Am I wasting my time?

Had a disappointing evening out tonight while trying to get some decent pics of M45, The Pleiades. At first things seemed okay. Put my scope onto the markers I'd made on my patio, checked the balance with the camera all set up, lined up on M45 and took a few test shots. At 30s, no trailing. At 1min, no trailing. Great! Not really any noticeable nebulosity at 1min though, so went to 2mins. Things on the preview were looking okay, so took a bunch of shots. (No guiding, no laptop...just me and the cold!)

On closer inspection of my images I'm seeing erratic errors...like I often do. This first link is to a comparison of the three of the better images I managed to get...as you can see, none of them were any good really as it turned out.

HTTP response: NOT FOUND | MIME changed to 'image/png'

HTTP response: NOT FOUND | MIME changed to 'image/png'

Don't give up Tim. I fought the same battles and many do, so you're not alone.

Assuming there was no wind and you carefully balanced the rig, then I would say periodic error and/or gear problems(slippage, debris, lubrication, etc.) are the culprit.

Have you been inside the mount to inspect the gears? That's where I would start. Be sure there's no debris, in fact a thorough cleaning and re lubricating with quality lube would not hurt. Also check the set screws that secure the gears to their axles. They can come loose and cause slippage. Make sure there's no unusual slop in the gears and that the gears are not too tightly meshed and causing them to bind. You should be able to turn the axles with your fingers and move the gears without too much difficulty/resistance.

I'm not familiar with the mechanics or accessibility of the workings of your mount but if you can get into where the main large RA gear is then I would clean it with a tooth brush and some denatured alcohol and then re lube it. You don't need to gob it on just enough to evenly lube the teeth of the gear.

It is entirely possible that the mount has problems that will require more cost to fix than it is worth but I would start by trying to find any obvious problems.

After making adjustments and working on my mount I was able to get it to perform quite well but it was frustrating so I understand what you're dealing with completely.

I hope you can get it straightened out but if you can't maybe an upgrade is the answer, if it's in the budget.

Thanks Steve, after a night's sleep I'm over the "I want to give up on this stupid hobby" thoughts, and I'll take a good look at the gears. I've had the EQ5 apart before, more to familiarise myself with things a bit, and I'll look to give it a good clean.

My main concern about the mount is the fact then when things are locked down, the RA axis has a lot of play in it. I can hold the scope or counter weight and it will wobble quite a bit, (though while tracking I can't see this causing too big a problem, but perhaps things are way too loose.) Hard to describe how much play there is, but I'll try and take a video sometime. There's certainly no play at all in the DEC axis.

There has to be some play(tolerance) otherwise the gears would bind.

BUT, too much slop will cause problems. Finding that sweet spot of how much is best for your mount takes some trial an error. The real question is can you adjust your gear tension in small increments? Since I've never personally seen this mount much less inside of it could you snap some photos of the inside with as much exposed as possible. A couple different angles would help.

When properly adjusted you should be able to turn the gear axle(small gear that drives the main gear(large) with your fingers fairly easily. When you test it by holding the counterweight shaft in one hand and the scope saddle mount in the other, you should be able to feel a slight "click" of movement but definitely not a lot of movement or wobble.

My mount allows for such fine tuning, although tricky it does help find that sweet spot.

Also, I mentioned earlier about bias weight on the east side of your mount. Doing this helps to keep the gears more evenly and consistently meshed while tracking. In fact I would wager some improvement even in the current tolerances of your gears although if they are as sloppy as you mentioned that needs to be addressed.

Periodic error is gear imperfection. Gear slop only compounds matters. The only way to minimize PE is to upgrade gear quality or have a mount that has PE programmable correction. Gear slop can be minimized by adjustment, if your mount allows it.

You may recall a while back I mentioned the process of eliminating imperfections or obstacles in this imaging process in order to get to a point of consistent results and hopefully more hassle-free nights out. These mechanical issues are job one. And they do occur in far more expensive gear than you or I have although usually far less frequently. Technique as well as proper set up/balance are also at the top of the list. I realize better mount quality can ease a lot of stress and work but if the budget doesn't allow let's see what we can do with what you have. I would have loved to get an NJP but I couldn't see that happening so I worked to get the most from my G-11. A pain at times but I've reached a point of contentment and understand it's limitations and strengths.

@ OP:

Nighthound has given you VERY god advice with which to start troubleshooting your rig. Might I ad just a couple quick points, hopefully they will help.

Your "patio" is it concrete? Sounds silly but even a strong wooden deck will have much play and vibrations can easily wreck a photo.

Your "balance" of your rig, is very important. If your motors and axis' are 'off' or have 'play' in them the off-balance of the rig will exacerbate these issues greatly.

Remember when balancing your rig, especially on a GEM when shooting high towards zenith and when crossing the Meridian. Its important to "rebalance" when the mount switches over.

Thank you for posing your M45, those sisters are beautiful

Thanks babel_fish, and yes, my patio is concrete slabs on a solid base, so very stable. (As I took each photo I tip-toed very gently away just in case I was causing vibrations, but sometimes I remained motionless next to my mount, and the effect was always pretty much the same.

Took my mount apart last night, and can't see a way to fix the wobble I've got. The gears linking the motor and drive shaft for the RA axis are nice and tight, and I can turn it by hand quite easily. The drive shaft is like an archimedian screw, and the RA head has grooves all round it, which are turned by the drive shaft...not sure if other EQ mounts are like this. Anyway, it's between the drive shaft and the head where the play is worse. I will take some pictures some time to explain.

I do think this play will only be a problem as the scope moves past the meridian, and M45 the other night was a fair bit in the east still, so I don't think it was causing my erratic star shapes the other night. I am thinking a mount upgrade is required.

Cheers again,
Tim.

babel_fish wrote in post #6903401
Thank you for posing your M45, those sisters are beautiful

I agree, they're a great sight, and I was pleased to see the nebulosity on my images for the first time.

Right, after a fairly major dismantling of my mount the other day, followed by cleaning out all the horrible, sticky, tree-sap-like "grease" that was used during manufacture, and re-lubing with silicone grease, fingers crossed it should be a lot better now.

If anyone has an EQ-5 they want to service, here's a good link. -> http://www.astronomybo​y.com/cg5/ Step by step instructions on dismantling, cleaning, re-lubing and reassembling the EQ5 type mounts.

Have tried it once, but was getting a DEC Overload error, which turned out to be the counter-weight shaft was screwed in too tight. It felt a lot smoother though, and quieter, and all I did was a bit of drift aligning. (But then I forgot to mark the patio again when I packed away! No matter, will need to drift align again anyway.) I'm just hoping I get straight drift lines the next time I try a long exposure, rather than the erratic, jagged lines.