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Time for yet another cry for help when it comes to choosing diagonal. I have read the many similar threads and gathered some knowledge (too many to start linking). I have come some way in my process and now that it is coming to final decisions I would like to hear from the experts. Not many of threads I have read end with the OP returning to deliver some review/verdict of his/her final decision. While I wait for response on some thread where I asked about the result, the eagerness in me forces me to write my own thread. Perhaps some of the people asking these questions before can now answer in my thread as experts!
I have the Nexstar Evolution 9.25 and am currently using the stock diagonal. My eyepieces are the Baader 8-24 mm zoom and the stock 40 mm Plössl. I would also like to upgrade EPs and there I'm looking at something better in 24 mm range, as well some nice low power for more FOV. I'm following threads about EPs and SCTs with great interest for this (on CN). Can say that I'm currently leaning towards the 1.25" 24 mm ES 68° and 2" 36 mm Hyperion aspheric (if going 2" route).
I'm thinking 2 alternatives (including a budget alternative for one of them). I'm looking at Baader mainly for ClickLock (and expect good optics):
Baader T2 Zeiss prism with a 1.25" ClickLock EP (T2 part #08) -OR- the 2" prism with 2" ClickLock (splurging that is). The budget alternative would be to get the non-Zeiss T2 prism instead for the 1.25". Worth noting that I would like to get the Celestron f/6.3 Reducer/Corrector. This would be for future purposes of delving into EAA but of course I would use it visually as well (especially if choosing the T2 route). The reasoning for my alternatives:
Go for the 2" Zeiss prism to theoretically get the best of the best in visual terms. I would make better use of the 46 mm baffle tube opening. Theoretically possible to combine with the R/C thanks to relative short light path (although not necessarily needed with 2" EPs). Downside of going to 2" accessories would be the cost, EPs, filters etc., on top of diagonal. Would not be able to spend all these costs at once. Cheaper route with T2 prism (especially the non-Zeiss), not only diagonal but also the other accessories. Cost of the R/C would be comparable to e.g. the 36 mm aspheric and give similar power and FOV with the 24 mm ES, i.e. the 24 mm would act as both. Extra plus is the ClickLock clamp for 1.25" with built in fine focusing not involving the mirror. Downside of knowing that not all light coming out of baffle tube is used. To get the wide FOV (24 mm + R/C) I'm adding glass to the optical train (theoretically not a good thing). I'm leaning towards the T2 as it would be a cheaper diagonal and for EPs I would only need the 24 mm and then the reducer instead of a 30-40 mm, so saving the expense of one EP. Then I would already have the reducer for continuing into EAA. The questions I hope the experts here can help with:
The old reducer vs 2" diagonal question. With R/C and the 24 mm I can get roughly the same mag and FOV as e.g. the 36 mm Hyperion (technically 38 mm vs 36 mm and 68° vs 72°). Also reading good things about the ES 68° and with R/C the EP should behave the same. Am I missing something here? The logics say that the I would lose some contrast with the R/C (not using full opening + adding elements), correct? Possibly flatter fields though (not important now, hopefully the EP threads might tell soon enough). The Zeiss vs non-Zeiss T2? Big differences? I have read a few posts on this so most to get some updated views here (have read that Baader has changed some things over the years). Using the R/C (f/6.3) with these prisms. I know f/7 is mentioned as "the limit" but also remember BillP's test where he was happy down to f/6 with the prisms (in 2014 at least). Perhaps most important: have I missed some other obvious alternative here? Maybe I have forgotten some question here but perhaps for the best as I assume those who have gotten this far are tired of reading now. Thanks for getting here though!
The Lightwave 0.8x focal reducer gives an 0.8x reduction in F-Ratio for faster exposure times, as well as a correspondingly wider field for astro-photography. Designed primarily for refractor telescopes of F6 or longer focal ratios, however also known to work with RC telescopes.
- Reduces and flattens phtographic field.
- 38mm Clear aperture
- Integral T-Ring adapter thread.
- Requires back-focus of 55mm to CCD Chip.
- For DSLRs a standard T-Thread adapter of approx. 10mm thickness is required.
- The standard 2" OD barrel will fit any 2" format telescope like an eyepiece.
- The base of the 2" OD barrel is threaded for 2" filters.
- CNC machined body with gloss black anodized finish.
- Includes a CNC machined T-threaded end-cap to protect against dust on the rear lens element which is more exposed than the front element. A plastic dust cap is included for the 2" OD front barrel.
Paypal byuer pays the fees
Postage expenses are on me
Shipping from Athens Greece
I've just fitted a 2" IDAS-D2 filter into the William Optics Flat61a flattener following on-line instructions.
It strikes me as odd that the filter is installed with the front of the filter facing the camera sensor rather than the 'sky', I'm assuming this is correct and shouldn't cause any reflection issues?
