SC vs. MC

I'm looking for a pickup and go scope for around the house and on camping trips. Has to be small and relatively light (otherwise I'd bring my 10" XTi ). Since I've spent a bundle on nice lenses over the last nine months, to keep the cost down I'm looking at used scopes. I've got a couple of Naglers (7mm, 12mm, 17mm), several 68 degree lenses (8mm, 21mm, 27mm, 35mm), a few plossls (10mm,25mm), and a 7mm UO ortho. Oh, I also have a TV 8-24 zoom.

Anyone care to explain the issues in deciding between a Mak and a Schmidt? Pros and Cons? I believe the Maks have a longer cool down time and longer focal lengths for a given size. Cool down time is a non-issue since it would be outdoors in a tent and the shorter focal lengths of an SC means a wider field with a given lense-right? What other factors/tradeoffs should I be thinking about?

Go to capability would be nice but not mandatory. BTW, am I correct in assuming the white tube C5 was meant as a spotting scope and the orange for astronomy? If so, does anyone know if there is a difference astronomically?

Thanks in advance.

Sharper images in the Mak, but the wider fields of the SCT are easier to use than the Mak. I take my Dob when I go camping though.

I'd go with the SCT. It is more general purpose than the Mak. It is easier to get more magnification than it is to get wider field, in my opinion.

(And I'm only saying get the SCT because that was the only choice you gave me. The real answer--if you don't want to take your Dob--is a high quality refractor at 75 or so mm or higher (3 inch or more).

Alex

Dennis Freeman said:

I'm looking for a pickup and go scope for around the house and on camping trips. Has to be small and relatively light (otherwise I'd bring my 10" XTi ). Since I've spent a bundle on nice lenses over the last nine months, to keep the cost down I'm looking at used scopes. I've got a couple of Naglers (7mm, 12mm, 17mm), several 68 degree lenses (8mm, 21mm, 27mm, 35mm), a few plossls (10mm,25mm), and a 7mm UO ortho. Oh, I also have a TV 8-24 zoom.

Anyone care to explain the issues in deciding between a Mak and a Schmidt? Pros and Cons? I believe the Maks have a longer cool down time and longer focal lengths for a given size. Cool down time is a non-issue since it would be outdoors in a tent and the shorter focal lengths of an SC means a wider field with a given lense-right? What other factors/tradeoffs should I be thinking about?

Go to capability would be nice but not mandatory. BTW, am I correct in assuming the white tube C5 was meant as a spotting scope and the orange for astronomy? If so, does anyone know if there is a difference astronomically?

Thanks in advance.

I've always taken my ETX105 camping with me. And no, you don't need a tripod with it. In fact, if you add some weight on one end of the OTA, you can use it Alt-Az with no 12v power at all...just manual.

Due to it's fork mount, it has a built-in Alt-Az mount with a wide enough base to not need a tripod. I've used tree stumps, boulders and even two stacked coolers to put it on.

The ETX125 is only an inch longer than my ETX105 and would also do nicely for camping trips.

Having said all that, they are both Maks so they aren't for wide field. But I use a TV32mm plossl and get some pretty nice views of Andromeda and the Pleides as just an example. Of course, the Maks are very sharp for planets and the moon.

If you want wide fields get a wide field refractor. Even a used Astroview 120ST from Orion is a fantastic (and cheap) wide field scope. Because it's not an APO you get a lot of false color on bright objects, but you won't have that on wide field objects anyway, so an achro like the 120ST would be my choice for a cheap camping refractor.

As far as cool down time on the Maks, I've never had to let the optics cool down any longer than 1/2 hour tops. You aren't really bringing them out from a heated environment when camping anyway.

My two choices would be either the ETX105/125 or an Astroview 100ST or 120ST, with the latter being sold dirt cheap even new, and greater deals on them used.

Hi Dennis:

I am coming late into this thread and you have already gotten a lot of good advice. Nonetheless, I want to share my experience with you along the lines of the questions you have proposed. For many years, I owned a C8 but found that its size and weight became an impediment when the kids and their stuff took over all of the available space in the car. Therefore, I went after a set up that was light and versatile and ended up doing something that has been hard to explain to the wife but has turned out to be a great learning experience. I bought both a C5 OTA and ETX 125 OTA and have repeatedly done side by side comparisons of the two over the last year with the purpose of keeping one and selling the other.

