Home made lens to shoot the moon

Started Dec 18, 2005 | Discussions
Hugov Regular Member • Posts: 143
Home made lens to shoot the moon

To see how good (or how bad) the results would be, I mounted a single close-up lens (+1.1 Diopter or 950mm focal length) at the end of a long tube.

The resulting lens was a 950mm/f32, with interior black cardboard lining and a plain UV filter at the base to prevent all the paper dust from getting in the camera.

THE SETUP:

THE RESULT (100% crop)

Focusing was quite difficult because of the low contrast and the fact that my arm was not long enough to reach the end of the tube while looking at the view finder.

The resulting image filled about 50% of the sensor height.

BTW, the lens is now decomissioned...

dfw Regular Member • Posts: 389
Re: Home made lens to shoot the moon

that's wild and a pretty good trick. focusing is a problem as you say. next time use 2 tubes, one inside the other for a push-pull focus.

i've got several DIY gadgets that i use. ie: reverseing ring, reverseing ring acc. add on, off camera shutter release, and an 24 high output LED ringlight, flash difuser, off camera flash bracket,etc.
--
roy
fujiS7000 & *istDs
http://www.texasbostons.com
saving one at a time

Bruce Oudekerk
Bruce Oudekerk Veteran Member • Posts: 3,636
I love it:)

Bruce

 Bruce Oudekerk's gear list:Bruce Oudekerk's gear list
Sony a7R II Sony Vario-Tessar T* FE 16-35mm F4 ZA OSS Sony FE 70-300mm F4.5-5.6 G OSS Sony FE 50mm F1.8 Sony FE 24-105mm F4
Jay Turberville Forum Pro • Posts: 12,918
Re: Home made lens to shoot the moon

Hugov wrote:

To see how good (or how bad) the results would be, I mounted a
single close-up lens (+1.1 Diopter or 950mm focal length) at the
end of a long tube.

The resulting lens was a 950mm/f32, with interior black cardboard
lining and a plain UV filter at the base to prevent all the paper
dust from getting in the camera.

OK. f/32 will give yous soft results on a typical DSLR sensor. You need to get down to f/16 or so. So for a 950mm lens, you need a 60mm lens. You also want something with some color correction in it. An achromat should do fine and you can find those cheap. Look at surplusshed.com.

http://www.surplusshed.com/pages/item/l2148.html
http://www.surplusshed.com/pages/item/l3002.html
http://www.surplusshed.com/pages/item/l3387.html
http://www.surplusshed.com/pages/item/l3435.html

-- hide signature --
Leonard Migliore
Leonard Migliore Forum Pro • Posts: 18,722
Re: Home made lens to shoot the moon

Jay Turberville wrote:

Hugov wrote:

To see how good (or how bad) the results would be, I mounted a
single close-up lens (+1.1 Diopter or 950mm focal length) at the
end of a long tube.

The resulting lens was a 950mm/f32, with interior black cardboard
lining and a plain UV filter at the base to prevent all the paper
dust from getting in the camera.

OK. f/32 will give yous soft results on a typical DSLR sensor.
You need to get down to f/16 or so. So for a 950mm lens, you need
a 60mm lens. You also want something with some color correction in
it. An achromat should do fine and you can find those cheap. Look
at surplusshed.com.

What's wrong with f/32 at a 950mm focal length? You're not going to get diffraction problems with a 30mm aperture.

Color correction is a good idea; narrow-band filtration is even better. Cheap achromats aren't going to do a good job across the visible spectrum at long focal lengths. That's one reason why mirrors are much more popular than lenses for astronomical telecscopes.

-- hide signature --

Leonard Migliore

 Leonard Migliore's gear list:Leonard Migliore's gear list
Canon PowerShot G12 Nikon D300 Nikon D750 Nikon AF-S DX Nikkor 16-85mm f/3.5-5.6G ED VR Nikon AF-S DX Nikkor 35mm F1.8G +11 more
ScottyNV Veteran Member • Posts: 3,889
Re: Home made lens to shoot the moon

Great Work! This kind of experimentation is LOTS of fun! .. the result (photographically speaking) is fabulous.. to the other posters who would have you change the setup: a large round of laughs - you just don't get it! The image is rather cool, gives us insight into the early days of astronomy and photography... and the fact that it worked at all is the bonus!

Keep on experimenting!

