Author Topic: How do I find things in viewfinder?  (Read 400 times)

Robert Donaldson

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How do I find things in viewfinder?
« on: December 24, 2017, 05:33:21 AM »
With the Zhumell Dobson I got at the Spring, I've mostly been looking at Brilliant things, Such as the Moon, Jupiter, or Saturn. It takes me some time to find these in the finderscope.  I visit them with my eye, but I need to hunt for them to get the finderscope on it.  On the whole, it might take me 30 seconds or so to put Saturn in the finderscope, which isn't awful, but certainly not as simple as I might like.

Yesterday evening I thought I would take out my telescope and see if I could observe the Andromeda Galaxy, Triangulum Galaxy, or Uranus.  Uranus was at the clouds, but Cassiopeia and Pegasus were in the clear, so I thought I would Attempt to find Andromeda.  I aimed the telescope toward Cassiopeia, and saw a bunch of stars at the finderscope that I couldn't see with my naked eye, and said, well great, now what?  Is this bright star one of the most important 5 stars of Cassiopeia?  Which one?  Even though I know I am considering Schedar (I doubt I had been), well how does that help me target my telescope in the Andromeda Galaxy?
I aimed the telescope at the general direction where I believed Andromeda ought to be, looked through the finderscope, and unsurprisingly, saw nothing.

I believe that the Zhumell finderscope appears to be reasonably nice for a kit extent.  But I feel like I need some kind of rough finderscope for your finderscope.  Do people attempt to prepare a non-magnified sighting program just like on a cheap .22 rifle?  Or do I just need more training?



Scott Bentley

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Re: How do I find things in viewfinder?
« Reply #1 on: December 29, 2017, 11:42:27 PM »
You can get a red dot finder, a Telrad or many other unity sights to add to your scope to help get in the right area. Or, you can get more practice. One trick I do is have both eyes open. One looking through the finder, and the other just looking at the sky. This way you can get the finder in the general area of the target fairly quickly. Over time you get familiar with what bright stars look like in the finder, so it is not that confusing.

acoplochop

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Re: How do I find things in viewfinder?
« Reply #2 on: December 30, 2017, 11:43:54 AM »
During daylight hours, get used to how a distant power pole appears (upside down) in your finderscope, and the learn what movements it takes to get it centered in your telescope's eyepiece. It takes practice. At sunset, you can practice on Saturn(which is low in the southwest) and use distant trees and landmarks to keep you oriented.

tidutamar

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Re: How do I find things in viewfinder?
« Reply #3 on: January 01, 2018, 05:06:22 AM »
Hi, the finder scope that came with your scope should be fine and what you need. Many people, me included, have added a Telrad finder to the scope. Others use a red dot finder or Rigel finder. The advantage of these type of finders is you will see exactly what you see naked eye without any magnification. So you will know immediately where the scope is pointed.

You do need to align the Telrad finder with the finder scope and the telescope focused with an eyepiece in the focused. This process only takes 1-2 minutes at the beginning of each viewing session. Once aligned, you are set for the whole night.

The viewing process for me:
1. Pick a DSO to view. I often locate it from the Skysafari app on my phone.
2. Point my scope in the general direction of the DSO target by picking the nearest brightest star to the DSO USING THE Telrad finder.
3. Fine tune my alignment with the DSO by star hopping using the finder scope.
4. Finally view the target DSO in the eyepiece. Maybe some final search is required with the EP depending on the FL of the eyepiece and DSO I'm looking to view.

The hunt for the new DSO can be a lot of fun.

Lesego Dowdy

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Re: How do I find things in viewfinder?
« Reply #4 on: January 03, 2018, 05:06:32 PM »
Yes this is tough and takes practice.

One trick is to extend your arms, put your hands together and point your fingers, then raise your arms at the shoulder together so they run down the center of the dob tube, then keep raising your arms into sky until the are pointing at the target. If you find your fingers aren't on your target, then you have to move your dob in the azimuth and try again.

Another way is to download sky safari or stellarium to a tablet. These programs will give you the real time
altitude for any object in the sky for your time and location. You can then buy a magentic digital angle meter.
and stick it to your tube. Now you can point your scope up until the angle meter matches the reading in
sky safari. Now you will just have to move the scope a little bit in azimuth (left / right) to get the object into your finder.

Sky safari also give azimuth readings too, and you can print out a set of setting circles for your dob.
This is a bit of work though. There are links on this site for more info

https://www.amazon.c...HYMKYF882RVXTYH

Another trick is to try an note star brightness and color. These properties can differentiate between the stars you see in your finder.

loasandkosem

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Re: How do I find things in viewfinder?
« Reply #5 on: January 04, 2018, 09:43:38 PM »
As I remember, the Zhumell Dobs were equipped with right-angle finderscopes -- in other words, you look into them at right angles to the direct that the finderscope and main scope are pointed. Is that right?

If so, your frustration is understandable. I, for one, find right-angle finderscopes almost useless without some kind of auxiliary finder to point the finderscope. Some people can get a right-angle finderscope to point to the correct spot in the sky just by feel, but I'm not one of them.

But with the addition of a simple, inexpensive red-dot finder -- or even better, a red-circle finder -- a right-angle finderscope becomes a joy to use. In that case, I use the simple finder to point to the right part of the sky, or to a known bright star near my target, and then star-hop to my final destination in the right-angle finderscope.

Old-fashioned straight-through finderscopes are easy to aim by keeping both eyes open. Line up what you see with the unaided eye with what you see through the finderscope, and bingo ... you're done. But straight-through finderscopes are unpleasant for extended star-hops due to the need to keep bending your neck at unnatural angles. It's one thing to do that for the few seconds needed for a red-circle finder and another thing entirely to keep your neck bent for the duration of a multi-minute star-hop.

David Washington

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Re: How do I find things in viewfinder?
« Reply #6 on: January 08, 2018, 07:39:27 AM »
In a pinch, by the way, you can always sight along the tube of the main telescope. That typically requires some contortions, and may even require you to lie down on the ground. But it can be surprisingly accurate. A useful fallback for when your fancy equipment fails, which it eventually will.

Rodney Slater

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Re: How do I find things in viewfinder?
« Reply #7 on: January 10, 2018, 05:20:35 PM »
Good thoughts, all, thanks.
Yes, the Zhumell finderscope is a right angle scope.
If I get a RDF, is it relatively straightforward to mount both it and the finderscope on my telescope?

I also like the app idea, and might try that out.

thanks

John Weiland

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Re: How do I find things in viewfinder?
« Reply #8 on: January 11, 2018, 03:49:04 PM »
Quote
With the Zhumell Dobson I got in the Spring, I've mostly been looking at bright things, like the Moon, Jupiter, or Saturn. It takes me some time to find these in the finderscope. I see them with my eye, but then I need to hunt for them to get the finderscope on it. On the whole, it might take me 30 seconds or so to put Saturn in the finderscope, which isn't awful, but certainly not as easy as I might like.

Last night I thought I'd take out my telescope and see if I could see the Andromeda Galaxy, Triangulum Galaxy, or Uranus. Uranus was in the clouds, but Cassiopeia and Pegasus were in the clear, so I thought I'd try to find Andromeda. I aimed the telescope toward Cassiopeia, and saw a bunch of stars in the finderscope that I couldn't see with my naked eye, and said to myself, well great, now what? Is this bright star one of the main 5 stars of Cassiopeia? Which one? Even if I know I'm looking at Schedar (I doubt I was), well how does that help me aim my telescope at the Andromeda Galaxy?
I aimed the telescope in the general direction where I thought Andromeda should be, looked through the finderscope, and unsurprisingly, saw nothing.

I think the Zhumell finderscope seems reasonably nice for a kit scope. but I feel like I need some kind of coarse finderscope for the finderscope. Do people try to set up a non-magnified sighting system like on a cheap .22 rifle? or do I just need more practice?

Yes. And yes.

I had the same difficulty as you have described it at first. It's a multi-faceted problem: aiming the finder is one; and sorting out what appears in the finderscope eyepiece is another.

The red-dot reflex finder is small enough to be almost unobtrusive if mounted correctly. It greatly speeds up aiming the finder to the desired spot. For me the red-dot is the aiming aid for the finderscope; and the finderscope is the aiming aid for the main telescope tube. I don't apologize for having to do it that way either.

It seems like everything that we attempt with telescopes has a steep learning curve. It takes quite a bit of practice before it feels natural. Fortunately, it's amazing how adaptable we are. After several outings, it will be second nature and you can begin studying the sky in earnest.

