Is a 4" Apochromatic ever going to beat a 8" reflector?

[Moonshane]

one thing you could try Nick is a Baader Neodymium filter. I have found that this has increased contrast in both of my reflectors on the moon as it reduces the general glare. they come up used every now and again, especially the 1.25" ones and might be worth a go. I can highly recommend it.

[spaceboy]

There was one on UKB&S and I'd been on the fence about it for a couple of days but checking today found the guy has a sale pending. I admit I am leaning more towards the Semi-apo as I was hoping to get a bit more use out of the Evo as well as possibly adding to the contrast of the reflector. £100 new although mind blowing would be cheaper than buying an Apo refractor and should fingers crossed offer something to all my scopes. I have been trying for weeks to get a 2nd hand BSA but it's looking like either an infinite wait or cough up for new.

[Moonshane]

you may be right. never even considered a semi apo filter.

what about this one U.K. Astronomy Buy & Sell

new / details here

Baader Baader Contrast Booster Filter 1.25" and 2"

[Ad Astra]

Hi folks,

I'd have to agree with most here, that a well colimated 8" will outperform the 4" Apo refractor on the moon. You can also make an aperture mask to change your 8" f/6 reflector into a 4" off-axis f/12! This does wonders for contrast on lunar and planetary views.

That said, there's refractors and refractors, if you take my meaning. I have a 133mm (5.25") f/12 refractor that blows the doors off any reflector of less than 12" aperture I've ever seen. But my Apomax is not a plain-jane Apo. 4-elements, oil-spaced, and fully baffled tube brings everything from near IR to long-wave UV into focus. The contrast and views are unbelievable.

You CAN get a small refractor to beat the 8", but for the same money, you can't get a refractor that comes close. Refractors of the Apomax class (Astro-Physics, Takahashi, TeleView) are not cheap - but there is a reason they are so popular. Just look through one - once will be enough to convince you!

Dan

[spaceboy]

you may be right. never even considered a semi apo filter.

what about this one U.K. Astronomy Buy & Sell

new / details here

Baader Baader Contrast Booster Filter 1.25" and 2"

Thanks for the heads up Shane but I tend to stick with 2" filters in the 2"/1.25" adapter to save keep swapping the filter with EP changes. (less fumbling around in the dark)

My mind is made up and I'm going to stay on the look out for a Semi Apo filter. Thanks to everyone for your advice but big money Apo refractors are beyond my reach and if a 4" budget apochromatic isn't going to cut the mustard against my 200P I may as well sit on my hands in the hope a filter comes up.

SPACEBOY

[Moonshane]

no worries mate just thought I'd mention it in case you wanted to try it.