Uranium235

Things just got serious:

Not sure how its going to cope @f2 as the QSI has 1.25" filters, wont know until I try it I guess.... but I've found the camera has a photo screw hole on the case, so ive just bolted it directly to the dovetail bar. The lens mod takes care of everything else, no need for further support  

EDIT:

Actually, I can test the illumination/vignetting later tonight - I'll just set the lens to infinity and take a few flats, that should tell me roughly whats what.

The canon 200mm bayonet seems to be held by 4 screws. But whether all the electronics come out with its removal is unknown.

With that in mind, the engineering would have to be precise. I need to see one in bits tbh.... but I dont think anyone is that brave...lol.

Yeah, the lens mod at the moment is only suitable for manual Samsung lenses. Canon autofocus lenses have electronics in the way, which might make disassembly and modification difficult (the Samsung can be modded by a monkey it's that easy).

I'd have to get my hands on one and take a closer look to see if its possible. 

2 hours ago, StamosP said:

During last month i tried to find a solution to modify the bayonette to a t2 male thread (i have a few ideas) but today i saw Rob's (i remember you from the legendary 130pds thread!) solution, very good indeed.

Any info about this?

Im just waiting for the dust to settle being as the SGL star party was cancelled. Then I'll ask FLO about getting a small production run sorted., maybe just kick off with 10 and see how we get on.

Oh ... no... I was hoping that this would be my only break in the run up to xmas   gutted....  Oh well, cant be helped I suppose!

Safety first, even if it was open I suspect a number of the roads will be impassable as well - Ive already had a couple of dodgy moments on country roads here in Worcestershire, I waited for someone else to try and drive through the flooded bits first before trying (very carefully) with my little car 

Clear tonight, so time for more testing.... 46x240 on Andromeda:

Hmmm interesting reading! I guess this could (in theory) apply to mounted filters since it takes little effort to remove one from its cell and flip it over. Might be something worth trying if you are getting large halos on your particular setup - I wonder if this applies to narrowband filters? (probably not, but its worth asking)

1 hour ago, teoria_del_big_bang said:

From reading many threads the majority of opinion says that of one side is shiney, like a mirror, then that points towards the direction of incoming light, that is the scope side. But oddly enough on the Baader website I read that this was true unless you had a flattener, or reducer in the optical train and then you reverse them so the shiney side points towards the camera.

Could you please point us to a link (reversing Baader filters) where this information is posted?  Otherwise it means that 99% of all imagers have been doing it wrong for many years (including myself), as practically every optical system requires a flattener or reducer for imaging

3 hours ago, George Gearless said:

Ok. I know this might seem like a daft question. But I am genuinly in doubt.

I have this camera: ZWO ASI 385MC USB 3.0 Colour Camera.

It says it has a "rolling shutter". I'm not sure what that is. In my mind I am picturing a spinning cylinder with a hole in it that blocks the light from getting to the sensor. Except when the hole is aligned with the sensor and the aperture, then it lets light through.

Anyway, the reason I'm asking is that when I set my Stellarmate up for "automatic darks" it asks if my camera has a shutter. And I am unsure if a 'rolling shutter' qualifies as such.

Anyone?

Rolling shutters are a feature of interline type sensors, and shutters are used for full frame transfer sensors. Its all about the speed of which the image is read from the sensor (interline = fast, full frame = slow)

http://www.optique-ingenieur.org/en/courses/OPI_ang_M05_C06/co/Contenu_07.html

http://www.optique-ingenieur.org/en/courses/OPI_ang_M05_C06/co/Contenu_09.html

But, to really test it I need to use the KAF8300 camera - and try and get the same performace Ive had previously.

Note to self: Get a finderscope....lol

Mod seems to work alright slightly better spacing and more diligent focusing required (ie: 2/3rds focusing). But, for just two hours - it aint bad I guess

2 hours ago, KyleStoke said:

Hi 

Am I not right in saying it can be short as this would just allow the lens to focus past infinity

Really, to get the best out of the lens you have to get the spacing to it focuses as close to infinity as possible. In the end ive had to add a whopping 4mm to the spacing to get it close (with a filter), without a filter it now focuses exactly on infinity.

