Experiment. Tak MT160 40D Omega cent

[Bassnut]

Hi Guys

I inherited an old Tak MT160 newt from Chris (Omaroo) on a whim, given it was in very good condition, is reputably of good quality (especially the optics), and I was looking for something portable for field use.

It was a bit of a punt due to doubts about weird adaptors, backfocus and suitability for imaging generally, but I purchased an MPCC and fitted it with a 40D with no trouble at all, with stock adaptors :D.

Reaching focus was no problem ( and the focuser is typical tak quality, solid and smooth as) with plenty of back focus to spare for my CCD and filter wheel later (but not an autofocuser, small sacrifice). The focuser also has a rotator built in, bonus for internal guide (but not OAG, unless I go a QSI cam).

Here (http://4256458530705943474-a-1802744773732722657-s-sites.googlegroups.com/site/fredsastro/temp/Omega%20cent%20B%20stretch.jpg?atta chauth=ANoY7cqDWehtiSF_KfJK03LCLmQ6 7-KvEeIYXa73oI5NOzTNvtGeWwnLLu-arij1LcMt0CHsk0T2IwwFN1gSo-eODGLRE2mo_iVZ9wPLV-pM5reJ1tUfxAblZdlZCknTW9hETb4UKAY2C n-30n-2b2zJl6uMV2Z1rJC9LeM_qV_l0uWPhl8Wbd AZuu9PWe-bM8VAp6jUjc-pl3J3fKvbXDtTwZaqNKaouQ%3D%3D&attredirects=0) is a pic of Omega cent with the 40D and MPCC. Its very large at 9megs, with a little stretching and colour correction and no croping or other processing. I posted a large pic, cause im interested if someone can tell me if they can determine the optical quality of this scope from the pic, and its suitablility for imaging before I go nuts and possibly select a cam for it and generally spend a lot of money on cam/mount etc for field use.

Seems to me its pretty good, with a good image circle for large chips, but I have no experience with short FL, wide field imaging, so I cant really tell.

The scope is 160mm 976FL at f5.7 with an image scale of 1.2 arc/secs with the 40D. It was guided with an ST10XME on a 10" RCOS RC at 2275FL, theres an irony there somewhere :lol:. The attachment shows the MT160 mounted on top of the RC. The PME just laughed at the load :D.

The pic was 20 off 2min subs with ICNR and no flats with the moon up, so there is a gradient. The short subs maybe hiding some defect, its not a deep exposure. Im suprised at the blocky stars, given the 1.2 arc/sec scale (with much zooming), not sure what to make of that.

Anyway....... Im tempted to procceed fitting a rig up with this OTA, would an EQ6 pro do you think?, with maybe a tiny ST80 for guiding?.

Opinions appreciated.

[strongmanmike]

:eyepop: ...I fear the greater than 10 arc min FOV's may cause you agoraphobia and general dizzyness :scared:

Looks pretty promising Fred the image looks quite good..go for it, getting colour images in every frame will be welcomed light relief :thumbsup:...actually I think about doing something like this myself sometimes :confuse3: LRGB can be a little annoying at times huh?

Mike

[Doomsayer]

Hi Fred.
Surprising you would do this knowing your usual predilections for long FL.
However, I am on a similar path. With my 12RC on PME with a 6"f3.9 CF tubed newt RFT about to piggyback. I'm glad to see the MT160 being exploited for imaging - they have such spectacular optics visually. I also have an MT130 for visual - an amazing visual scope - I may yet give it a go with a camera and the MPCC. I hadn't tried this since I thought the dedicated but rare Tak corrector-reducer was the only way to go.

I plan to take the 6" RFT (almost fully built) in the field for imaging as well (hopefully to SPSP), riding on a Tak EM200. So I'd say a 'tweaked' EQ6 should handle the MT160 fine (I have seen your MT in the flesh elsewhere). My 6 will probably weigh about the same as the MT160 or more?, since It will have a heavy duty focuser cage mount to carry a PDF focuser, PL11002M and filter wheel, with an internally mounted MPCC.

cheers
guy

[Bassnut]

Well, funny you say that, im tempted also by a large chip one shot colour cam and avoid the expense of large filter wheel and filters etc. Especially one with internal guide as it would be not filtered, and save the bother of an external guide scope. Despite the lower QE, it would be very convienient for portable field use for dark skies LRGB (hopeless in Sydney)and guarentee a result regardless of fleating "conditions" (including mine :D).



