Mandy D

1 hour ago, alacant said:

That's the Crayford-friction model as fitted to the Quattro range. It works without introducing tilt and holds the position at which it is locked. Out of the box, usually.

HTH

Thanks. I am considering replacing the one on my 300PDS and transferring the original to my 200P, as the fixing centres are the same. I'd like the Baader Diamond Steeltrack, but it is a touch expensive for my pocket at the moment, so I'm considering an OVL 2 speed low profile Crayford, which has the advantage of giving me more back-focus, but I don't know if it will provide a performance improvement.

@alacant which one is which in your photos? The one on the right looks like a rack & pinion focuser. The one on the left is the same as on my 300PDS. What is so awful about it?

1 hour ago, steviebee said:

Yes definitely need pictures of Fliss🕷️. l want a jumping spider but my daughter is terrified of them so not an option lol. 

Introduce her to a blue tarantula. She'll probably be so obsessed with how beautiful they are that she'll forget to be scared!

1 hour ago, Malc Spring said:

Split from my wife and now living with my only companion. A tarantula named Fliss in a flat.

Is Fliss going to get involved in star-gazing?

Can you find an octet of octoculars for your little buddy?

We need pictures of the spider!

3 minutes ago, Dimitrisanagn said:

I tried it a bit and improved it slightly,  but I think I'll live with this offset error.  I also read a collimation guide that suggests that it is very common for F/5 and faster scopes to have this kind of offset error.

Thank you again for all your help! 

Yes secondary mirror offset is normal on fast scopes and is designed in. Don't worry about it, as a star test will confirm proper collimation.

9 hours ago, HaplessWonder said:

Im indebted to you for all your help, I am an idiot for jumping in on this telescope believing it a good deal. 

Could you advise on a telescope for a budget of around £500-£600 that will allow me to observe the planets and galaxies, I'd at least like to see the swirling gases on Jupiter or as I said before the poles on Mars.

As @NGC 1502 mentioned you could buy a brand new 200P with that budget (£379) or even the 250PX that you thought you were getting (£559), both complete with Dobsonian base. Obviously, you would have little left over to buy eyepieces if you went for the 250PX, but they do both come with a pair of eyepieces, 10 mm and 25 mm. Now that you have had the 200P in your hands, you are better informed about it's size and weight so should have an idea about whether you want to handle a larger, heavier tube. The 200P weighs about 8.5 kg and the 250PX is 12.7 kg. The bases are the same at about 20 kg., with a diameter of 520 mm. Max realistic magnification for the 200P is 400x and for 250PX, 500x, but you are unlikely to get above 250x very often in the UK due to the sky. The 250PX will offer brighter images at the same mag, but is marginally more difficult to collimate perfectly.

10 minutes ago, HaplessWonder said:

With the vane and pin as it is, does that actually cause an issue? I will now be sending this back but I will be without a telescope, I am now looking at a Celestron NexStar 6SE, it seems to offer everything we wanted.

The bent vane will cause the diffraction spikes on bright stars and the brighter planets to be distorted. On the Moon, it will probably make little difference to be fair. Those pins are roll pins and are made from spring steel. You could probably squeeze it back in with mole grips, but I would want to remove the vane and properly straighten it, first. The other thing the bent vane will have done is to decentralise the secondary mirror, but that can be adjusted back into place using the knurled knobs on the outside of the tube.

I've never used 6SE, so cannot comment on it, but they seem to be regarded as good telescopes. Obviously, it would be best if you posted pics and asked questions in here once you have found one and before you buy. It does have a slightly longer focal length than the 200P, 1500 mm against 1200 mm, which will cause you problems if you want to image the whole of the full Moon with a crop sensor DSLR, but visually with an eyepiece, it will just be a little more difficult to point and provide higher (but dimmer) magnifications than the 200P using the same eyepiece. It's maximum useable magnification will also be lower. Hopefully, you will find what you want.

47 minutes ago, HaplessWonder said:

Here is a closer shot of that mounting point you highlighted, I asked another forum user above the same, the vane itself is bent as if folded at one time. 

As for the focus puller, should it be so stiff and hard to move? it's like there is grit or rust gripping or catching it inside.

