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DSLR+500mm F/6.3 mirror lens

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#1 Moromete

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Posted 13 May 2014 - 01:49 AM

Has anyone tested this lens http://www.samyang-l...irror-lens.html for DSO astrophotography with a DSLR?

I want to know if it is a viable alternative to a small APO (witch more expensive and heavier for a similar focal length and speed) for DSO astrophotography.

It should have no chromatic aberation due to its 7 optical elements.
It has a T2 connection.
The same lens is sold under Vivitar, Opteka,Rokinon, Walimex, Bower, Pro-Optik name.
Also it's light, cheap and can be used on a tripod with a DSLR.

If you have any DSO pictures taken with such a lens please post them here.

Thanks.

#2 jblaschke

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Posted 13 May 2014 - 10:16 AM

Those Samyang mirror lenses are pretty cheap all the way around and don't have a good reputation for decent image quality. And from what I understand, their f/6.3 aperture is more a case of wishful thinking than anything else.

If you really want to get one of the old-school mirror lenses, the Nikon Reflex-NIKKOR f/8 N and the Canon FD 500mm f/8 are both going to give you much better quality. The Tamron SP 500mm F/8 Mirror Model 55BB is also well-regarded (the earlier 55B version has issues). The Zeiss Mirotar is the gold standard of this bunch, and will cost $$$. Sigma's mirror lenses are generally considered a step below the others, but still better than the Samyangs.

I have the Canon FD, converted myself to EF mount with an Optix V5+ AF confirmation chip. It's a fun super-telephoto to play with, and once you get over the manual focus learning curve it's possible to get very good shots with it. But it's not really optimal for astrophotography. I've taken decent lunar shots with it, but it's not fast enough to do wide-field astrophotography from a tripod. Focusing is achieved by rotating the central ring on the lens barrel, and this is loose, with no way to lock it down. It's very light, so it might do well piggybacked, but I've not attempted such.

Meade and Celestron both produced versions of these lenses in the 80s but IIRC, they were 1000mm.

The long and short of it is, you'll likely be disappointed by the Samyang for what you want to use it for, the other lenses not quite so much, but they'll still be challenging.

#3 Campos

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Posted 13 May 2014 - 10:31 AM

If you're looking for a good mirror lens search on ebay for Russian MTO's or Rubinar ;)

#4 cherokawa

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Posted 13 May 2014 - 05:47 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image

#5 Campos

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Posted 13 May 2014 - 06:20 PM

For what I see on that pleiades image I'd say it's well worth the price for sure, it has a nice corrected field, great pin point stars and no C.A.I'm impressed! I think you can't go wrong with it :)
It makes for a nice grab and go setup.

Cheers,

#6 cherokawa

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Posted 13 May 2014 - 06:25 PM

For what I see on that pleiades image I'd say it's well worth the price for sure, it has a nice corrected field, great pin point stars and no C.A.I'm impressed! I think you can't go wrong with it :)
It makes for a nice grab and go setup.

Cheers,


Luis, you should ask Paulo about this lens - he owns it now :D.
Had I been able to mount a Nikon camera on my lens, I would still own it (my lens came with a Canon mount).

#7 jzeiders

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Posted 13 May 2014 - 09:30 PM

Nikon also made a 500mm f/5 mirror (reflex) lens. They are a bit bulky and the concentric focus ring near the camera body can be a pain. They run $300-500 used. Out of focus donuts annoy many photographers so they didn't sell well. The one I had was actually quite good but I sold it when I got a 300 f/2.8 ED. I see them on ebay from time to time.

Jack

#8 SteveRosenow

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Posted 13 May 2014 - 09:38 PM

I have a 500mm Spiratone f/8 catadioptric lens.

One of the best $25 investments I ever made.

Bought it at an antique store, whose owner had no idea what it was. LOL
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#9 17.5Dob

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Posted 13 May 2014 - 09:54 PM

But my 80mm X 560mm APO refractor triplet only ran me $359, brand new, with diagonal, EP's, etc. No central obstruction

I don't own a tracking mount that can handle it .. yet ..

But here's a snap taken through it as a super zoom in my back yard this evening.

Posted Image

#10 Campos

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Posted 14 May 2014 - 03:33 AM

For what I see on that pleiades image I'd say it's well worth the price for sure, it has a nice corrected field, great pin point stars and no C.A.I'm impressed! I think you can't go wrong with it :)
It makes for a nice grab and go setup.

Cheers,


Luis, you should ask Paulo about this lens - he owns it now :D.
Had I been able to mount a Nikon camera on my lens, I would still own it (my lens came with a Canon mount).


Hehehe, thanks for the tip, I will check it out :)

Best,

#11 Moromete

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Posted 15 May 2014 - 12:24 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image


Very nice image taken with such a cheap and light lens!

Do you have the same image uncropped to see its corners?

#12 cherokawa

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Posted 15 May 2014 - 02:32 PM

Thanks, Moromete. Let me see if I have some raw files that I can share with you later today.

#13 jblaschke

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Posted 15 May 2014 - 04:00 PM

Cherokawa, you're not talking about the famed Vivitar "solid CAT" are you? If so, I'm envious. That's reputed to be among the best-performing mirror lenses, yet are scarce as hen's teeth!

http://www.luminous-...solid_cat.shtml

#14 cherokawa

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Posted 15 May 2014 - 04:14 PM

I don't think so, Jayme. I bought mine used on Ebay, but it seemed like it was recently manufactured and it was a 500mm lens, not 800mm. Here's a pic -

Attached Thumbnails

  • 6527368-821668-2.jpg


#15 cherokawa

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Posted 15 May 2014 - 10:02 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image


Very nice image taken with such a cheap and light lens!

Do you have the same image uncropped to see its corners?



Here's a 3-min Raw file. Keep in mind that I was struggling with wind and high clouds that night. https://db.tt/rWHtthy9

#16 Moromete

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Posted 18 May 2014 - 03:12 PM

Sorry for answering so late.

Thank you for the RAW file!

Judging by the stars captured in your RAW file I would say the 500mm F/6.3 lens is an excelent performer, considering its price too.

Now I want this lens badly because it has almost no optical abberations, it's cheap and light!

Just imagine using this lens with a DSLR like the new Sony A7S or Nikon D3S with exposures up to 30s and ISO12800...all mounted on CG5GT mount and without any guiding! :jump:

#17 tazer

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Posted 18 May 2014 - 07:38 PM

I have the same lens as cherokawa (Vivitar Series 1 500mm f/6.3.) It's worth the sub-$100 purchase price but definitely not an excellent performer for a few reasons:

1) Focusing is brutal. You're turning the entire lens to focus and combined with a very small FOV it's not easy to get critical focus. Also, the focusing mechanism turns pretty easily so it's easy to knock out of focus.

2) Attached to a DSLR (Sony NEX-5 in my case) it isn't secured very well and vibrates very easily for several seconds (exacerbating the focusing problems.) Since there's not even a 1/4-20 mount point you have to come up with a mechanism to brace the lens. When experimentally imaging with mine I had to put a shim between the dovetail and the back portion of the lens.

3) I believe the primary is glued on or, at least, attached poorly. At temperatures near freezing stars take on weird shapes. Even after leaving the lens/camera out for an hour.

4) No lens hood which make it susceptible to stray light. You can fashion something but will only make the focusing and vibration issues worse (unless properly braced.)

5) At f/6.3 I can only see the very brightest stars on my NEX-5 live view. Focusing requires trial and error exposures.

You can ameliorate some of these issues by using a 100mm tube ring to give rigidity and lock focus. Not super simple but definitely doable. Of course the ring might cost as much as the lens itself.


Just imagine using this lens with a DSLR like the new Sony A7S or Nikon D3S with exposures up to 30s and ISO12800...all mounted on CG5GT


Well, there's only so many photons raining down on the sensor during that 30s period regardless of ISO. Lower noise and better QE will certainly help but you have to expose longer (eventually autoguiding) to go deeper. Those cameras will make live view focusing of dim objects much easier however.

#18 cherokawa

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Posted 19 May 2014 - 11:07 AM

Hi Taser,
I agree with some of your points - lack of a lens-hood bothered me a little bit and focusing does need a gentle touch. But I never focus using live view - I used my bahtinov mask with this lens and it worked well with 3 second exposures on a bright star. Focusing this lens was far easier at f/6.3 than the other f/2.8 lenses I have.

I used the 1/4-20 socket on the camera to secure it to the dovetail and didn't bother securing the lens separately - the lens was light enough to not cause any issues.

#19 jblaschke

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Posted 19 May 2014 - 12:03 PM

I don't think so, Jayme. I bought mine used on Ebay, but it seemed like it was recently manufactured and it was a 500mm lens, not 800mm. Here's a pic -

Ah, well, you'd know it if you did--those Vivitars were heavy boogers!

In my experience, these lenses can be used for AP, but they're not designed for that use, and are thus challenging. I believe the majority of them are Maks, so there's no real reason why they can't be great performers. Except most are built on the cheap these days and fall far short of potential. I'd still advise hunting down a 70s/early 80s mirror lens for overall better quality.

#20 Mr.Magoo

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Posted 19 May 2014 - 01:41 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image


I'd say pretty darn good for $80. Makes me wanna spend $80.

#21 Moromete

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Posted 19 May 2014 - 04:04 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image


I'd say pretty darn good for $80. Makes me wanna spend $80.


I like your attitude! :grin:

#22 Mr.Magoo

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Posted 19 May 2014 - 04:12 PM

I had the Vivitar Series 1 version of this lens. It was a decent performer, but you can't really compare it to an apo due to the huge central obstruction. I think an apo will show better contrast. Anyway, here is a shot of M45 I shot a while ago. Considering the $80 I paid on eBay, I'd say it was an excellent performer :)

Posted Image


I'd say pretty darn good for $80. Makes me wanna spend $80.


I like your attitude! :grin:


Yeah, that attitude got me broke a few times... but I have lots of toys to show for it :)

:funny:

#23 jgs99v

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Posted 20 May 2014 - 01:02 PM

Guys - I started a thread on this some time ago, with respect to the F10 - which I abandoned.
The Samyang unit I did get - however I had to be very patient for focusing - and with the Skytracker setup worked very well for the costs. Only reservation is sharp focusing and maintaining this focus over the course of your session.

#24 bojan

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Posted 15 June 2017 - 08:28 PM

I have one of those...

Very light and short, ideal for carrying around.

However, my specimen has significant coma, visible even with APS sensor (see attached crops from corner and frame centre below).

I am wandering if my lens has manufacturing problem (like misplaced field lens assembly)? Did anybody else experienced this problem?

Attached Thumbnails

  • Corner.jpg
  • Centre.jpg

Edited by bojan, 15 June 2017 - 08:33 PM.



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