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MTO 500mm f6.3 cat
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PostPosted: Mon Mar 24, 2014 7:17 pm    Post subject: MTO 500mm f6.3 cat Reply with quote
Hi everyone,
I'm looking for this catadioptric 500mm for astronomical and "sunday" use, i've found one here in Italy: 500mm f6,3, bag, 3 coloured filters at 150 euros. Is the price good?
The seller say to me that the mto doesn't fit in the 500d due the canon flash-case but it is possible change the "infinity" mto backfocus ( by a tecnichan and loosing a little bit of focus at minimal distance) and use a 7mm extension.
What i've to do?


PostPosted: Mon Mar 24, 2014 7:35 pm    Post subject: Reply with quote
Price is normal (not overpriced but also not very cheap) if condition is good.
For astrowork I would rather look for the MTO 1000mm F10 though.

Do you already have eyepieces etc.? It might be easier to look/wait for an Celestron, Meade etc. Schmidt Cassegrain with mount+tripod+eyepieces set on Ebay etc., no work by a technician necessary and ready to start.

Instead of spending money into a technician you could also look for an used mirrorless camera body like NEX or µFT (can be had for 80-180€).


PostPosted: Mon Mar 24, 2014 7:52 pm    Post subject: Reply with quote
Hi!
F10 is too dark for deep sky image, i've just 3 telescope but i'm lookin for a 500 mm to take deep sky image when i go to mountain and i can't carry mount, telescope etc.


PostPosted: Mon Mar 24, 2014 8:20 pm    Post subject: Reply with quote
You need a good mount anyway if you want to take photos at 500mm...


PostPosted: Mon Mar 24, 2014 8:38 pm    Post subject: Reply with quote
I've an eq6 and an heq5 and i take pic at 1370mm to with my RC Smile


PostPosted: Tue Mar 25, 2014 4:34 pm    Post subject: Reply with quote
betacapricorni wrote:
Hi!
F10 is too dark for deep sky image, i've just 3 telescope but i'm lookin for a 500 mm to take deep sky image when i go to mountain and i can't carry mount, telescope etc.

1000mm F10 gives actually a brighter image at the same magnification as an 500 F6.3 and has better IQ as far as I know; simply use an longer focal length eyepiece.
My 2000mm F10 works quite well for deep sky btw., "only" F10 but actually several times brighter than a 500/6.3

If you want something fast and bright you could look for an "Comet Catcher" like Celestron 500/3.6 - works very good for photography aswell (very sharp center) and compact enough to put it into a backpack and light enough to mount it on a decent photocamera tripod. I bought mine for 180€ on Ebay two years ago.
http://forum.mflenses.com/celestron-500mm-f3-6-comet-catcher-t55297,highlight,%2Bcelestron.html
Lichtenknecker has similar speed mirror lenses for astro photography which have awesome IQ btw., but they are rare as they are not longer in production since the 80ies.

Last edited by ForenSeil on Sat Mar 29, 2014 3:26 pm; edited 1 time in total


PostPosted: Tue Mar 25, 2014 7:28 pm    Post subject: Reply with quote
Yes but for every exposition minute with 6.3 i've to expose 4 minutes at f10 to have the same nose/signal ratio. Too slow for deep sky image. I've had a comet catcher, it was a "comet factory" for the coma in the corners Very Happy


PostPosted: Wed Mar 26, 2014 1:00 am    Post subject: Reply with quote
I have 500mm 6.3 long time ago, I didn't use it much , but I was amazed by quality so I kept it as one of the best 500mm lens what I can afford. (bellow 500 USD) I had 1000mm at least twice , I did try it once, I was pretty amazed by sharpness and distance , but... I never use it for sure so I sold it.


PostPosted: Wed Mar 26, 2014 10:37 am    Post subject: Reply with quote
Thanx for informations Attila!


PostPosted: Wed Mar 26, 2014 11:09 am    Post subject: Re: MTO 500mm f6.3 cat Reply with quote
betacapricorni wrote:
...The seller say to me that the mto doesn't fit in the 500d due the canon flash-case but it is possible change the "infinity" mto backfocus ( by a tecnichan and loosing a little bit of focus at minimal distance) and use a 7mm extension.
What i've to do?


