SLR 2x convertor fits DSLR T-mount

[Pinwheel (Doug)]

WOW, what luck My old 30 year old Nikon A1 mount 2x convertor fits my telescope's t-mount adapter & fits the DSLR camera too!. So what this means is I double the image size. Will need to use on manual, but you would need to anyway!

[raymo]

Very lucky Doug. Don't forget that your subs will have to be
twice as long.
raymo

[Pinwheel (Doug)]

Originally Posted by raymo

Very lucky Doug. Don't forget that your subs will have to be
twice as long.
raymo

Not up to testing this out just yet as I've started converting the Field-bin Observatory. Hoping to start the floor today.

[cometcatcher (Kevin)]

Originally Posted by raymo

Don't forget that your subs will have to be
twice as long.

For a 2X converter, exposures have to be 4 times as long. A 1.5X converter would be twice as long. For instance a 2X converter would take an F5 optical system to F10.

[raymo]

Oops!!!
raymo

[Pinwheel (Doug)]

So your saying it will be disadvantage to use it? Slower exposure time or more subs required.

[cometcatcher (Kevin)]

Would be okay for the moon or planets where you need the image scale, maybe for tiny planetary nebula, but doesn't work well for deep sky.

[raymo]

Sorry about my slip, I was forgetting it's not a linear progression. I plead
old age. Regarding your teleconverter; it doesn't matter how you increase magnification, barlow, teleconverter, or eyepiece projection, you will always have a dimmer image that will require longer subs. The three items do however have different purposes and properties. Cheaper barlows usually have only one or two lenses, and are designed only to magnify, usually 2 or 3 x .Teleconverters are designed to work with camera lenses that are generally well corrected, hence have usually either 4 or 7 elements designed to try and maintain that good correction. Eyepieces are another ball game altogether, each type introducing it's own specific qualities and optical aberrations. For simple 2x mag you're
better off using a barlow rather than EP projection for the above mentioned reasons. I have never tried using a teleconverter with a scope, but because it is trying to maintain the good correction of the image that
passes through it, it might possibly introduce aberrations of it's own.
I will be interested to see how you fare with it.
raymo

[Renato1 (Renato)]

Originally Posted by Pinwheel

WOW, what luck My old 30 year old Nikon A1 mount 2x convertor fits my telescope's t-mount adapter & fits the DSLR camera too!. So what this means is I double the image size. Will need to use on manual, but you would need to anyway!

Must be a Nikon thing.
Sony DSLR owners would be ropeable if their 30 year old Minolta A mount lenses and teleconverters didn't work on their current cameras.

Asssuming your teleconverter is good quality, it should be pretty much like using your camera connected to a Barlow.
Cheers,
Renato

[Steffen]

Originally Posted by Renato1

Must be a Nikon thing.
Sony DSLR owners would be ropeable if their 30 year old Minolta A mount lenses and teleconverters didn't work on their current cameras.

And that happens to be the case only because Sony (with no SLR history of themselves) decided as recently as 2005 to acquire what was left of Konica Minolta's SLR business.

The Nikon F-mount is in fact the oldest SLR mount still in use, having been introduced in 1959. AI (auto-indexing) is not a mount, but a feature added to the F-mount in the late 70s. The mount had several features (incl. AF) added over time and managed to remain backward compatible to this day.

I can put a 1959 Nikkor on my D7000 and it'll work just fine. That doesn't mean one shouldn't be delighted by this

Cheers
Steffen.