Paragon 500mm f8

neuro20 · Joined: 14 Jan 2010 Posts: 5 Location: Brunei

Hello Everyone,

Im new here in MFlenses, just got bitten by the M42 bug and within 2 months acquired around 15 lenses altogether..played around with them on my DSLR and had excellent results. (well, almost all of them javascript:emoticon(' Confused

'))

I recently purchased a Paragon 500mm f8 (also have a 300mm f6.3 version) and i found out something strange about this 500mm..

There seem to be an extension tube (?) of some sort, that can be detached. I googled the paragon 500mm, none of them has this mystery tube at all. The screw mount end of this tube is a M39 though. So since i have a spare M39 adaptor, i mounted it on, tested every range and found out i couldnt do an infinity focus! Strangely, i can take closer range objects clearly and detailed.

I proceeded to take out the "extension tube" only to find that the lens screw end is not a M39 nor a M42. But i managed to force a M42 adaptor in, only halfway through. I tested it again on my cam, I can do an infinity focus but not closer range objects!

Can anyone share any thoughts on this? attached some pics. with and without the mystery tube.

Mystery tube circled in red:

Close range object with the tube attached (about 30feet):

Infinity without the tube, with a M42 adaptor forced into the lens screw (pic taken through my windows grills):

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ludoo · Expire: 2011-12-05

poilu · Expire: 2019-08-29

welcome neuro
have a nice stay with us

neuro20 · Joined: 14 Jan 2010 Posts: 5 Location: Brunei

thanks ludoo, poilu...its been a long time since i touched forums..

Can anyone solve this mystery tube?

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

I have a suspicion that the threads that are almost M42 are actually T-mount threads. T-mount threads and M42 threads are very close, but not quite the same. I can't say with certainty without seeing a better photo of the entire lens, but I suspect your Panagor is one of the many different brands of preset T-mount 500mm f/8 refractor lenses that were sold by many camera stores during the 1970s and 1980s. They were attractively priced (around $70US or so), and delivered quite good optical performance.

One aspect of these lenses, as can be seen by the distance scale on the barrel, is that they do not focus very closely at all -- like 20 or 30 feet. I'm thinking that the extension tube is just that -- a T-mount extension tube to allow for close focus that wouldn't otherwise be possible.

neuro20 · Joined: 14 Jan 2010 Posts: 5 Location: Brunei

hi cool touch,

thanks for the info, i'll check into details soon and post more pics..

i would prefer to have an infinity focus rather than a close range focus..beats the purpose of getting a 500mm if i cant take distant shots!

are there such things as a tmount to M42 adaptor? i rather use the lens without the extension tube..direct to my cam (or to my m42 3x tele)

thanks again cool touch..

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

thomasb · Joined: 18 Jan 2010 Posts: 51 Location: Glasgow

I have one of these without the extension, which I agree is a t-mount extension for close focus as mine doesn,t focus close.
just remove it and replace with a t-mount to m42 mount, which mine has.
i love this big lens , easy to use and easy to focus.

neuro20 · Joined: 14 Jan 2010 Posts: 5 Location: Brunei

thanks all for the advise. i have just purchased a Tmount>M42 adaptor..hopefully it'll work out. Are there more than 1 type of Tmount? Or a generic standard Tmount will do?

Overall within the short time ive experimented with this lens, i can say the pictures turned out fine, sharp, nice contrast. But needs very strong lighting,i.e. on a bright sunny day. Turns out pretty good for a f8 lens!
Cant wait for moonshots Smile

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

T-mount adapters are all the same, when it comes to the T-mount threaded portion. Of course, they will differ depending upon which camera mount you go with. All the T-mount adapters I've see are actually two-piece: they have an inner and outer ring, and usually three small screws recessed into the outer ring. After mounting the lens to the camera, if you loosen the screws, you can rotate the lens until the lens's aligment marks are where you want them. Then you tighten the screws back down, and your T-mount is then configured so that the lens will be oriented correctly for that camera.

For moonshots, if you camera has Live View, I recommend you use it to insure precise focus. Also a tripod and a remote release -- or a 10-second self timer -- of course.

It bears mentioning as well -- the moon is reflecting sunlight, and is quite bright. Correct exposure at ISO 100 is 1/125 with an aperture of f/8 or f/11. I prefer f/11 because it provides for less chance of blown-out highlights and usually provides better contrast, I have found.

I posted this image here several months ago, but I'll go ahead and do so again. Canon XS (1000D) with Century Precision Optics 500mm f/5.6. Live View with 10-second self timer, ISO 100, 1/125 @ f/11. The only post processing I did was a slight bump in contrast. Your Panagor should provide similar results.

neuro20 · Joined: 14 Jan 2010 Posts: 5 Location: Brunei

thanks for the valuable info michael. That's exactly what i wanted to achieve!
Fantastic Moonshot!

Did you use a tele converter for this? cropped or just pure 500mm lens?
The view of the moon in my country is quite small to be magnified this large..
i'll be lucky if i can get half the size your moonshot..

Let's see how it goes, i'll be posting some moonshot pics on this post very soon.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas