Need advice on super-portable frac

[BGazing]

Now that I have sated my aperture fever (and moved from 127 Mak to Evo 8), the time has come, I think, to sell the little Mak and replace it with a small superportable frac. And I need your advice in chosing it, as the last frac I manned was 30 years ago, and it was a Zeiss 110/2050 behemoth at a local observatory. That unwieldy thing scared me into buying a small Mak upon my return to the hobby. By the way, a restored Zeiss 110/1650 is now sold for 190 thousand euros...never would have guessed when manning the big beast.

Anyway, the idea is as follows. I bought a little goto Mak in order to have a telescope for every situation. I soon realized that is not possible. First, I do not have a garden, so my observations are always planned and involve at least a 30 min drive, so it matters little whether I have a 5 inch Mak or an 8 inch SCT. And for intercontinental flights (changing planes etc) going to equator and below, the Mak was kind of a drag and I opted for the bins. So I plopped for Evo 8, which leaves the other bit (a little portable thing) as a niche to fill. I need it when I go below, to skies that I do not normally observe (so I cannot whine about lack of aperture), or for those rare occasions when I cannot be really bothered to lug Evo 8 (local park for kids to see the Moon, etc.).

I also considered astronomy bins (which can use filters), but those are super heavy, and I would need a mount and two filters. 

So, when it comes to a small frac, I have a couple of thoght and a couple of questions:

- I would need it strictly for visual. I am not really into astrophotography. Yet. I know people who are, and I cannot really see myself going that way. Yet. So no need for a super duper quadruplet whatever.

- How little can it be aperture-wise? 80mm fracs all seem to be heavier than I would like. 70mm? 60mm?

- I really really need it to be portable, because that will greatly affect my use of it. If it is small and light, I will take it as much as I can when travelling far by plane. If not, I will not.

- When selling Mak, should I sell its Synscan Goto mount? It is kinda big and kinda drag to pack in the check-in, and a widefield frac would - I guess - be OK on a non-Goto to scan wide fields.

- What is the most portable mount that would support a small frac? I assume they have those alt az adjusting things?

Given the shipping constraints, i was mostly looking at the European vendors. Would this frac satisfy my needs 

http://www.teleskop-express.de/shop/product_info.php/info/p1151_TS-ED-70mm-f-6-Travel-Apochromat-with-carbon-tube-and-2--Crayford-focuser.html

I assume that, in order to balance it on some travel mount, I would have to stick to 1.25 diagonal and 1.25 EPs. In 1.25 I have ES 24 68mm and a 15mm Gold Synta Erfle (the later I guess would not perform that well in a fast scope) and  Baader Zoom (which, I assume is heavy for the purpose of balance...

Any recommendations you might have would be much appreciated.

 

[Alan64]

Here's a 50mm... http://www.teleskop-express.de/shop/product_info.php/info/p5632_TS-50mm-f-6-6-APO-Doublet-Refractor---Day-Night-Scope-and-Tele-Objective.html

But I would want at least an 80mm... http://www.teleskop-express.de/shop/product_info.php/info/p7169_TS-ED-80mm-f-7-refractor-telescope-with-2--Crayford-focuser.html

There are somewhat shorter, and more expensive, 80mm refractors in addition.

[jetstream]

My 90mm f7 SV is a very good, compact scope and will show much better than the sub 80's.

[BGazing]

9 hours ago, jetstream said:

My 90mm f7 SV is a very good, compact scope and will show much better than the sub 80's.

I know how it works, and I undrerstand the aperture point. But unless i keep it small and super portable, it is not going on the plane. Hence the limit. 

Sub 80s will show more than the naked eye.

[Stu]

What kind of budget do you have?

Probably my best airline portable kit used a Takahashi FC-76DC. This was basically a Tak FS-60C with the 76mm objective upgrade so the tube would split in two, making an extremely portable setup, but with fantastic optics still from the fluorite doublet. The FS-60C itself is tiny and still very capable for visual.

I use a Giro-WR mount which weighs under a kilo but takes the 76mm with ease on a decent photo tripod.

[BGazing]

Huh, that is a nice one, but the price is 1400 dollars. I would like to say that money is no object, but, even though i know that the one who buys cheap buys twice and that Taks are supposed to be gems, I fear that it would be an equivalent of buying a BMW for a scope that would get a relatively limited use. I was looking at something around 500, or 600 for the OTA. Exceptions are always made, I know... But your advice is noted, thanks! The thing looks light, too.

Giro WR looks interesting. Never used tripods for that before...so basically it screws itself on the photo tripod. No counterweights needed for a small frac?

[Alan64]

One of the two 72mm refractors, illustrated here in black and white, would be ideal...

https://www.astronomics.com/astro-tech-refractor-telescopes_c5.aspx

...as this one might, too...

http://www.teleskop-express.de/shop/product_info.php/info/p1151_TS-ED-70mm-f-6-Travel-Apochromat-with-carbon-tube-and-2--Crayford-focuser.html

[D4N]

I really love my Canon 15x50 IS for their portability.

Being bins 50mm works out like a 70mm scope as you are using both eyes.