Yeah well, long FL is just too hard in the field, im not going to lug a PME around, so realistically its WW (wide field wooze) there im afraid :P.

I too was concerned about the lack of the rare dedicated Tak reducer/corrector availability (I only have the f8 corrector), but the MPCC seems to do the trick nicely, I am pleasently supprised, and I would imagine it would also work on the MT130. I suspect now it would be fine with the PL11k

The visual use aspect of the MT160 is also attractive, I well, never look through an eyepiece, I would dare in dark skies with this OTA :P.

From the end of the focuser to the imaging chip seems to be some 60mm (with focus travel to spare), I can find you more detail if you wish if you are thinking of the PL11k/PDF focuser/filterwheel, but I think that might be a stretch.

[telecasterguru]

Fred,

I can't get too technical with your question about suitability of the scope for imaging but I think that the image you have produced when limiting your imaging setup is very nice indeed. It appears clear right across the field. I would love to be able to produce that quality of image with a DSLR.

Frank

[TrevorW]

Fred hows the collimation on the scope ??

[Bassnut]

It was with no effort, click and print :). Left bottom shows some elongation



The collimation looks ok on this CCD inspector analisys, but the curvature seems a bit more extreme than the pic shows. Is this bad?.

[Omaroo]

Fantastic Fred, glad to see it being tried out. :thumbsup: This scope produced the best lunar images I've seen from any of my scopes - and I think that the OmegaCen shot of yours is pretty tight. I mentioned to you when I delivered the MT that you may have a little collimation tweaking to perform, as it had not been collimated for months and the trip over would have shaken it a little too. I took it to our dark sky site the weekend before, and that is over dirt roads.

I reckon that it has great potential - especially as a wide-field scope on the run. Put a decent EP in and enjoy the view. It's pretty spectacular when collimated.

Anyway - I'm glad that the MPCC and associated gubbins give you adequate focus travel. I think that it'd make a great field scope for you, and am super-keen to see what you can get from it over time. Persist with it - it's worth the effort. :)

[Bassnut]

Thanks Chris, im well pleased, the collimation is actually fine IMO, a mark of good construction. I dont think curvature is a problem either, the stars in the pic look fine IMO.

[Jen]

:thumbsup::thumbsup::thumbsup: nice pic Fred :D

[gregbradley]

There is some evidence of tilt there Fred. Bottom left hand side of the image shows coma but not anywhere else so its tilt.

So either your camera attachment is sagging or there was some focuser sag.

I imagine the focuser is fine so you'll need screw type adapters if you didn't already use them.

Also some dust donuts there so and vignetting so I take it no flats were used.

Other than that it shows great promise and typical Tak workability.

How do you mount your ME? I have an ME I am about to use soon and need to work out the
mounting plates required etc.


Greg.

[TrevorW]

Fred from what remember it's not recommended to use CCD Inspector on star clusters

I can see a slight elongation bottom right side of stars so I thought it may be a collimation issue

[Tandum]

I've got a stellarvue F60M3 finder guiding a 10" newt on an eq6. It struggles a bit with the weight but works ok. That finder is a straight through with a 2" helical focuser, about US$200 + rings.

[multiweb]

Collimation is good. The pattern you're getting is because you took a picture of a star cluster so don't worry about the donut shape. You have a slight tilt as the donut is darker on the right compared to the left. Also a fairly big value for the field curvature but that could be because of the DSO you've imaged. Try again on another starfield more uniform (around A Crux for instance). Other than the tilt I wouldn't change anything else in the set-up. You're good to go and the pic looks great. :thumbsup:

[Bassnut]

Thanks Jen, im hoping to have many more :D



Im using screw adaptors. The 40D adaptor, as mentioned elsewhere by others is loose, daft really, seems to be designed that way, but will be gone with a CCD. No flats were taken. To mount the PME, I used this. It allows easy attachment to any pier in lots of different ways


https://www.bisque.com/help/paramountme/image49.jpg
Figure 1 – Heavy-duty Wedge to Pier Adaptor Plate.

