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Old 11-09-2017, 10:50 PM
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Crushellon (Tim)
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TS 80mm f6 Triplet APO test image: Pleiades

So I got a few test images with the new triplet early in the morning the other weekend. Couldn't get the spacing quite right, it's about 1.5mm off cause the thread is far too long on the reducer and I cant get my spacers to screw all the way down to the bottom of the thread. And I also have some flex between the camera and the adaptor... possibly because my camera is too heavy (5D III with battery grip and 2 batteries is a bit to hang off an EOS adaptor) or possibly because the adaptor is a bit low on quality, not that I cheaped out with it... but alas who knows. Eventually Ill get an astro cam and it'll be all threaded anyway so I might not even worry about that too much for now.

Anyway, this is 20x 40sec (sky limited...) at 1600iso f4.74 379.2mm with Canon 5DIII

The low res doesn't show much detail so here's the astrobin link: https://www.astrobin.com/311871/0/
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Old 12-09-2017, 12:10 AM
glend (Glen)
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Nice Tim, it looks fine to me. The corners are ok. Did you try it without the reducer as a comparison?

Last edited by glend; 12-09-2017 at 12:22 AM.
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Old 12-09-2017, 10:56 AM
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tim you only need a 6mm spacer / adapter for that setup correct?
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Old 12-09-2017, 12:17 PM
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Crushellon (Tim)
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Yeh, but the thread on the reducer is 6.5mm long. So no matter how small a spacer you put o the closest you can get is 7.5mm.
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Old 12-09-2017, 12:42 PM
glend (Glen)
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Quote:
Originally Posted by Crushellon View Post
Yeh, but the thread on the reducer is 6.5mm long. So no matter how small a spacer you put o the closest you can get is 7.5mm.
Tim if your running the 3" Photoline reducer, the working distance to your camera sensor for your scope should be 61mm. The standard Canon setback is 55mm. You should have 6mm to play with. Also in my experience with that reducer on my TS115 and TS80, it has some latitude in spacing. Don't forget that if you have any sort of filter on the front of your DSLR it will length the focal length slightly, as per the "Rule of 3rds". On my ASO1600MM-C that means adding an extra 1mm to the back spacing due to the filter and AR cover window on the camera.

BTW, the TS Canon bayonet is thinner than some others, like the Bintel ones. I bought a TS bayonet and it was 8.62mm thick, the Bintel one i measured at 10mm. Re the combined M48 spacer to the sttep down to T2 at the bayonet, just make sure that tube has enough depth at the front end to take the Photoline threads. I am running my Nikon D5300 on my TS80 and 3" Photoline reducer without spacing issues, and on my f7 version the backspacing is just 58mm. Key to this is the depth of M48 thread in my adaptor, which takes all that 6.5mm male thread to the reducer shoulder.

Last edited by glend; 12-09-2017 at 01:01 PM.
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Old 12-09-2017, 01:04 PM
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ah tricky, i see
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Old 12-09-2017, 01:20 PM
glend (Glen)
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Here is a photo of my M48 spacer that I rigged up for the ASi1600, notice the depth of the thread on the inside - that is 10mm deep, and will easily take the male M48 of the 3" Photoline. So all you need to worry about it the overall length of your combo M48 spacer. You can see that I put mine together from several M48 sections and a M48-to M42 step down to screw into the filter wheel housing - this is pretty much the same way I do it with the Nikon D5300, the overall length of the M48 section is just a little different.
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Old 12-09-2017, 02:05 PM
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That won't work for me as I'm using a full frame camera, I need to use all m48 to keep the open aperture for the sensor size. I'm just gonna lathe down the m48-eos adaptor down so it's closer. I wasn't aware that the TS oneswere shorter though, do you know if they are suppose to be 10mm for the usual 55mm that canon cameras usually have with an adaptor on?
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Old 12-09-2017, 02:56 PM
glend (Glen)
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Quote:
Originally Posted by Crushellon View Post
That won't work for me as I'm using a full frame camera, I need to use all m48 to keep the open aperture for the sensor size. I'm just gonna lathe down the m48-eos adaptor down so it's closer. I wasn't aware that the TS oneswere shorter though, do you know if they are suppose to be 10mm for the usual 55mm that canon cameras usually have with an adaptor on?
Tim, i am not suggesting you copy my setup. I realise your full frame and need to carry the 2" tube to the bayonet. Perhaps i was going into too much detail. The intent of the photo was to show the depth of the M48 thread in the front of my 2" section, which should resolve your reducer attachment issue. I suspect you are using a 2" front section with a filter thread cut in it, which is only deep enough to screw in a filter. If you were using something like a 2" variable tube, they are always tapped for significant depth to accomodate the reducer thread.
I will stay out of it from here.
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Old 12-09-2017, 03:09 PM
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Looks a cracker Tim gotta love small apos...
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