I'm not sure if the 44mm they quote for canon sensor distance is to the glass on the sensor or to the sensor silica itself and that glass is normall 1.5 to 2mm thick. I'm sure the real tak adapters would put the distance spot on. But the 56mm will be to the canon sensor so the adapters should be 12mm plus the flattener thread depth I guess.
I think my distances are out by a little as I'm using adapters off ebay to cobble my filter wheel to the flattener. I think it shows up here as my normally parfocal filters not being parfocal, they are all slightly out. L&R&B are very very close but not exact while G definately needs refocusing and being around F4 the focus point is very narrow.
by my measurements, I am only about 1mm out. Would this be enough to give me the stars in the pics above??
The T-Ring + Tak adapter is 16.0mm thick and the flattener thread screws into this by 5.0mm - which gives a net of 11mm - add this to the 44mm for the canon sensor distance gives 55mm....
I will have to wait until the genuine kosher Tak part arrives to find out.
I just took a close look at my last pics from the FS-60CB with flattener and Nikon DSLR and they look pretty good in the corners. I've never checked the back focus distance to see if it's accurate, but I guess it is. I got my adapter from Peter Tan. If you want me to measure anything or send you some images let me know...
Thanks Rick - if you could post an image with a crop of one of the corners that would be really helpful.
I also ordered the adapters from Peter - the Tak T-Ring didn't find its way into the shipment though - he is sending it with my next batch of stuff. Should be here any day.
I'm not sure whether there is any point measuring your gear if it is Nikon, unless the flange/sensor distance happens to be 44mm also??
I've just read that the sensor distance on Nikon is 46.5mm, so by my reckoning, on your setup, the distance marked 'a' on the diagram attached should be 14.5mm. On mine I think it should be 17mm, but I currently have 16mm...
I've just read that the sensor distance on Nikon is 46.5mm, so by my reckoning, on your setup, the distance marked 'a' on the diagram attached should be 14.5mm. On mine I think it should be 17mm, but I currently have 16mm...
Adam
Let me see if I can find the hardware in my office pile 'o crap. I'm still getting things back in order after a long time exercise with our builder to find and finally fix the water leak in my subterranean abode...
well - they are a damn sight better than the stars in mine.....
thanks for that.
Adam
Hey, it's a Nikon. I know all the Canon folks have the jump on me for astrophotography so it's nice to feel slightly superior for a few nanoseconds, even if only by accident
well - I was able to whip the scope and mount out for a few short trial exposures the other night. I got the new T-ring, and I don't think it has made much, if any, difference. I think it added maybe an extra 0.5mm - so now I think my flattener to sensor distance is 55.5mm - in theory only 0.5mm out.
I think what I am going to have to do is unscrew the adapter a little to see whether the extra distance will help - although it will introduce its own problems with a bit of sag leading to the sensor not being perpendicular, it might show me whether I am heading in the right direction...?
Any other ideas?
Cheers
Adam
EDIT - the image is a crop again from the top left
Last edited by adman; 29-04-2011 at 01:13 PM.
Reason: pic added
how good was last night in Brisbane?!! (if you don't count the lack of sleep )
it gave me a chance to fiddle around with spacings etc with the FS-60 flattener, and it was one of those nights where everything just worked . Guiding was just set and forget, everything balanced well, despite it being a last minute SBS job cobbled together from bits lying around, and any adjustments to balance, PHD settings etc did just what I wanted them to, not to mention it was cloud free....maybe there is a god...
Anyway the good news (as you can see from the pics below) is that I have got the spacing right and am getting a nice flat field (the crop is from bottom left). The bad news is that I had to unscrew the T-Ring from the scope slightly to get it right, and now its just flopping around in the breeze...In the end, the difference between my last pic I posted and these was about 0.7mm (I bought myself a better set of vernier calipers... )
The only way I can see that I am going to be able to secure it is with some spacing rings so I can screw everything up tight.
However, there is no 'shoulder' on the flattener to sit these spacing rings against - the threads just sort of stop.
Has anyone faced this issue before and found a solution?
I'm trying to figure out the exact part numbers I need to hook up my FS-60CB + flattener to my Canon DSLRs. I'm still confused after reading through this thread...
Any suggestions on the exact parts (and part numbers) that I'll need? The Tak system guide manuals for the FS-60CB/Q were no help. I'd also like to get the Nikon mounting rings too - I don't have one, but many of my friends do
I went ahead and ordered the FS-60CB specific wide T-mounts for Canon from Peter Tan. It came with a standard Canon EOS T-ring adapter plus two different sizes of the adapter shown in Adam's first post of this thread. Thanks to Peter's post, I managed to figure out what had to be swapped around.
The whole set up (FS-60CB + adapter + CAA + SD ring + flattener + wide T-mount + Canon 5DmkII) works, but I'm getting really bad field curvature in the corners - as per Adam's later posts.
Any suggestions on how to get the flattener-camera spacing exactly right?
Ah-ha! It looks like I was shipped the wrong T-ring (despite my care in specifying the part from the system guide), so the flattener doesn't connect to the camera as in this picture from the Tak website.
I was connecting the Canon EOS adapter directly to the flattener without the bit in between... hence the spacing was off.
)
