Technical aspects of the AFS 300mm f/4 E PF lens

[Mike G]

From Eric "Only reports I have heard about the 300mm PF is that it is actually brighter T stop than f/4"

Eric what is a T stop? thats a new one on me?

I'm afraid I haven't quite got the hang of inserting a quote properly!

[Akira]

From Eric "Only reports I have heard about the 300mm PF is that it is actually brighter T stop than f/4"

Eric what is a T stop? thats a new one on me?

I'm afraid I haven't quite got the hang of inserting a quote properly!

Mike, you can simply click REPLY button and click "Insert Quote" at the top right of each previous post displayed below the typing window while typing your reply.

T-stop is another indication of the speed of the lens based on the actual amount of the transmission of the light, as opposed to the F-stop which is based on the physical proportion of the focal length and the diameter of the entrance pupil.  In the cinema world, T-stop is the standard which gurarantees constant exposure between multiple lenses indicated according to T-stop standard.

[Erik Lund]

T-stops are used for movie and video equipment 

[Øivind Tøien]

I would not trust the metering readout of the camera, I would definitely make the exposure and look at it as well...

Only reports I have heard about the 300mm PF is that it is actually brighter T stop than f/4

Sure, no metering involved for that last test, just pairs of similar manual exp (shutter speed/aperture), and center wide open was not much different. My initial impression before this test was that the PF was slightly brighter than the AF 300/4, so the last word about that might not have been said, as this was indoor lighting without repeated tests. Color temperature of light source could have influenced results; AF300/4 seems warmer/greener than 300/4 PF. Also distance to the subject could matter as the 300PF shows slight focus breathing. Note that this is a comparison to the non-AFS version (with 82mm front filter), the AFS -non-VR version could of course differ from that with respect to T-stop. What stands though is that the light falloff towards the edges wide open is more pronounced with the 300/4 PF than the AF 300/4 , which is not surprising at all considering its compact size. At f/5.6 that difference seems to be be mostly gone.

[Erik Lund]

The light fall off, vigneting  is actually often really nice for a lot of images/applications so I don't dislike that, the good performance of sensors/raw files and converters these days makes a no-issue as long as it's only about a stop or so - sure above two stops like some Zeiss wa lenses you have difficulty when removing it...

[Øivind Tøien]

Agree, sometimes it gives a 3D feeling or focus to the images. I have already processed several images from the 300PF where I evaluated using vignetting correction, but liked the result better without it.

Edit: Sorry we got astray here, I was thinking about asking to move this part to the 300PF thread.

[Erik Lund]

Please put two and two together... 

The most easy DIY job ever it turns out

[Erik Lund]

Shot up close, doesn't seem to be off in exposure... Camera set for f/8 on camera

[Erik Lund]

The PN11 tripod collar fits exactly over the TC-20E Mark I and with a little cutting it will also fit TC-17E mark II and TC-20E mark III it's alittle too deep for the TC-14E but custom fit would be possible
Also TC-201 fits.

[Øivind Tøien]

The PN11 tripod collar fits exactly over the TC-20E Mark I and with a little cutting it will also fit TC-17E mark II and TC-20E mark III it's alittle too deep for the TC-14E but custom fit would be possible
Also TC-201 fits.

Now we are talking. What did it take to get it off the PN-11?
Any disassembly required for it to slip onto TC-20E?

What is the extension provided by the TC-20E tube?

[Akira]

Now we are talking. What did it take to get it off the PN-11?
Any disassembly required for it to slip onto TC-20E?

Yup, that's the question!

[Bjørn Rørslett]

I gave Erik a PN-11 disassembled into its individual pieces. Thus the collar was free .... Ready to slide on the TC I'd guess.

[Øivind Tøien]

Not many clues from the PN-11 electrification page either. He seems to have only have disassembled the internals:
http://damien.douxchamps.net/photo/pn11/
There is an interesting discussion of the TC-20E as extension tube, and its electrical side in this thread:
http://www.dpreview.com/forums/post/42602800

[Erik Lund]

Just like Bjørn states; PN11 came disassembled... So I just put the two together.

Seams a dead end disconnecting pins... No real need for that IMHO

The result with the 300mm PF and extension gave a huge hotspot, not usable as predicted.

If I decide to use the collar for the other TC's I will have to modify the collar slightly to make room for the locking pin tap on the short TC's and modify the TC-20E Mark III body since it has these grooves around the middle - but so far undecided about that

Balance is really nice with the Collar on the TC for short lenses like the 300mm PF Micro 105mm f/4 Ais etc

[Erik Lund]

Just read the description on DPR, they are missing a crucial point in the description of how to modify the TC to make it work properly...