First time out with new kit

[Willi1972]

Hi all,

I just thought I'd share some experiences from last night. I have done a lot of photography for years and had always enjoyed night landscapes including stars and the milky way. I had even tinkered with DSS on a few occasions. However, recently, I made the decision to take the next step. I knew I needed to track what I was shooting, and so after reading a lot on these forums, decided to go with a used EQ5 Synscan mount. I was undecided about the telescope, so for the moment, I will stick with my Nikon D7100 and prime lenses.

Last night, I assembled the mount according to the instructions. All went well, and I was very pleased with myself! It was a clear night, so I decided to take everything outside to get used to how everything worked. My first problem was that with a 3 star alignment, I had real difficulty seeing the necessary star through the viewfinder. I guess this is something I will need to get used to; I just need to be selective over which stars I choose to align with. My second problem with that the RA motor did not seem to move anything. After reading the forums, I checked the gear meshing, and sure enough, the servo must have moved in transit so that it was not meshing. 5 minutes with an allen key sorted that out.  After about an hour, I had finally managed to align with 3 stars. The handset warned that the alignment may be poor, but I decided to go ahead anyway.

I was using a very nice 60mm lens (90mm in real money) just so that I had a nice wide field. I decided to do what must be the normal thing for a fist time, and go for M32. I ended up having to adjust the mount quite a lot to get it centered, but I go there in the end. I did 15 lights, 10 darks, 10 biases. All were ISO 3200 at 30 seconds. Afterwards, I checked on the display and found that I had left the aperture at f8. Duh!  I tried another set which looked a lot better this time. At 01:30 I got DSS working on these, and after 15 minutes or so it spat out a TIFF where I could actually see M32. Not very well, as the alignment was off, so I did have trails on all stars. I was surprised that DSS coped with it.

I had read that M32 was around 3 degrees of the field of view. However, mine was nothing close to that, so I think I really have to increase the exposure time once I get the tracking working well. However, I was pleased because I had started to get to grips with the mount and had made some useful mistakes - not to be repeated. I just can't wait for the next clear night now!

I am still not decided on the scope to go for. I intend to do mainly AP, but would like a relatively portable rig. I can get to some nice site with about a 10 minute walk. The EQ5 is luggable for that distance. I need a scope that is also luggable. I was thinking of a refractor, but I think something like an ED80 will need some saving for. I had also considered a 400mm lens. What is the difference in quality between, say, and ED80 and an old 400mm lens? I was thinking of one of the old Pentaxs, as I heard they were good.

Regards

Richard

[idigitize]

Hi Richard,

I bought an ST-80 to get me started... which is in theory a very cheap 400mm f5 lens, added bonus you can look through it as a telescope and d7100 connects on the end with 1 ring... about £100 all in.

You get some good results with the st80 and also you can pimp it up a little to make it even better for next to nothing.

Its very portable and like mine, will have use further down the road, as either a guiding scope or a very portable set up.

Cheaper camera can work , but may also suffer from lots of CA, zoom creep and all sorts.. the st80 won hands down for me.

After 6 months of mount and st80, I only got round to buying an ed80 last week.

[idigitize]

Edit  that should say ***cheaper camera lenses can work***

[Kropster]

A 9x50 finder scope with cross hairs would help a lot with alignment and target finding.

Camera viewfinders are not that good for that and the finder would add very little weight.

[Rico]

Welcome Richard and congratulations on your new purchase. From what I've understood so far, the 3 star alignment is a way to calibrate the GOTO system, which will help in finding objects. But to get pinsharp images, you'll need to home in on the polar alignment. What sort of procedures to take to align the mount?  

[Willi1972]

Hi Rico

I'm on a steep learning curve here. I had (apparently mistakenly) assumed that I should centre Polaris in the viewfinder when the info about Polaris came up on the handset. It seemed logical at the time that if the assembly knew where Polaris and three other stars were, along with date, time, lat and long, it would do everything itself. I have had a look at some tutorials on the subject, and will have a go tonight if the clouds stay away.

Regards

Richard

[Willi1972]

Hi all,

I just got back in after spending a lot of time setting my mount up: perfectly level, balanced etc. I watched some videos about polar alignment. I did a fairly simple alignment. The whole thing with date rings etc. is a bit higher up the learning curve than I am at the moment. Unfortunately, there was some very high cloud that obscured some of the stars around Polaris, making it very difficult to tell if I had the right star or not. Next time will be faster, I hope.

I then did a 3 star alignment for the Synscan unit, and it seemed to be happy with the result. I did a test shot of a star at 30 seconds with a 60mm lens to see if there were trails - there were not! I then tried the same with a 200mm lens. Same result; perfectly round stars. Bingo! I then set out to try M32 again. 2 shots into the sequence, and in came the cloud. This must be some kind of astronomy law: the longer it takes to get set up, the quicker the cloud comes in. The forecast for the rest of the week looks good, though.

Lots learned tonight, and I'm getting closer to taking real shots.

Regards

Richard

[Kropster]

There are some programs to help with Polar Alignment.

I use 'Polar Finder'... it shows where Polaris should be in the field of view relative to the Polar axis at the current time.

Makes polar alignment a lot easier.

[Willi1972]

Hi Kropster,

thanks, I'll have a look at that app. Finding Polaris by eye was the easy part. The problem was that the polar scope showed more stars that were visible to the naked eye. Not entirely surprising, but it made it difficult to compare the inverted image in the scope with what my eye was seeing. I just need practice I suppose.

Regards

Richard

[Gomtuu]

There's also a polar alignment feature on the Synscan

[Knight of Clear Skies]

Yes, it's all quite a learning curve but it does get easier with repetition.

Unfortunately you probably won't be able to use old M42 lenses with the Nikon as they won't reach infinity focus with a simple adaptor. It is possible to get one with a glass element but I don't know what that will do to the image quality.

DSS often produces very dark images, have you tried adjusting the histogram? There might be a bit more of your target in there than you think.

[Rico]

Richard, I hear you on the steep learning curve! I'm on it myself!

With only 3/4 imaging nights under my belt, I still have so much to learn. With the polar alignment, I've been using the polaris in transit information - very simple procedure.

Line up the mount so that polaris is dead center in the reticule (in the middle of the cross-hairs), then switch the mount on and synscan will ask for the geographical location, date and time (put these values in).

Then it will give you two times ... the FIRST is how long ago Polaris was in transit (i.e. at the highest point in the sky - which is the lowest point in the reticule) and the SECOND is how it should 'appear' in the reticule at this point in time.  

Adjust the altitude in the mount (assuming your mount is well levelled) so that Polaris drops to the boundary of the LARGE circle that marks its trajectory around the celestial pole. Now rotate the mount around the RA axis until the smallest circle encircles polaris through the reticule. Now set the RA circle to zero and tighten the grubs screws. Then rotate the mount around the RA axis until the time it shows on the circle is the FIRST of the two times given to you by synscan. (The rotation direction apparently depends on whether you're in the southern or northern hemisphere). At this point, polaris is no longer centered in the small circle since you've rotated the mount, so you have to adjust the altitude and azimuth so that polaris once again appears in the smallest circle through the reticule.

At this point, polaris should appear to be at a location in the reticule equal to the SECOND time given to you by synscan upon start-up. e.g. if the second time on synscan is 9 o'clock then polaris will be on the left side of the reticule.

On a side note, it might be good to check at some point if the reticule is aligned as well.

This is all based on a eq6 mount, I hope this translates to your mount as well ... and if anybody thinks this is wrong or if there is a better method, please let me know.