On 14/10/2019 at 23:23, Adreneline said:

I am still interested please Rob.

Adrian

Im hoping to test it tonight, partially cloudy but thats close enough for me...lol..

Still not sure on the spacing, Ive left it 0.5mm short for the moment and will add delrin spacers if required.

Starter for 10...lol

41 minutes ago, Davey-T said:

Its not the winning it's the taking part, well that's our excuse, were only there to make Robs team look good 😂

Dave

Yay! Scumbag College

Ohhh yes..... Its done. Pro job, and hopefully soon to be commecially available if there is enough interest:

Oh btw, the tripod mount for the lens cost me something like 12 quid... amazon bargain...lol. It just needed padding out with some sticky back velcro and its pretty snug now. The whole arrangement is now simplified to screw fittings, and its rock solid.... no droop.

Measuring fwhm on one star only measures it for that particular area of the corrected field. You need to take the whole field into consideration when focusing. That's why it's a bit of a compromise at times

The corners on the pacman are much improved. That leads me to think that the focus can be tweaked slightly to improve the overall field.

One thing I used to do is use a ROI box on the offending corner (for quick loop), take an exposure, then tweak the focus very slightly.... "are the stars better or worse?", if not, go the other way... if yes - check the other corners to see if youve knocked anything out of focus - if its still good, youre ready to rock. Sometimes its bit of a compormise. It takes a bit of time to do, but its worth it.

On 12/09/2019 at 17:14, Adreneline said:

Took this one of the Heart and Soul last night unguided on my new iOptron CEM25-EC.

The image is 10x 120s + 180s + 300s multi-session combined in APP and post-processed in PI. I chose to use all the subs, even the one with the aircraft trail. There is minimal cropping to remove edge effects.

I think the star shapes are pretty good for unguided. I think the odd shape stars in the corners are down to the lens but I'd be interested to hear what others think.

Took thos one of NGC1499 after I'd finished the Ha of the Heart and Soul. This is also unguided, all 300s - 12 x Ha and OIII.

The combination of CEM25 and 135mm+ASI1600 could make a great grab-n-go setup.

 

Thanks for looking.

Adrian

The right hand side of your images displays out of focus stars. This also corresponds with the master flat you posted earlier.

Whether that is due to droop in your imaging train, I dont know. But an idea would be to test the lens on a DSLR and take some flats with that - if you get the same vignetting pattern, it will be the lens. If not, then you need to look at the way its attached to your astro camera as to what is causing it.

Update on the lens mod:

Should be a week, maybe two at tops. Once its back I'll have a better understanding of how much spacing Ive got to fill. I want it to be as close to the infinity stop as possible (in order to get the best corrected field).

Might be worth upgrading to the ccd cls filter. It has a harsher cutoff and slightly better transmission.

Fashionably late to the party  

Just booked, Fri & Sat night.

Behold... it's a miracle!! Three weeks this took (plus a load of chasing emails) 

But it's now "game on" 

On 02/09/2019 at 21:07, JamesAstro2002 said:

3 Hours of data on Andromeda with the 600D from last night.

I noticed that I seem to have them oddly shaped stars again. Last time, I fixed this by undoing the primary mirror retention clips a bit as they were tight up against the mirror. Now that i've been able to get back out for a night of imaging, they're back again! Any ideas as to why this could be ? I double checked the clips again and they're still loose, although they are still touching the mirror, are they supposed to touch it or not? I also made sure that the primary collimation locking screws aren't overly tightened. Also, through my cheshire, collimation looks to be spot on.

As for the mirror clips, there should be just enough room to slip a fag paper between the clip and the mirror... so get down the corner shop and grab a pack of rizla..lol 

On 29/08/2019 at 10:57, Adam J said:

FOV looks too big for it to be the ASI178mm cool but I may be proved wrong when Rob replies. 

Sorry, I've been a bit ill the past few days.

The veil shot was with the qsi 683 ☺ overall I was pleased with the field flatness on that shot. It did quite well over a 22mm diagonal sensor. 

I'll be firing up the 178 when I get my hands on the long overdue 135mm f2 lens. Been waiting over 2 weeks for it now... it's starting to take the Michael.