The wheel with the holes which appears to turn a gear that moves the focuser in and out does work with some force but the motorised unit now longer functions even with a new battery.

Hmm, that vane is distinctly bent. The pin that holds the outer end in the tensioner is also not properly in place. Someone has been messing around with tht scope. The focuser should run smoothly, taking very little effort to turn the knob; it is a friction drive, so no gears in there.

In light of all these problems, I think you are right to seek a refund and return this. It's a shame, as these are generally such good scopes.

I've attached a photo of mine to show how the spider should look. You can clearly see the fixings at the outer ends.

20 minutes ago, ollypenrice said:

It might very well simply stop working, though. A guest here made a cool box for his DSLR and killed it! I'm pretty sure he would have been nowhere near -20C either.

In the last 8 years, very cold nights here have simply stopped happening, as has significant snowfall. We'd routinely see -12C and sometimes -19C. Nowadays -6C counts as cold.

Olly

For the Nikon D800, I've seen claims on line of it being used at -38 °C! There are many people using them in temperatures of -30 °C with no problems. I've used my D3200 at -24 °C. Nikon give an operating temperature range of 0 °C to 40 °C, but I think that is to cover themselves. It is wholly impractical to expect that cameras will not be used in freezing conditions. A point which is raised regards the LCD potentially failing at low temperatures, which makes a lot of sense. The other thing that is mentioned is condensation due to changes in temperature. Now, that is where I would expect damage to occur. I'm not sure that I would deliberately cool my DSLRs, but I don't go nuts protecting them from the cold. If it is not too cold for me, then it is OK for my cameras is my philosophy.

@HaplessWonder I paid £200 for my 200P second-hand, complete, but no laser, no motorised focuser, but with the standard finderscope. I would say for the OTA on it's own, £245 is too much. I'd want to pay no more than about £150. I guess you had shipping costs as part of your price, whereas I collected.

OK, to get the focuser working there are two things you may have to do. Remove the motor unit. Next, there is locking screw on the focuser barrel, with a knurled knob. You need to loosen that in order for the focuser drawtube to slide in and out. You can see the locking knob to the left in your third photo.

If it is not focusing, make sure you have the extension piece in the focuser, which appears to be shown fitted in the same photo. Then point the scope at a distant object and rack the focuser in and out. If it still does not focus, start pulling the eyepiece out of the focuser. At some point it should focus. If that fails, remove the extension and try without to get the eyepiece closer in. You'll have to hold the eypiece square by hand as the drawtube has a 2" bore. Mine will easily focus on the church clock a quarter mile up the road. If you are getting a blurry image, this is simply going to be down to the closeness of the object and the position the eyepiece needs to be in. It will almost certainly focus at some point.

EDIT: Can you check the spider vane mounting point as indicated by my pink circling? It might be nothing but it looks damaged to me. It should look like the other 3.

I would not worry about the motorised focuser, as you don't need it and the same goes for the laser. Avoid the aggro of return shipping and getting your money back if you can by asking for a rebate agains the non-working parts and just send those back if he wants them. But, try new batteries first. It is no good testing batteries by measuring their voltage with a multimeter as that does not load them and they will likely show full voltage regardless.

I think, once you get through the disappointmenet and start fixing it up, you'll be a lot happier. As long as you have not overpaid for this after any rebates, it is worth keeping. |Do you have eyepieces with it? You might have to remove the motorised focuser bit to focus manually, but I'm not sure. It will be very easy if necessary and you have the knob on the other side that you can focus with manually.

Good to see you are not fazed by making the mount.

22 minutes ago, HaplessWonder said:

Hi Mandy, it's arrived but I have to say I feel somewhat disappointed. Maybe it is my rush to grab it from ebay. Anyway, here are some pics of it and it's features, I am unsure now that this is a 250PX as per the listing as google searches show a different model.

I would like to test it if I can with what I have, there must be some way to. It doesnt have a mount but if I can at least test it to see that it all works.

