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Old 10-07-2018, 06:11 AM
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fixing DSLR lenses to CCD camera

I have Canon EOS mount lenses, and a QSI583ws-8 camera. I recall QSI had EOS adapters available, but they're not cheap - US$199 from OPT.

Bintel have the ZWO T2 to EOS adapter for AU$59 and I'm wondering if there's any reason this can't be used instead?

My camera is a T mount (42x0.75), and I think T2 is the same? Backfocus on my camera is 35.56mm. Pretty sure backfocus on EOS lenses is 55mm.

The specs on the ZWO seem to use different terminology, because they talk about the ASI1600 only having 6mm backfocus, which doesn't sound right? There is a filterwheel version of the adapter that's thinner.
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Old 10-07-2018, 06:38 AM
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multiweb (Marc)
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Same issue with TAK adapters. You pay through the nose. The first thing to do is to machine or buy one single adapter from camera/scope to a thread that's compatible with all the other bits you own. Then get a cheaper standard Canon adapter lens to M42 or other. I did that for my TAK and I reused all the bits and pieces I collected over the years, extension tubes, OAG, AO, etc...
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Old 10-07-2018, 06:39 AM
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Atmos (Colin)
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The back focus of a Canon lens is 44mm and 46.5mm for a Nikon.

The QSI one may be a lot more expensive but it’s got the correct back focus and I imagine, considerably better build quality than the Bintel one.
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Old 10-07-2018, 06:39 AM
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lazjen (Chris)
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The 6mm (it's really 6.5mm from memory) referred to for ZWO is the camera itself, i.e. how much focus it takes up. It's the distance from the sensor to the connecting thread edge.
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Old 10-07-2018, 07:33 AM
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I have used camera lenses on a range of CCD cameras.

My current one is a FLI adapter that screws into the FLI filter wheel (it used to clip the filters and stop them from turning so I had to grind it down a bit).

That particular adapter is for Nikon F. Then any ebay adapter to Nikon mount allowed the mount of different brand lenses.

Depending on how large the lens is you may also need a lens mounting ring to stop flex and wobbles. The mount adapter may not be all that strong.

More of an issue perhaps when you start using 200-300mm lenses.

In my case the FLI Nikon lens adapter is a bit of a fail if I were giving it a rating. The lenses do not click stop and can continue to rotate and come off.
Its too thick but everything comes to focus.

Pick lenses with manual aperture ring (not many Canikon's have that),
also with a nice focuser ring with as much travel as possible as you may be manually focusing. Temperature and focus shift seems much less of an issue with lenses.

Here are the lenses I have found to be good:

Nikon 55 F1.8G
Nikon 50 F1.8 (older lens not latest)
Nikon 105 F2.5 AIS
Pentax 67 75 F4.5, 165 F2.8 ( a very good one and sharp wide open)

I haven't used many Canon's. I had a few Canon FD but they were pretty ordinary. I imagine the Canon ef 50 1.8 would be good as its virtually identical to the Nikon. The range of 35 to 200mm should be good.

Pentax 67 lenses are cheap and have something like 85mm of backfocus which is about the most of any lens system. They also will cover a 16803 chip with round stars to the corners as they were designed for 60 x 70mm film.

Ultrawide lenses are not so easy to use. I tried to mount a Nikon 14-24 and it was a mess.

A QSI583 would take just about any lens as that is a micro 4/3rds size sensor so it does require a large corrected circle. Many lenses though are poor wide open in the corners and astro work really shows this up. Terrestial imaging is far less demanding by comparison. So don't expect your favourite L lens to necessarily perform. It might or it might not.

Greg.
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Old 10-07-2018, 08:13 AM
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Merlin66 (Ken)
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What's a ""micro 4/3rds size sensor" - in real numbers??

Edit: Ahhhh, it's a 5.4 x 5.4micron, 3326 x 2504 pixel (17.96 x 13.52mm) chip with a QE of 57%

Last edited by Merlin66; 10-07-2018 at 08:47 AM.
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Old 10-07-2018, 01:04 PM
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Thanks so much guys. That'll teach me for posting so early in the morning - got the numbers all jumbled up off the top of my head. The 55 should have been 44, and 6.5 not 6.

So - looks like as long as the adapter is 8mm or so, it should work. Need 44mm from lens flange to sensor. Sensor is 35.56mm from face of camera, leaving 8mm max thickness of a T to EOS adapter.

Greg - thanks for the experience with lenses. It'll probably be my 135/2L and 35/1.4L. Both with good manual focus rings. I have the 85/1.2L but it doesn't manual focus well without elec contacts (by design).
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Old 10-07-2018, 01:08 PM
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Hmmm - looks like the ZWO one is 17mm or so thick, so no good anyway.

Googling these things is hard, because searching for T thread and EOS usually turns up adapters to connect DSLRs to scopes via T thread, not the other way around connecting CCD camera T thread to EOS lens...
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Old 10-07-2018, 01:39 PM
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Quote:
Originally Posted by troypiggo View Post
Thanks so much guys. That'll teach me for posting so early in the morning - got the numbers all jumbled up off the top of my head. The 55 should have been 44, and 6.5 not 6.

So - looks like as long as the adapter is 8mm or so, it should work. Need 44mm from lens flange to sensor. Sensor is 35.56mm from face of camera, leaving 8mm max thickness of a T to EOS adapter.

Greg - thanks for the experience with lenses. It'll probably be my 135/2L and 35/1.4L. Both with good manual focus rings. I have the 85/1.2L but it doesn't manual focus well without elec contacts (by design).
If you are using a mount then more lenses are usable as you simply stop them down. I haven't done it but if you don't want sunstars on bright stars you can get a small stop down ring that screws onto the end of the lens and stops it down a tad. Being round it does not produce the sunstars.

There are exceptions but fast lenses tend not to be useful wideopen.

Greg.
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Old 10-07-2018, 02:00 PM
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I made a couple of adaptors using the Canon extension tubes and fitted a central boss for 1.25"> T thread nosepiece.....
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Old 10-07-2018, 02:02 PM
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Yes, the diff spikes from the lens aperture blades do show up. I usually stop down a little and don't use wide open. But if you're starting with a faster lens, you can stop down to the equivalent wide open of slower lenses. Plus if I'm using a smaller sensor than FF 5DII, that should take out any residual edge issues, since sensor more in the middle of light path. That's my thinking, anyway.

Tried stop-down rings once before with FF 5DII and got vignetting. I put it down to external apertures being on front of lens, not where they should be at the aperture blade distance.
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