Focusing the finder's optics and collimating the optical axis of the finderscope with that of the main telescope will come back to bite you if you fail to faithfully accomplish these important tasks. Nothing but frustration otherwise. Do the major axis alignment during daylight on a target as far away as you can see. Then finish fine alignment on a bright celestial object while you are waiting for your telescope to cool.
--------
C

James Gruber

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Re: How do I find things in viewfinder?
« Reply #9 on: January 12, 2018, 08:14:59 AM »
you should be able to attach the RDF with good double sided tape or velcro for easy removal during storage if needed.

Many planetarium apps are free. Skysafari and Stellarium are popular. I have both. I bought Skysafari 5 pro after using it for a short while. Both are great apps.

unetankem

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Re: How do I find things in viewfinder?
« Reply #10 on: January 13, 2018, 05:21:50 AM »
Have you made sure your finder scope is aligned with your main telescope? That's easiest to do during daylight.

Bill Godschalk

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Re: How do I find things in viewfinder?
« Reply #11 on: January 18, 2018, 02:39:40 AM »
Greetings and welcome to the wonderful world of Deep Sky Objects (DSO's).

A Telrad is the best $40 you will ever spend in astronomy. It made all the difference for me when I was first starting out.

As has been mentioned, aligning your finder makes for successful finding of any objects. The orientation of what you see in a small finder telescope will NOT be the same orientation as naked eye. The mental gymnastics of figuring out how the finder scope represents what you see, versus what is shown on the star map, is a skill to master. With practice, it gets easier.

Have you tried good, BIG paper star maps instead of an astronomy mobile phone app? That might help. Starry Night classifieds sometimes has pre-owned large-format sky charts for sale at reasonable prices.

Star hopping is a good skill to learn. Think of it as a sport. You won't be a great tennis player your first time on the court, but with practice, you can become pretty darned good at it. Same with star hopping, from one naked eye star, to a fainter star viewable in the finderscope, to the dimmer-than-naked eye object.

Pat yourself on the back. Your brain when trained properly works just as well as the mechanisms and microchips in a GOTO mount.

rankkozical

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Re: How do I find things in viewfinder?
« Reply #12 on: January 18, 2018, 05:22:50 AM »
A simple RDF works well with the Zhumell RACI finder and runs less than $20. This sort of system or Telradis what I use with all of my scopes that have RA or RACI finders. The RDF gets you in the region with a naked eye star that is then visible in the finder's field. From there the star hoppingcontinues in the finder or the main scope.

Mounting of the RDF can be done different ways. I made two more holes in the tube and put two thinblack/dark machine screws up through the inside to serve as posts for the RDF base. Nuts hold the posts in place and the RDF baseis mounted on them with two more, larger knurled nuts that are easy to turn by hand. This allows me to remove the RDF easily for packing/transport.

gimartutin

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Re: How do I find things in viewfinder?
« Reply #13 on: January 20, 2018, 02:59:21 PM »
As Tony suggested, you can sight along the telescope, but that's not quite possible with a Dobsonian (although I do it if I run out of other choices). What I do is sight along the outside of the finder scope! With a little practice it becomes fairly easy, although for some reasons it seems more difficult with a RACI finder. Try to place in the finderscope first a bright star near your target, and then slowly move it up to the target, after having studied the star patterns in the area. For instance, to find M31, you first place in the finder the bright star Mirach (beta), then while looking through the finder you slowly move the scope up at 90 degrees away from the Andromeda line until you see one brightish star, then another, and then right next to it there is the galaxy!

Michael Hobbs

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Re: How do I find things in viewfinder?
« Reply #14 on: January 22, 2018, 09:08:37 PM »
I have only really found one finder that I find is easy to use useful and that is a GLP in a holder and adjusted to align with the main OTA.
I do use an RDF but that means looking along the body of the scope and on a reflector that is not always convenient, on a refractor not much of a problem.
Telrads and me just do not get along.

I have noticed that the club I visit if they just cannot locate an object they revert to laying a pointer along the body of the scope and aiming it that way, usually with success.

Before you jump in and if you can try out a few of the various finders. I tried for a whole night to use a telrad and in simple terms failed totally and utterly miserably. Also be realistic, all the manufacturers will say how good and easy and successful any particular finder will be for you.

I like the illistrations of "This what you will see." so far 100% none resemblance to what I see.

Mainly align the finder and scope and then get out and practise and play. The play is likely more useful, bit less serious.