Alien 13

5 hours ago, JamesF said:

There may perhaps be physiological factors involved as well?  Please do expand on your reasoning though.  I certainly think it would be interesting in the light of my own experience.  I have absolutely no problem viewing the Moon through my 127 Mak, or ST120, but using the 10" dob it is genuinely painful.  I can overcome that reaction given a little time and determination, but initially it is highly unpleasant.

James

I was making a general statement about light from extended objects and perceived brightness vs magnification but you are correct that reality doesn't fit theory exactly, the amount of light transmitted by a scope is never 100% some designs are better that others and the dark adapted eye can be overwhelmed when its suddenly sees something bright too.

Alan

It would be mad if people think some distilled water dissolves mirrors like acid, I cleaned mine once a month for years and never had an issue.... clean them...............

Alan

2 minutes ago, johnfosteruk said:

Thanks Alan, I don't know about beating the 127 but the 102 does certainly punch above it's weight!

I think Maks work better with higher f ratios so that could be why I see the advantage that the 102 has.

Alan

Great images, am I imagining it or does the Skymax 102 produce better Luna images of a full disk moon than any other scope, from what I have seen it certainly beats the 127mm hands down.

Alan

The way optics work and the resultant exit pupil size combined with the magnification available must mean that the observed brightness is similar whatever size scope you are using... I cant see the need for filters at all unless the naked eye view is too bright.

Alan

10 minutes ago, smr said:

oh a little OT but what aperture should I stop the lens down to to avoid coma ? 

Would f/2.8 be good?

I have the 50mm f/1.8 STM and find f/4 is the best all round option if doing longer tracked exposures however if I am shooting on a fixed tripod with foreground features then using f/2.8 is still fine. In both cases focus about a third of the distance away from the center along an imaginary diagonal for best coma performance.

Alan

They sure are great bits of kit, had my RA viewfinder a few years now and they certainly save your back and knees.

Alan

I realy like the starless image its captivating to view....I agree with Adrian in that a starless thread would be nice.

Alan

1 hour ago, Gasman said:

Hi folks

Just watched an interesting episode on BBC1 where a chap and his son brought an old homemade reflector made by his late father to see if the guys could repair it and make it workable again. Amazing build from old parts found around Portsmouth area, mirror fomerly a porthole various other bits and bob's to make an equatorial mount. They got the mirror recoated and made a great job of the restoration. Took me back a few years having made my own reflector and mirror 😁. Should be on catchup!

Steve

Its on BBC iPlayer...

Alan

I do like that program, on one episode they stripped and refurbished some WW2 binoculars, fascinating stuff.

Alan

I have dabbled with eyepiece projection but always found it fiddly and the results highly dependent on the quality of the eyepiece in use. A better method in my view is to use a barlow lens instead, the magnification factor can also be played around with by extending or reducing the distance to the camera sensor with those tubes you have.

Alan

6 hours ago, scitmon said:

As someone who has been using a Canon 700D, I'm not aware of this... can you elaborate?

The problem that is sometimes reported when using the 650/700/750D models is horizontal banding, now this usually only shows up when an image is heavily stretched (I never noticed it when I had a 650D).

The cause of this banding is the hybrid AF system that these cameras use for live view focusing when shooting video for example, the hybrid system uses extra rows of sensors in between the normal sensor pixels, the other system often used by Canon for AF is the dual pixel configuration as used on the **D and mirrorless cameras that has eliminated the problem.

Alan  

1 hour ago, ollypenrice said:

That's a nice method. Ps has so many ways of doing the same thing. You can also click to activate your chosen channel and 'Save as,'  giving it an appropriate name. It's always interesting when you find that someone uses a different method because it may lead you to new ideas.

Olly

Much prefer this type of action, I have a thing against using any shortcuts with PS.

Alan

1 minute ago, xtreemchaos said:

thanks Alan, do you know if it can still be hardlined to the pc if thay have wifi like the 1200d. charl.

Not sure but my Canon with wifi can be wired directly to the PC but I never use it that way..

Alan

I dont know anything about that camera but the Canon wifi option is great for live view shooting remotely when using a phone/tablet or EOS utils on a PC.

Alan 

24 minutes ago, Stub Mandrel said:

I'm beginning to suspect this is the case.

@Alien 13 you're a computer performance guru. I need a new computer for business how would you rate this:

https://store.hp.com/UKStore/Merch/Product.aspx?id=7GM19EA&opt=ABU&sel=NTB

Obviously not a super duper gaming machine...

Looks like a well balanced machine, the 512Gb SSD is good to have but it would be interesting to know if it had spare slots so you could fit a HDD at some point if you started to run out of storage space. 

Alan

Wow 631 pages...

Alan

5 minutes ago, sloz1664 said:

I can't understand ZWO's logic on a square sensor. All computer / tv screens are widescreen, which lends itself to rectangular sensors.

Steve

Ideally all sensors should be round but square is the next best thing, you are rejecting an awful lot of data with a rectangular one...

Alan

The star adventurer is a nice mount to use with camera lenses, the Rokinon/Samyang lens you mention is probably the best "astro" lens available at any price. Have a look at this topic....

Alan

Are there any good glass filters for camera lenses, I need a 77 mm one that fits the filter thread.... 

Alan

3 minutes ago, Hallingskies said:

It’s not just me, then!  I must admit I stick to Baader film on the front of the frac on the rare occasions I do any solar observing or imaging.  First off, it’s cheaper than a Herschel wedge, but mostly it’s because I really am not all that comfortable with the idea of funnelling 100w or so of solar heating down through frangible precision optics....😱😱😱🔥🔥🔥

I feel the same too, its not just the optics either that get blasted with heat, the focusser and grease within it also gets hot and worse problems sill if there are any plastic bits in there...

Alan

10 minutes ago, Helen said:

I only took one - caption competition!!

I think I would get on my knees and pray for a Tak Epsilon....best scope in the world...probably.

Alan

58 minutes ago, jetstream said:

Me neither lol!

I'm trying to figure out a nice USB microscope set up for the 10 yr old grand daughter, who has an interest in science, geology etc and I want to fan the flames with easy,early success and with a touch of "tech".

Thanks much for the info- I was actually wondering about the advertised 5mp and it seemed low on pixels to me, but I know zero about this stuff.

Ok, some info says the final "magnification" is dependent on the screen size? how so?

she has a small tablet- can this limit the resolution depending on its own screen pixels?

I have piles of questions actually, including how to automatically stack the images taken at different focus points to produce a razor sharp image across a 3d object... one manufacturer provides a on click stacking function at a deadly expensive price though.

And...lol! and I wonder if the "f ratio" or f stop as in photography plays a role with these cameras in regard to a large portion of the target in "focus". I would imagine but dont know that the f ratio or stop is fixed in these?

Thanks Vlaiv

You mention a tablet there, can it run the required capture software?

Alan

7 minutes ago, Uranium235 said:

Its not quite in true focus Dave, so there may be more to come    the filters are now clean, but I didnt get a look at the sensor since the shutter was closed.

If the bunnies are on the sensor then they will always be in focus no matter what the lens focus is like...

Alan

I found this information regarding sensor requirements here, I do think there are subtle differences between astro and microscopy cameras due to the latters requirement to take dimensional measurements in some applications. The big plus with microscope optics is that they nearly all follow a strict DIN standard so camera compatibility is easier to get right.

Alan