Nope, that is not a 250PX, it is, instead a 200P. Both are fine telescopes and both have the same 1200 mm focal length. I am sorry that you have suffered this problem with your purchase. It seems to have a motorised focuser attachment, a laser pointer and a finder. If you cannot, or do not want to return this for refund, then it is possible to make a really good setup with it. The 200P has an 8 inch mirror, instead of the 10 inch that you were expecting. It will only gather 64% of the light of the larger instrument, but that is still a lot! I have both the 200p and 250PX and am disappointed with neither.

You will need to build a Dobsonian base for it, but that is not difficult, especially as you have the altitude mounts already on the tube. To test it, all you need to do is lay it down on a table and prevent it from rolling, then point it at something, in daylight (not the Sun!) a long way off, put an eyepiece in and see if you can focus it. Don't worry if all you see through the eyepiece is black, that will just mean the collimation is so far out that the eyepiece cannot see the primary mirror. My 200P arrived like that and it took 5 minutes to sort.

I think it is likely that you have a very decent telescope there. I have taken some stunning images of the Moon with mine. We are all here to help you get through these teething problems and build things up to the point where this no longer looks like a problem, but an opportunity. You will certainly learn a lot by sorting it, but there really is not much to go wrong with these telescopes and nearly everything is esy to fix. Just check the primary mirror by looking down the tube. There should be some dust on it, but it should be highly reflective. Do NOT attempt to clean it in any way at this time! That can come later if necessary.

44 minutes ago, Nikolai De Silva said:

Are they really going out of collimation? And isn't it possible to collimate if it goes out of collimation?

Hopefully, it left the factory in near-perfect collimation. With the mirror bonded in place, there is not a lot that can cause it to move, so should hold collimation very well. I guess the biggest worry amongst the connoisseurs in here is that you cannot improve the fixed collimation by studying the Airey rings of stars, but that does not make it inherently bad.

My 200P was collimated months ago and has not been touched since. I checked it last week and it is still in collimation. It is unlikely that you will be able to find a way to collimate your telescope without a complete strip-down and rebuild, but will you ever need to? As long as the mirror is good, you should be OK.

2 hours ago, HaplessWonder said:

Ill have to take a look when the scope gets here, I'm not sure if bearings are needed or where the balance point is etc, I will consider it.

If this is a 250PX as you say, then it will have the alt mounting points on the tube, unless they have been removed. In which case, you will see, clearly, where they were, so no problem finding the balance point. I've included a photo of my 200P, which shows the Dobsonian mounting points - the large black bit. The thread in the middle is M10 x 1.5. It is possible that these may have been removed, but you can still mount it using rings, like I have.

21 minutes ago, mikey152 said:

metric fine is more common than coarse

In what world? Metric coarse is the standard across virtually the whole of engineering, with fine threads being used only where required, or are you talking about some small specific part of astronomy such as filter threads?

27 minutes ago, HaplessWonder said:

That looks very good indeed, wonder if he would share his plans?

You could always ask him. Drop him a private message ...

@Nick543 It sounds like you might be referring to the pitch of the thread, i.e. the distance between adjacent turns, which for a standard M12 is 1.75 mm. Finer pitches are possible, such as 1.5 mm, but are not common. It seems weird that someone would use a finer pitch, here. Maybe, they also make automotive parts, where fine pitches are not uncommon.

12 minutes ago, bosun21 said:

I'm afraid the largest Starsense is 10".

Yes, but it matters not, as you can transfer the Starsense unit to other telescopes, so can have a 12" Starsense equipped one if you so desire. Many are choosing to buy the cheapest Starsense refractor for this purpose and is something I am considering for my telescopes, which include a 12".

@HaplessWonder There is a great home-made Dobsonian mount built for a 200P by @PeterStudz on this forum. It is a rather unique design as it has cutouts of the Moon and constellations in the uprights and has even been lit with a red lamp in some pictures. Here is a link to one of his pictures of it. He has posted better pictures, but I didn't dig far enough to find them, tonight.