Both scopes are mounted on Bogen 3021 tripods with heavy duty heads designed for Medium Format cameras (model # 410). In this set up all tracking is done manually, but on the positive side there is no need for batteries or polar alignment, and the tripod and head weight is only 8 lbs. The C5 brought the weight up to 15 pounds and the ETX to 17, but either way I could easily pick up the whole thing and move it in and out of the house, or to a darker spot in the yard.

Here is what I learned.

Cooling times are in general not much of an issue, unless you are in truly in cold weather. In which case, the C5 will be ready for use faster. The ETX is definitely heavier and was more difficult to balance in the mount I am using, but with the fork version you are interested in this will pose less of a problem. Of note, the weight difference between the two is primarily a function of the greater thickness of the corrector plate in the Mak.

Optically, they are very different scopes. There is no doubt in my mind that the Mak has sharper images and is obviously not prone to decollimation (although apparently it can happen with rough use). In this regard, it’s unlikely you will have to fiddle with the collimation screws (difficult to do in a Mak apparently) thus making it a less demanding scope to use for the beginner. The Maks’ longer focal length makes it a great match for a 2 eyepiece choice, namely a TV 32 mm and a TV 8-24 zoom. With the latter, you have a range of magnification between 59x and 237x. The images remain sharp throughout the range. Some say that the ETX is capable of 350x in prime conditions but I have never had good enough seeing where I am to test this claim. Its sharp images make it a good scope for planetary work and double star viewing, where I think it has a distinct edge over the C5. All this made me realize why the ETX has such a faithful following. A major downside is that the finder that comes with the ETX is truly a piece of junk, but can easily be replaced with an Orion 6x30 finder.

Obviously I am singing the praises of the ETX 125, so you may be surprised to find that the C5 has won out in the end. How come? It came down to my acquisition of the f6.3 reducer lens that can be screwed into the visual back. It changes the focal length from 1250mm to 787 mm. Although initially designed to augment the utility of SCT’s for photography, it does great things for the visual capabilities of the C5. It allows wide field views at low powers (25x with a 32 mm) that are impossible to achieve with the Mak, even if a similar reducer lens could somehow be deviced for it. The reducer lens in the C5 also sharpened the images, and eradicated the differences in acuity beween the two at least up to 200x. Beyond 200x, I still think that the ETX is sharper but, most of my observing is done in the 50x to 200x range anyway. It requires that I add another eyepiece or two to the set up in order to get high mag but I found it is a price worth paying, and when traveling, eyepieces don’t same to take a lot of room. Note however that the C5 has to be well collimated to rival the ETX, but it is not so difficult to learn to do it if you replace the collimation screws with Bob’s knobs. In the end, I have leaned on the side of overall versatility over high mag performance.

Then I started to look at refractors… but that’s a story for another time.

I hope that you find this helpful.

Rey Cordero

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Consider the Orion Starblast. Often available used here.

Dennis:

Just my two cents at the tail end...

I have owned an ETX-125 as well as currently own a C-5 (with the F/6.3 focal reducer Ray discusses.)

Of the two, I preferred the C-5 because it is capable of some wider fields of view. The slow focal ratio of the ETX-15 (F/15) means a narrow field of view and a small exit pupil. At a dark site, one of the true pleasures with a smaller scope is wandering around looking at the big view, the rivers and valleys, blotches and voids, in the Milky Way. With the ETX-125, this just doesn't happen, with the C-5 operating at F/6.3, it's not bad.

But my own preference goes towards either towards my ED-80 which goes most everywhere with me or to the Starblast or other short fast parabolic Newtonian.

In particular the ED-80 makes a good companion to your 10 inch DOB, it has a 600mm focal length and a 2 inch focuser so 4 degree FOVs at 15x-20x are quite possible and nice and sharp to the edge.

Best wishes

jon