They also have filter threads on the front so if you buy a couple of cheap adaptors you can fit Astro filters to them, I have a pair of UHC-S filters on mine.

Being IS they don't need a tripod either, although I found they do benefit from one and it takes the weight off your arms.

 

 

Telescope wise I have taken my 70mm frac on planes and it works ok on a photo tripod.

I use my Baader zoom eyepiece for this as it also helps keep everything portable.

 

The scope obviously has the advantage in having variable magnification, the bino's have the advantage in being extremely portable.

 

I have also used my 50mm mak but this is really too long a focal length for such a small scope so it is mainly useful for solar or lunar. I have used that one for imaging and it did really well on the sun.

[Stu]

56 minutes ago, BGazing said:

Huh, that is a nice one, but the price is 1400 dollars. I would like to say that money is no object, but, even though i know that the one who buys cheap buys twice and that Taks are supposed to be gems, I fear that it would be an equivalent of buying a BMW for a scope that would get a relatively limited use. I was looking at something around 500, or 600 for the OTA. Exceptions are always made, I know... But your advice is noted, thanks! The thing looks light, too.

Giro WR looks interesting. Never used tripods for that before...so basically it screws itself on the photo tripod. No counterweights needed for a small frac?

Yep, the Tak is certainly not a budget option, I no longer have mine because I needed the cash more! Lovely though.

The Giro-WR will operate without a Counterweight for light scopes, and yes, just screws into the top of a photo tripod. There is also the mini Ercole if you want more capacity.

If you can find one, the William Optics SD ZS66mm is a tiny little gem, pretty nice optically and would be in budget.

 

[Stu]

I note there is a William Optic ZS 71mm on ABS which may be worth looking at? Nothing to do with me!

http://www.astrobuysell.com/uk/propview.php?view=115942

[BGazing]

suppose i get a 70ish mm one which is f/6...and given that the mount is a fairly simple one with no tracking, what should be the ep lineup? i could use my es 24 68mm for scanning widefield at 4mm exit pupil at about 20x, what else? 15mm synta gold is, i reckon, unuseable. two quality widefield eps with shorter lenghts and a good barlow? would hyperion zoom be useful at all?

[D4N]

Yes the Hyperion zoom is great for a portable setup, especially if you have the matched Barlow you get a great range of magnifications in minimal space.

[BGazing]

nope. no barlow but worth considering.

and...i just realized that a photo tripod and a mount might not be that much more than cannibalising synscan goto mount from my 127 mak. does it make any sense? after all, tripod is 2 kg and the mount is 2 kg...

[happy-kat]

I can't add the link as it crashes Chrome every time but there is a recent thread I think you would find interesting.

My new travel scope - may have made all others obsolete!

[BGazing]

thank you, it is this one, i guess

very interesting, and uses manfrotto tripod and a video head. looks like 66 or 70 really is a way to go as far as travel compactness is considered.

was a bit surprised to see the OP use baader zoom at 8mm for low power, i would not have expected that the zoom would perform well in such a fast scope. but other than a 8mm, i guess there has to be a 5 mm and a barlow...or some other combination. having had folded optics so far only, i am completely devoid of short focal length eps...and i know that a good one with one view will cost...a lot.

i'll ask in the thread directly, i guess...

 

[Roy Challen]

I'll add my tuppence - how about the TeleVue TV60? Gets good reports, weighs very little and doesn't cost too much. Haven't looked through one myself, but wouldn't say no if given the opportunity

[BGazing]

On 07/08/2016 at 20:07, Stu said:

I note there is a William Optic ZS 71mm on ABS which may be worth looking at? Nothing to do with me!

http://www.astrobuysell.com/uk/propview.php?view=115942

actually this looks sweet for the price, although i would have to consider somewhat higher shipping costs. half the price of a new one on flo.

[BGazing]

Coming back to this, has anyone used small Borg EDs? They look very lightweight and very very modular...ideal for airline travel.

Something like this https://www.firstlightoptics.com/borg-astrograph-telescopes/borg-77edii-f6-6-basic-ota-set.html

Helical focuser...never used it. One puts diagonal in and basically draws it back and forth, right?

[Louis D]

Just saw your thread revived.  I have been using an AT-72ED for a couple of years now, and it is wonderful.  The only color is a slight bluish-purple fringe on bright planets above 100x.  You really have to look for it.  There's no comparison to my ST80.  I couldn't stand the color fringing on it at all.  The AT-72ED's 2" focuser is great for using wide angle 2" eyepieces to scan the skies at super low powers.  The belt of Orion truly looks like an open cluster with it (Collinder 70).  It is a relatively heavy scope at about 5 pounds compared to an ST80.  Add a 2" diagonal, red dot finder, 31mm Nagler T5, and a 6 to 8 inch dovetail bar and you're up around 8 pounds.  You'll need the dovetail bar to properly balance it because it gets so back heavy with such a short tube.  I tried using it on a Manfrotto 128RC fluid head, but above 30 to 40 degrees it just flops backward due to severe imbalance.  I ended up getting a DSV-1 mount for it.  To handle the weight, I use a Manfrotto 058B tripod.  I'm sure you could get by with a much lighter mount and tripod, but I wanted rock solid stability.  With Sorbothane pads under each leg, vibrations dampen out in under a second.  The case it comes in is quite nice and compact with spots for a 2" diagonal and a chunky eyepiece.  I keep a Celestron Regal Zoom in that eyepiece spot.  It fits perfectly.  I picked up everything second hand, so I have about $600 invested in the telescope, mount, tripod, 2" diagonal, dovetail bar, and Regal eyepiece.  New, it would have been much more.  Watch the classifieds and see what pops up.

