings but this is a nice little comparison.
http://www.youtube.com/watch?v=KKD98G59snA

I've always like them because they are internal focus movement (so great for matte boxes), have apeture rings and built like a tank. If they are actually parfocal they'd be perfect.
 
Duke,
I've owned both of the Tokina's. While they are in my experience the best of the 2nd tier inexpensive zooms, they are not as tack sharp as the Nikons and the contrast is worse. My thinking is - when you've bought a $14, 000 camera with all kinds of accessories why not spend $1000 on your glass instead of $250. But that's beside the point. (Actually for just $4-500 the Nikon push pull 80-200 is sharp.
In my experience they also were not Parfocal but i never tried adjusting the back focus with them. I know when I had the backfocus on my 35mm adapter optimized for my 80-200 Nikon neither of the other lenses held focus. Also both Tokina's have different focus marks on the barrell for the wide and tele parts of the lens. However even that is not a true indicator since my 80-200 Nikon also has 2 witness marks. on the Nikon it turns out that was for InfraRed. I think it was for normal shooting on the Tokinas. Best thing is just to test them.

I emailed Nikon tech support a few days ago to ask about what lenses were parfocal and was told "none of our lenses are parfocal." OK then why are mine - and why are there many threads on the web explaining which ones are and which ones aren't? Test yourself!
 
At f2.8 they are soft, and f4 still a bit soft. At f5.6 they are very sharp. At that point they are pretty much the same as the Nikons.

I figure the F3 and FS100 are senstive enough that much of the time I won't want to open it more than f5.6. Its also a matter of prioritizing purchases.

If I want 'see in the dark' sensitivity I'll go for my Nikon primes at f1.4, or f1.8. The bokeh and sharp focus of a Nikon 105mm f1.8 is outstanding.
 
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a little off topic, but since its my thread, I figured I would get a pass. :grin:

I know some people that use Super 16mm lenses on their RED's. I am assuming that since its the same mounting option, that its a possibility on the F3 as well? from time to time I might need a good telephoto, and I am assuming I can find a cheaper 16mm rather than a 35mm.

also, where would one find a good used lens?

thanks!
 
They use them on red's because when you shoot 2k with one, they use a 2/3" piece of the sensor. The F3 uses the whole 35mm sensor so using a 16mm lens wont work unless you want major vignetting.
 
another question. I have the vocas mb 255 that clamps on to the sony primes. what is the diamater on the red 17-50? will I be able to clamp onto the front of that?
 
Returning back to the Nikon parfocal discussion. I just got a chance to try out another 28-70 and an 80-200 f2.8 ED Nikons. The 80-200 was parfocal on my camera but the 28-70 wasn't, reinforcing my suspicion that QC might not be that good on the Nikons. Thank god the good one was mine. I didn't try to see if it would have been parfocal at a different back focus point, but I will ask the owner of the lens on Thursday.

A wildly different possibility is that I recall reading somewhere that there were 2 versions of the Nikon 28-70 (a Mk1 and Mk2) and the first one was Parfocal while the second wasn't. But they look exactly the same and no one else has ever heard of these 2 versions.
 
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ian515 said:
another question. I have the vocas mb 255 that clamps on to the sony primes. what is the diamater on the red 17-50? will I be able to clamp onto the front of that?
Click to expand...

from what i remember the front element on the 17-50 is 144mm
i use it with the OBOX from ocoonor with rod and they will have a clamp on adaptor 150mm to 144mm
 
Lenilenapi said:
Returning back to the Nikon parfocal discussion. I just got a chance to try out another 28-70 and an 80-200 f2.8 ED Nikons. The 80-200 was parfocal on my camera but the 28-70 wasn't, reinforcing my suspicion that QC might not be that good on the Nikons. Thank god the good one was mine. I didn't try to see if it would have been parfocal at a different back focus point, but I will ask the owner of the lens on Thursday.

A wildly different possibility is that I recall reading somewhere that there were 2 versions of the Nikon 28-70 (a Mk1 and Mk2) and the first one was Parfocal while the second wasn't. But they look exactly the same and no one else has ever heard of these 2 versions.
Click to expand...
Wow this one went off on a tangent. Lenny did you have all your lenses verified first to be focused correctly?
Parfocal has nothing to do with back focus but rather with how the lens holds focus in the mid range of the zoom range. If you keep chasing your lens back focus with the camera flange you'll never have them all working correctly.
Here is how it should work:
1. Verify all your lenses to be back focused correctly within .001" or so
2. Set your camera flange depth correctly with a tool (preferred method)
3. Verify your back focus with the lens mounted on camera- to do that:
a.focus wide open on a target close to the minimum focus - at the long end of the lens
b. zoom out (all the way wide) and see if you can refocus the lens at the wide end- if yes the back focus/flange are incorrect. if no proceed to point 4
4. focus wide open on close target at the long end of the lens.
5. zoom 1/2-2/3 way out and see if you can refocus. If yes the lens is not parfocal. If not the lens is parfocal.
Now there are ways to correct focus tracking error by changing the air spacing between the lens groups. It's part of cine lens maintenance but for designated still lenses it's unheard of since the application doesn't require it (parfocal/focus tracking- same thing)
 
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Olivier Biron said:
since the red zoom are still zoom rehoused
is it possible to correct focus tracking error ???
Click to expand...
I don't know that until I try. Sometimes if the basic design is not parfocal it won't budge. The 17-50 seems to be (parfocal design) since I've seen a few posts confirming that...
 
opitek.
I have plenty of experience checking the focus on zoom lenses both in video and long ago in a film rental house using collimaters.
In present circumstances I have no way to check whether my lenses are back-focused correctly other than what I did :

I assume Parfocal top mean the lens tracks focus throughout the zoom not just the mid areas. I already knew my 80-200 held focus throughout the zoom range after adjusting a 35mm adapter 's flange focal distance (back focus) much like you do with a 2/3" video camera.

So I decided to try adjusting my F3's back focus adjustment until the 80 - 200 held focus. I next tried the 28-70 and the rest of my lenses and found with a few more adjustments a back focus spot that seemed to work for all the lenses- presumably this is correct. I had a bit of slop in my methods as a 17" monitor only resolves so much. I found for example that the 80-200 was less sensitive to very minor adjustments and the 28-70 was the most critical. The wide angles had more depth of field to begin with so were more difficult to check.

I'm hoping to double check with the PL adapter & PL zooms tomorrow.
 
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