Cheers,
Scotty
--

  • How deep does the Rabbit Hole go? *

Free the Images
Best Light**

OP Hugov Regular Member • Posts: 143
Re: Home made lens to shoot the moon

Thanks for the feedback. It was so much fun that I took the paper, cardboard and tape out of the drawers to make a new experiment from the remnants of the 950/32.

Tonight, I should be able to use my new home made 450/16 achromat doublet (two close-up lens facing outward with the aperture in the center).

The moon will be smaller, but the symetrical lens should be sharper.

OP Hugov Regular Member • Posts: 143
Colour Filtering

Mmmm. Colour filters would be another interesting avenue indeed.

To stay in the realm of the cheapo-haywire approach I would like to use something I already have, or a combination of them.

Red filter for B&W photography
Green filter for B&W photography
Hoya72 infrared filter (720 nm and above)

The green might have spectrum narrow enough to make a difference... I guess I will have to test all three.

Any suggestions?

Jay Turberville Forum Pro • Posts: 12,918
Re: Home made lens to shoot the moon

OK. f/32 will give yous soft results on a typical DSLR sensor.
You need to get down to f/16 or so. So for a 950mm lens, you need
a 60mm lens. You also want something with some color correction in
it. An achromat should do fine and you can find those cheap. Look
at surplusshed.com.

What's wrong with f/32 at a 950mm focal length? You're not going to
get diffraction problems with a 30mm aperture.

You will begin to have problems with diffraction at around f/11 with a sensor such as the one on a Canon 20D. By the time you are at f/32, you will have large diffraction effects. You can only resolve about 50 lp/mm at the Rayleigh limit at f/32. A 20D sensor is can resolve about 62 lp/mm and if you want sharp results, you should give it about 62 lp/mm or better not at Rayleigh, but at an MTF50 resolution - which is at about f/12.

Color correction is a good idea; narrow-band filtration is even
better. Cheap achromats aren't going to do a good job across the
visible spectrum at long focal lengths.

It will do better than a one element meniscus type "close-up" lens. And I'm pretty sure an achromat will do better at a long focal length than at a shorter one.

That's one reason why
mirrors are much more popular than lenses for astronomical
telecscopes.

Yes. But the point was to suggest a simple way to get better results.

-- hide signature --
ScottyNV Veteran Member • Posts: 3,889
Re: Home made lens to shoot the moon

Sounds great! Kindly let us know how it works out! No moon for me this week.. RAIN for the next 4 days... I wonder how much mag I might get using my 600/8 mirror lens, 50/1.8 and a tube.. could be 'interesting'.. however I need to learn how to use my new printer first! (PIXMA MP500)...

Cheers,
Scotty
--

  • How deep does the Rabbit Hole go? *

Free the Images
Best Light**

nickleback Forum Pro • Posts: 11,111
Re: Home made lens to shoot the moon

Leonard Migliore wrote:

What's wrong with f/32 at a 950mm focal length?

APS-C sensors are already into diffraction at f/16.

You're not going to
get diffraction problems with a 30mm aperture.

You will if it is a 900mm lens. Diffraction is related to aperture ratio, not apparent aperture.

Bruce Oudekerk
Bruce Oudekerk Veteran Member • Posts: 3,636
would enlarger lenses work?

Bruce

 Bruce Oudekerk's gear list:Bruce Oudekerk's gear list
Sony a7R II Sony Vario-Tessar T* FE 16-35mm F4 ZA OSS Sony FE 70-300mm F4.5-5.6 G OSS Sony FE 50mm F1.8 Sony FE 24-105mm F4
Jay Turberville Forum Pro • Posts: 12,918
There aren't many 900mm focal length enlarging lenses.(nt)
-- hide signature --
Bruce Oudekerk
Bruce Oudekerk Veteran Member • Posts: 3,636
true:)

I vaguely remember reading years ago something about using a (reverse?) enlarging lens for a rear element in "home made" long focal length lens or telescope. Didn't understand it then and I've likely got it wrong now because of that.

Should’a kept my mouth shut…:(

Bruce

 Bruce Oudekerk's gear list:Bruce Oudekerk's gear list
Sony a7R II Sony Vario-Tessar T* FE 16-35mm F4 ZA OSS Sony FE 70-300mm F4.5-5.6 G OSS Sony FE 50mm F1.8 Sony FE 24-105mm F4
Keyboard shortcuts:
FForum MMy threads