[BGazing]

I hear you on the weight...and much as I like my nice Baader clicklock diagonal and 2 inch eps I will try my best to stick to 1.25 inch diagonal and eps to keep it low.

AT72 really looks nice. 

Has anyone tried this http://www.teleskop-express.de/shop/product_info.php/language/en/info/p8866_TS-Photoline-70-mm-f-6-FPL53-Triplet-Apo---2--Zahnstangenauszug.html

Cheap triplet at 1.87 kgs....sounds too good to be true, where's the catch? Evidently, it is a bit more pricey, but still not exorbitantly so.

[D4N]

I have the TSED70Q which appears to be quite similar, really nice and portable, the dovetail fitting is a bit small to achieve balance if you have anything weighty on the focuser end but I have solved this with a small dovetail on mine.

[Alan64]

3 hours ago, BGazing said:

I hear you on the weight...and much as I like my nice Baader clicklock diagonal and 2 inch eps I will try my best to stick to 1.25 inch diagonal and eps to keep it low.

AT72 really looks nice. 

Has anyone tried this http://www.teleskop-express.de/shop/product_info.php/language/en/info/p8866_TS-Photoline-70-mm-f-6-FPL53-Triplet-Apo---2--Zahnstangenauszug.html

Cheap triplet at 1.87 kgs....sounds too good to be true, where's the catch? Evidently, it is a bit more pricey, but still not exorbitantly so.

It could certainly do double-duty, for visual and imaging, but I would think a doublet to be hardier for travelling and perhaps a tad brighter.

[BGazing]

On 07/09/2016 at 16:49, Louis D said:

 I ended up getting a DSV-1 mount for it.  To handle the weight, I use a Manfrotto 058B tripod.  I'm sure you could get by with a much lighter mount and tripod, but I wanted rock solid stability.  With Sorbothane pads under each leg, vibrations dampen out in under a second.  The case it comes in is quite nice and compact with spots for a 2" diagonal and a chunky eyepiece.  I

Thanks @Louis D, @Alan64 and everyone who contributed, it is much appreciated. 

I will probably end up with the 1.7 kg TS ED 70 carbon and Giro Mini WR (which is just under 1 kg), as suggested by @Stu. Puls dovetail plate, 1.25 diagonal and eyepieces, each of which will hopefully weigh not more than 250 g.

How light can I go with the tripod? Would this be enough, or do I have to go heavier? If so, what with? (let's stick with Manfrotto if possible)

[Helen]

+1 for the giro mini and a photo tripod.  I was asking similar questions before a trip to the US earlier in the year and the recommendation for a widefield eyepiece was a TV Pan 24.  I got one, and love it!  I used it with a Borg 77 while away.  The helical focuser of the Borgs is much more sophisticated than a draw tube!  More like a camera focuser ring, non-rotating and very precise.

Helen

[Louis D]

18 minutes ago, BGazing said:

How light can I go with the tripod? Would this be enough, or do I have to go heavier? If so, what with? (let's stick with Manfrotto if possible)

As long as you're minimizing the weight of what gets mounted to it to 4 kg or less, that tripod should suffice.  Remember that you should avoid extending the center column to avoid adding additional damping time.  I'll admit I extend mine rather than the legs when temporarily observing near zenith.  The geared column is really handy for that.  Once locked down, the extra damping time is tolerable.

I would think carbon fiber would damp more quickly than metal, but you'll still want to make some vibration damping pads.  To make mine on the cheap, I bought some new old stock 1980s era 100% Sorbothane insoles off ebay for $6 and cut them into squares that I put under each tripod foot.  I tend to forget they're there when I pack up in the dark, and it can be a pain to find them because they are dark blue and tend to stick to the feet temporarily.  I need to spray paint them fluorescent orange.

I also wanted to mention that I've read that FPL-51 in smaller apertures (as in the scope you're interested in) is equivalent to FPL-53 in larger apertures as far as color correction.

Lastly, watch out for field curvature in a small refractor if you're used to using a 1000mm or longer Newtonian.  I ended up adding this field flattener to the front of my 2" diagonal with a spacer ring to improve things.  It's not perfect, but it is much improved.  Probably the most expensive part of my rig.  It would have to be threaded onto the front of the 2" to 1.25" adapter when using it with a 1.25" diagonal.  It's not that I'm OCD about having perfect edges, it's that the edges were way out of focus in wide field 2" eyepieces.  I don't think it matters as much at higher powers.  You'll have to see if it bothers you in your observing.  I don't drop $200 lightly.  It really bugged me.

Let us know how your rig turns out.  I went the cheaper but heavier route (except for the field flattener).