The heavy-duty adaptor plate (see Figure 1) is made of solid aluminum and weighs approximately 5.4 kg (12 lbs.). The Paramount ME attaches to the adaptor plate using the four "pier attachment knobs" near the corners (9.4-inch spacing).

Notes

<LI class=p>The heavy-duty base plate is recommended for permanent installations.
Shipping box dimensions: 36 cm x 36 cm x 14 cm (14-in x 14-in x 5.5-in); Weight: 5.9 kg (13 lbs)




Yes, ill take a pic of a sparser star field, it seems the elongation is hopefully just tilt.



Struggles a bit doesnt sound too good, but this is a (albiet fairly heavy) 6 inch. Ill have to do more homework on this methinks.



Excellent, thanks Marc. Ill definitely image another starfield and CCD inspect again and see if I can correct the tilt.

[AlexN]

Whats this.... Fred... Wide Field?? :eek:

I reckon with your Paramount the Stellarvue F60M3 finder that Robin mentioned would EASILY be enough.... The reason I suspect that Robin said it struggles a bit is because his 10" newt weighs 14kgs with no camera, no guide scope, nada.. Just the OTA.. start adding bits and pieces and it gets heavy, the EQ6 doesn't like heavy! :)

The MT160 + ST80 or finderscope would work well I think... Considered an OAG given the wide field nature of the scope?

[Screwdriverone]

Holey Moley Fred,

Nice pic, I quite like the result, core isnt blown out and the FOV is nice too, but what sort of MONSTER mount is that????

Must be nice to be able to just whack another scope on top of the RC10 and fire away, certainly looks strong enough to carry a CAR!

Cheers

Chris

[Bassnut]

Yeah well, I dont facy long FL in the field :P.
The tak is for a field mount, although I might just leave it where it is mean time and take NF and WF at the same time :D.

From memory, the tak is 12kg by itself, so im starting to get iffy about the EQ6, Ill look into it more, just dont want to shell out for a G11....again. Yes, itll be easy to guide.



Its a Paramount (guad, what a wanky name :lol:), but I dont want to lug it around.

The pic wasnt meant to be a masterpiece, but I recon the stars are nice and small/round anyway, that has to be a good start :).

[multiweb]

Regardless I'm starting to think AO is the way to go for a mobile set-up on the field. Think about it. Makes sense. Always on the move. Mount alignment/balance as good as you can get them without sacrificing too much imaging time. That's my next buy. Saving my pennies now.

[Bassnut]

Marc, carefull my friend, if saving time is the goal with AO, then get all the gear and software required, and set up just so in advance. IMO it would be marginal in hyperstar mode, but if not (long FL), yes.

If alignment is not good then you get too many mount bumps, same effect as with no AO. AO kills bad PE effectively though, a big bonus.

Tight integration with The Sky (or SN) with its FOV indicator and an auto rotator is a given, or youll be fishing around for a guide star far too long, and you need to calibrate mount guiding (and the AO) after every rotate move, unless you use automation software.

OAG generally (with autorotate) would suit field use to reduce setup time/mount load and improve long exposure, but AO is an extra burden that would give the same advantages as with a fixed rig, no time saving really, it still requires *almost* as good alignment .

[bert]

Fred I have to agree with marc. I get a star on my AO8/st4000 combo around 80% (except galaxy hunting with the vc200l....sigh) of the time without having to hunt for a star in the sky6. The guide star is selected by maxim, in ccdap.

I use a heavily loaded eq6 and NEVER have elongation (@1800mm) with the ao runnining even if I have the ao at 2hz or slower. I cheat by using a osc and dont have to have a bright star, because of no light loss via colour/nb filters, so the guide star can be very dim and still get successful A0 guiding without oag's.

I think the Adaptive optics is one of the best investments I have made as regards imaging.

Brett