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Moon projected through 18-55mm lens @18mm
Lens: 18-55mm @18mm through Z71ED telescope Camera: K3II Photo Location: Pritchard B.C. ISO: 100 Shutter Speed: 1/50s 
Posted By: aitrus3, 02-04-2020, 07:58 PM

So some are following my camera lens-used-as-eyepiece-of-telescope experiment.
I did a test yesterday but I had problems with my 2x teleconverter no longer communicating aperture value, so I had to remove it, unfortunately!
This is my 18-55mm lens @ 18mm focused to the closest point attached to my Z 71ED telescope with an adapter I made. Behind the lens is 60mm of extension (should have been 72mm but I didn't notice i had taken 12mm off along with the teleconverter) That little mistake caused the moon to just barely fit inside the vignette, and as a result the bottom got distorted slightly. I doubt this would have happened with the entire setup.
It gives me probably around 1.5x more magnification than doing prime focus photography with the 2x teleconverter. This is not cropped. Excited to keep experimenting with this. For the time being I've carefully glued open the aperture control of the teleconverter, so it can't stop my lens down to f29. I'll need to buy another auto 2x teleconverter.


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02-04-2020, 08:01 PM - 1 Like   #2
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I don't really have the technical aspects of what you did, but it is an impressive and very sharp image!
02-04-2020, 08:05 PM   #3
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QuoteOriginally posted by SSGGeezer Quote
I don't really have the technical aspects of what you did, but it is an impressive and very sharp image!
haha neither do I! What I wanted to do was build something so I could use my lenses as eyepieces. And that works, VERY VERY well. Camera lenses, especially my 50mm f2 is AMAZING to view the stars. Then I got the idea to attach my camera to the back of the lens. That opened up a can of experimental worms which has led me here. I have no idea how this works, but it does.
Can't wait to try it through my 14mm lens, although being 14mm there's some things I am very uncertain of.
02-04-2020, 08:07 PM - 1 Like   #4
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Edge sharpness versus center of the frame for one! At least if an older 14mm.

02-04-2020, 08:19 PM - 1 Like   #5
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Well, I also have no idea of the technicalities of how your physical lens/telescope fit and work together:
BUT
That is one amazingly sharp and detailed photograph! Really makes me wish I could make the financial leap and buy a telescope.
02-04-2020, 08:20 PM   #6
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Good picture of the moon and I really like the explanation of your setup. Please share more, this sounds fun. I should try something similar.
02-04-2020, 08:55 PM   #7
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QuoteOriginally posted by Lake Quote
Good picture of the moon and I really like the explanation of your setup. Please share more, this sounds fun. I should try something similar.
I have a post or two about the technical details. Essentially I've built an adapter out of metal that slides into my 2" focuser. The lens side of my adapter has a repurposed old ring flash part. It's essentially a small piece of aluminum with 52mm filter threads on one side. I epoxied that to my 2" pipe and I can attach my 18-55mm lens directly to it. I also have a 49mm-52mm step up ring and I have a 55mm-52mm adapter as well.
I've ordered a 77-52mm step down for my 14mm. That's where I'm unsure if it'll be ok; quite a large step down, but might be able to get it working. We shall see in a few days.
It's not enough to just attach the camera though. While this works visually the camera ends up seeing a huge portion of the tube and the image circle is small. So i had the idea of using extension tubes to push the focus distance of the lens waaaayyy forward, and it worked. If I had more extension I wouldn't need the 2x converter. But essentially I found that the further forward the focal point was pushed, the less the vignetting was visible but also got more magnification from it as well.
If you did the math, 72mm of extension tubes on an 18mm lens would probably push the focal point near the camera body. It wouldn't work if you were to try this as a macro setuo because the subject would come to focus inside the lens tube. I figured though as light is the subject in this case, it can come to focus behind the front element of the 18-55mm lens. Im sure I'll hit a limit of what's possible. I'm sure too wide will push the focus point beyond the sensor. But it's been a fun experiment.
Oh, if you do use a 2x converter, it has to be at the body of the camera. Anywhere else and it causes the image circle to be waaaayyy smaller.

---------- Post added 02-04-2020 at 07:59 PM ----------

QuoteOriginally posted by SSGGeezer Quote
Edge sharpness versus center of the frame for one! At least if an older 14mm.
It's more the fact that I have to step it down from 77 to 52mm. And then being 14mm, it might not be able to come to focus. There is a chance that my focus point will be pushed past my sensor.

02-05-2020, 01:54 AM - 1 Like   #8
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I am impressed. I love to see the work of experimenters - and this really works!
02-05-2020, 06:58 AM   #9
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QuoteOriginally posted by PJ1 Quote
I am impressed. I love to see the work of experimenters - and this really works!
Thanks PJ!
It's fun experimenting for sure. You'd think this idea would gain more traction in the Astronomy groups, but the only answer I ever get from them (aside from a few of the older folks in the crowd) is "why?"
Sometimes i feel the 'younger' generation (40 and under, my generation) lacks imagination. Not all of us do though.
The "why" usually comes from the folks who have the money to purchase thousands of dollars worth of equipment that can do this easier. But the older generation tends to understand, because they grew up in an era where these kinds of toys hadn't yet been invented, so if they wanted to do something, they needed to build it themselves and learn something along the way.
Up until now, I didn't think it would be remotely possible for me to be getting even closer shots of the moon with my DSLR, but I am excited at the possibilities it might open up. To be able to (maybe) get even closer with my APS-C sensor at the full 24mpx is definitely exciting.

* I should add, I think this might be possible for others if they were able to find 48mm filter thread step-up/down rings. You'd need female 48mm to male XXmm and then a set of 2" telescope extension tubes, as they are threaded 48mm 0.75mm pitch, same pitch as our filter threads.
07-19-2021, 01:02 AM   #10
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QuoteOriginally posted by aitrus3 Quote
So some are following my camera lens-used-as-eyepiece-of-telescope experiment.
I did a test yesterday but I had problems with my 2x teleconverter no longer communicating aperture value, so I had to remove it, unfortunately!
This is my 18-55mm lens @ 18mm focused to the closest point attached to my Z 71ED telescope with an adapter I made. Behind the lens is 60mm of extension (should have been 72mm but I didn't notice i had taken 12mm off along with the teleconverter) That little mistake caused the moon to just barely fit inside the vignette, and as a result the bottom got distorted slightly. I doubt this would have happened with the entire setup.
It gives me probably around 1.5x more magnification than doing prime focus photography with the 2x teleconverter. This is not cropped. Excited to keep experimenting with this. For the time being I've carefully glued open the aperture control of the teleconverter, so it can't stop my lens down to f29. I'll need to buy another auto 2x teleconverter.

Very impressive !
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