For storage and transportation in a car, there really is no difference between an 8" and 10" Dobsonian mounted Newt. Based on my own measurements of the Skywatcher range, the base is 520 mm diameter for all the scopes from 6" to 10". They all take up the same floor space if the tube (OTA) is stored on the base and pointed upwards. The difference is the weight, with the 8" OTA at 8.5 kg and the 10" at 12.7 kg. If you can fit the 8" in your car, you will be able to fit the 10" in. IIRC, the base weighs around 13.5 kg, so you will have to manage that weight whichever option you go for. Given that the two of you will be observing together, it makes the lugging that much easier. I can comfortably manage my 8" fully assembled on my own over shorter distances. The 10", assembled, is more of a struggle.  My partner is 5'3" and has to bend over to reach the eyepiece even when the OTA is pointed at the zenith.  I would also add that the views through the 10" are noticeably brighter and it supports higher magnifications more comfortably. Generally, they are both 1200 mm focal length.

On 2023 11 29, I was facing north and setting up the D800 with a 14 mm lens in live view at ISO-3200 when I saw a streak cut down through my field of view. It was quite rapid and gone in under half a second. It appeared red on the screen with a visible track length of maybe 10 - 15°.

I would say that is certainly not the same filter in his photos. It looks light grey around the outside, whereas yours is clearly black. It does, however, appear to say L-eX... around the outside of his. It sounds like a typical Ebay buyer scam to me. Unfortunately, I guess Ebay will side with him and will give him your money back and a black mark if you don't refund him first. I'd call his bluff and ask for it to be returned for inspection, carriage paid.

No longer relevant.

@Samop I think I see the problem, here. Without the eypiece there is no magnification of the image formed by the primary mirror. Look into your focuser tube with no eyepiece and the telescope pointed at the Moon and you will see an extremely bright, but very small image of the Moon. I recommend wearing sunglasses if you try this. I did it accidentally, just this morning!

To figure out what size this image is at the focal plane, we can simply place a camera there and calculate, from the camera's resolution and sensor size, the actual size of the image in mm. @Mr Spock has kindly provided a suitable image for me to do this with, but unfortunately, he has scaled the image. If I resize it using GIMP to the number of pixels across his sensor (5568) then count the pixels across the height of the Moon, knowing the length of the sensor (23.4 mm) I can calculate the height of the Moon in mm on his sensor. I make it about 3580 pixels, so 23.4 x 3580/5568 = 15 mm. I think his Barlow is actually giving a bit more than 2x magnification, but with Barlows there is some adjustment possible, so we can ignore that.

Now, if we project Mr Spock's image onto the sensor of my D800, it will cover a smaller proportion of the space available, as being a full-frame camera as opposed to the D500 being a crop sensor camera, so the image will appear smaller when we print the full image at the same size. Now, if you use a mobile phone with a very small sensor (after carefully removing it's lens to keep things equal), the opposite happens and the image will spill over the edges. So, the number of pixels we grab for a given focal length (assuming the image fits on the sensor) depends only on the focal length and pixel size, not the sensor dimensions. As it turns out, my D800 has larger pixels than the D500, so I get a lower resolution image at the same focal length.

So, now we know what size the image is that is formed by the primary mirror of the telescope, we can consider it as a photograph placed at the focal plane of the telescope, so we now look at it with a magnifying glass, which we call an eyepiece, to make it look bigger and dimmer. Hence, your magnification comes from the eyepiece. A longer focal length of telescope will produce a larger image to start with, so less magnification is required from the eyepiece to get the same view.

Finally, let's look at the actual magnification of the Moon by the telescope, rather than angular magnification. It is the latter that we are after when using a telescope visually as that will determine how big the image is on your retina. But, what is the ratio of the image formed by the telescope at prime focus (or after Barlow amplification in this case) and it is simply image size / Moon size. So, the Moon is about 3475 km, or 3 475 000 000 mm in diameter and our image is 15 mm, which gives a 'magnification' of about 4.3 x 10^-9.

@Nikolai De Silva Vlaid is right. But, also, I suspect that is Jupiter and it's moons you are trying to image, in which case you will need high ISO and long(ish) exposure for the moons. Not so much so for Jupiter itself. Remote shutter release is pretty much essential, but self-timer will also work.

For Jupiter's moons you might be down at 1/30 (as Vlad says, 30ms) with ISO as high as 6400. For the planet, drop the ISO to 100-400 and shorten the exposure to see surface detail. Also, make sure your camera/phone is solidly mounted to the focuser or eyepiece.