For info, I've attached a couple of daylight images of the filter in 'action' on a colour calibration chart showing the natural colour cast
The image above, without the filter fitted, is colour profiled in LR and white balanced using the middle grey colour patch
The image above, with the filter fitted, uses the colour profile of the first image and the white balance is also from the first image
The last image below was colour balanced using the middle grey colour patch in LR and clearly failed lol Assessing the grey colour patch there is no red in it at all so obviously the calibration would fail. It will be interesting to see it working under normal conditions photographing the night sky
The postman was kind to me today and dropped off a William Optics Zenithstar 61 and Flat61A flattener and the gods smiled on me with clear skies for 30 minutes. It would be a shame not to christen the new toys
I only managed 10 lights so I didn't even consider darks or flats. The 10 lights from the Canon 5D MkIV, shot at iso 1600 x 60 seconds, were stacked and aligned in PS, median filtered for some noise reduction and then a few layer/curves tweaks to pull out some basic detail so I could look at the star profiles and and any vignetting.
Overall impression is extremely good build quality and the focusing through the mask is ok on very bright stars but quite a challenge on lesser star magnitudes. Very little vignetting through the imaging train so the image circle cover the full frame sensor and it will be simple to either remove the gradients in PS or use flats and sharp stars corner to corner with no obvious colour aberrations.
I do need to check where the weird smudges are in the imaging train because they weren't on the camera sensor yesterday, hopefully I'll find them pretty quickly because they are nasty!
Screenshots are also included of APT focusing, Stellarium for the imaging area after plate solving in APT and then PHD2 for the guiding with the ZWO ASI120mm-mini camera on a ZWO 30mm f/4 scope (I've no idea if the guiding is good or bad but the polar alignment was achieved with the iPolar camera in the SkyGuider Pro mount
I think at some point I'll add an 2" IDAS D2 filter into the imaging train and see if I can counter some local light pollution we have around here.
By Ken Mitchell
As the title says
I've finally, after owning a 7nm Baader Ha filter for more than a half year, did my first imaging session in Ha. My target was the Lagoon Nebula because the weekend before I captured 4.5 hours on it and wanted to see what difference it would make. It's also very bright so easy to locate and it helped my getting focus as well.
Focus was kind of a challenge as I had to locate the nebula without the filter first ( the Star Adventurer has no GoTo), screw on the filter and take numerous amounts of test shots (max iso at 30sec) to finally get the focus right. Though I still think the focus was a bit off. For some reasons I had problems with the B-mask and focusing will have to do more tests in the future on this.
That said and done I was ready to start clicking, used settings of iso 1600 and 180sec subs. This was what I saw on the back of the camera after 3 minutes.
Pretty exited! Just the fact that I had something showing up amazed me. Decided to keep the exposure at 3minutes and planned on getting 1 hour of data at least before calling it a night.
Quick info on the gear used here:
-Camera: self modded Nikon d90(Ha data), Nikon d610(RGb data)
-Optics: TS-Optics Photoline 72mm f/6 FPL53+TSflat72
-Mount: Skywatcher Star Adventurer
-Guidescope: TS-Optics Optics 50 mm DeLuxe Mini
-Guidecamera: ZWO ASI120MC-S
-Filters: Baader 7nm 2" Ha
Back on imaging. After 1hour and 18min I stopped the session, took 10 flats, 10 darks and 20 bias frames and called it a night.
The day after loaded everything in DSS, imported the stack in Photoshop and did a little stretch on the red channel. This was the result (1hr 18min at iso 1600).
First there is so so much more data than I'd captured the weekend before with my unmodded Nikon d610 and almost x4 as much integration. That was a real excitement!
Second is a question(s), the diagonal pattern you see is this walking noise? Will dithering remove these lines? and is it even possible to dither with the SA? I've seen the dithering option in PHD2 but not sure if the combination with the Sa works.
So I've left the noise ,to be hopefully resolved in the future, and tried to combine the Ha with the previous captured RGB.
The RGB data ,as said before, was captured using a full frame Nikon d610. Aligning the two was kind of a challenge but eventually with all the twisting and turning managed to get it almost perfect.
This is the fully processed image from ONLY the RGB data the week before. 4.5hrs of data with the unmodded d610.
Combining the datasets I decided to re-edit the RGB set with just a curves and levels stretch and some minor tweaks in Adobe raw. Followed a simple tutorial of changing the red channel of the RGB set with the red channel of the Ha set and adding another Ha layer on top to use as a luminance layer. The result was a bit weird to be honest, green in the background and pretty ugly colors in the nebula. ( I didn't had the original to show so just now I made a quick alignment just to show more or less the results.
Should it look like this? Hope to find out what caused this.
Made some tweaks in the channel color mixer in Ps to get rid of the odd colors(in my eyes at least) and did more editing to get a final image. Besides some tweaks here and there I added an extra layer from the RGB set and used 'color' as blending mode.
This is the result I came up with.
Apart from perfect alignment of both data sets and maybe a better color balance I'd have to say the image itself looks a lot cleaner and more pleasant to the eye.
Though it seems the image is not as sharp as just the RGB image, maybe that's because it has less stars and it only appears to be more fuzzy?
Hope to get some input and cc on my workflow and/or the images to improve my results.
PS. For those interested I've also did some imaging with the unmodded d610 + Ha filter to show the differences and if it is worth it to use a Ha filter with an unmodded dslr.
I'll see if I can make a separate thread for this.