Upgrades for 250PX

[RikM]

I have a 250PX solid tube and my most used EP is 14mm. My top three are 20mm, 14mm and 7mm for deep sky and then 5mm for planetary. I also have a 28/68° but don't use it as much as my 20mm due to my mid/high local light pollution. From dark sites, the 28mm gets much more use, especially with an Oiii filter.

[warpi]

Now I have placed the order for the four eyepieces

Explore Scientific 82° N2 Eyepiece 4,7mm (1,25")
Explore Scientific 82° N2 Eyepiece 8,8mm (1,25")
Explore Scientific 82° N2 Eyepiece 14mm (1,25")
Explore Scientific Maxvision 68° Okular 28mm

and they are estimated to arrive on tuesday next week

[YKSE]

Congratulations for the very nice choice. they should serve you many years if you're interested in using the scope

[warpi]

Only thing that I am wondering about is the 4.7mm. Maybe it would have been better to purchase a barlow since the objects looking at with 4.7mm will be very bright ones (jupiter, moon etc) so the light lost using a barlow would not matter?

[YKSE]

4.7mm should work on Mars and Saturn too, also for splitting tight double stars.

[Paul73]

Good choice. Nice collection.

Barlows are not essential. I've got one but it only gets used when messing about. For the price of a decent barlow you can buy most of a decent eyepiece and not be sticking extra glass between you and the target.

Enjoy.

Paul

[MattJenko]

Nice. I have the 28mm 68" MV for my 250px and it is my favourite and most used at the moment.

[Stuart1974]

Hi Warpi. I'm in exactly the same position as you, having bought a Skyliner 250px two months ago and am now looking at upgrading to some better EPs.

I'd be really interested in hearing how you are getting along with your new EPs. Having read this forum (and assuming you are happy with your new EPs) I am thinking about buying the MV 28, ES11/82 and a 2x Barlow which will also give me 14 and 5.5. Plus a Nebula filter for the 28 perhaps.

Would be grateful for any experiences and thoughts that you, or indeed anyone else here, might be prepared to share. Am looking at the skywatcher 2" ED Deluxe 2x Barlow too - would this degrade the image significantly?

One other question: what's the difference between an OIII, CLS, Beta and UHC filter. I understand all are for nebulae but why would I opt for one over the others?

Best regards

Stuart

[RikM]

The CLS is a good but generic light pollution filter and more use for photography that observing.

A UHC is good nebula filter that dims the sky background allowing you to see more of the faint wisps from emission nebulae like the Orion Nebula. This is probably the best filter to get first as it it gives some improvement on many objects.

An OIII filter is similar to a UHC but more aggressive in blocking out the sky background and brighter stars, so gives even more contrast especially in the darker dust lanes within nebulae. Also good for planetary nebulae. The OIII is generally the preferred filter for experienced observers.

An H-beta is effective for a smaller number of objects but is often the only way of making them visible. This is 'limit of visual detection' stuff and probably best left 'till later.

[John]

I think Rik's advice is spot on.

I have UHC, O-III and an H-Beta filter. The H-Beta hardly gets any ues to be honest because the objects that it helps with are few and pretty challenging. The O-III gives the most impressive improvement on certain objects moving them from the "is anything really there ?" category to "Oh, wow, how did I miss that ?". Well worth having in the tool box I feel. The UHC gives more subtle improvements and sometimes I use it but sometimes I prefer the unfiltered views.

I had a CLS type filter (and Orion Skyglow) long ago but really found it rather inneffective.

With the Summer constellations on their way, an O-III filter is worth considering for the Veil Nebula (in Cygnus) alone. It's a large, complex and stunning object with such a filter even in my 4" scope but is almost invisible without it. Worth the price of the filter on it's own I reckon

[Stuart1974]

Many thanks for your replies, gents. In terms of my location I live in Portishead, which is affected somewhat by LP from Royal Portbury and Avonmouth docks a few miles to my east. In view of this would O-III help cut out more LP than the UHC or is it less straightforward than that?

Also, I'd be grateful for your suggestion on my EP thoughts above. RikM, I see you have a 250 px: would the 2" MV 28mm be too heavy for this scope? And the same question with a 2" Barlow added.

When I started thinking about upgrading my EPs it seemed I had a vague idea of what to buy, but having read many forums I feel like I'm more confused about EP than I was when I started!

[John]

Many thanks for your replies, gents. In terms of my location I live in Portishead, which is affected somewhat by LP from Royal Portbury and Avonmouth docks a few miles to my east. In view of this would O-III help cut out more LP than the UHC or is it less straightforward than that?

Well as it happens I'm based in Portishead as well !!

Neither the UHC or the O-III filters actually reduce LP. They do help pick nebulae up under less than ideal skies but work even better under dark skies.

The 28mm MV would be good for the 250PX I'd have thought although you might need to think about putting a magnetic counterweight or similar on the other end of the tube if the top end gets too heavy.

I'm not to keen on barlowing longer focal length eyepieces because their eye relief gets pushed out by the barlow and you can end up having to "hover" your eye someway off the top of the eyepiece.

[RikM]

My longest focal length eyepiece is an Explore Scientific 28mm and I think very similar to the MV 28. I have also used an ES 30/82 in this scope and found it to be fine to use if you tighten the tension handle just a little bit. My 250PX doesn't seem that sensitive to balance issues.

I agree with John about barlows. I prefer to use single eyepieces for each focal length. A 2" Barlow would add some extra weight but also adds length sticking out of the focuser and the stock focuser on the Skywatcher scopes, while perfectly usable, aren't the strongest. I would worry about the weight and leverage pulling it out of alignment.

[Stuart1974]

Hi and thanks again. Having read and thought some more I'm inclining towards buying the ES 16/68 plus the ES 24/68 Maxvision. Thinking of the 24 MV rather than 28 because it is 1.25" , meaning I don't have to double up on filters. And it would be compatible with a 1.25" Barlow should I try to, although I'm very grateful for your steer on this issue.

I guess my question would be whether I would be losing out by going for the 24 rather than 28 MV. Apart from the obvious lower magnification does the 2" barrel make a difference compared to the 1.25"?

[John]

The 2" barrel just allows a wide field of view with the longer focal length eyepiece. There is no other advantage.

Frankly your preference for the 24mm might be sound. Being from your neighbourhood, I find I don't use my 31mm eyepiece that much but my 21mm

delivers darker skies so that gets more use. It's the higher magnfication that makes the difference.