For some of my lenses I had the same problem, the EOS flash case is to big, so I cut it away:



PostPosted: Wed Mar 26, 2014 9:48 pm    Post subject: Reply with quote
betacapricorni wrote:
Yes but for every exposition minute with 6.3 i've to expose 4 minutes at f10 to have the same nose/signal ratio. Too slow for deep sky image. I've had a comet catcher, it was a "comet factory" for the coma in the corners Very Happy

Ah okay, I didn't get that you wan't to use an F6.3 only lens for deep sky photography directly. I though you would like to use it as telescope visually and as "normal" lens.
And of course the comet catcher would be an unusable coma catcher on APS-C sized sensors for deep sky, that would be more something for µFT maybe. But are you sure you need an 500mm for deep sky photography, that's pretty long, do you already have an 180/2.8 etc.? Then the MTO 500/6.3 should be the best choice indeed if you don't want to spend much more or wait for an Lichtenknecker Flatfield (unlike the Comet Catcher they don't have coma issues)!


PostPosted: Thu Mar 27, 2014 2:35 am    Post subject: Reply with quote
You can alter the focus/infinity stop on these lenses, yes.
Under the rubber body cover, there are three screws, and a pair of stop limit screws - easily done, and there's a couple of web pages (including a couple of posts here ) on how to do it.
I did similar with my Rubinar 300, to fit my Pentax (same problem with the flash mount). I made a simple mount extension to physically space the lens from the body, then re-set the infinity stop.


PostPosted: Thu Mar 27, 2014 12:12 pm    Post subject: Reply with quote
@ZoneV
the flash works correctly yet?

@ForenSeil
i've an helios 44/2, a jupiter 135 f3.5 and a Jupiter 200 f4 but all of this must work at f4 because the narrowband Halfa filter works correctly only from f4

@Farside
may you post me a webpage please? ( in italian i can't find nothing )


PostPosted: Thu Mar 27, 2014 4:18 pm    Post subject: Reply with quote
betacapricorni wrote:

i've an helios 44/2, a jupiter 135 f3.5 and a Jupiter 200 f4 but all of this must work at f4 because the narrowband Halfa filter works correctly only from f4


Some work at f/2.8 too. There's even one guy who did narrowband with a 200mm f/1.8 Canon wide open, but don't know what filters he used.


PostPosted: Thu Mar 27, 2014 5:09 pm    Post subject: Reply with quote
I've an Astronomik 12nm and i'll try as soon as possible at f2 with helios 44


PostPosted: Thu Mar 27, 2014 8:11 pm    Post subject: Reply with quote
betacapricorni wrote:
@ZoneV
the flash works correctly yet?


Yes, this is only a housing for the flash in the off position.


PostPosted: Sat Mar 29, 2014 1:14 pm    Post subject: Reply with quote
betacapricorni wrote:

@Farside
may you post me a webpage please? ( in italian i can't find nothing )


http://forum.mflenses.com/mount-extension-for-russian-500mm-f-8-lens-t15717.html

https://www.google.ie/search?q=russian+mirror+lens+infinity+focus+adjust&ie=utf-8&oe=utf-8&rls=Palemoon:en-US:official&client=firefox&gws_rd=cr&ei=tMY2U-D3MuaI7Abn44GQCQ


PostPosted: Mon Mar 31, 2014 7:57 pm    Post subject: Reply with quote
Thanks so much!


PostPosted: Mon Mar 31, 2014 9:22 pm    Post subject: Reply with quote
betacapricorni wrote:
I've an Astronomik 12nm and i'll try as soon as possible at f2 with helios 44


Looking forward your results! I've never made any deep sky with narrowband filters Smile
In my experience only a very very few 50mm lenses do work well for deep sky and Biotar design is not known to have good corners. The filter might improve IQ (or at least reduce CAs) though.
Usually it's easiest to start with a decent 135mm-200mm lenses for beginners and large and bright objects like andromeda.
Good luck (and good weather!)!

Smile


PostPosted: Sat Apr 12, 2014 7:47 pm    Post subject: Reply with quote
as soon as possible when i take some pic i'll post!
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